100+ Free ABR TMP Practice Questions

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Question 1

Score: 0/0

According to TG-51, what is the standard reference depth for photon beam calibration in water?

dmax

10 cm

d80

5 cm

to track

2026 Statistics

Key Facts: ABR TMP Exam

Pass/Fail

Scoring Method

ABR criterion-referenced

~125

Part 2 Questions

Computer-based, 5 hours

$1,630

Total Exam Fees

Parts 1 + 2 + 3 combined

3 Parts

Certification Exams

General, Specialty, Oral

75-85%

Part 2 Pass Rate

CAMPEP first-time takers

CAMPEP

Required Training

Accredited program + residency

The ABR Therapeutic Medical Physics exam is a three-part certification process administered by the American Board of Radiology. Part 2 is a 5-hour computer-based specialty exam with approximately 125 multiple-choice questions covering radiation therapy physics. The total certification cost is $1,630 ($210 Part 1 + $640 Part 2 + $780 Part 3). First-time pass rates for CAMPEP-enrolled candidates on Part 2 typically range from 75-85%.

Sample ABR TMP Practice Questions

Try these sample questions to test your ABR TMP exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1According to TG-51, what is the standard reference depth for photon beam calibration in water?

A.dmax

B.10 cm

C.d80

D.5 cm

Explanation: TG-51 specifies a reference depth of 10 cm in water for the calibration of photon beams. This depth is chosen because it is beyond the region of electron contamination and provides a stable measurement point where the dose gradient is relatively smooth, reducing positioning uncertainties.

2In the TG-51 calibration protocol, the absorbed dose to water is determined using which quantity associated with the ion chamber?

A.Cavity gas calibration factor (Ngas)

B.Air kerma calibration factor (NK)

C.Exposure calibration factor (Nx)

D.Absorbed-dose-to-water calibration coefficient (ND,w)

Explanation: TG-51 uses the absorbed-dose-to-water calibration coefficient (ND,w) obtained from an Accredited Dosimetry Calibration Laboratory (ADCL). This is a key distinction from the older TG-21 protocol, which was based on the cavity gas calibration factor. The ND,w approach simplifies the calibration chain and reduces overall uncertainty.

3Which correction factor in TG-51 accounts for the difference in beam quality between the calibration beam and the user's clinical beam?

A.Pion

B.PTP

C.kQ

D.Ppol

Explanation: The beam quality conversion factor kQ converts the calibration coefficient from the Co-60 calibration beam quality to the user's clinical beam quality. It accounts for differences in the chamber's response due to different photon or electron spectra. Values of kQ are tabulated in TG-51 for various chamber models and beam qualities.

4The beam quality specifier for photon beams in TG-51 is:

A.The tissue-phantom ratio at 20 cm and 10 cm depth (TPR20,10)

B.The percentage depth dose at 10 cm depth (%dd(10)x)

C.The nominal accelerating potential in MV

D.The half-value layer in mm of aluminum

Explanation: TG-51 uses the percentage depth dose at 10 cm depth due to photons only, denoted %dd(10)x, as the beam quality specifier for photon beams. The 'x' subscript indicates that electron contamination has been removed, either by measurement with a lead foil or by using empirical relationships. This approach provides a more accurate characterization than nominal MV.

5The temperature-pressure correction factor (PTP) in ion chamber dosimetry corrects for changes in:

A.The wall material stopping power

B.The W/e value for air

C.The chamber stem effect

D.The mass of air in the chamber cavity

Explanation: The PTP correction factor accounts for changes in the mass of air within the ion chamber cavity due to variations in temperature and pressure from standard conditions (22°C, 101.325 kPa). Since ion chambers are typically vented to the atmosphere, the air density inside the cavity changes with ambient conditions, directly affecting the number of air molecules available for ionization.

6Which type of detector is most commonly used for scanning relative dose distributions (beam profiles and depth doses) in a water phantom?

A.Thermoluminescent dosimeter (TLD)

B.Optically stimulated luminescence dosimeter (OSLD)

C.Small-volume ion chamber or diode

D.Farmer-type ion chamber

Explanation: Small-volume ion chambers (e.g., 0.01-0.13 cc) and silicon diodes are the preferred detectors for scanning beam profiles and depth doses in water phantoms due to their small sensitive volume, which provides good spatial resolution. Diodes offer higher sensitivity per unit volume but require corrections for energy and dose-rate dependence. Farmer chambers are too large for accurate profile measurements.

7What is the primary advantage of a parallel-plate (plane-parallel) ion chamber over a cylindrical chamber for electron beam dosimetry?

A.It minimizes the perturbation of electron fluence at the measurement point

B.It eliminates the need for temperature-pressure corrections

C.It has higher sensitivity to radiation

D.It is less sensitive to cable leakage

Explanation: Parallel-plate chambers are preferred for electron beam dosimetry, especially at shallow depths and for low-energy electron beams, because their thin entrance window minimizes the perturbation of the electron fluence at the measurement point. Cylindrical chambers have a significant displacement effect in electron beams due to their cavity volume, leading to larger measurement uncertainties.

8The ion recombination correction factor (Pion) for a pulsed radiation beam can be determined using which method?

A.The two-voltage technique

B.Comparing ion chamber and diode readings

C.Varying the source-to-detector distance

D.Measuring with different chamber volumes

Explanation: The two-voltage technique is the standard method for determining the ion recombination correction factor (Pion) in a pulsed beam. The chamber is measured at the normal operating voltage and at a reduced voltage (typically half the operating voltage), and the ratio of the two readings is used to calculate Pion using Boag's theory. This corrects for charge lost to recombination before collection.

