Page 1 of 154
ABR Medical Physics Certification Exam QUESTIONS
AND VERIFIED ANSWERS WITH RATIONALES JUST
RELEASED
ABR Medical Physics Certification Exam
Summarized Exam Topics Covered in Point Form
Exam Structure & Eligibility
• Part 1 Qualifying Exam: Computer-based, General section (~5 hours, 130 questions), Clinical
section (~3 hours, 80 questions)
• Part 2 Qualifying Exam: Specialty-specific (Diagnostic, Therapeutic, or Nuclear), computer-
based, ~5 hours, one session
• Part 3 Oral Certifying Exam: Remote oral exam, ~4 hours, five examiners testing five categories
• Eligibility: CAMPEP-accredited graduate/certificate/DMP program enrollment/completion +
CAMPEP-accredited residency for Part 2/3
• Fees: Application 250,Part1250,Part1250, Part 2 640,Part3640,Part3780; re-exam fees apply
Medical Physics - Part 1 General Section Topics
• Radiation Physics (44 questions): Atomic/nuclear structure, radioactive decay, photon/matter
interactions, charged particle interactions
• Radiation Measurement (16 questions): Ion chambers, TLD, film dosimetry, electrometer,
calibration protocols
• Radiation Protection & Safety (12 questions): ALARA, shielding design (TVL, HVL), NCRP
recommendations, occupational/public dose limits, transportation, contamination control
• Diagnostic Medical Physics (16 questions): X-ray tube, fluoroscopy, mammography, CT, image
quality, QC
• Nuclear Medical Physics (16 questions): Scintillation cameras, PET, SPECT,
radiopharmaceuticals, gamma counting
• Therapy Medical Physics (16 questions): Linac, electron/photon beams, brachytherapy,
dosimetric calculations
• Math & Statistics (8 questions): Poisson, Gaussian, uncertainty propagation, error analysis
Medical Physics - Part 1 Clinical Section Topics
• Anatomy (20 questions): Major organ systems, anatomical terminology, cross-sectional
anatomy (CT, MRI), vertebral levels, cranial nerves, brain anatomy (circle of Willis, corpus
callosum), GI tract, cardiovascular system
• Radiation Biology & Pathology (20 questions): Cell cycle, radiosensitivity (M > G2 > G1 > S),
fraction of cells, oxygen enhancement ratio (OER), linear-quadratic model, BED, normal tissue
complications, acute radiation syndrome, stochastic/deterministic effects, LD50/60
• Medical Terminology (20 questions): Standard medical prefixes/suffixes, disease terminology,
procedural terminology
Diagnostic Medical Physics - Part 2/3
• X-ray Imaging: X-ray tube (anode, cathode, filament), generators (single-phase, three-phase,
high-frequency), filtration (inherent, added), beam collimation, grids (grid ratio, cut-off),
automatic exposure control (AEC)
• Fluoroscopy: Image intensifier, flat panel detectors, dose area product (DAP), last image hold,
pulsed fluoroscopy, dose management
, Page 2 of 154
• Mammography: X-ray target/filter combinations (Mo/Mo, Rh/Rh, W), compression, grid,
magnification, AEC positioning
• Computed Tomography (CT): Generations, helical/spiral CT, multi-detector CT, cone-beam CT,
image reconstruction (FBP, iterative), window/level, dose metrics (CTDI, DLP, SSDE), artifacts
(beam hardening, photon starvation, metal, motion)
• Magnetic Resonance Imaging (MRI): T1/T2 relaxation, spin echo, gradient echo, inversion
recovery (STIR, FLAIR), k-space, coils, artifacts (chemical shift, aliasing, susceptibility, motion),
safety (AC/DC/RF fields), SAR
• Ultrasound (US): Transducer design (piezoelectric, λ/2 thickness), frequency selection,
resolution (axial, lateral, elevational), Doppler (color, power, spectral), artifacts (shadowing,
enhancement, reverberation, aliasing), biological effects (thermal, mechanical/MI)
Nuclear Medical Physics - Part 2/3
• Instrumentation: Scintillation (NaI(Tl)) cameras, photomultiplier tubes (PMTs), pulse height
analyzer, collimators (parallel, converging, diverging, pinhole), energy resolution, count rate
performance
• Planar Imaging & SPECT: Image acquisition, reconstruction (FBP, iterative), attenuation
correction (Chang, CT-based), scatter correction, dead time, uniformity, resolution
• Positron Emission Tomography (PET): Annihilation coincidence detection, time-of-flight (TOF),
