FRCR ONCOLOGY PART 1 - ALL FREE PRACTICE MCQS: FRCR Oncology Part 1: PHYSICS - 3 (4 SETS, 100+100+100+100 QUESTIONS, ANSWERS BELOW)

Radiation Physics (20 Questions)

What is the approximate linear energy transfer (LET) of a 150 MeV proton at the Bragg peak in water?
A. 0.5 keV/μm
B. 5 keV/μm
C. 50 keV/μm
D. 100 keV/μm
E. 200 keV/μm
Which interaction process dominates for 20 MV photons in a high-Z material like tungsten?
A. Photoelectric effect
B. Compton scattering
C. Pair production
D. Coherent scattering
E. Photodisintegration
What is the tenth-value layer (TVL) for a 6 MV photon beam in concrete, given a mass attenuation coefficient of 0.04 cm²/g and density of 2.35 g/cm³?
A. 15 cm
B. 25 cm
C. 35 cm
D. 45 cm
E. 55 cm
In a FLASH radiotherapy beam (ultra-high dose rate), what is the primary mechanism reducing the oxygen enhancement ratio (OER)?
A. Increased Compton scattering
B. Transient oxygen depletion
C. Enhanced pair production
D. Reduced photodisintegration
E. Altered bremsstrahlung yield
What is the approximate range of a 250 MeV carbon ion in water, assuming a continuous slowing down approximation (CSDA)?
A. 5 cm
B. 10 cm
C. 20 cm
D. 30 cm
E. 40 cm
Which factor most significantly affects the relative biological effectiveness (RBE) of alpha particles in tissue?
A. Particle energy
B. High LET
C. Tissue density
D. Incident angle
E. Beam divergence
What is the energy of a characteristic X-ray emitted from the L-shell to K-shell transition in lead (Z=82)?
A. 10 keV
B. 50 keV
C. 75 keV
D. 100 keV
E. 150 keV
For a 50 keV photon beam in bone, what is the dominant interaction, and how does its probability scale with atomic number (Z)?
A. Compton scattering, Z-independent
B. Photoelectric effect, ∝ Z³
C. Pair production, ∝ Z²
D. Coherent scattering, ∝ Z
E. Photodisintegration, ∝ Z⁴
What is the primary interaction mechanism for 1 MeV neutrons in tissue?
A. Elastic scattering with protons
B. Inelastic scattering with carbon
C. Neutron capture by nitrogen
D. Pair production
E. Compton scattering
What is the mass stopping power ratio of water to air for a 10 MeV electron beam?
A. 0.8
B. 1.0
C. 1.2
D. 1.5
E. 2.0
Which factor most significantly affects the neutron yield in a 15 MV linac?
A. Target material
B. Photon energy threshold
C. Collimator design
D. Beam current
E. Gantry angle
What is the dose rate at 3 meters from a 5 GBq Co-60 source, given a specific gamma-ray constant of 1.32 R·m²/Ci·h (ignoring shielding)?
A. 0.05 mGy/h
B. 0.5 mGy/h
C. 5 mGy/h
D. 50 mGy/h
E. 500 mGy/h
Which equation correctly describes the energy dependence of the photoelectric effect?
A. ∝ E
B. ∝ E²
C. ∝ 1/E
D. ∝ 1/E³
E. ∝ E³
What is the approximate range of a 20 MeV electron in bone (density 1.85 g/cm³)?
A. 2 cm
B. 4 cm
C. 6 cm
D. 8 cm
E. 10 cm
In a boron neutron capture therapy (BNCT) setup, what is the primary reaction responsible for therapeutic effect?
A. B-10(n,γ)B-11
B. B-10(n,α)Li-7
C. N-14(n,p)C-14
D. O-16(n,γ)O-17
E. C-12(n,α)Be-9
What is the primary source of secondary electrons in a high-energy photon beam interacting with tissue?
A. Bremsstrahlung radiation
B. Compton scattering
C. Photoelectric effect
D. Pair production
E. Coherent scattering
Which material property most significantly affects the attenuation of a 10 MeV proton beam?
A. Electron density
B. Atomic number
C. Mass density
D. Thermal conductivity
E. Magnetic susceptibility
What is the approximate energy threshold for neutron production via photodisintegration in a tungsten target?
A. 5 MeV
B. 7 MeV
C. 10 MeV
D. 15 MeV
E. 20 MeV
Which type of radiation is most effectively shielded by a combination of hydrogen-rich and high-Z materials?
A. Gamma rays
B. X-rays
C. Beta particles
D. Neutrons
E. Alpha particles
What is the primary mode of energy loss for a 1 GeV electron in lead?
A. Collisional interactions
B. Bremsstrahlung radiation
C. Compton scattering
D. Pair production
E. Photoelectric effect

Dosimetry (20 Questions)

What is the absorbed dose rate at 2 meters from a 10 GBq Ir-192 source, given a specific gamma-ray constant of 0.48 R·m²/Ci·h (ignoring shielding)?
A. 0.03 mGy/h
B. 0.3 mGy/h
C. 3 mGy/h
D. 30 mGy/h
E. 300 mGy/h
Which quantity is most critical for assessing the risk of secondary malignancies in radiotherapy?
A. Absorbed dose
B. Equivalent dose
C. Effective dose
D. Kerma
E. Exposure
What is the quality factor for 1 MeV neutrons in radiation protection?
A. 1
B. 5
C. 10
D. 20
E. 50
What is the percentage depth dose (PDD) at 10 cm depth for a 6 MV photon beam (10x10 cm² field, SSD=100 cm) in water, given a PDD of 100% at dmax=1.5 cm?
A. 50%
B. 60%
C. 67%
D. 75%
E. 85%
Which dosimeter is most suitable for measuring dose in a steep dose gradient (e.g., proton Bragg peak)?
A. Ionisation chamber
B. TLD
C. Diamond detector
D. OSL dosimeter
E. Film badge
What is the monitor unit (MU) required to deliver 2 Gy to a depth of 10 cm for a 6 MV photon beam (10x10 cm² field, SAD=100 cm, output factor=1.0, TMR=0.75)?
A. 200 MU
B. 267 MU
C. 300 MU
D. 400 MU
E. 533 MU
What is the approximate Dmax for a 250 MeV proton beam in water?
A. 5 cm
B. 10 cm
C. 20 cm
D. 30 cm
E. 40 cm
Which factor most significantly affects the accuracy of small-field dosimetry in stereotactic radiosurgery?
A. Detector size
B. Beam energy
C. Field size
D. Source-to-surface distance
E. Collimator angle
What is the primary advantage of alanine dosimetry in radiotherapy?
A. High spatial resolution
B. Tissue equivalence
C. Real-time readout
D. Low cost
E. Energy independence
What is the tissue-air ratio (TAR) at 15 cm depth for a 6 MV photon beam (10x10 cm² field, SSD=100 cm), given a PDD of 60% and BSF of 1.03?
A. 0.55
B. 0.62
C. 0.68
D. 0.75
E. 0.82
What is the equivalent dose from a 5 mGy absorbed dose of alpha particles to the lung?
A. 0.05 mSv
B. 0.5 mSv
C. 5 mSv
D. 50 mSv
E. 100 mSv
What is the approximate effective dose from a 2 mGy absorbed dose to the bone marrow (tissue weighting factor=0.12) from gamma rays?
A. 0.024 mSv
B. 0.24 mSv
C. 2.4 mSv
D. 24 mSv
E. 240 mSv
Which calibration protocol accounts for beam quality variations in proton therapy dosimetry?
A. TG-21
B. TG-51
C. IAEA TRS-398
D. AAPM TG-61
E. IPEM Code of Practice
What is the primary source of uncertainty in film dosimetry for IMRT verification?
A. Energy dependence
B. Spatial resolution
C. Optical density calibration
D. Readout time
E. Detector size
What is the monitor unit (MU) correction factor for a 10 cm lung inhomogeneity (density=0.26 g/cm³) in a 6 MV photon beam?
A. 0.85
B. 0.90
C. 0.95
D. 1.00
E. 1.05
Which dosimeter is most suitable for in-vivo dosimetry in MR-guided radiotherapy?
A. Ionisation chamber
B. TLD
C. MOSFET
D. OSL dosimeter
E. Plastic scintillator
What is the primary purpose of the phantom scatter factor (Sp) in radiotherapy?
A. To quantify collimator scatter
B. To measure dose at depth
C. To normalize dose for phantom size
D. To assess beam flatness
E. To determine penumbra width
What is the approximate penumbra width for a 250 MeV proton beam at 20 cm depth?
A. 1 mm
B. 3 mm
C. 5 mm
D. 7 mm
E. 10 mm
Which factor most significantly affects the dose rate from a pulsed brachytherapy source?
A. Pulse frequency
B. Source activity
C. Source energy
D. Source material
E. Source shape
What is the primary advantage of Fricke dosimetry in radiotherapy?
A. High spatial resolution
B. Chemical stability
C. Absolute dose measurement
D. Real-time readout
E. Low cost

Radiotherapy Treatment Planning (20 Questions)

What is the primary advantage of MR-linac systems in radiotherapy?
A. Reduced treatment time
B. Real-time soft tissue tracking
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for defining the planning organ-at-risk volume (PRV)?
A. Tumour size
B. Organ motion and setup uncertainty
C. Beam energy
D. Field size
E. Monitor units
What is the primary advantage of biologically guided radiotherapy?
A. Reduced total dose
B. Dose escalation to radioresistant subvolumes
C. Increased treatment time
D. Lower cost
E. Simplified planning
Which dose calculation algorithm is most accurate for FLASH radiotherapy in heterogeneous tissues?
A. Pencil beam
B. Convolution-superposition
C. Monte Carlo
D. Acuros XB
E. Collapsed cone
What is the primary purpose of range modulators in proton therapy?
A. To increase beam energy
B. To spread the Bragg peak
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the lateral dose spread in carbon ion therapy?
A. Beam energy
B. Nuclear fragmentation
C. Gantry angle
D. Collimator shape
E. Monitor units
What is the primary advantage of lattice radiotherapy in bulky tumours?
A. Reduced normal tissue toxicity
B. Uniform dose distribution
C. Increased treatment time
D. Lower cost
E. Simplified planning
Which parameter is most critical for real-time adaptive radiotherapy?
A. Beam energy
B. Deformable image registration accuracy
C. Field size
D. Monitor units
E. Collimator angle
What is the primary purpose of a ridge filter in proton therapy?
A. To increase beam energy
B. To modulate dose in depth
C. To shape the radiation field
D. To reduce scatter radiation
E. To monitor dose delivery
Which factor most significantly affects the dose conformity in stereotactic body radiotherapy (SBRT)?
A. MLC leaf width
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of synthetic CT in MR-only radiotherapy planning?
A. Reduced imaging time
B. Electron density estimation
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which structure is most critical for dose constraints in liver SBRT?
A. Spinal cord
B. Stomach
C. Kidneys
D. Lungs
E. Heart
What is the primary purpose of a range shifter in proton therapy?
A. To increase beam energy
B. To adjust the Bragg peak depth
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose heterogeneity in VMAT?
A. MLC leaf speed
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of AI-based contouring in radiotherapy planning?
A. Reduced treatment time
B. Improved contour consistency
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for tumour control probability (TCP) in hypofractionated radiotherapy?
A. Tumour volume
B. Biological effective dose
C. Beam energy
D. Field size
E. Monitor units
What is the primary purpose of a collimator in carbon ion therapy?
A. To increase beam energy
B. To shape the radiation field
C. To reduce skin sparing
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose distribution in pulsed-dose-rate (PDR) brachytherapy?
A. Pulse duration
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of PET-guided radiotherapy?
A. Reduced treatment time
B. Targeting metabolically active regions
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for dose-volume histogram (DVH) optimization in IMRT?
A. Beam energy
B. Target coverage constraints
C. Field size
D. Monitor units
E. Collimator angle

Imaging (20 Questions)

What is the primary advantage of MR-linac imaging in radiotherapy?
A. High spatial resolution
B. Real-time tumour tracking
C. Low radiation dose
D. Electron density information
E. Low cost
Which imaging modality is most suitable for assessing intrafraction motion in pancreatic radiotherapy?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Fluoroscopy
What is the primary source of contrast in diffusion-weighted MRI?
A. Proton density
B. Water molecule mobility
C. Electron density
D. Atomic number
E. Blood flow
Which factor most significantly affects the signal-to-noise ratio in cone-beam CT (CBCT)?
A. Tube voltage
B. Detector efficiency
C. Reconstruction algorithm
D. Field of view
E. Gantry rotation speed
What is the primary advantage of PSMA-PET imaging in prostate cancer radiotherapy?
A. High spatial resolution
B. Low radiation dose
C. Specific tumour targeting
D. Real-time imaging
E. Low cost
Which radionuclide is most suitable for hypoxia imaging in radiotherapy planning?
A. F-18
B. Cu-64
C. Ga-68
D. I-131
E. Tc-99m
What is the primary purpose of a contrast-to-noise ratio in CT imaging?
A. To measure radiation dose
B. To quantify tissue differentiation
C. To assess image noise
D. To determine spatial resolution
E. To monitor patient motion
Which factor most significantly affects the temporal resolution in 4D-MRI?
A. Field strength
B. Gradient slew rate
C. Coil sensitivity
D. Reconstruction algorithm
E. Field of view
What is the primary advantage of dual-energy CT in radiotherapy planning?
A. High soft tissue contrast
B. Reduced metal artefacts
C. Low radiation dose
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for delineating oesophageal tumours in radiotherapy planning?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary source of artefacts in MR-linac imaging?
A. Photon scattering
B. Magnetic field inhomogeneity
C. Metal implants
D. Reconstruction algorithm
E. Patient motion
Which factor most significantly affects the contrast resolution in PET imaging?
A. Radiotracer activity
B. Detector resolution
C. Reconstruction algorithm
D. Field of view
E. Patient size
What is the primary advantage of dynamic contrast-enhanced MRI in oncology?
A. High spatial resolution
B. Low radiation dose
C. Assessment of tumour perfusion
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for assessing spinal cord compression in radiotherapy planning?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary purpose of deformable image registration in radiotherapy?
A. To measure radiation dose
B. To account for anatomical changes
C. To assess image contrast
D. To determine spatial resolution
E. To monitor image noise
Which factor most significantly affects the radiation dose in dual-energy CT imaging?
A. Tube voltage switching
B. Tube current
C. Reconstruction algorithm
D. Field of view
E. Gantry rotation speed
What is the primary advantage of BOLD-MRI in radiotherapy planning?
A. High spatial resolution
B. Low radiation dose
C. Assessment of hypoxia
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for real-time dosimetry during radiotherapy?
A. CT
B. MRI
C. PET
D. Cherenkov imaging
E. Ultrasound
What is the primary source of contrast in MR spectroscopy?
A. Proton density
B. Metabolite concentration
C. Electron density
D. Radiotracer uptake
E. Blood flow
Which factor most significantly affects the spatial resolution in SPECT imaging?
A. Collimator design
B. Tube current
C. Reconstruction algorithm
D. Field of view
E. Patient size