9Radiochromic film (e.g., GafChromic EBT) is particularly useful for dosimetry because it:

A.Requires chemical processing before readout

B.Is more sensitive than ion chambers at all energies

C.Has near tissue-equivalent composition and is self-developing

D.Has no energy dependence across the diagnostic and therapeutic range

Explanation: GafChromic EBT film is nearly tissue-equivalent in composition (low effective Z), which minimizes energy-dependent response variations, and is self-developing, meaning it does not require chemical processing — it changes color upon irradiation. These properties make it ideal for applications such as IMRT QA, SRS dose verification, and skin dose measurements.

10For a 6 MV photon beam, what is the approximate percentage depth dose at 10 cm depth for a 10 x 10 cm² field at 100 cm SSD?

A.67%

B.78%

C.50%

D.58%

Explanation: For a 6 MV photon beam with a 10 x 10 cm² field at 100 cm SSD, the PDD at 10 cm depth is approximately 67%. This is a commonly tested benchmark value. Higher energy beams have higher PDD values at this depth (e.g., ~77% for 15 MV), while lower energies have lower values. Knowing these approximate values is essential for clinical dose calculations.

About the ABR TMP Exam

The ABR Therapeutic Medical Physics certification covers three exams: Part 1 (General + Clinical), Part 2 (TMP specialty), and Part 3 (Oral). The Part 2 exam focuses on radiation therapy physics including dosimetry, treatment machines, treatment planning, brachytherapy, and radiation biology. Passing all three parts earns ABR board certification in therapeutic medical physics.

Questions

125 scored questions

Time Limit

5 hours (Part 2)

Passing Score

Criterion-referenced (pass/fail)

Exam Fee

$1,630 (total Parts 1-3) (American Board of Radiology (ABR))

ABR TMP Exam Content Outline

20%

Reference and Relative Dosimetry

Absolute calibration for photon and electron beams, dosimeter design, characteristics, application and QA, survey detector design

20%

Treatment Machines

Photon/electron medical accelerators, proton accelerators, specialized machines, beam characteristics, delivery hardware, QA, and shielding

20%

Therapy Imaging, Patient Safety & Professionalism

Imaging for therapy simulation, shielding and radiation safety, treatment localization, QC, error prevention, computing, and ethics

20%

Treatment Planning

Photon and electron treatment planning, SRS, SBRT, inter- and intra-fraction variation management, planning system safety and QA

20%

Brachytherapy, Radiation Protection & Biology

Brachytherapy isotopes, delivery systems, planning, QA, shielding, radiation protection regulations, personnel monitoring, radiation biology

How to Pass the ABR TMP Exam

What You Need to Know

Passing score: Criterion-referenced (pass/fail)
Exam length: 125 questions
Time limit: 5 hours (Part 2)
Exam fee: $1,630 (total Parts 1-3)

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

ABR TMP Study Tips from Top Performers

1Master absolute calibration protocols (TG-51) for photon and electron beams — this is fundamental

2Understand linac design, beam characteristics, and QA procedures for photon and electron delivery

3Study treatment planning thoroughly — photon, electron, IMRT, SRS, SBRT, and proton planning

4Know brachytherapy source characteristics, dose calculations, and TG-43 formalism

5Review radiation protection regulations, shielding calculations (NCRP 151), and personnel monitoring

6Practice clinical scenarios involving patient-specific QA, error prevention, and incident reporting

7Use the ABR TMP content guide and sample questions on theabr.org for targeted preparation

Frequently Asked Questions

What is the ABR Therapeutic Medical Physics exam?

The ABR Therapeutic Medical Physics (TMP) exam is a three-part certification process administered by the American Board of Radiology. Part 1 covers general and clinical physics, Part 2 is a specialty exam focusing on radiation therapy physics (dosimetry, treatment machines, treatment planning, brachytherapy), and Part 3 is an oral certifying exam. Passing all three parts earns board certification in therapeutic medical physics.

How many questions are on the ABR TMP Part 2 exam?

The ABR TMP Part 2 exam is a computer-based test with approximately 125 multiple-choice questions delivered in one 5-hour session. Question types include traditional multiple-choice, case-based, multiple-select, fill-in-the-blank, and point-and-click formats. The exam uses criterion-referenced scoring where your performance is measured against a fixed standard.

What topics are covered on the ABR TMP exam?

The ABR TMP Part 2 exam covers five main content areas: (1) reference and relative dosimetry including absolute calibration, (2) treatment machines including linacs and proton units, (3) therapy imaging, patient safety, and professionalism, (4) external beam treatment planning for photons, electrons, SRS, and SBRT, and (5) brachytherapy, radiation protection, and radiation biology.

What are the ABR medical physics exam fees?

The total ABR medical physics certification fees are $1,630: Part 1 exam costs $210, Part 2 exam costs $640, and Part 3 oral exam costs $780. There is also a $250 initial application fee. Re-exam fees are $250 for Parts 1/2 and $390 for Part 3. All fees are nonrefundable but transfer to your next exam if you cancel or miss.

What are the prerequisites for ABR TMP certification?

To pursue ABR Therapeutic Medical Physics certification, you must graduate from a CAMPEP-accredited graduate program in medical physics and complete a CAMPEP-accredited medical physics residency with a focus on radiation therapy. Clinical training must include linac QA, treatment planning, brachytherapy, and radiation protection. You have six years from residency completion to finish certification.

How is the ABR TMP oral exam (Part 3) structured?

The Part 3 oral exam is a remote video exam lasting approximately 4 hours. You meet with five examiners covering: (1) reference and relative dosimetry, (2) treatment machines, (3) external beam treatment planning and uncertainty management, (4) brachytherapy and radiation protection, and (5) patient safety, data transfer, professionalism, and ethics. Each session lasts about 30 minutes with five questions per examiner.