100+ Free ABMP MRI for Radiation Therapy Practice Questions

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Question 1

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Which nucleus is most commonly used for clinical MRI signal generation?

Carbon-13

Hydrogen-1 (proton)

Sodium-23

Phosphorus-31

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2026 Statistics

Key Facts: ABMP MRI for Radiation Therapy Exam

50%

2025 Pass Rate

ABMP

4 hours

Exam Duration

Part II written

$690

Part II Fee

2026

Content Domains

ABMP outline

2 parts

Certification Path

No Part I required

2021

First Offered

ABMP sub-specialty

The ABMP MRI for Radiation Therapy Part II written exam is nominally 4 hours and covers 9 weighted content domains. The 2026 Part II application fee is $690. This is a two-part certification (Part II written + Part III oral) with no Part I required, as candidates must already hold certification in MRI Physics, Diagnostic Imaging, or Radiation Therapy Physics. Pass rates for MR for RT Part II were 100% (2023), 100% (2024), and 50% (2025).

Sample ABMP MRI for Radiation Therapy Practice Questions

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

1Which nucleus is most commonly used for clinical MRI signal generation?

A.Carbon-13

B.Hydrogen-1 (proton)

C.Sodium-23

D.Phosphorus-31

Explanation: Hydrogen-1 (proton) is the nucleus used in virtually all clinical MRI applications because of its high natural abundance in the body (primarily in water and fat) and its relatively large gyromagnetic ratio, which yields a strong MR signal. Other nuclei such as C-13, Na-23, and P-31 are used in specialized research applications but produce much weaker signals.

2The Larmor equation relates the precession frequency of a nuclear spin to which quantity?

A.The RF pulse duration

B.The static magnetic field strength (B0)

C.The gradient coil temperature

D.The T1 relaxation time of the tissue

Explanation: The Larmor equation states that the precession frequency (omega) equals the product of the gyromagnetic ratio (gamma) and the external static magnetic field strength B0. This fundamental relationship is the basis for all MRI signal generation and spatial encoding. The precession frequency is independent of RF pulse characteristics, gradient coil temperature, or tissue relaxation properties.

3T1 relaxation describes the recovery of magnetization along which axis?

A.The transverse (x-y) plane

B.The axis perpendicular to both B0 and the gradient

C.The direction of the applied RF pulse

D.The longitudinal (z) axis parallel to B0

Explanation: T1 relaxation, also known as spin-lattice relaxation, describes the exponential recovery of the net magnetization vector along the longitudinal axis (z-axis), which is parallel to the main magnetic field B0. T2 relaxation, by contrast, describes the decay of magnetization in the transverse (x-y) plane. Understanding these distinct relaxation mechanisms is fundamental to MRI contrast generation.

4What is the primary difference between T2 and T2* relaxation?

A.T2* includes additional dephasing from static magnetic field inhomogeneities while T2 does not

B.T2 is always longer than T2*

C.T2 is caused by spin-lattice interactions and T2* by spin-spin interactions

D.T2* only occurs at field strengths above 1.5 T

Explanation: T2* relaxation incorporates both the intrinsic T2 spin-spin dephasing and additional dephasing caused by local static magnetic field (B0) inhomogeneities. This makes T2* always shorter than or equal to T2. Spin echo sequences can refocus the static field inhomogeneity component, recovering pure T2 contrast, while gradient echo sequences are sensitive to T2* effects. This distinction is particularly important in MRI for radiation therapy where geometric accuracy depends on field homogeneity.

5A 180-degree refocusing RF pulse in a spin echo sequence primarily compensates for which effect?

A.T1 relaxation differences between tissues

B.Chemical shift artifacts

C.Static magnetic field inhomogeneity-induced dephasing

D.Gradient nonlinearity distortion

Explanation: The 180-degree refocusing pulse in a spin echo sequence reverses the phase accumulated by spins due to static (time-invariant) magnetic field inhomogeneities, thereby recovering signal lost to T2* dephasing. This refocusing produces an echo that reflects true T2 relaxation. It does not compensate for T1 relaxation differences, chemical shift artifacts, or gradient nonlinearity distortion, which require different correction strategies.

6In MRI, the flip angle of the net magnetization vector is determined by which combination of factors?

A.The repetition time (TR) and echo time (TE)

B.The main magnetic field strength and patient weight

C.The amplitude and duration of the applied RF pulse (B1 field)

D.The receiver bandwidth and number of signal averages

Explanation: The flip angle is determined by the product of the gyromagnetic ratio, the amplitude of the B1 (RF) field, and the duration of the RF pulse. Increasing either the amplitude or duration of the RF pulse increases the flip angle. TR and TE are sequence timing parameters that affect contrast but do not directly determine flip angle. Receiver bandwidth and number of averages affect signal-to-noise ratio rather than excitation.