detectors (BGO, LYSO, LSO), randoms, scatter, normalization, attenuation correction (CT,
transmission), quantification (SUV), partial volume effect
• Radiopharmaceuticals: 99mTc (6h), 18F (110m), 131I (8d), 123I (13h), 201Tl (73h), 111In (2.8d),
67Ga (3.3d), 68Ga (68m), 82Rb (75s), cyclotron vs generator production
• Quality Control & Safety: Daily/weekly QC, dose calibrator constancy, well counter, survey
meter, contamination monitoring, shielding (syringe shields, L-block), sources decay correction
Therapeutic Medical Physics - Part 2/3
• Linear Accelerators (Linacs): Electron gun, accelerator structure (traveling/standing wave),
microwave components (magnetron/klystron), bending magnet, target (photon), scattering foil
(electron), flattening filter/flattening filter free (FFF), MLC, ion chamber monitor
• Photon Beam Dosimetry: Percentage depth dose (PDD), tissue maximum ratio (TMR), tissue
phantom ratio (TPR), output factors (Sc, Sp, Scp), off-axis factor, wedge factor, tray factor, block
factor
• Electron Beam Dosimetry: Mean energy at surface, practical range (Rp), depth of maximum
dose (dmax), surface dose, X-ray contamination, cutout factors, effective SSD, cone selection,
energy selection
• Treatment Planning (Photons/Electrons): Isodose distributions, dose-volume histogram (DVH),
IMRT, VMAT, SBRT, SRS, heterogeneity corrections (lung, bone), algorithm types (pencil beam,
convolution/superposition, Monte Carlo, Acuros), plan evaluation
• Brachytherapy: Sealed sources (125I, 103Pd, 192Ir, 137Cs, 60Co, 131Cs), HDR vs LDR, manual
afterloading vs remote afterloader (HDR), TG-43 formalism, source strength specification (air
kerma strength, reference air kerma rate), treatment planning (interstitial, intracavitary),
prostate seed implant dosimetry
• Radiation Protection in Therapy: Linac bunker shielding (TVL, NCRP 151), neutron shielding (18
MV+), maze design, door design, controlled/uncontrolled areas, patient release after I-131,
brachytherapy source handling (syringe shields, L-block, forceps, time/distance/shielding)
Radiobiology
• Cellular Effects: Direct vs indirect DNA damage (hydrolysis, OH radicals), linear energy transfer
(LET), relative biological effectiveness (RBE), oxygen enhancement ratio (OER = 2.5-3 for low LET,
~1 for high LET), cell survival curves (shoulder = repair capacity), cell cycle radiosensitivity (M
, Page 3 of 154
phase most sensitive, late S phase most resistant), radiation-induced apoptosis, mitotic
catastrophe
• Fractionation: Linear-quadratic model (α/β ratio: early-responding tissues 10 Gy, late-
responding tissues 2-3 Gy), biologically effective dose (BED = nd[1 + d/(α/β)]), EQD2, isoeffect
relationships, repair (sublethal, potentially lethal)
• Normal Tissue Effects: Early vs late reactions, serial vs parallel organs, TD5/5, TD50/5, volume
effects, complication probability models (NTCP, LKB model)
• Tumor Effects: 4 R's of radiobiology (Repair, Repopulation, Reoxygenation, Redistribution),
tumor control probability (TCP), accelerated repopulation, hypoxia, heterogeneity
• Acute Radiation Syndrome: Hematopoietic (2-5 Gy), GI (10-15 Gy), CNS (>30 Gy), LD50/60 (3.5-4
Gy with supportive care, ~5 Gy with medical support)
• Radiation Carcinogenesis: Stochastic effect, latency period (leukemia shortest, solid tumors
longer), risk coefficients (4-10%/Sv), heritable effects, dose-response models (linear no-
threshold)
Professionalism, Ethics, & Safety
• ABR Code of Ethics: Professional conduct, conflicts of interest, gift policies (<$100 non-cash
acceptable)
• Patient Safety: Wrong site/patient prevention, incident learning systems (ILS), time outs,
checklists, informed consent (all treatment options), TG-275
• Regulatory Compliance: NRC (10 CFR 19, 20, 35) - occupational vs public limits (50 mSv vs 1
mSv/yr), licensing, RAM transportation (DOT, IATA, Yellow II/III labels), NARM, agreement
states, patient release criteria (7 mrem/hr at 1 m), medical events (reporting criteria)
Question 1
Which of the following is the correct order of cell cycle phases based on diminishing radiosensitivity
(most sensitive to least sensitive)?