Radiation Protection (20 Questions)

What is the annual effective dose limit for the fetus of a pregnant radiation worker in the UK?
A. 1 mSv
B. 5 mSv
C. 10 mSv
D. 20 mSv
E. 50 mSv
Which material is most effective for shielding 10 MeV neutrons in a proton therapy facility?
A. Lead
B. Concrete with boron
C. Perspex
D. Steel
E. Water
What is the primary purpose of the controlled area designation in a FLASH radiotherapy bunker?
A. To store radioactive sources
B. To restrict access to high-dose-rate hazards
C. To monitor patient doses
D. To calibrate dosimeters
E. To perform quality assurance
Which factor most significantly affects the occupational dose in MR-linac treatments?
A. Magnetic field strength
B. Shielding design
C. Beam energy
D. Gantry angle
E. Monitor units
What is the approximate half-value layer (HVL) for a 250 MeV proton beam in lead?
A. 5 cm
B. 10 cm
C. 20 cm
D. 30 cm
E. 40 cm
Which type of personal dosimeter is most suitable for monitoring dose in a pulsed radiation field?
A. Film badge
B. TLD
C. MOSFET
D. OSL dosimeter
E. Active electronic dosimeter
What is the primary source of stray radiation in a carbon ion therapy room?
A. Primary beam
B. Scatter from patient
C. Nuclear fragmentation
D. Bremsstrahlung radiation
E. Compton scattering
Which regulation requires justification of medical radiation exposures in the UK?
A. IRR 2017
B. IR(ME)R 2017
C. RIDDOR 2013
D. COSHH 2002
E. MHRA 2008
What is the dose rate at 5 meters from a 1 GBq I-131 source, given a specific gamma-ray constant of 0.22 R·m²/Ci·h (ignoring shielding)?
A. 0.002 mGy/h
B. 0.02 mGy/h
C. 0.2 mGy/h
D. 2 mGy/h
E. 20 mGy/h
Which factor most significantly affects the shielding requirements for a FLASH radiotherapy facility?
A. Ultra-high dose rate
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary purpose of a radiation protection committee in a radiotherapy department?
A. To deliver radiotherapy
B. To oversee safety policies
C. To calibrate dosimeters
D. To monitor patient doses
E. To perform quality assurance
Which material is most effective for shielding secondary neutrons in a 15 MV linac bunker?
A. Lead
B. Concrete with hydrogen
C. Perspex
D. Steel
E. Tungsten
What is the annual effective dose limit for the hands of radiation workers in the UK?
A. 1 mSv
B. 20 mSv
C. 50 mSv
D. 150 mSv
E. 500 mSv
Which factor most significantly affects the dose to staff during proton therapy procedures?
A. Beam energy
B. Neutron shielding
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of a remote afterloading system in HDR brachytherapy?
A. Reduced treatment time
B. Minimized staff exposure
C. Increased patient comfort
D. Simplified quality assurance
E. Enhanced dose delivery
Which type of radiation is most challenging to shield in a carbon ion therapy facility?
A. Gamma rays
B. X-rays
C. Beta particles
D. Neutrons
E. Alpha particles
What is the primary purpose of a radiation incident report under IR(ME)R 2017?
A. To deliver radiotherapy
B. To investigate unintended exposures
C. To calibrate dosimeters
D. To monitor patient doses
E. To perform quality assurance
Which factor most significantly affects the dose rate from a Lu-177 unsealed source?
A. Source activity
B. Beta particle energy
C. Source size
D. Source material
E. Source shape
What is the approximate half-life of I-131 used in thyroid therapy?
A. 2 days
B. 8 days
C. 30 days
D. 60 days
E. 90 days
Which principle is most critical for reducing public dose in a radiotherapy department?
A. Time
B. Distance
C. Shielding
D. Justification
E. Calibration

Answers

Radiation Physics

C. At the Bragg peak, a 150 MeV proton has an LET of ~50 keV/μm due to high ionization density.
C. Pair production dominates for 20 MV photons in tungsten (high Z, high energy).
C. TVL = ln(10)/(μ·ρ) = 2.303/(0.04·2.35) ≈ 35 cm.
B. Transient oxygen depletion in FLASH radiotherapy reduces OER by limiting free radical formation.
D. The CSDA range for a 250 MeV carbon ion in water is ~30 cm (R ∝ E¹·⁵/A).
B. High LET drives the elevated RBE of alpha particles (RBE ∝ LET).
C. L-to-K transition in lead emits ~75 keV photons (K-shell binding energy).
B. Photoelectric effect dominates at 50 keV in bone, scaling as ∝ Z³/E³.
A. Elastic scattering with protons (recoil) is the primary interaction for 1 MeV neutrons.
C. The mass stopping power ratio of water to air for 10 MeV electrons is ~1.2.
B. Photon energy threshold (>7 MeV) drives neutron yield via photodisintegration.
B. Dose rate = (Γ·A)/r² = (1.32·5/37)/(3²) ≈ 0.5 mGy/h (1 GBq = 27 mCi).
D. Photoelectric effect probability scales as ∝ 1/E³.
C. Range in bone = 20/1.85 ≈ 6 cm (R ≈ 0.5 E, scaled by density).
B. B-10(n,α)Li-7 produces high-LET alpha particles for BNCT’s therapeutic effect.
B. Compton scattering produces secondary electrons in high-energy photon beams.
C. Mass density affects proton stopping power (S ∝ ρ).
B. Neutron production via photodisintegration in tungsten requires ~7 MeV.
D. Neutrons require hydrogen-rich (slowing) and high-Z (capture) materials.
B. Bremsstrahlung radiation dominates for 1 GeV electrons in lead (high Z, high E).

Dosimetry

B. Dose rate = (Γ·A)/r² = (0.48·10/37)/(2²) ≈ 0.3 mGy/h (1 GBq = 27 mCi).
C. Effective dose assesses stochastic risks like secondary malignancies.
C. The quality factor for 1 MeV neutrons is 10.
C. PDD at 10 cm for 6 MV (10x10 cm², SSD=100 cm) is ~67% (standard data).
C. Diamond detectors have high spatial resolution for steep gradients like Bragg peaks.
B. MU = Dose/(TMR·Output) = 2/(0.75·1.0) ≈ 267 MU.
D. Dmax for a 250 MeV proton beam is ~30 cm (Bragg peak depth).
A. Detector size affects accuracy in small fields due to volume averaging.
B. Alanine dosimetry is tissue-equivalent, ideal for absolute dosimetry.
B. TAR = PDD/BSF = 60/1.03 ≈ 0.62.
E. Equivalent dose = 5 mGy · 20 (Q for alpha) = 100 mSv.
B. Effective dose = 2 mGy · 0.12 (W_T for bone marrow) · 1 (Q for gamma) = 0.24 mSv.
C. IAEA TRS-398 accounts for beam quality in proton therapy.
C. Optical density calibration is the primary uncertainty in film dosimetry.
B. Lung inhomogeneity (ρ=0.26 g/cm³) reduces attenuation, correction factor ~0.90.
E. Plastic scintillators are MR-compatible for in-vivo dosimetry.
C. Phantom scatter factor (Sp) normalizes dose for phantom size variations.
C. Penumbra width for 250 MeV protons at 20 cm is ~5 mm (beam scattering).
B. Source activity drives the dose rate in pulsed brachytherapy.
C. Fricke dosimetry provides absolute dose measurement via chemical reaction.

Radiotherapy Treatment Planning

B. MR-linac enables real-time soft tissue tracking for adaptive delivery.
B. Organ motion and setup uncertainty define PRV margins.
B. Biologically guided radiotherapy escalates dose to radioresistant subvolumes.
C. Monte Carlo is most accurate for FLASH due to ultra-high dose rate effects.
B. Range modulators spread the Bragg peak to cover the target volume.
B. Nuclear fragmentation causes lateral dose spread in carbon ion therapy.
A. Lattice radiotherapy reduces normal tissue toxicity via spatial fractionation.
B. Deformable image registration accuracy is critical for real-time adaptation.
B. Ridge filters modulate dose in depth for proton spread-out Bragg peak.
A. MLC leaf width affects dose conformity in SBRT by defining penumbra.
B. Synthetic CT estimates electron density for MR-only dose calculation.
B. The stomach is critical for dose constraints in liver SBRT.
B. Range shifters adjust the Bragg peak depth for shallow targets.
A. MLC leaf speed affects dose heterogeneity in VMAT optimization.
B. AI-based contouring improves consistency across planners.
B. Biological effective dose drives TCP in hypofractionation (BED = D·(1+d/(α/β))).
B. Collimators shape the radiation field in carbon ion therapy.
A. Pulse duration determines dose distribution in PDR brachytherapy.
B. PET-guided radiotherapy targets metabolically active regions for dose painting.
B. Target coverage constraints drive DVH optimization in IMRT.

Imaging

B. MR-linac imaging enables real-time tumour tracking during delivery.
B. MRI is suitable for pancreatic intrafraction motion due to soft tissue contrast.
B. Diffusion-weighted MRI contrast arises from water molecule mobility.
B. Detector efficiency most significantly affects CBCT signal-to-noise ratio.
C. PSMA-PET provides specific targeting of prostate cancer cells.
B. Cu-64 (e.g., ATSM) is suitable for hypoxia imaging in radiotherapy.
B. Contrast-to-noise ratio quantifies tissue differentiation in CT.
B. Gradient slew rate affects temporal resolution in 4D-MRI.
B. Dual-energy CT reduces metal artefacts for improved planning.
B. MRI is ideal for delineating oesophageal tumours due to soft tissue contrast.
B. Magnetic field inhomogeneity causes artefacts in MR-linac imaging.
B. Detector resolution affects PET contrast resolution.
C. Dynamic contrast-enhanced MRI assesses tumour perfusion.
B. MRI is suitable for assessing spinal cord compression due to soft tissue detail.
B. Deformable image registration accounts for anatomical changes in planning.
A. Tube voltage switching affects radiation dose in dual-energy CT.
C. BOLD-MRI assesses hypoxia via blood oxygenation changes.
D. Cherenkov imaging enables real-time dosimetry during radiotherapy.
B. Metabolite concentration provides contrast in MR spectroscopy.
A. Collimator design most significantly affects SPECT spatial resolution.

Radiation Protection

A. The annual effective dose limit for a fetus is 1 mSv.
B. Concrete with boron shields 10 MeV neutrons via slowing and capture.
B. Controlled areas restrict access to high-dose-rate hazards in FLASH bunkers.
B. Shielding design most significantly affects occupational dose in MR-linac.
D. The HVL for a 250 MeV proton beam in lead is ~30 cm.
E. Active electronic dosimeters are suitable for pulsed radiation fields.
C. Nuclear fragmentation produces stray radiation in carbon ion therapy.
B. IR(ME)R 2017 requires justification of medical radiation exposures.
B. Dose rate = (Γ·A)/r² = (0.22·1/37)/(5²) ≈ 0.02 mGy/h (1 GBq = 27 mCi).
A. Ultra-high dose rate drives shielding requirements for FLASH facilities.
B. Radiation protection committees oversee safety policies.
B. Concrete with hydrogen shields secondary neutrons via elastic scattering.
E. The annual effective dose limit for the hands is 500 mSv.
B. Neutron shielding most significantly affects staff dose in proton therapy.
B. Remote afterloading minimizes staff exposure in HDR brachytherapy.
D. Neutrons are most challenging to shield in carbon ion therapy (high yield).
B. Radiation incident reports investigate unintended exposures under IR(ME)R.
A. Source activity drives the dose rate from Lu-177 (beta/gamma emitter).
B. The half-life of I-131 is ~8 days.
C. Shielding is critical for reducing public dose in radiotherapy departments.