7Which mechanism is responsible for the phenomenon of stimulated echoes in multi-pulse MR sequences?

A.Rephasing of transverse magnetization stored along the longitudinal axis by a subsequent RF pulse

B.Constructive interference between multiple gradient echoes

C.Resonance amplification from parallel receive coil elements

D.RF power deposition exceeding the SAR threshold

Explanation: Stimulated echoes arise when transverse magnetization is tipped into the longitudinal axis by an RF pulse, stored there (decaying with T1 rather than T2), and then restored to the transverse plane by a subsequent RF pulse. This creates an additional echo pathway distinct from primary spin echoes. Understanding stimulated echoes is important for optimizing multi-echo and fast spin echo sequences used in radiation therapy planning.

8What is the purpose of crusher gradients applied immediately before and after a 180-degree refocusing pulse in a spin echo sequence?

A.To increase the signal-to-noise ratio of the echo

B.To reduce the specific absorption rate (SAR)

C.To eliminate signals from imperfectly refocused magnetization (FID contamination)

D.To correct for gradient nonlinearity distortion

Explanation: Crusher gradients are applied symmetrically around 180-degree refocusing pulses to dephase any residual free induction decay (FID) signal generated by imperfections in the refocusing pulse. Only the properly refocused spin echo pathway survives the crusher gradient pair. This improves image quality by eliminating unwanted stimulated echo and FID contamination, which is important for accurate imaging in radiation therapy planning.

9At 1.5 T, what is the approximate Larmor frequency for hydrogen protons?

A.64 MHz

B.42 MHz

C.21 MHz

D.128 MHz

Explanation: The Larmor frequency for hydrogen protons is calculated using the Larmor equation: frequency = gyromagnetic ratio x B0. The gyromagnetic ratio for hydrogen is approximately 42.58 MHz/T. At 1.5 T, this yields approximately 63.87 MHz, which is commonly rounded to 64 MHz. At 3.0 T, the Larmor frequency doubles to approximately 128 MHz. This frequency determines the RF transmit and receive frequencies for the MRI system.

10In MRI, what physical process is described by T2 (spin-spin) relaxation?

A.Reduction in signal from eddy currents in the gradient coils

B.Recovery of magnetization along the longitudinal axis due to energy exchange with the lattice

C.Signal loss caused by patient motion during acquisition

D.Loss of phase coherence among spins in the transverse plane due to molecular interactions

Explanation: T2 (spin-spin) relaxation describes the irreversible loss of phase coherence among precessing spins in the transverse plane caused by fluctuating magnetic fields from neighboring nuclei and molecular interactions. Unlike T2* dephasing from static field inhomogeneities, T2 relaxation cannot be reversed by refocusing pulses. T1 relaxation, by contrast, describes recovery along the longitudinal axis. Understanding these relaxation mechanisms is essential for optimizing MRI contrast in radiation therapy treatment planning.

About the ABMP MRI for Radiation Therapy Exam

The ABMP MRI for Radiation Therapy Part II exam is the written sub-specialty examination for physicists already certified in MRI Physics, Diagnostic Imaging Physics, or Therapeutic Radiological Physics. It tests competence across 9 domains covering MR signal physics, radiation therapy planning, MR-LINAC systems, image co-registration, and MR safety specific to the radiation therapy environment. This sub-specialty certification was first offered by the ABMP in 2021.

Questions

100 scored questions

Time Limit

4 hours

Passing Score

Pass/Fail (set by Board)

Exam Fee

$690 (ABMP)

ABMP MRI for Radiation Therapy Exam Content Outline

10%

MR Signal Generation and Manipulation

NMR fundamentals, T1/T2 relaxation, spin echo and gradient echo formation, signal contrast mechanisms, and fat saturation methods relevant to radiation therapy planning.

10%

Spatial Encoding and Image Formation

Slice selection, frequency and phase encoding, k-space concepts, Fourier transform reconstruction, 2D vs 3D imaging, and radial/non-Cartesian acquisitions.

10%

Image Pulse Sequences, SNR, and Image Contrast

Spin echo, fast spin echo, gradient echo sequences, SNR optimization, contrast weighting (T1, T2, PD), and motion management techniques for RT planning.