A) G1 → S → G2 → M
B) M → G2 → G1 → S
C) S → G1 → G2 → M
D) G2 → M → S → G1
Answer: B
, Page 4 of 154
Rationale: Cells are most radiosensitive in M phase (mitosis) and most resistant in late S phase (DNA
synthesis). The order of decreasing radiosensitivity is M > G2 > G1 > S .
Question 2
A 6 MV photon beam has a maximum energy of 6 MeV at the accelerator exit window. What is the
approximate average energy of this beam?
A) 2 MeV
B) 3 MeV
C) 6 MeV
D) 12 MeV
Answer: A
Rationale: The average energy of a clinical photon beam is approximately 1/3 of the maximum energy.
For a 6 MV beam, the average energy is about 2 MeV .
Question 3
What is the approximate percentage depth dose (PDD) at dmax for a 6 MV photon beam with a 10 × 10
cm² field size and 100 cm SSD compared to Co-60?
A) 75%
ABR Medical Physics Certification Exam QUESTIONS
AND VERIFIED ANSWERS WITH RATIONALES JUST
RELEASED
ABR Medical Physics Certification Exam
Summarized Exam Topics Covered in Point Form
Exam Structure & Eligibility
• Part 1 Qualifying Exam: Computer-based, General section (~5 hours, 130 questions), Clinical
section (~3 hours, 80 questions)
• Part 2 Qualifying Exam: Specialty-specific (Diagnostic, Therapeutic, or Nuclear), computer-
based, ~5 hours, one session
• Part 3 Oral Certifying Exam: Remote oral exam, ~4 hours, five examiners testing five categories
• Eligibility: CAMPEP-accredited graduate/certificate/DMP program enrollment/completion +
CAMPEP-accredited residency for Part 2/3
• Fees: Application 250,Part1250,Part1250, Part 2 640,Part3640,Part3780; re-exam fees apply
Medical Physics - Part 1 General Section Topics
• Radiation Physics (44 questions): Atomic/nuclear structure, radioactive decay, photon/matter
interactions, charged particle interactions
• Radiation Measurement (16 questions): Ion chambers, TLD, film dosimetry, electrometer,
calibration protocols
• Radiation Protection & Safety (12 questions): ALARA, shielding design (TVL, HVL), NCRP
recommendations, occupational/public dose limits, transportation, contamination control
• Diagnostic Medical Physics (16 questions): X-ray tube, fluoroscopy, mammography, CT, image
quality, QC
• Nuclear Medical Physics (16 questions): Scintillation cameras, PET, SPECT,
radiopharmaceuticals, gamma counting
• Therapy Medical Physics (16 questions): Linac, electron/photon beams, brachytherapy,
dosimetric calculations
• Math & Statistics (8 questions): Poisson, Gaussian, uncertainty propagation, error analysis
Medical Physics - Part 1 Clinical Section Topics
• Anatomy (20 questions): Major organ systems, anatomical terminology, cross-sectional
anatomy (CT, MRI), vertebral levels, cranial nerves, brain anatomy (circle of Willis, corpus
callosum), GI tract, cardiovascular system
• Radiation Biology & Pathology (20 questions): Cell cycle, radiosensitivity (M > G2 > G1 > S),
fraction of cells, oxygen enhancement ratio (OER), linear-quadratic model, BED, normal tissue
complications, acute radiation syndrome, stochastic/deterministic effects, LD50/60
• Medical Terminology (20 questions): Standard medical prefixes/suffixes, disease terminology,
procedural terminology
Diagnostic Medical Physics - Part 2/3
• X-ray Imaging: X-ray tube (anode, cathode, filament), generators (single-phase, three-phase,