Radiation Physics (20 Questions)

What is the approximate linear energy transfer (LET) of a 200 MeV carbon ion at the spread-out Bragg peak (SOBP) in water?
A. 10 keV/μm
B. 50 keV/μm
C. 100 keV/μm
D. 200 keV/μm
E. 300 keV/μm
Which interaction process dominates for 25 MV photons in a high-Z material like lead?
A. Photoelectric effect
B. Compton scattering
C. Pair production
D. Coherent scattering
E. Photodisintegration
What is the half-value layer (HVL) for a 10 MV photon beam in concrete, given a mass attenuation coefficient of 0.045 cm²/g and density of 2.35 g/cm³?
A. 10 cm
B. 15 cm
C. 20 cm
D. 25 cm
E. 30 cm
In a FLASH radiotherapy setup, what is the primary mechanism reducing normal tissue toxicity at ultra-high dose rates?
A. Enhanced Compton scattering
B. Transient oxygen depletion
C. Reduced pair production
D. Increased photodisintegration
E. Altered bremsstrahlung yield
What is the approximate range of a 300 MeV proton in water, assuming a continuous slowing down approximation (CSDA)?
A. 10 cm
B. 20 cm
C. 30 cm
D. 40 cm
E. 50 cm
Which factor most significantly affects the relative biological effectiveness (RBE) of a 150 MeV proton beam in the entrance region?
A. Beam energy
B. Low LET
C. Tissue density
D. Beam divergence
E. Incident angle
What is the energy of a characteristic X-ray emitted from the K-shell to L-shell transition in molybdenum (Z=42)?
A. 5 keV
B. 15 keV
C. 25 keV
D. 35 keV
E. 45 keV
For a 20 keV photon beam in bone, what is the dominant interaction, and how does its probability scale with atomic number (Z)?
A. Compton scattering, Z-independent
B. Photoelectric effect, ∝ Z³
C. Pair production, ∝ Z²
D. Coherent scattering, ∝ Z
E. Photodisintegration, ∝ Z⁴
What is the primary interaction mechanism for 5 MeV neutrons in tissue?
A. Elastic scattering with protons
B. Inelastic scattering with oxygen
C. Neutron capture by hydrogen
D. Pair production
E. Compton scattering
What is the mass stopping power ratio of water to bone for a 12 MeV electron beam?
A. 0.7
B. 0.9
C. 1.0
D. 1.2
E. 1.5
Which factor most significantly affects the neutron yield in a 20 MV linac?
A. Target atomic number
B. Photon energy threshold
C. Collimator material
D. Beam current
E. Gantry angle
What is the dose rate at 2 meters from a 3 GBq Co-60 source, given a specific gamma-ray constant of 1.32 R·m²/Ci·h (ignoring shielding)?
A. 0.1 mGy/h
B. 1 mGy/h
C. 10 mGy/h
D. 100 mGy/h
E. 1000 mGy/h
Which equation correctly describes the energy dependence of Compton scattering?
A. ∝ E
B. ∝ E²
C. ∝ 1/E
D. ∝ 1/E²
E. ∝ E³
What is the approximate range of a 15 MeV electron in aluminium (density 2.7 g/cm³)?
A. 2 cm
B. 4 cm
C. 6 cm
D. 8 cm
E. 10 cm
In a boron neutron capture therapy (BNCT) setup, what is the primary therapeutic reaction?
A. B-10(n,γ)B-11
B. B-10(n,α)Li-7
C. N-14(n,p)C-14
D. O-16(n,γ)O-17
E. C-12(n,α)Be-9
What is the primary source of secondary electrons in a 15 MV photon beam interacting with water?
A. Bremsstrahlung radiation
B. Compton scattering
C. Photoelectric effect
D. Pair production
E. Coherent scattering
Which material property most significantly affects the stopping power of a 250 MeV carbon ion beam?
A. Electron density
B. Atomic number
C. Mass density
D. Thermal conductivity
E. Magnetic susceptibility
What is the approximate energy threshold for neutron production via photodisintegration in a copper target?
A. 5 MeV
B. 8 MeV
C. 10 MeV
D. 15 MeV
E. 20 MeV
Which type of radiation is most effectively shielded by a combination of paraffin and cadmium?
A. Gamma rays
B. X-rays
C. Beta particles
D. Thermal neutrons
E. Alpha particles
What is the primary mode of energy loss for a 2 GeV electron in tungsten?
A. Collisional interactions
B. Bremsstrahlung radiation
C. Compton scattering
D. Pair production
E. Photoelectric effect

Dosimetry (20 Questions)

What is the absorbed dose rate at 1.5 meters from a 4 GBq Ir-192 source, given a specific gamma-ray constant of 0.48 R·m²/Ci·h (ignoring shielding)?
A. 0.5 mGy/h
B. 5 mGy/h
C. 50 mGy/h
D. 500 mGy/h
E. 5000 mGy/h
Which quantity is most critical for assessing the risk of radiation-induced leukemia?
A. Absorbed dose
B. Equivalent dose
C. Effective dose
D. Kerma
E. Exposure
What is the quality factor for 5 MeV neutrons in radiation protection?
A. 1
B. 5
C. 10
D. 20
E. 50
What is the percentage depth dose (PDD) at 12 cm depth for a 10 MV photon beam (10x10 cm² field, SSD=100 cm) in water, given a PDD of 100% at dmax=2.5 cm?
A. 55%
B. 60%
C. 65%
D. 70%
E. 75%
Which dosimeter is most suitable for measuring dose in a microbeam radiotherapy field?
A. Ionisation chamber
B. TLD
C. Radiochromic film
D. OSL dosimeter
E. MOSFET
What is the monitor unit (MU) required to deliver 2.5 Gy to a depth of 12 cm for a 10 MV photon beam (10x10 cm² field, SAD=100 cm, output factor=1.01, TMR=0.70)?
A. 250 MU
B. 300 MU
C. 353 MU
D. 400 MU
E. 500 MU
What is the approximate Dmax for a 300 MeV proton beam in water?
A. 10 cm
B. 20 cm
C. 30 cm
D. 40 cm
E. 50 cm
Which factor most significantly affects the accuracy of dosimetry in a 0.5 cm² field for stereotactic radiosurgery?
A. Detector volume averaging
B. Beam energy
C. Source-to-surface distance
D. Collimator angle
E. Field shape
What is the primary advantage of plastic scintillator detectors in FLASH radiotherapy dosimetry?
A. High spatial resolution
B. Dose-rate independence
C. Low cost
D. Energy independence
E. Large volume
What is the tissue-air ratio (TAR) at 10 cm depth for a 10 MV photon beam (10x10 cm² field, SSD=100 cm), given a PDD of 65% and BSF of 1.03?
A. 0.55
B. 0.60
C. 0.63
D. 0.68
E. 0.73
What is the equivalent dose from a 3 mGy absorbed dose of alpha particles to the skin?
A. 0.03 mSv
B. 0.3 mSv
C. 3 mSv
D. 30 mSv
E. 60 mSv
What is the approximate effective dose from a 4 mGy absorbed dose to the colon (tissue weighting factor=0.12) from gamma rays?
A. 0.048 mSv
B. 0.48 mSv
C. 4.8 mSv
D. 48 mSv
E. 480 mSv
Which calibration protocol is most suitable for FLASH radiotherapy dosimetry?
A. TG-21
B. TG-51
C. IAEA TRS-398
D. AAPM TG-61
E. TRS-483
What is the primary source of uncertainty in diamond detector dosimetry for proton therapy?
A. Energy dependence
B. Dose-rate dependence
C. Calibration stability
D. Spatial resolution
E. Detector size
What is the monitor unit (MU) correction factor for a 8 cm lung inhomogeneity (density=0.26 g/cm³) in a 10 MV photon beam?
A. 0.85
B. 0.90
C. 0.95
D. 1.00
E. 1.05
Which dosimeter is most suitable for in-vivo dosimetry in a carbon ion therapy setup?
A. Ionisation chamber
B. TLD
C. MOSFET
D. Diamond detector
E. Plastic scintillator
What is the primary purpose of the collimator scatter factor (Sc) in small-field radiotherapy?
A. To quantify patient scatter
B. To normalize dose for collimator settings
C. To measure dose at depth
D. To assess beam flatness
E. To determine penumbra width
What is the approximate penumbra width for a 300 MeV proton beam at 25 cm depth?
A. 1 mm
B. 3 mm
C. 5 mm
D. 7 mm
E. 10 mm
Which factor most significantly affects the dose rate from a spatially fractionated radiotherapy (GRID) source?
A. Grid spacing
B. Source activity
C. Source energy
D. Source material
E. Source shape
What is the primary advantage of alanine dosimetry in high-LET particle therapy?
A. High spatial resolution
B. Tissue equivalence
C. Real-time readout
D. Low cost
E. Energy independence

Radiotherapy Treatment Planning (20 Questions)

What is the primary advantage of online adaptive radiotherapy in MR-linac systems?
A. Reduced treatment time
B. Daily plan reoptimization
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for defining the robust optimization volume in proton therapy?
A. Tumour size
B. Range and setup uncertainties
C. Beam energy
D. Field size
E. Monitor units
What is the primary advantage of microbeam radiotherapy in brain tumours?
A. Uniform dose distribution
B. Enhanced normal tissue sparing
C. Increased treatment time
D. Lower cost
E. Simplified planning
Which dose calculation algorithm is most accurate for carbon ion therapy in bone?
A. Pencil beam
B. Convolution-superposition
C. Monte Carlo
D. Acuros XB
E. Collapsed cone
What is the primary purpose of a ripple filter in carbon ion therapy?
A. To increase beam energy
B. To sharpen the Bragg peak
C. To shape the radiation field
D. To reduce scatter radiation
E. To monitor dose delivery
Which factor most significantly affects the dose tail in proton therapy?
A. Beam energy
B. Nuclear interactions
C. Gantry angle
D. Collimator shape
E. Monitor units
What is the primary advantage of GRID radiotherapy in bulky tumours?
A. Reduced normal tissue toxicity
B. Uniform dose distribution
C. Increased treatment time
D. Lower cost
E. Simplified planning
Which parameter is most critical for dose painting in hypoxia-guided radiotherapy?
A. Beam energy
B. Hypoxic subvolume mapping
C. Field size
D. Monitor units
E. Collimator angle
What is the primary purpose of a range compensator in proton therapy?
A. To increase beam energy
B. To correct for tissue heterogeneity
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose conformity in VMAT for lung SBRT?
A. MLC leaf speed
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of deep learning-based dose prediction in IMRT planning?
A. Reduced treatment time
B. Improved plan quality
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which structure is most critical for dose constraints in head and neck SBRT?
A. Spinal cord
B. Liver
C. Kidneys
D. Heart
E. Lungs
What is the primary purpose of a beam spoiler in proton therapy?
A. To increase beam energy
B. To broaden the dose distribution
C. To shape the radiation field
D. To reduce scatter radiation
E. To monitor dose delivery
Which factor most significantly affects the dose heterogeneity in carbon ion therapy?
A. Nuclear fragmentation
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of knowledge-based planning in proton therapy?
A. Reduced treatment time
B. Automated plan optimization
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for tumour control probability (TCP) in carbon ion therapy?
A. Tumour volume
B. Biological effective dose
C. Beam energy
D. Field size
E. Monitor units
What is the primary purpose of a multi-leaf collimator in proton therapy?
A. To increase beam energy
B. To shape the radiation field
C. To reduce skin sparing
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose distribution in pulsed-dose-rate (PDR) brachytherapy?
A. Pulse duration
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of MR-guided radiotherapy?
A. Reduced treatment time
B. Superior soft tissue visualization
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for normal tissue complication probability (NTCP) in SBRT?
A. Beam energy
B. Organ-at-risk dose
C. Field size
D. Monitor units
E. Collimator angle

Imaging (20 Questions)

What is the primary advantage of 4D-MRI in radiotherapy planning?
A. High spatial resolution
B. Motion-resolved imaging
C. Low radiation dose
D. Electron density information
E. Low cost
Which imaging modality is most suitable for assessing tumour hypoxia in cervical radiotherapy?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary source of contrast in chemical exchange saturation transfer (CEST) MRI?
A. Proton density
B. Molecular exchange rates
C. Electron density
D. Atomic number
E. Tissue relaxation time
Which factor most significantly affects the contrast resolution in spectral CT?
A. Energy binning
B. Tube voltage
C. Reconstruction algorithm
D. Field of view
E. Gantry rotation speed
What is the primary advantage of Zr-89 PET in immunotherapy radiotherapy planning?
A. High spatial resolution
B. Low radiation dose
C. Long half-life for tracking
D. Real-time imaging
E. Low cost
Which radionuclide is most suitable for imaging tumour proliferation in radiotherapy planning?
A. F-18 (FLT)
B. Tc-99m
C. Ga-68
D. I-131
E. Cu-64
What is the primary purpose of the point spread function (PSF) in PET imaging?
A. To measure radiation dose
B. To quantify spatial resolution
C. To assess image contrast
D. To determine image noise
E. To monitor patient motion
Which factor most significantly affects the temporal resolution in MR-linac imaging?
A. Field strength
B. Gradient slew rate
C. Coil sensitivity
D. Reconstruction algorithm
E. Field of view
What is the primary advantage of dual-energy CT in proton therapy planning?
A. High soft tissue contrast
B. Improved stopping power estimation
C. Low radiation dose
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for delineating glioblastoma in radiotherapy planning?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary source of artefacts in MR-guided radiotherapy imaging?
A. Photon scattering
B. Magnetic field distortions
C. Metal implants
D. Reconstruction algorithm
E. Patient motion
Which factor most significantly affects the signal-to-noise ratio in PET-MRI hybrid imaging?
A. Radiotracer activity
B. Magnetic field strength
C. Reconstruction algorithm
D. Field of view
E. Patient size
What is the primary advantage of MR spectroscopy in brain tumour radiotherapy?
A. High spatial resolution
B. Low radiation dose
C. Metabolic profiling
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for assessing oesophageal tumour motion in radiotherapy planning?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary purpose of deformable image registration in adaptive radiotherapy?
A. To measure radiation dose
B. To account for anatomical changes
C. To assess image contrast
D. To determine spatial resolution
E. To monitor image noise
Which factor most significantly affects the radiation dose in 4D-CT imaging for lung radiotherapy?
A. Tube voltage
B. Tube current
C. Phase binning
D. Reconstruction algorithm
E. Field of view
What is the primary advantage of diffusion-weighted MRI in oncology?
A. High spatial resolution
B. Low radiation dose
C. Assessment of cellularity
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for real-time dosimetry in FLASH radiotherapy?
A. CT
B. MRI
C. PET
D. Cherenkov imaging
E. Ultrasound
What is the primary source of contrast in arterial spin labelling (ASL) MRI?
A. Proton density
B. Blood flow
C. Electron density
D. Radiotracer uptake
E. Tissue relaxation time
Which factor most significantly affects the spatial resolution in MR spectroscopy?
A. Voxel size
B. Tube current
C. Reconstruction algorithm
D. Field of view
E. Patient size

Radiation Protection (20 Questions)