10%

Distortion and Other Image Artifacts

B0 inhomogeneity distortion, gradient-induced distortion, susceptibility artifacts, chemical shift, motion/flow artifacts, and distortion reduction strategies for RT accuracy.

20%

Physics in Radiation Therapy

Treatment simulation, localization and verification, photon treatment planning, inter/intra-fraction management, dose effects from magnetic fields, treatment modes (IMRT, VMAT), and MR-LINAC treatment delivery.

10%

Image Segmentation, Co-Registration, and MR-only Treatment Planning

Deformable and rigid registration algorithms, MRI-to-CT co-registration, MRsim workflows, synthetic CT methods, bulk density overrides, atlas-based conversion, and adaptive RT.

10%

Hardware and Instrumentation

MRI scanner components, superconducting magnets, gradient systems, RF coils, MR simulator requirements, LINAC physics and beam characteristics, and MR-LINAC system design.

10%

Site Planning, Commissioning, and QA for MRsim and MR-LINAC

Facility siting requirements, MR-LINAC commissioning procedures, routine QA protocols, geometric accuracy verification, and dual-modality equipment considerations.

10%

Safety Considerations

Static magnetic field effects, RF irradiation hazards, gradient dB/dt limits, implant screening for RT patients, gadolinium contrast safety, MR-LINAC-specific safety protocols, and risk-benefit analysis.

How to Pass the ABMP MRI for Radiation Therapy Exam

What You Need to Know

Passing score: Pass/Fail (set by Board)
Exam length: 100 questions
Time limit: 4 hours
Exam fee: $690

Keys to Passing

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

ABMP MRI for Radiation Therapy Study Tips from Top Performers

1Prioritize Physics in Radiation Therapy (20%) — the heaviest-weighted domain covering treatment planning, MR-LINAC delivery, and magnetic field dose effects

2Understand MR-LINAC systems thoroughly: know the differences between commercial platforms and their clinical workflows

3Master image co-registration methods: deformable vs. rigid registration, accuracy evaluation, and MRI-to-CT workflows

4Study synthetic CT generation methods: bulk density overrides, tissue segmentation, atlas-based approaches, and machine learning methods

5Review MR distortion sources and correction strategies — geometric accuracy is critical for radiation therapy treatment planning

6Know MR safety protocols specific to the RT environment: pacemaker management, implant screening, and MR-LINAC-specific hazards

7Study the four basic MR pulse sequence families and how each is used in RT planning and real-time MR-guided therapy

8Review QA procedures for MR simulators and MR-LINAC systems, including geometric accuracy and dosimetric verification

Frequently Asked Questions

What is the ABMP MRI for Radiation Therapy exam pass rate?

The ABMP publishes annual pass rates. Recent Part II MR for RT pass rates were 100% (2023), 100% (2024), and 50% (2025). The small candidate pool means pass rates can vary significantly year to year. This sub-specialty certification was first offered in 2021.

What are the prerequisites for the ABMP MRI for Radiation Therapy exam?

Unlike the other ABMP exams, there is no Part I requirement. Candidates must already hold a current certification in MRI Physics (ABMP), Diagnostic Imaging Physics (ABMP, ABR, or CCPM), or Therapeutic Radiological Physics (ABMP, ABR, or CCPM) and be participating in Maintenance of Certification. A graduate degree and two endorsement letters are also required.

How is the ABMP MRI for RT exam structured?

The MRI for Radiation Therapy certification is a two-part sequence: Part II (written exam, nominally 4 hours) and Part III (oral exam). Both parts cover the same 9 content categories. The written exam uses multiple-choice, matching, choose-all-that-apply, and Type S question formats administered through ExamSoft.

How much does the ABMP MRI for RT exam cost?

The 2026 ABMP exam fees for MRI for Radiation Therapy are: Part II written exam $690 and Part III oral exam $790 (or $395 for a conditional retake). PayPal payments add a convenience fee. The total cost for both parts is approximately $1,480 at standard rates.

What topics are most heavily weighted on the MRI for RT exam?

Physics in Radiation Therapy is the most heavily weighted domain at 20%, covering treatment simulation, photon planning, dose effects from magnetic fields, and MR-LINAC delivery. The remaining 8 domains each carry 10% weight, covering MR signal physics, imaging, artifacts, co-registration, hardware, QA, and safety.

Where and when can I take the ABMP MRI for RT exam?

In 2026, the Part II MR for RT exam is offered at the ISMRM meeting (Cape Town, South Africa, May 9) and the AAPM meeting (Vancouver, BC, Canada, July 18). Part III oral exams are available at the AAPM meeting. Exams are administered through ExamSoft on the candidate's own device.