high-frequency), filtration (inherent, added), beam collimation, grids (grid ratio, cut-off),
automatic exposure control (AEC)
• Fluoroscopy: Image intensifier, flat panel detectors, dose area product (DAP), last image hold,
pulsed fluoroscopy, dose management
, Page 2 of 154
• Mammography: X-ray target/filter combinations (Mo/Mo, Rh/Rh, W), compression, grid,
magnification, AEC positioning
• Computed Tomography (CT): Generations, helical/spiral CT, multi-detector CT, cone-beam CT,
image reconstruction (FBP, iterative), window/level, dose metrics (CTDI, DLP, SSDE), artifacts
(beam hardening, photon starvation, metal, motion)
• Magnetic Resonance Imaging (MRI): T1/T2 relaxation, spin echo, gradient echo, inversion
recovery (STIR, FLAIR), k-space, coils, artifacts (chemical shift, aliasing, susceptibility, motion),
safety (AC/DC/RF fields), SAR
• Ultrasound (US): Transducer design (piezoelectric, λ/2 thickness), frequency selection,
resolution (axial, lateral, elevational), Doppler (color, power, spectral), artifacts (shadowing,
enhancement, reverberation, aliasing), biological effects (thermal, mechanical/MI)
Nuclear Medical Physics - Part 2/3
• Instrumentation: Scintillation (NaI(Tl)) cameras, photomultiplier tubes (PMTs), pulse height
analyzer, collimators (parallel, converging, diverging, pinhole), energy resolution, count rate
performance
• Planar Imaging & SPECT: Image acquisition, reconstruction (FBP, iterative), attenuation
correction (Chang, CT-based), scatter correction, dead time, uniformity, resolution
• Positron Emission Tomography (PET): Annihilation coincidence detection, time-of-flight (TOF),
detectors (BGO, LYSO, LSO), randoms, scatter, normalization, attenuation correction (CT,
transmission), quantification (SUV), partial volume effect
• Radiopharmaceuticals: 99mTc (6h), 18F (110m), 131I (8d), 123I (13h), 201Tl (73h), 111In (2.8d),
67Ga (3.3d), 68Ga (68m), 82Rb (75s), cyclotron vs generator production
• Quality Control & Safety: Daily/weekly QC, dose calibrator constancy, well counter, survey
meter, contamination monitoring, shielding (syringe shields, L-block), sources decay correction
Therapeutic Medical Physics - Part 2/3
• Linear Accelerators (Linacs): Electron gun, accelerator structure (traveling/standing wave),
microwave components (magnetron/klystron), bending magnet, target (photon), scattering foil
(electron), flattening filter/flattening filter free (FFF), MLC, ion chamber monitor
• Photon Beam Dosimetry: Percentage depth dose (PDD), tissue maximum ratio (TMR), tissue
phantom ratio (TPR), output factors (Sc, Sp, Scp), off-axis factor, wedge factor, tray factor, block
factor
• Electron Beam Dosimetry: Mean energy at surface, practical range (Rp), depth of maximum
dose (dmax), surface dose, X-ray contamination, cutout factors, effective SSD, cone selection,
energy selection
• Treatment Planning (Photons/Electrons): Isodose distributions, dose-volume histogram (DVH),
IMRT, VMAT, SBRT, SRS, heterogeneity corrections (lung, bone), algorithm types (pencil beam,
convolution/superposition, Monte Carlo, Acuros), plan evaluation
• Brachytherapy: Sealed sources (125I, 103Pd, 192Ir, 137Cs, 60Co, 131Cs), HDR vs LDR, manual
afterloading vs remote afterloader (HDR), TG-43 formalism, source strength specification (air