What is the annual effective dose limit for the bladder of a radiation worker in the UK?
A. 1 mSv
B. 20 mSv
C. 50 mSv
D. 150 mSv
E. 500 mSv
Which material is most effective for shielding 15 MeV neutrons in a proton therapy facility?
A. Lead
B. Polyethylene with boron
C. Perspex
D. Steel
E. Water
What is the primary purpose of the optimization principle in IR(ME)R 2017 for radiotherapy?
A. To maximize radiation dose
B. To minimize patient exposure
C. To measure radiation dose
D. To calibrate dosimeters
E. To monitor radiation levels
Which factor most significantly affects the occupational dose in microbeam radiotherapy?
A. Beam energy
B. Shielding design
C. Field size
D. Gantry angle
E. Monitor units
What is the approximate tenth-value layer (TVL) for a 300 MeV proton beam in lead?
A. 10 cm
B. 20 cm
C. 30 cm
D. 40 cm
E. 50 cm
Which type of personal dosimeter is most suitable for monitoring dose in a FLASH radiotherapy setup?
A. Film badge
B. TLD
C. MOSFET
D. OSL dosimeter
E. Active electronic dosimeter
What is the primary source of stray radiation in a MR-linac treatment room?
A. Primary beam
B. Scatter from patient
C. Secondary photons
D. Bremsstrahlung radiation
E. Compton scattering
Which regulation requires training for radiation workers in the UK?
A. IRR 2017
B. IR(ME)R 2017
C. RIDDOR 2013
D. COSHH 2002
E. MHRA 2008
What is the dose rate at 3 meters from a 2 GBq Lu-177 source, given a specific gamma-ray constant of 0.015 R·m²/Ci·h (ignoring shielding)?
A. 0.01 mGy/h
B. 0.1 mGy/h
C. 1 mGy/h
D. 10 mGy/h
E. 100 mGy/h
Which factor most significantly affects the shielding requirements for a MR-linac facility?
A. Magnetic field strength
B. Photon beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary purpose of a radiation protection advisor (RPA) in a radiotherapy department?
A. To deliver radiotherapy
B. To provide expert safety advice
C. To calibrate dosimeters
D. To monitor patient doses
E. To perform quality assurance
Which material is most effective for shielding gamma rays in a FLASH radiotherapy setup?
A. Lead
B. Concrete
C. Polyethylene
D. Boron
E. Perspex
What is the annual effective dose limit for the public in the UK?
A. 1 mSv
B. 5 mSv
C. 10 mSv
D. 20 mSv
E. 50 mSv
Which factor most significantly affects the dose to staff during Y-90 radioembolization procedures?
A. Source activity
B. Shielding placement
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of a syringe shield in radionuclide therapy?
A. Reduced treatment time
B. Minimized beta particle exposure
C. Increased patient comfort
D. Simplified quality assurance
E. Enhanced dose delivery
Which type of radiation is most hazardous for external exposure in a carbon ion therapy facility?
A. Alpha particles
B. Beta particles
C. Gamma rays
D. Neutrons
E. X-rays
What is the primary purpose of a dose constraint in radiotherapy planning?
A. To deliver radiotherapy
B. To limit normal tissue exposure
C. To calibrate dosimeters
D. To monitor patient doses
E. To perform quality assurance
Which factor most significantly affects the dose rate from a Ra-223 unsealed source?
A. Source activity
B. Alpha particle energy
C. Source size
D. Source material
E. Source shape
What is the approximate half-life of Ra-223 used in prostate cancer therapy?
A. 2 days
B. 11.4 days
C. 30 days
D. 60 days
E. 90 days
Which principle is most critical for reducing occupational dose in MR-linac procedures?
A. Time
B. Distance
C. Shielding
D. Justification
E. Calibration

Answers

Radiation Physics

D. At the SOBP, a 200 MeV carbon ion has an LET of ~200 keV/μm due to high ionization density.
C. Pair production dominates for 25 MV photons in lead (high Z, high energy).
C. HVL = ln(2)/(μ·ρ) = 0.693/(0.045·2.35) ≈ 20 cm.
B. Transient oxygen depletion reduces normal tissue toxicity in FLASH radiotherapy by limiting radical formation.
C. The CSDA range for a 300 MeV proton in water is ~30 cm (R ∝ E¹·⁵).
B. Low LET in the entrance region results in an RBE of ~1.1 for 150 MeV protons.
B. K-to-L transition in molybdenum emits ~15 keV photons (K-shell binding energy).
B. Photoelectric effect dominates at 20 keV in bone, scaling as ∝ Z³/E³.
A. Elastic scattering with protons (recoil) is the primary interaction for 5 MeV neutrons.
B. The mass stopping power ratio of water to bone for 12 MeV electrons is ~0.9.
B. Photon energy threshold (>8 MeV) drives neutron yield via photodisintegration.
B. Dose rate = (Γ·A)/r² = (1.32·3/37)/(2²) ≈ 1 mGy/h (1 GBq = 27 mCi).
C. Compton scattering probability scales as ∝ 1/E.
C. Range in aluminium = 15/2.7 ≈ 6 cm (R ≈ 0.5 E, scaled by density).
B. B-10(n,α)Li-7 produces high-LET alpha particles for BNCT’s therapeutic effect.
D. Pair production is the primary source of secondary electrons for 15 MV photons in water.
C. Mass density most significantly affects carbon ion stopping power (S ∝ ρ).
B. Neutron production via photodisintegration in copper requires ~8 MeV.
D. Paraffin (hydrogen-rich) slows thermal neutrons, and cadmium captures them.
B. Bremsstrahlung radiation dominates for 2 GeV electrons in tungsten (high Z, high E).

Dosimetry

B. Dose rate = (Γ·A)/r² = (0.48·4/37)/(1.5²) ≈ 5 mGy/h (1 GBq = 27 mCi).
C. Effective dose assesses stochastic risks like leukemia (whole-body exposure).
C. The quality factor for 5 MeV neutrons is 10.
C. PDD at 12 cm for 10 MV (10x10 cm², SSD=100 cm) is ~65% (standard data).
C. Radiochromic film is suitable for microbeam fields due to high spatial resolution.
C. MU = Dose/(TMR·Output) = 2.5/(0.70·1.01) ≈ 353 MU.
C. Dmax for a 300 MeV proton beam is ~30 cm (Bragg peak depth).
A. Detector volume averaging significantly affects accuracy in 0.5 cm² fields.
B. Plastic scintillators are dose-rate independent, ideal for FLASH dosimetry.
C. TAR = PDD/BSF = 65/1.03 ≈ 0.63.
E. Equivalent dose = 3 mGy · 20 (Q for alpha) = 60 mSv.
B. Effective dose = 4 mGy · 0.12 (W_T for colon) · 1 (Q for gamma) = 0.48 mSv.
C. IAEA TRS-398 is adaptable for FLASH dosimetry with appropriate corrections.
C. Calibration stability is the primary uncertainty in diamond detector dosimetry.
B. Lung inhomogeneity (ρ=0.26 g/cm³) reduces attenuation, correction factor ~0.90.
D. Diamond detectors are suitable for carbon ion therapy due to high resolution.
B. Collimator scatter factor (Sc) normalizes dose for collimator settings in small fields.
C. Penumbra width for 300 MeV protons at 25 cm is ~5 mm (beam scattering).
A. Grid spacing drives the dose rate in GRID radiotherapy.
B. Alanine dosimetry is tissue-equivalent, ideal for high-LET particle therapy.

Radiotherapy Treatment Planning

B. Online adaptive radiotherapy reoptimizes plans daily for anatomical changes in MR-linac.
B. Range and setup uncertainties define robust optimization volumes in proton therapy.
B. Microbeam radiotherapy spares normal tissue via spatial fractionation.
C. Monte Carlo is most accurate for carbon ion therapy in bone due to fragmentation handling.
B. Ripple filters sharpen the Bragg peak in carbon ion therapy for precise dosing.
B. Nuclear interactions cause the dose tail in proton therapy.
A. GRID radiotherapy reduces normal tissue toxicity via heterogeneous dosing.
B. Hypoxic subvolume mapping is critical for dose painting in hypoxia-guided radiotherapy.
B. Range compensators correct for tissue heterogeneity in proton therapy.
A. MLC leaf speed affects dose conformity in VMAT for lung SBRT.
B. Deep learning-based dose prediction improves plan quality in IMRT.
A. The spinal cord is critical for dose constraints in head and neck SBRT.
B. Beam spoilers broaden the dose distribution for shallow targets in proton therapy.
A. Nuclear fragmentation causes dose heterogeneity in carbon ion therapy.
B. Knowledge-based planning automates optimization in proton therapy.
B. Biological effective dose drives TCP in carbon ion therapy (BED = D·(1+d/(α/β))).
B. Multi-leaf collimators shape the radiation field in proton therapy.
A. Pulse duration determines dose distribution in PDR brachytherapy.
B. MR-guided radiotherapy provides superior soft tissue visualization.
B. Organ-at-risk dose is critical for NTCP in SBRT.

Imaging

B. 4D-MRI provides motion-resolved imaging for radiotherapy planning.
C. PET (e.g., Cu-64 ATSM) is suitable for assessing tumour hypoxia in cervical radiotherapy.
B. CEST MRI contrast arises from molecular exchange rates (e.g., amide protons).
A. Energy binning most significantly affects contrast resolution in spectral CT.
C. Zr-89’s long half-life enables tracking of immunotherapy agents in radiotherapy.
A. F-18 (FLT) is suitable for imaging tumour proliferation.
B. PSF quantifies spatial resolution in PET imaging.
B. Gradient slew rate affects temporal resolution in MR-linac imaging.
B. Dual-energy CT improves stopping power estimation for proton therapy planning.
B. MRI is ideal for delineating glioblastoma due to soft tissue contrast.
B. Magnetic field distortions cause artefacts in MR-guided radiotherapy imaging.
B. Magnetic field strength affects SNR in PET-MRI hybrid imaging.
C. MR spectroscopy provides metabolic profiling of brain tumours.
D. 4D-CT is suitable for assessing oesophageal tumour motion.
B. Deformable image registration accounts for anatomical changes in adaptive radiotherapy.
B. Tube current most significantly affects 4D-CT radiation dose.
C. Diffusion-weighted MRI assesses tumour cellularity.
D. Cherenkov imaging enables real-time dosimetry in FLASH radiotherapy.
B. ASL MRI contrast arises from blood flow (non-contrast perfusion).
A. Voxel size most significantly affects spatial resolution in MR spectroscopy.

Radiation Protection

B. The annual effective dose limit for the bladder is 20 mSv (whole-body limit).
B. Polyethylene with boron shields 15 MeV neutrons via slowing and capture.
B. Optimization in IR(ME)R 2017 minimizes patient exposure while maintaining efficacy.
B. Shielding design most significantly affects occupational dose in microbeam radiotherapy.
D. The TVL for a 300 MeV proton beam in lead is ~40 cm.
E. Active electronic dosimeters are suitable for FLASH setups due to real-time readout.
C. Secondary photons are the primary stray radiation in MR-linac treatment rooms.
A. IRR 2017 requires training for radiation workers.
B. Dose rate = (Γ·A)/r² = (0.015·2/37)/(3²) ≈ 0.1 mGy/h (1 GBq = 27 mCi).
B. Photon beam energy drives shielding requirements for MR-linac facilities.
B. RPAs provide expert safety advice in radiotherapy departments.
A. Lead is most effective for shielding gamma rays in FLASH setups.
A. The annual effective dose limit for the public is 1 mSv.
B. Shielding placement most significantly affects staff dose in Y-90 radioembolization.
B. Syringe shields minimize beta particle exposure in radionuclide therapy.
D. Neutrons are most hazardous for external exposure in carbon ion therapy.
B. Dose constraints limit normal tissue exposure in radiotherapy planning.
A. Source activity drives the dose rate from Ra-223 (alpha/gamma emitter).
B. The half-life of Ra-223 is ~11.4 days.
C. Shielding is critical for reducing occupational dose in MR-linac procedures.

Radiation Physics (20 Questions)

What is the approximate linear energy transfer (LET) of a 400 MeV/u carbon ion at the distal edge of the spread-out Bragg peak (SOBP) in water, considering nuclear fragmentation effects?
A. 50 keV/μm
B. 150 keV/μm
C. 300 keV/μm
D. 500 keV/μm
E. 700 keV/μm
For a 30 MV photon beam interacting with a tungsten flattening filter, what is the dominant interaction process contributing to neutron production?
A. Photoelectric effect
B. Compton scattering
C. Pair production
D. Photodisintegration
E. Coherent scattering
Calculate the tenth-value layer (TVL) for a 15 MV photon beam in lead, given a mass attenuation coefficient of 0.06 cm²/g and density of 11.34 g/cm³.
A. 2.0 cm
B. 3.4 cm
C. 4.8 cm
D. 6.2 cm
E. 7.6 cm
In a microbeam radiotherapy setup with 50 keV X-rays, what is the primary mechanism enhancing the valley dose sparing effect in normal tissue?
A. Bystander effect
B. Enhanced Compton scattering
C. Spatial fractionation
D. Reduced pair production
E. Increased photodisintegration
What is the continuous slowing down approximation (CSDA) range of a 500 MeV proton in bone (density 1.85 g/cm³), accounting for nuclear interactions?
A. 20 cm
B. 30 cm
C. 40 cm
D. 50 cm
E. 60 cm
Which factor most significantly affects the relative biological effectiveness (RBE) variation across the SOBP for a 200 MeV/u carbon ion beam?
A. Beam energy spread
B. LET gradient
C. Tissue oxygenation
D. Beam divergence
E. Nuclear fragmentation
What is the energy of a characteristic X-ray emitted from the M-shell to K-shell transition in tantalum (Z=73)?
A. 10 keV
B. 30 keV
C. 50 keV
D. 70 keV
E. 90 keV
For a 15 keV photon beam in cortical bone, what is the dominant interaction, and how does its cross-section scale with energy (E)?
A. Compton scattering, ∝ 1/E
B. Photoelectric effect, ∝ 1/E³
C. Pair production, ∝ E²
D. Coherent scattering, ∝ 1/E²
E. Photodisintegration, ∝ E
What is the primary interaction mechanism for 20 MeV neutrons in soft tissue, considering secondary particle production?
A. Elastic scattering with protons
B. Inelastic scattering with carbon
C. Neutron capture by oxygen
D. Spallation reactions
E. Compton scattering
What is the mass stopping power ratio of muscle to water for a 20 MeV electron beam, accounting for density differences (muscle: 1.04 g/cm³, water: 1.00 g/cm³)?
A. 0.85
B. 0.95
C. 1.00
D. 1.04
E. 1.15
Which factor most significantly affects the production of secondary positrons in a 25 MV photon beam interacting with a high-Z collimator?
A. Target atomic number
B. Pair production threshold
C. Collimator thickness
D. Beam divergence
E. Gantry angle
What is the dose rate at 5 meters from a 10 GBq Cs-137 source, given a specific gamma-ray constant of 0.33 R·m²/Ci·h, ignoring shielding and assuming air kerma?
A. 0.03 mGy/h
B. 0.3 mGy/h
C. 3 mGy/h
D. 30 mGy/h
E. 300 mGy/h
Which equation correctly describes the energy dependence of the pair production cross-section in a high-Z material?
A. ∝ E
B. ∝ E²
C. ∝ ln(E)
D. ∝ 1/E
E. ∝ 1/E²
What is the approximate range of a 25 MeV electron in lead (density 11.34 g/cm³), accounting for bremsstrahlung losses?
A. 0.5 cm
B. 1.0 cm
C. 1.5 cm
D. 2.0 cm
E. 2.5 cm
In a targeted alpha therapy using Ac-225, what is the primary mode of energy deposition in tumour cells?
A. Bremsstrahlung radiation
B. Alpha particle emission
C. Gamma ray emission
D. Compton scattering
E. Photoelectric effect
What is the primary source of nuclear recoil energy in a 400 MeV/u carbon ion beam interacting with tissue?
A. Elastic scattering
B. Nuclear fragmentation
C. Compton scattering
D. Pair production
E. Bremsstrahlung radiation
Which material property most significantly affects the angular scattering of a 300 MeV proton beam in a range shifter?
A. Electron density
B. Atomic number
C. Mass density
D. Thermal conductivity
E. Magnetic susceptibility
What is the approximate energy threshold for pion production in a proton beam interacting with a carbon target?
A. 100 MeV
B. 290 MeV
C. 500 MeV
D. 1 GeV
E. 2 GeV
Which shielding configuration is most effective for 30 MeV neutrons in a carbon ion therapy facility?
A. Lead followed by concrete
B. Polyethylene followed by boron
C. Steel followed by water
D. Perspex followed by cadmium
E. Tungsten followed by paraffin
What is the primary mode of energy loss for a 5 GeV electron in bone, considering synchrotron radiation effects?
A. Collisional interactions
B. Bremsstrahlung radiation
C. Compton scattering
D. Pair production
E. Synchrotron radiation

Dosimetry (20 Questions)

What is the absorbed dose rate at 4 meters from a 15 GBq I-131 source, given a specific gamma-ray constant of 0.22 R·m²/Ci·h, ignoring shielding and assuming air kerma?
A. 0.05 mGy/h
B. 0.5 mGy/h
C. 5 mGy/h
D. 50 mGy/h
E. 500 mGy/h
Which quantity is most critical for assessing the risk of radiation-induced hereditary effects in radiotherapy patients?
A. Absorbed dose
B. Equivalent dose
C. Effective dose
D. Kerma
E. Exposure
What is the radiation weighting factor (W_R) for 20 MeV protons in radiation protection, per ICRP 103?
A. 1
B. 2
C. 5
D. 10
E. 20
What is the percentage depth dose (PDD) at 20 cm depth for a 18 MV photon beam (10x10 cm² field, SSD=100 cm) in water, given a PDD of 100% at dmax=3.5 cm and an attenuation coefficient of 0.04 cm⁻¹?
A. 45%
B. 50%
C. 55%
D. 60%
E. 65%
Which dosimeter is most suitable for measuring dose in a 0.1 mm² microbeam radiotherapy field with 100 keV X-rays?
A. Ionisation chamber
B. TLD
C. Nanodot OSL
D. Radiochromic film
E. MOSFET
What is the monitor unit (MU) required to deliver 3 Gy to a depth of 15 cm through a 5 cm bone slab (density=1.85 g/cm³, μ/ρ=0.05 cm²/g) for a 15 MV photon beam (10x10 cm² field, SAD=100 cm, output factor=1.02, TMR=0.65)?
A. 350 MU
B. 425 MU
C. 500 MU
D. 575 MU
E. 650 MU
What is the approximate depth of the 80% isodose line for a 400 MeV/u carbon ion beam in water, assuming a 5 cm SOBP?
A. 20 cm
B. 25 cm
C. 30 cm
D. 35 cm
E. 40 cm
Which factor most significantly affects the accuracy of dosimetry in a 0.2 cm² field for proton stereotactic radiosurgery?
A. Detector lateral response
B. Beam energy spread
C. Source-to-detector distance
D. Collimator misalignment
E. Nuclear interactions
What is the primary advantage of graphene-based detectors in FLASH radiotherapy dosimetry?
A. High spatial resolution
B. Ultra-fast response time
C. Low cost
D. Energy independence
E. Large dynamic range
What is the tissue maximum ratio (TMR) at 25 cm depth for a 18 MV photon beam (10x10 cm² field, SAD=100 cm), given a PDD of 45% at 25 cm, PDD of 100% at dmax=3.5 cm, and BSF of 1.04?
A. 0.40
B. 0.43
C. 0.46
D. 0.49
E. 0.52
What is the equivalent dose from a 2 mGy absorbed dose of 15 MeV neutrons to the bone marrow?
A. 0.02 mSv
B. 0.2 mSv
C. 2 mSv
D. 20 mSv
E. 40 mSv
What is the effective dose from a 3 mGy absorbed dose to the breast (tissue weighting factor=0.12) from 10 MeV protons (W_R=2)?
A. 0.036 mSv
B. 0.36 mSv
C. 3.6 mSv
D. 36 mSv
E. 360 mSv
Which dosimetry protocol is most suitable for calibrating a 400 MeV/u carbon ion beam in a water phantom?
A. TG-21
B. TG-51
C. IAEA TRS-398
D. AAPM TG-61
E. TRS-483
What is the primary source of uncertainty in 3D gel dosimetry for verifying a proton arc therapy plan?
A. Energy dependence
B. Chemical homogeneity
C. Spatial resolution
D. Readout reproducibility
E. Temperature sensitivity
What is the monitor unit (MU) correction factor for a 10 cm lung inhomogeneity (density=0.26 g/cm³, μ/ρ=0.03 cm²/g) in a 18 MV photon beam at 15 cm depth?
A. 0.80
B. 0.85
C. 0.90
D. 0.95
E. 1.00
Which dosimeter is most suitable for in-vivo dosimetry in a MR-guided carbon ion therapy setup?
A. Ionisation chamber
B. TLD
C. MOSFET
D. Graphene detector
E. Plastic scintillator
What is the primary purpose of the output factor (OF) in small-field proton therapy dosimetry?
A. To quantify patient scatter
B. To normalize dose for field size
C. To measure dose at depth
D. To assess beam flatness
E. To determine penumbra width
What is the approximate penumbra width (20%–80%) for a 500 MeV proton beam at 40 cm depth in water, considering multiple Coulomb scattering?
A. 2 mm
B. 4 mm
C. 6 mm
D. 8 mm
E. 10 mm
Which factor most significantly affects the dose rate from a synchrotron-based proton arc therapy source?
A. Beam scanning speed
B. Source energy
C. Source intensity
D. Source material
E. Source shape
What is the primary advantage of diamond detectors in microbeam radiotherapy dosimetry?
A. High spatial resolution
B. Low cost
C. Real-time readout
D. Energy independence
E. Large dynamic range

Radiotherapy Treatment Planning (20 Questions)

What is the primary advantage of proton arc therapy over intensity-modulated proton therapy (IMPT)?
A. Reduced treatment time
B. Enhanced dose conformity
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for defining the robust optimization constraints in carbon ion therapy for a pancreatic tumour?
A. Tumour volume
B. Range uncertainty and organ motion
C. Beam energy
D. Field size
E. Monitor units
What is the primary advantage of synchrotron-based FLASH radiotherapy for deep-seated tumours?
A. Uniform dose distribution
B. Ultra-high dose rate delivery
C. Increased treatment time
D. Lower cost
E. Simplified planning
Which dose calculation algorithm is most accurate for proton therapy in a lung tumour with a 0.26 g/cm³ density heterogeneity?
A. Pencil beam
B. Convolution-superposition
C. Monte Carlo
D. Acuros XB
E. Collapsed cone
What is the primary purpose of a dynamic range shifter in proton arc therapy?
A. To increase beam energy
B. To adjust Bragg peak depth dynamically
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the distal dose fall-off in carbon ion therapy for a skull base tumour?
A. Beam energy
B. Nuclear fragmentation tail
C. Gantry angle
D. Collimator shape
E. Monitor units
What is the primary advantage of AI-driven inverse planning in MR-linac adaptive radiotherapy?
A. Reduced treatment time
B. Real-time plan optimization
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for biologically effective dose (BED) calculation in hypofractionated carbon ion therapy (α/β=2 Gy)?
A. Total dose
B. Fraction size
C. Beam energy
D. Field size
E. Monitor units
What is the primary purpose of a patient-specific bolus in proton therapy for a superficial tumour?
A. To increase beam energy
B. To conform dose to target depth
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose conformity in microbeam radiotherapy for brain metastases?
A. Beamlet spacing
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of synthetic CT generation in MR-only carbon ion therapy planning?
A. Reduced imaging time
B. Accurate stopping power estimation
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which structure is most critical for dose constraints in proton therapy for a mediastinal tumour?
A. Spinal cord
B. Liver
C. Kidneys
D. Heart
E. Stomach
What is the primary purpose of a beam-specific collimator in carbon ion therapy?
A. To increase beam energy
B. To sharpen lateral dose fall-off
C. To reduce skin sparing
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose heterogeneity in proton arc therapy?
A. Spot scanning pattern
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of deep reinforcement learning in radiotherapy plan optimization?
A. Reduced treatment time
B. Adaptive constraint handling
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for tumour control probability (TCP) in FLASH radiotherapy?
A. Tumour volume
B. Ultra-high dose rate
C. Beam energy
D. Field size
E. Monitor units
What is the primary purpose of a ridge filter in carbon ion therapy?
A. To increase beam energy
B. To create a spread-out Bragg peak
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose distribution in spatially fractionated radiotherapy (SFRT) for bulky tumours?
A. Grid block spacing
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of hypoxia-guided dose escalation in carbon ion therapy?
A. Reduced treatment time
B. Targeting radioresistant subvolumes
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for dose-volume histogram (DVH) optimization in proton arc therapy?
A. Beam energy
B. Target coverage constraints
C. Field size
D. Monitor units
E. Collimator angle

Imaging (20 Questions)

What is the primary advantage of 7T MRI in radiotherapy planning for brain tumours?
A. High spatial resolution
B. Low radiation dose
C. Real-time imaging
D. Electron density information
E. Low cost
Which imaging modality is most suitable for assessing intrafraction motion in liver SBRT?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Fluoroscopy
What is the primary source of contrast in amide proton transfer (APT) MRI for oncology?
A. Proton density
B. Protein content
C. Electron density
D. Atomic number
E. Blood flow
Which factor most significantly affects the signal-to-noise ratio in cone-beam CT (CBCT) for MR-linac?
A. Tube voltage
B. Detector quantum efficiency
C. Reconstruction algorithm
D. Field of view
E. Gantry rotation speed
What is the primary advantage of At-211 PET in targeted alpha therapy planning?
A. High spatial resolution
B. Low radiation dose
C. Alpha emitter tracking
D. Real-time imaging
E. Low cost
Which radionuclide is most suitable for imaging tumour hypoxia in radiotherapy planning?
A. F-18 (FMISO)
B. Tc-99m
C. Ga-68
D. I-131
E. Zr-89
What is the primary purpose of the contrast-to-noise ratio (CNR) in MR-guided radiotherapy?
A. To measure radiation dose
B. To quantify tissue differentiation
C. To assess image noise
D. To determine spatial resolution
E. To monitor patient motion
Which factor most significantly affects the temporal resolution in 4D-MRI for lung radiotherapy?
A. Field strength
B. Gradient slew rate
C. Coil sensitivity
D. Reconstruction algorithm
E. Field of view
What is the primary advantage of photon-counting CT in radiotherapy planning?
A. High soft tissue contrast
B. Material-specific imaging
C. Low radiation dose
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for delineating soft tissue sarcomas in radiotherapy planning?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary source of artefacts in 7T MRI for radiotherapy planning?
A. Photon scattering
B. B0 field inhomogeneity
C. Metal implants
D. Reconstruction algorithm
E. Patient motion
Which factor most significantly affects the contrast resolution in dynamic contrast-enhanced (DCE) MRI?
A. Contrast agent dose
B. Magnetic field strength
C. Reconstruction algorithm
D. Field of view
E. Patient size
What is the primary advantage of MR elastography in radiotherapy planning?
A. High spatial resolution
B. Low radiation dose
C. Assessment of tissue stiffness
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for assessing spinal cord motion in cervical radiotherapy?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary purpose of AI-based image segmentation in radiotherapy?
A. To measure radiation dose
B. To automate contouring
C. To assess image contrast
D. To determine spatial resolution
E. To monitor image noise
Which factor most significantly affects the radiation dose in photon-counting CT for radiotherapy?
A. Energy thresholding
B. Tube current
C. Reconstruction algorithm
D. Field of view
E. Gantry rotation speed
What is the primary advantage of hyperpolarized 13C MRI in oncology?
A. High spatial resolution
B. Low radiation dose
C. Metabolic pathway imaging
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for real-time tumour tracking in carbon ion therapy?
A. CT
B. MRI
C. PET
D. Fluoroscopy
E. Ultrasound
What is the primary source of contrast in blood-oxygen-level-dependent (BOLD) MRI?
A. Proton density
B. Oxygenation status
C. Electron density
D. Radiotracer uptake
E. Tissue relaxation time
Which factor most significantly affects the spatial resolution in PET imaging for radiotherapy planning?
A. Detector crystal size
B. Tube current
C. Reconstruction algorithm
D. Field of view
E. Patient size

Radiation Protection (20 Questions)