kerma strength, reference air kerma rate), treatment planning (interstitial, intracavitary),
prostate seed implant dosimetry
• Radiation Protection in Therapy: Linac bunker shielding (TVL, NCRP 151), neutron shielding (18
MV+), maze design, door design, controlled/uncontrolled areas, patient release after I-131,
brachytherapy source handling (syringe shields, L-block, forceps, time/distance/shielding)
Radiobiology
• Cellular Effects: Direct vs indirect DNA damage (hydrolysis, OH radicals), linear energy transfer
(LET), relative biological effectiveness (RBE), oxygen enhancement ratio (OER = 2.5-3 for low LET,
~1 for high LET), cell survival curves (shoulder = repair capacity), cell cycle radiosensitivity (M
, Page 3 of 154
phase most sensitive, late S phase most resistant), radiation-induced apoptosis, mitotic
catastrophe
• Fractionation: Linear-quadratic model (α/β ratio: early-responding tissues 10 Gy, late-
responding tissues 2-3 Gy), biologically effective dose (BED = nd[1 + d/(α/β)]), EQD2, isoeffect
relationships, repair (sublethal, potentially lethal)
• Normal Tissue Effects: Early vs late reactions, serial vs parallel organs, TD5/5, TD50/5, volume
effects, complication probability models (NTCP, LKB model)
• Tumor Effects: 4 R's of radiobiology (Repair, Repopulation, Reoxygenation, Redistribution),
tumor control probability (TCP), accelerated repopulation, hypoxia, heterogeneity
• Acute Radiation Syndrome: Hematopoietic (2-5 Gy), GI (10-15 Gy), CNS (>30 Gy), LD50/60 (3.5-4
Gy with supportive care, ~5 Gy with medical support)
• Radiation Carcinogenesis: Stochastic effect, latency period (leukemia shortest, solid tumors
longer), risk coefficients (4-10%/Sv), heritable effects, dose-response models (linear no-
threshold)
Professionalism, Ethics, & Safety
• ABR Code of Ethics: Professional conduct, conflicts of interest, gift policies (<$100 non-cash
acceptable)
• Patient Safety: Wrong site/patient prevention, incident learning systems (ILS), time outs,
checklists, informed consent (all treatment options), TG-275
• Regulatory Compliance: NRC (10 CFR 19, 20, 35) - occupational vs public limits (50 mSv vs 1
mSv/yr), licensing, RAM transportation (DOT, IATA, Yellow II/III labels), NARM, agreement
states, patient release criteria (7 mrem/hr at 1 m), medical events (reporting criteria)
Question 1
Which of the following is the correct order of cell cycle phases based on diminishing radiosensitivity
(most sensitive to least sensitive)?
A) G1 → S → G2 → M
B) M → G2 → G1 → S
C) S → G1 → G2 → M
D) G2 → M → S → G1
Answer: B
, Page 4 of 154
Rationale: Cells are most radiosensitive in M phase (mitosis) and most resistant in late S phase (DNA
synthesis). The order of decreasing radiosensitivity is M > G2 > G1 > S .
Question 2
A 6 MV photon beam has a maximum energy of 6 MeV at the accelerator exit window. What is the
approximate average energy of this beam?
A) 2 MeV
B) 3 MeV
C) 6 MeV
D) 12 MeV
Answer: A
Rationale: The average energy of a clinical photon beam is approximately 1/3 of the maximum energy.
For a 6 MV beam, the average energy is about 2 MeV .
Question 3
What is the approximate percentage depth dose (PDD) at dmax for a 6 MV photon beam with a 10 × 10
cm² field size and 100 cm SSD compared to Co-60?
A) 75%