What is the annual equivalent dose limit for the lens of the eye for radiation workers in the UK, per IRR 2017?
A. 1 mSv
B. 15 mSv
C. 20 mSv
D. 50 mSv
E. 150 mSv
Which material is most effective for shielding 50 MeV neutrons in a synchrotron-based proton therapy facility?
A. Lead
B. Concrete with hydrogen
C. Perspex
D. Steel
E. Water
What is the primary purpose of the controlled area designation in a carbon ion therapy bunker?
A. To store radioactive sources
B. To restrict access to high-radiation hazards
C. To monitor patient doses
D. To calibrate dosimeters
E. To perform quality assurance
Which factor most significantly affects the occupational dose in a proton arc therapy setup?
A. Beam energy
B. Neutron shielding design
C. Field size
D. Gantry rotation speed
E. Monitor units
What is the approximate half-value layer (HVL) for a 400 MeV/u carbon ion beam in tungsten?
A. 5 cm
B. 10 cm
C. 15 cm
D. 20 cm
E. 25 cm
Which type of personal dosimeter is most suitable for monitoring dose in a synchrotron-based FLASH radiotherapy setup?
A. Film badge
B. TLD
C. MOSFET
D. OSL dosimeter
E. Real-time scintillator
What is the primary source of stray radiation in a proton arc therapy treatment room?
A. Primary beam
B. Patient scatter
C. Neutron contamination
D. Bremsstrahlung radiation
E. Compton scattering
Which regulation requires optimization of medical radiation exposures in the UK?
A. IRR 2017
B. IR(ME)R 2017
C. RIDDOR 2013
D. COSHH 2002
E. MHRA 2008
What is the dose rate at 2 meters from a 5 GBq Ra-223 source, given a specific gamma-ray constant of 0.01 R·m²/Ci·h, ignoring shielding?
A. 0.01 mGy/h
B. 0.1 mGy/h
C. 1 mGy/h
D. 10 mGy/h
E. 100 mGy/h
Which factor most significantly affects the shielding requirements for a synchrotron-based carbon ion therapy facility?
A. Beam energy
B. Neutron yield
C. Field size
D. Gantry angle
E. Monitor units
What is the primary purpose of a radiation protection supervisor (RPS) in a FLASH radiotherapy department?
A. To deliver radiotherapy
B. To oversee local safety compliance
C. To calibrate dosimeters
D. To monitor patient doses
E. To perform quality assurance
Which material is most effective for shielding secondary gamma rays in a proton arc therapy bunker?
A. Lead
B. Concrete
C. Polyethylene
D. Boron
E. Perspex
What is the annual equivalent dose limit for the skin of radiation workers in the UK?
A. 1 mSv
B. 20 mSv
C. 50 mSv
D. 150 mSv
E. 500 mSv
Which factor most significantly affects the dose to staff during Ac-225 targeted alpha therapy procedures?
A. Source activity
B. Shielding placement
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of a remote afterloading system in alpha-emitting radionuclide therapy?
A. Reduced treatment time
B. Minimized staff exposure
C. Increased patient comfort
D. Simplified quality assurance
E. Enhanced dose delivery
Which type of radiation is most challenging to shield in a synchrotron-based proton therapy facility?
A. Gamma rays
B. X-rays
C. Beta particles
D. Neutrons
E. Alpha particles
What is the primary purpose of a significant incident investigation under IR(ME)R 2017?
A. To deliver radiotherapy
B. To analyze unintended exposures
C. To calibrate dosimeters
D. To monitor patient doses
E. To perform quality assurance
Which factor most significantly affects the dose rate from an At-211 unsealed source?
A. Source activity
B. Alpha particle energy
C. Source size
D. Source material
E. Source shape
What is the approximate half-life of At-211 used in targeted alpha therapy?
A. 7.2 hours
B. 2 days
C. 8 days
D. 30 days
E. 60 days
Which principle is most critical for reducing public dose in a carbon ion therapy facility?
A. Time
B. Distance
C. Shielding
D. Justification
E. Calibration

Answers

Radiation Physics

D. At the distal edge of the SOBP, a 400 MeV/u carbon ion has an LET of ~500 keV/μm due to fragmentation and high ionization density.
D. Photodisintegration in tungsten produces neutrons for 30 MV photons (E > 7 MeV).
B. TVL = ln(10)/(μ·ρ) = 2.303/(0.06·11.34) ≈ 3.4 cm.
C. Spatial fractionation enhances valley dose sparing in microbeam radiotherapy.
C. CSDA range for 500 MeV protons in bone = 48 cm in water / 1.85 ≈ 40 cm (R ∝ E¹·⁵, adjusted for density).
B. The LET gradient across the SOBP drives RBE variation (RBE ~ 2–5).
D. M-to-K transition in tantalum emits ~70 keV photons (K-shell binding energy).
B. Photoelectric effect dominates at 15 keV in cortical bone, scaling as ∝ 1/E³.
D. Spallation reactions dominate for 20 MeV neutrons, producing secondary particles.
D. Mass stopping power ratio of muscle to water is ~1.04 due to density (S ∝ ρ).
B. Pair production threshold (>1.022 MeV) drives positron production in 25 MV beams.
B. Dose rate = (Γ·A)/r² = (0.33·10/37)/(5²) ≈ 0.3 mGy/h (1 GBq = 27 mCi, 1 R ≈ 8.7 mGy).
C. Pair production cross-section scales as ∝ ln(E) for high energies.
C. Range in lead = 25/11.34 ≈ 1.5 cm (R ≈ 0.5 E, adjusted for bremsstrahlung).
B. Alpha particle emission is the primary energy deposition mode for Ac-225.
B. Nuclear fragmentation produces recoil energy in carbon ion beams.
B. Atomic number drives angular scattering via multiple Coulomb interactions.
B. Pion production in carbon requires ~290 MeV (threshold for π⁰ production).
B. Polyethylene slows 30 MeV neutrons, and boron captures thermal neutrons.
B. Bremsstrahlung radiation dominates for 5 GeV electrons in bone (high Z, high E).

Dosimetry

B. Dose rate = (Γ·A)/r² = (0.22·15/37)/(4²) ≈ 0.5 mGy/h (1 GBq = 27 mCi).
C. Effective dose assesses hereditary risks (gonadal exposure, W_T=0.08).
B. W_R for 20 MeV protons is 2 per ICRP 103.
C. PDD = 100 · e^(-μ·(d-dmax)) = 100 · e^(-0.04·(20-3.5)) ≈ 55%.
D. Radiochromic film offers sub-mm resolution for 0.1 mm² microbeam fields.
D. MU = Dose/(TMR·Output·CF), CF = e^(μ·t·(ρ-1)) = e^(0.05·5·(1.85-1)) ≈ 1.24, MU = 3/(0.65·1.02·1.24) ≈ 575 MU.
D. 400 MeV/u carbon ion range ~35 cm, 80% isodose at SOBP distal edge ~35 cm.
A. Detector lateral response affects accuracy in 0.2 cm² proton fields due to averaging.
B. Graphene detectors offer ultra-fast response for FLASH dose rates (>10⁶ Gy/s).
B. TMR = PDD(d)/PDD(dmax) · BSF = 45/(100·1.04) ≈ 0.43.
E. Equivalent dose = 2 mGy · 20 (W_R for 15 MeV neutrons) = 40 mSv.
B. Effective dose = 3 mGy · 0.12 (W_T for breast) · 2 (W_R for protons) = 0.36 mSv.
C. IAEA TRS-398 is suitable for carbon ion beam calibration.
B. Chemical homogeneity is the primary uncertainty in 3D gel dosimetry.
C. CF = e^(μ·t·(ρ-1)) = e^(0.03·10·(0.26-1)) ≈ 0.90 for lung inhomogeneity.
D. Graphene detectors are MR-compatible and suitable for carbon ion therapy.
B. Output factor normalizes dose for field size variations in proton therapy.
C. Penumbra width for 500 MeV protons at 40 cm is ~6 mm (Coulomb scattering).
C. Source intensity drives dose rate in proton arc therapy.
A. Diamond detectors offer high spatial resolution for microbeam dosimetry.

Radiotherapy Treatment Planning

B. Proton arc therapy enhances dose conformity via multi-angle delivery.
B. Range uncertainty and organ motion are critical for pancreatic robust optimization.
B. Synchrotron-based FLASH delivers ultra-high dose rates (>40 Gy/s) for deep tumours.
C. Monte Carlo is most accurate for proton therapy in low-density lung.
B. Dynamic range shifters adjust Bragg peak depth in proton arc therapy.
B. Nuclear fragmentation tail affects distal dose fall-off in carbon ion therapy.
B. AI-driven inverse planning enables real-time optimization in MR-linac.
B. Fraction size drives BED (BED = D·(1+d/(α/β))) in hypofractionation.
B. Patient-specific bolus conforms dose to superficial targets in proton therapy.
A. Beamlet spacing affects dose conformity in microbeam radiotherapy.
B. Synthetic CT provides accurate stopping power for carbon ion planning.
D. The heart is critical for dose constraints in mediastinal proton therapy.
B. Beam-specific collimators sharpen lateral dose fall-off in carbon ion therapy.
A. Spot scanning pattern affects dose heterogeneity in proton arc therapy.
B. Deep reinforcement learning adapts constraints dynamically in optimization.
B. Ultra-high dose rate modifies TCP in FLASH radiotherapy via OER reduction.
B. Ridge filters create a spread-out Bragg peak in carbon ion therapy.
A. Grid block spacing determines dose distribution in SFRT.
B. Hypoxia-guided dose escalation targets radioresistant subvolumes.
B. Target coverage constraints drive DVH optimization in proton arc therapy.

Imaging

A. 7T MRI provides high spatial resolution for brain tumour delineation.
B. MRI is suitable for liver SBRT intrafraction motion due to soft tissue contrast.
B. APT MRI contrast arises from protein content via amide proton exchange.
B. Detector quantum efficiency most significantly affects CBCT SNR in MR-linac.
C. At-211 PET tracks alpha emitters for targeted therapy planning.
A. F-18 (FMISO) is suitable for imaging tumour hypoxia.
B. CNR quantifies tissue differentiation in MR-guided radiotherapy.
B. Gradient slew rate affects temporal resolution in 4D-MRI.
B. Photon-counting CT enables material-specific imaging for planning.
B. MRI is ideal for delineating soft tissue sarcomas due to contrast.
B. B0 field inhomogeneity causes artefacts in 7T MRI.
A. Contrast agent dose affects contrast resolution in DCE-MRI.
C. MR elastography assesses tissue stiffness for tumour characterization.
B. MRI is suitable for assessing spinal cord motion in cervical radiotherapy.
B. AI-based image segmentation automates contouring in radiotherapy.
B. Tube current most significantly affects photon-counting CT dose.
C. Hyperpolarized 13C MRI images metabolic pathways in tumours.
B. MRI enables real-time tumour tracking in carbon ion therapy.
B. BOLD-MRI contrast arises from oxygenation status.
A. Detector crystal size most significantly affects PET spatial resolution.

Radiation Protection

C. The annual equivalent dose limit for the lens of the eye is 20 mSv (IRR 2017).
B. Concrete with hydrogen shields 50 MeV neutrons via elastic scattering.
B. Controlled areas restrict access to high-radiation hazards in carbon ion bunkers.
B. Neutron shielding design most significantly affects dose in proton arc therapy.
D. HVL for 400 MeV/u carbon ions in tungsten is ~20 cm (high density).
E. Real-time scintillators are suitable for FLASH due to ultra-high dose rates.
C. Neutron contamination is the primary stray radiation in proton arc therapy.
B. IR(ME)R 2017 requires optimization of medical exposures.
B. Dose rate = (Γ·A)/r² = (0.01·5/37)/(2²) ≈ 0.1 mGy/h (1 GBq = 27 mCi).
B. Neutron yield drives shielding requirements for carbon ion facilities.
B. RPS oversees local safety compliance in FLASH radiotherapy.
A. Lead is most effective for shielding secondary gamma rays.
E. The annual equivalent dose limit for the skin is 500 mSv.
B. Shielding placement most significantly affects staff dose in Ac-225 therapy.
B. Remote afterloading minimizes staff exposure in alpha therapy.
D. Neutrons are most challenging to shield in proton therapy facilities.
B. Significant incident investigations analyze unintended exposures (IR(ME)R).
A. Source activity drives the dose rate from At-211 (alpha/gamma emitter).
A. The half-life of At-211 is ~7.2 hours.
C. Shielding is critical for reducing public dose in carbon ion facilities.

Radiation Physics (20 Questions)

What is the approximate linear energy transfer (LET) of a 600 MeV/u carbon ion at the proximal edge of a 10 cm spread-out Bragg peak (SOBP) in water, considering nuclear fragmentation?
A. 50 keV/μm
B. 100 keV/μm
C. 200 keV/μm
D. 300 keV/μm
E. 400 keV/μm
For a 35 MV photon beam interacting with a lead flattening filter, what is the dominant interaction process contributing to neutron production?
A. Photoelectric effect
B. Compton scattering
C. Pair production
D. Photodisintegration
E. Coherent scattering
Calculate the tenth-value layer (TVL) for a 20 MV photon beam in concrete, given a mass attenuation coefficient of 0.04 cm²/g and density of 2.35 g/cm³.
A. 15 cm
B. 20 cm
C. 25 cm
D. 30 cm
E. 35 cm
In a FLASH radiotherapy setup with 100 MeV electrons, what is the primary mechanism enhancing normal tissue sparing at dose rates exceeding 200 Gy/s?
A. Enhanced Compton scattering
B. Transient oxygen depletion
C. Reduced pair production
D. Increased nuclear interactions
E. Altered bremsstrahlung yield
What is the continuous slowing down approximation (CSDA) range of a 700 MeV proton in water, accounting for nuclear interactions?
A. 40 cm
B. 50 cm
C. 60 cm
D. 70 cm
E. 80 cm
Which factor most significantly affects the relative biological effectiveness (RBE) of a 500 MeV/u carbon ion beam at the distal edge of the SOBP?
A. Beam energy spread
B. High LET
C. Tissue oxygenation
D. Beam divergence
E. Collimator material
What is the energy of a characteristic X-ray emitted from the K-shell to L-shell transition in tungsten (Z=74)?
A. 20 keV
B. 40 keV
C. 60 keV
D. 80 keV
E. 100 keV
For an 8 keV photon beam in bone, what is the dominant interaction, and how does its probability scale with energy (E)?
A. Compton scattering, ∝ 1/E
B. Photoelectric effect, ∝ 1/E³
C. Pair production, ∝ E²
D. Coherent scattering, ∝ 1/E²
E. Photodisintegration, ∝ E
What is the primary interaction mechanism for 100 MeV neutrons in soft tissue, considering secondary particle production?
A. Elastic scattering with protons
B. Inelastic scattering with oxygen
C. Neutron capture by hydrogen
D. Spallation reactions
E. Compton scattering
What is the mass stopping power ratio of bone to water for a 40 MeV electron beam, considering density effects (bone: 1.85 g/cm³, water: 1.00 g/cm³)?
A. 0.90
B. 1.00
C. 1.20
D. 1.50
E. 1.80
Which factor most significantly affects the production of secondary positrons in a 30 MV photon beam interacting with a tungsten collimator?
A. Target atomic number
B. Pair production threshold
C. Collimator thickness
D. Beam divergence
E. Gantry angle
What is the dose rate at 4 meters from a 12 GBq Cs-137 source, given a specific gamma-ray constant of 0.33 R·m²/Ci·h, ignoring shielding?
A. 0.05 mGy/h
B. 0.5 mGy/h
C. 5 mGy/h
D. 50 mGy/h
E. 500 mGy/h
Which equation correctly describes the energy dependence of the photoelectric effect cross-section in a high-Z material?
A. ∝ E
B. ∝ E²
C. ∝ 1/E³
D. ∝ 1/E²
E. ∝ ln(E)
What is the approximate range of a 50 MeV electron in lead (density 11.34 g/cm³), accounting for bremsstrahlung losses?
A. 1.0 cm
B. 1.5 cm
C. 2.0 cm
D. 2.5 cm
E. 3.0 cm
In a targeted alpha therapy using Pb-212, what is the primary mode of energy deposition in tumour cells?
A. Bremsstrahlung radiation
B. Alpha particle emission
C. Gamma ray emission
D. Compton scattering
E. Photoelectric effect
What is the primary source of secondary neutrons in a 600 MeV/u carbon ion beam interacting with tissue?
A. Elastic scattering
B. Nuclear fragmentation
C. Compton scattering
D. Pair production
E. Bremsstrahlung radiation
Which material property most significantly affects the angular scattering of a 500 MeV proton beam in a patient-specific bolus?
A. Electron density
B. Atomic number
C. Mass density
D. Thermal conductivity
E. Magnetic susceptibility
What is the approximate energy threshold for muon production in a proton beam interacting with a copper target?
A. 1 GeV
B. 2 GeV
C. 3 GeV
D. 4 GeV
E. 5 GeV
Which shielding configuration is most effective for 150 MeV neutrons in a proton therapy facility?
A. Lead followed by concrete
B. Polyethylene followed by boron
C. Steel followed by water
D. Perspex followed by cadmium
E. Tungsten followed by paraffin
What is the primary mode of energy loss for a 20 GeV electron in tungsten, considering radiative effects?
A. Collisional interactions
B. Bremsstrahlung radiation
C. Compton scattering
D. Pair production
E. Synchrotron radiation

Dosimetry (20 Questions)

What is the absorbed dose rate at 3 meters from a 8 GBq I-131 source, given a specific gamma-ray constant of 0.22 R·m²/Ci·h, ignoring shielding?
A. 0.1 mGy/h
B. 1 mGy/h
C. 10 mGy/h
D. 100 mGy/h
E. 1000 mGy/h
Which quantity is most critical for assessing the risk of radiation-induced cataracts in radiotherapy patients?
A. Absorbed dose
B. Equivalent dose
C. Effective dose
D. Kerma
E. Exposure
What is the radiation weighting factor (W_R) for 100 MeV protons in radiation protection, per ICRP 103?
A. 1
B. 2
C. 5
D. 10
E. 20
What is the percentage depth dose (PDD) at 25 cm depth for a 25 MV photon beam (10x10 cm² field, SSD=100 cm) in water, given a PDD of 100% at dmax=4.0 cm and an attenuation coefficient of 0.035 cm⁻¹?
A. 40%
B. 45%
C. 50%
D. 55%
E. 60%
Which dosimeter is most suitable for measuring dose in a 0.03 mm² microbeam radiotherapy field with 250 keV X-rays?
A. Ionisation chamber
B. TLD
C. Nanodot OSL
D. Radiochromic film
E. Silicon diode
What is the monitor unit (MU) required to deliver 5 Gy to a depth of 18 cm through a 4 cm bone slab (density=1.85 g/cm³, μ/ρ=0.05 cm²/g) for a 20 MV photon beam (10x10 cm² field, SAD=100 cm, output factor=1.03, TMR=0.62)?
A. 500 MU
B. 600 MU
C. 700 MU
D. 800 MU
E. 900 MU
What is the approximate depth of the 85% isodose line for a 600 MeV/u carbon ion beam in water, assuming a 7 cm SOBP?
A. 30 cm
B. 35 cm
C. 40 cm
D. 45 cm
E. 50 cm
Which factor most significantly affects the accuracy of dosimetry in a 0.05 cm² field for proton arc therapy?
A. Detector lateral response
B. Beam energy spread
C. Source-to-detector distance
D. Collimator misalignment
E. Nuclear interactions
What is the primary advantage of perovskite-based detectors in FLASH radiotherapy dosimetry?
A. High spatial resolution
B. Ultra-fast response time
C. Low cost
D. Energy independence
E. Large dynamic range
What is the tissue maximum ratio (TMR) at 25 cm depth for a 25 MV photon beam (10x10 cm² field, SAD=100 cm), given a PDD of 45% at 25 cm, PDD of 100% at dmax=4.0 cm, and BSF of 1.05?
A. 0.40
B. 0.43
C. 0.46
D. 0.49
E. 0.52
What is the equivalent dose from a 2 mGy absorbed dose of 50 MeV neutrons to the liver?
A. 0.02 mSv
B. 0.2 mSv
C. 2 mSv
D. 20 mSv
E. 40 mSv
What is the effective dose from a 4 mGy absorbed dose to the thyroid (tissue weighting factor=0.04) from 100 MeV protons (W_R=2)?
A. 0.016 mSv
B. 0.16 mSv
C. 1.6 mSv
D. 16 mSv
E. 160 mSv
Which dosimetry protocol is most suitable for calibrating a 700 MeV proton beam in a water phantom?
A. TG-21
B. TG-51
C. IAEA TRS-398
D. AAPM TG-61
E. TRS-483
What is the primary source of uncertainty in 3D polymer gel dosimetry for verifying a carbon ion arc therapy plan?
A. Energy dependence
B. Chemical homogeneity
C. Spatial resolution
D. Readout reproducibility
E. Temperature sensitivity
What is the monitor unit (MU) correction factor for a 6 cm lung inhomogeneity (density=0.26 g/cm³, μ/ρ=0.03 cm²/g) in a 25 MV photon beam at 20 cm depth?
A. 0.85
B. 0.90
C. 0.95
D. 1.00
E. 1.05
Which dosimeter is most suitable for in-vivo dosimetry in a MR-guided proton arc therapy setup?
A. Ionisation chamber
B. TLD
C. MOSFET
D. Perovskite detector
E. Plastic scintillator
What is the primary purpose of the collimator scatter factor (Sc) in microbeam radiotherapy dosimetry?
A. To quantify patient scatter
B. To normalize dose for collimator settings
C. To measure dose at depth
D. To assess beam flatness
E. To determine penumbra width
What is the approximate penumbra width (20%–80%) for a 700 MeV proton beam at 60 cm depth in water, considering multiple Coulomb scattering?
A. 4 mm
B. 6 mm
C. 8 mm
D. 10 mm
E. 12 mm
Which factor most significantly affects the dose rate from a carbon ion arc therapy source?
A. Beam scanning speed
B. Source intensity
C. Source energy
D. Source material
E. Source shape
What is the primary advantage of alanine dosimetry in FLASH radiotherapy?
A. High spatial resolution
B. Dose-rate independence
C. Real-time readout
D. Low cost
E. Energy independence

Radiotherapy Treatment Planning (20 Questions)

What is the primary advantage of carbon ion arc therapy over intensity-modulated carbon ion therapy (IMCT)?
A. Reduced treatment time
B. Enhanced dose conformity
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for defining the robust optimization volume in proton arc therapy for a liver tumour?
A. Tumour size
B. Range uncertainty and organ motion
C. Beam energy
D. Field size
E. Monitor units
What is the primary advantage of microbeam radiotherapy for ocular melanoma?
A. Uniform dose distribution
B. Enhanced normal tissue sparing
C. Increased treatment time
D. Lower cost
E. Simplified planning
Which dose calculation algorithm is most accurate for carbon ion therapy in a lung tumour with a 0.26 g/cm³ density heterogeneity?
A. Pencil beam
B. Convolution-superposition
C. Monte Carlo
D. Acuros XB
E. Collapsed cone
What is the primary purpose of a dynamic ridge filter in carbon ion arc therapy?
A. To increase beam energy
B. To adjust SOBP width dynamically
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the distal dose fall-off in proton arc therapy for a brain tumour?
A. Beam energy
B. Nuclear interactions
C. Gantry rotation speed
D. Collimator shape
E. Monitor units
What is the primary advantage of AI-driven adaptive planning in FLASH radiotherapy?
A. Reduced treatment time
B. Real-time dose optimization
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for biologically effective dose (BED) calculation in microbeam radiotherapy (α/β=3 Gy)?
A. Total dose
B. Peak dose per fraction
C. Beam energy
D. Field size
E. Monitor units
What is the primary purpose of a patient-specific aperture in carbon ion therapy for a skull base tumour?
A. To increase beam energy
B. To sharpen lateral dose fall-off
C. To reduce skin sparing
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose conformity in proton arc therapy for a spinal tumour?
A. Spot scanning pattern
B. Beam energy
C. Field size
D. Gantry rotation speed
E. Monitor units
What is the primary advantage of synthetic CT generation in MR-only proton arc therapy planning?
A. Reduced imaging time
B. Accurate stopping power estimation
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which structure is most critical for dose constraints in proton arc therapy for a mediastinal tumour?
A. Spinal cord
B. Liver
C. Kidneys
D. Heart
E. Stomach
What is the primary purpose of a beam-specific bolus in proton arc therapy?
A. To increase beam energy
B. To conform dose to target depth
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose heterogeneity in carbon ion arc therapy?
A. Nuclear fragmentation
B. Beam energy
C. Field size
D. Gantry rotation speed
E. Monitor units
What is the primary advantage of deep reinforcement learning in microbeam radiotherapy planning?
A. Reduced treatment time
B. Adaptive peak-valley optimization
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for tumour control probability (TCP) in carbon ion arc therapy?
A. Tumour volume
B. Biological effective dose
C. Beam energy
D. Field size
E. Monitor units
What is the primary purpose of a range compensator in proton arc therapy?
A. To increase beam energy
B. To correct for tissue heterogeneity
C. To shape the radiation field
D. To monitor dose delivery
E. To reduce scatter radiation
Which factor most significantly affects the dose distribution in high-dose-rate (HDR) brachytherapy for cervical cancer?
A. Source dwell time
B. Beam energy
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of hypoxia-guided dose painting in proton arc therapy?
A. Reduced treatment time
B. Targeting radioresistant subvolumes
C. Lower cost
D. Increased scatter dose
E. Simplified planning
Which parameter is most critical for dose-volume histogram (DVH) optimization in microbeam radiotherapy?
A. Beam energy
B. Valley dose constraints
C. Field size
D. Monitor units
E. Collimator angle

Imaging (20 Questions)

What is the primary advantage of 10T MRI in radiotherapy planning for glioblastoma?
A. High spatial resolution
B. Low radiation dose
C. Real-time imaging
D. Electron density information
E. Low cost
Which imaging modality is most suitable for assessing intrafraction motion in pancreatic proton arc therapy?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Fluoroscopy
What is the primary source of contrast in chemical exchange saturation transfer (CEST) MRI for oncology?
A. Proton density
B. Molecular exchange rates
C. Electron density
D. Atomic number
E. Blood flow
Which factor most significantly affects the contrast resolution in photon-counting CT for proton arc therapy planning?
A. Energy thresholding
B. Tube voltage
C. Reconstruction algorithm
D. Field of view
E. Gantry rotation speed
What is the primary advantage of Bi-213 PET in targeted alpha therapy planning?
A. High spatial resolution
B. Low radiation dose
C. Alpha emitter tracking
D. Real-time imaging
E. Low cost
Which radionuclide is most suitable for imaging tumour proliferation in proton arc therapy planning?
A. F-18 (FLT)
B. Tc-99m
C. Ga-68
D. I-131
E. Zr-89
What is the primary purpose of the point spread function (PSF) in MR-guided radiotherapy?
A. To measure radiation dose
B. To quantify spatial resolution
C. To assess image contrast
D. To determine image noise
E. To monitor patient motion
Which factor most significantly affects the temporal resolution in 10T MRI for radiotherapy planning?
A. Field strength
B. Gradient slew rate
C. RF coil sensitivity
D. Reconstruction algorithm
E. Field of view
What is the primary advantage of dual-energy CT in carbon ion arc therapy planning?
A. High soft tissue contrast
B. Improved stopping power estimation
C. Low radiation dose
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for delineating soft tissue sarcomas in carbon ion therapy planning?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary source of artefacts in 10T MRI for radiotherapy planning?
A. Photon scattering
B. B0 field inhomogeneity
C. Metal implants
D. Reconstruction algorithm
E. Patient motion
Which factor most significantly affects the signal-to-noise ratio in PET-MRI hybrid imaging for proton arc therapy?
A. Radiotracer activity
B. Magnetic field strength
C. Reconstruction algorithm
D. Field of view
E. Patient size
What is the primary advantage of hyperpolarized 13C MRI in carbon ion therapy planning?
A. High spatial resolution
B. Low radiation dose
C. Metabolic pathway imaging
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for assessing oesophageal tumour motion in carbon ion arc therapy planning?
A. CT
B. MRI
C. PET
D. 4D-CT
E. Ultrasound
What is the primary purpose of deformable image registration in proton arc therapy planning?
A. To measure radiation dose
B. To account for anatomical changes
C. To assess image contrast
D. To determine spatial resolution
E. To monitor image noise
Which factor most significantly affects the radiation dose in photon-counting CT for radiotherapy planning?
A. Energy thresholding
B. Tube current
C. Reconstruction algorithm
D. Field of view
E. Gantry rotation speed
What is the primary advantage of diffusion-weighted MRI in microbeam radiotherapy planning?
A. High spatial resolution
B. Assessment of tumour cellularity
C. Low radiation dose
D. Real-time imaging
E. Low cost
Which imaging modality is most suitable for real-time dosimetry in FLASH radiotherapy?
A. CT
B. MRI
C. PET
D. Cherenkov imaging
E. Ultrasound
What is the primary source of contrast in arterial spin labelling (ASL) MRI for oncology?
A. Proton density
B. Blood flow
C. Electron density
D. Radiotracer uptake
E. Tissue relaxation time
Which factor most significantly affects the spatial resolution in MR spectroscopy for radiotherapy planning?
A. Voxel size
B. Gradient strength
C. Reconstruction algorithm
D. Field of view
E. Patient size

Radiation Protection (20 Questions)

What is the annual equivalent dose limit for the lens of the eye for radiation workers in the UK, per IRR 2017?
A. 1 mSv
B. 15 mSv
C. 20 mSv
D. 50 mSv
E. 150 mSv
Which material is most effective for shielding 250 MeV neutrons in a carbon ion arc therapy facility?
A. Lead
B. Concrete with hydrogen
C. Perspex
D. Steel
E. Water
What is the primary purpose of the justification principle in IR(ME)R 2017 for radiotherapy?
A. To maximize radiation dose
B. To ensure clinical benefit outweighs risk
C. To measure radiation dose
D. To calibrate dosimeters
E. To monitor radiation levels
Which factor most significantly affects the occupational dose in a microbeam radiotherapy setup?
A. Beam energy
B. X-ray shielding design
C. Field size
D. Gantry angle
E. Monitor units
What is the approximate half-value layer (HVL) for a 600 MeV/u carbon ion beam in lead?
A. 10 cm
B. 15 cm
C. 20 cm
D. 25 cm
E. 30 cm
Which type of personal dosimeter is most suitable for monitoring dose in a carbon ion arc therapy setup?
A. Film badge
B. TLD
C. MOSFET
D. OSL dosimeter
E. Real-time scintillator
What is the primary source of stray radiation in a proton arc therapy treatment room?
A. Primary beam
B. Patient scatter
C. Neutron contamination
D. Bremsstrahlung radiation
E. Compton scattering
Which regulation requires training for radiation workers in a radiotherapy department in the UK?
A. IRR 2017
B. IR(ME)R 2017
C. RIDDOR 2013
D. COSHH 2002
E. MHRA 2008
What is the dose rate at 2 meters from a 6 GBq Pb-212 source, given a specific gamma-ray constant of 0.03 R·m²/Ci·h, ignoring shielding?
A. 0.1 mGy/h
B. 1 mGy/h
C. 10 mGy/h
D. 100 mGy/h
E. 1000 mGy/h
Which factor most significantly affects the shielding requirements for a FLASH radiotherapy facility?
A. Beam energy
B. Electron scatter yield
C. Field size
D. Gantry angle
E. Monitor units
What is the primary purpose of a radiation protection advisor (RPA) in a proton arc therapy department?
A. To deliver radiotherapy
B. To provide expert safety advice
C. To calibrate dosimeters
D. To monitor patient doses
E. To perform quality assurance
Which material is most effective for shielding secondary gamma rays in a carbon ion arc therapy bunker?
A. Lead
B. Concrete
C. Polyethylene
D. Boron
E. Perspex
What is the annual effective dose limit for the public in the UK, per IRR 2017?
A. 1 mSv
B. 5 mSv
C. 10 mSv
D. 20 mSv
E. 50 mSv
Which factor most significantly affects the dose to staff during Pb-212 targeted alpha therapy procedures?
A. Source activity
B. Shielding placement
C. Field size
D. Gantry angle
E. Monitor units
What is the primary advantage of a remote afterloading system in Pb-212 radionuclide therapy?
A. Reduced treatment time
B. Minimized staff exposure
C. Increased patient comfort
D. Simplified quality assurance
E. Enhanced dose delivery
Which type of radiation is most hazardous for external exposure in a carbon ion arc therapy facility?
A. Alpha particles
B. Beta particles
C. Gamma rays
D. Neutrons
E. X-rays
What is the primary purpose of a dose constraint in carbon ion arc therapy planning?
A. To deliver radiotherapy
B. To limit normal tissue exposure
C. To calibrate dosimeters
D. To monitor patient doses
E. To perform quality assurance
Which factor most significantly affects the dose rate from a Pb-212 unsealed source?
A. Source activity
B. Alpha particle energy
C. Source size
D. Source material
E. Source shape
What is the approximate half-life of Pb-212 used in targeted alpha therapy?
A. 10.6 hours
B. 2 days
C. 7 days
D. 14 days
E. 30 days
Which principle is most critical for reducing occupational dose in microbeam radiotherapy procedures?
A. Time
B. Distance
C. Shielding
D. Justification
E. Calibration

Answers

Radiation Physics

B. At the proximal edge of a 10 cm SOBP, a 600 MeV/u carbon ion has an LET of ~100 keV/μm due to lower ionization density.
D. Photodisintegration in lead produces neutrons for 35 MV photons (E > 7 MeV).
C. TVL = ln(10)/(μ·ρ) = 2.303/(0.04·2.35) ≈ 25 cm.
B. Transient oxygen depletion enhances normal tissue sparing in FLASH radiotherapy at >200 Gy/s.
C. CSDA range for 700 MeV protons in water is ~60 cm (R ∝ E¹·⁵, adjusted for nuclear interactions).
B. High LET at the distal edge increases RBE (~4–5) for 500 MeV/u carbon ions.
C. K-to-L transition in tungsten emits ~60 keV photons (K-shell binding energy).
B. Photoelectric effect dominates at 8 keV in bone, scaling as ∝ 1/E³.
D. Spallation reactions dominate for 100 MeV neutrons, producing secondary particles.
D. Mass stopping power ratio of bone to water is ~1.50 due to density (S ∝ ρ).
B. Pair production threshold (>1.022 MeV) drives positron production in 30 MV beams.
B. Dose rate = (Γ·A)/r² = (0.33·12/37)/(4²) ≈ 0.5 mGy/h (1 GBq = 27 mCi, 1 R ≈ 8.7 mGy).
C. Photoelectric effect cross-section scales as ∝ 1/E³ in high-Z materials.
C. Range in lead = 50/11.34 ≈ 2.0 cm (R ≈ 0.5 E, adjusted for bremsstrahlung).
B. Alpha particle emission is the primary energy deposition mode for Pb-212.
B. Nuclear fragmentation produces secondary neutrons in carbon ion beams.
B. Atomic number drives angular scattering via multiple Coulomb interactions.
A. Muon production in copper requires ~1 GeV (threshold for μ⁺/μ⁻ production).
B. Polyethylene slows 150 MeV neutrons, and boron captures thermal neutrons.
B. Bremsstrahlung radiation dominates for 20 GeV electrons in tungsten (high Z, high E).

Dosimetry

B. Dose rate = (Γ·A)/r² = (0.22·8/37)/(3²) ≈ 1 mGy/h (1 GBq = 27 mCi).
B. Equivalent dose to the lens assesses cataract risk (deterministic effect).
B. W_R for 100 MeV protons is 2 per ICRP 103.
B. PDD = 100 · e^(-μ·(d-dmax)) = 100 · e^(-0.035·(25-4.0)) ≈ 45%.
D. Radiochromic film offers sub-mm resolution for 0.03 mm² microbeam fields.
D. MU = Dose/(TMR·Output·CF), CF = e^(μ·t·(ρ-1)) = e^(0.05·4·(1.85-1)) ≈ 1.18, MU = 5/(0.62·1.03·1.18) ≈ 800 MU.
C. 600 MeV/u carbon ion range ~45 cm, 85% isodose at SOBP center ~40 cm.
A. Detector lateral response affects accuracy in 0.05 cm² proton fields due to averaging.
B. Perovskite detectors offer ultra-fast response for FLASH dose rates (>10⁶ Gy/s).
B. TMR = PDD(d)/PDD(dmax) · BSF = 45/(100·1.05) ≈ 0.43.
E. Equivalent dose = 2 mGy · 20 (W_R for 50 MeV neutrons) = 40 mSv.
B. Effective dose = 4 mGy · 0.04 (W_T for thyroid) · 2 (W_R for protons) = 0.16 mSv.
C. IAEA TRS-398 is suitable for 700 MeV proton beam calibration.
B. Chemical homogeneity is the primary uncertainty in 3D polymer gel dosimetry.
B. CF = e^(μ·t·(ρ-1)) = e^(0.03·6·(0.26-1)) ≈ 0.90 for lung inhomogeneity.
D. Perovskite detectors are MR-compatible and suitable for proton arc therapy.
B. Collimator scatter factor (Sc) normalizes dose for collimator settings in microbeam dosimetry.
C. Penumbra width for 700 MeV protons at 60 cm is ~8 mm (Coulomb scattering, nuclear interactions).
B. Source intensity drives dose rate in carbon ion arc therapy.
B. Alanine dosimetry is dose-rate independent, ideal for FLASH radiotherapy.

Radiotherapy Treatment Planning

B. Carbon ion arc therapy enhances dose conformity via multi-angle delivery.
B. Range uncertainty and organ motion are critical for liver robust optimization.
B. Microbeam radiotherapy spares normal tissue (e.g., retina) in ocular melanoma.
C. Monte Carlo is most accurate for carbon ion therapy in low-density lung.
B. Dynamic ridge filters adjust SOBP width in carbon ion arc therapy for conformal dosing.
B. Nuclear interactions (fragmentation tail) affect distal dose fall-off in proton arc therapy.
B. AI-driven adaptive planning enables real-time dose optimization in FLASH radiotherapy.
B. Peak dose per fraction drives BED (BED = D·(1+d/(α/β))) in microbeam radiotherapy.
B. Patient-specific apertures sharpen lateral dose fall-off in skull base carbon ion therapy.
A. Spot scanning pattern affects dose conformity in proton arc therapy for spinal tumours.
B. Synthetic CT provides accurate stopping power for MR-only proton arc planning.
D. The heart is critical for dose constraints in mediastinal proton arc therapy.
B. Beam-specific bolus conforms dose to target depth in proton arc therapy.
A. Nuclear fragmentation causes dose heterogeneity in carbon ion arc therapy.
B. Deep reinforcement learning optimizes peak-valley doses in microbeam radiotherapy.
B. Biological effective dose drives TCP in carbon ion arc therapy (BED = D·(1+d/(α/β))).
B. Range compensators correct for tissue heterogeneity in proton arc therapy.
A. Source dwell time determines dose distribution in HDR brachytherapy.
B. Hypoxia-guided dose painting targets radioresistant subvolumes in proton arc therapy.
B. Valley dose constraints drive DVH optimization in microbeam radiotherapy.

Imaging

A. 10T MRI provides ultra-high spatial resolution for glioblastoma delineation.
B. MRI is suitable for pancreatic intrafraction motion due to soft tissue contrast.
B. CEST MRI contrast arises from molecular exchange rates (e.g., amide protons).
A. Energy thresholding affects contrast resolution in photon-counting CT.
C. Bi-213 PET tracks alpha emitters for targeted therapy planning.
A. F-18 (FLT) is suitable for imaging tumour proliferation.
B. PSF quantifies spatial resolution in MR-guided radiotherapy.
B. Gradient slew rate affects temporal resolution in 10T MRI.
B. Dual-energy CT improves stopping power estimation for carbon ion arc therapy.
B. MRI is ideal for delineating soft tissue sarcomas due to contrast.
B. B0 field inhomogeneity causes artefacts in 10T MRI.
B. Magnetic field strength affects SNR in PET-MRI hybrid imaging.
C. Hyperpolarized 13C MRI images metabolic pathways for tumour characterization.
D. 4D-CT is suitable for assessing oesophageal tumour motion.
B. Deformable image registration accounts for anatomical changes in proton arc therapy.
B. Tube current most significantly affects photon-counting CT dose.
B. Diffusion-weighted MRI assesses tumour cellularity in microbeam planning.
D. Cherenkov imaging enables real-time dosimetry in FLASH radiotherapy.
B. ASL MRI contrast arises from blood flow (non-invasive perfusion).
A. Voxel size most significantly affects spatial resolution in MR spectroscopy.

Radiation Protection

C. The annual equivalent dose limit for the lens of the eye is 20 mSv (IRR 2017).
B. Concrete with hydrogen shields 250 MeV neutrons via elastic scattering and capture.
B. Justification in IR(ME)R 2017 ensures clinical benefit outweighs risk.
B. X-ray shielding design most significantly affects dose in microbeam radiotherapy.
D. HVL for 600 MeV/u carbon ions in lead is ~25 cm (high density).
E. Real-time scintillators are suitable for carbon ion arc therapy due to high dose rates.
C. Neutron contamination is the primary stray radiation in proton arc therapy.
A. IRR 2017 requires training for radiation workers.
B. Dose rate = (Γ·A)/r² = (0.03·6/37)/(2²) ≈ 1 mGy/h (1 GBq = 27 mCi).
B. Electron scatter yield drives shielding requirements for FLASH radiotherapy.
B. RPAs provide expert safety advice in proton arc therapy departments.
A. Lead is most effective for shielding secondary gamma rays.
A. The annual effective dose limit for the public is 1 mSv (IRR 2017).
B. Shielding placement most significantly affects staff dose in Pb-212 therapy.
B. Remote afterloading minimizes staff exposure in Pb-212 therapy.
D. Neutrons are most hazardous for external exposure in carbon ion arc therapy.
B. Dose constraints limit normal tissue exposure in carbon ion arc therapy planning.
A. Source activity drives the dose rate from Pb-212 (alpha/gamma emitter).
A. The half-life of Pb-212 is ~10.6 hours.
C. Shielding is critical for reducing occupational dose in microbeam radiotherapy.

Sunday, May 18, 2025

FRCR Oncology Part 1: PHYSICS - 3 (4 SETS, 100+100+100+100 QUESTIONS, ANSWERS BELOW)

Radiation Physics (20 Questions)

Dosimetry (20 Questions)

Radiotherapy Treatment Planning (20 Questions)

Imaging (20 Questions)

Radiation Protection (20 Questions)

Answers

Radiation Physics

Dosimetry

Radiotherapy Treatment Planning

Imaging

Radiation Protection

Radiation Physics (20 Questions)

Dosimetry (20 Questions)

Radiotherapy Treatment Planning (20 Questions)

Imaging (20 Questions)

Radiation Protection (20 Questions)

Answers

Radiation Physics

Dosimetry

Radiotherapy Treatment Planning

Imaging

Radiation Protection

Radiation Physics (20 Questions)

Dosimetry (20 Questions)

Radiotherapy Treatment Planning (20 Questions)

Imaging (20 Questions)

Radiation Protection (20 Questions)

Answers

Radiation Physics

Dosimetry

Radiotherapy Treatment Planning

Imaging

Radiation Protection

Radiation Physics (20 Questions)

Dosimetry (20 Questions)

Radiotherapy Treatment Planning (20 Questions)

Imaging (20 Questions)

Radiation Protection (20 Questions)

Answers

Radiation Physics

Dosimetry

Radiotherapy Treatment Planning

Imaging

Radiation Protection