- What This Certification Actually Is
- Eligibility and the Training Pathway
- The Written Exam: Format and Scoring
- The Oral Examination
- Fees, Registration, and Remote Delivery
- Content Outline: Physics First, Imaging Second
- Sequencing Your Preparation by Domain
- Staying Certified: OCC Requirements
- What to Verify Before You Commit
- Frequently Asked Questions
- This credential is issued by the American Osteopathic Board of Radiology (AOBR), not the ABR, and is separate from ARRT credentials.
- The written exam is 300 multiple-choice questions in three 100-minute sections: roughly 50 physics and 250 imaging items.
- Written and oral fees are $800 each, so the two standard initial-stage fees total $1,600.
- The written passing score is a scaled 500 on a 200-800 scale.
What This Certification Actually Is
Primary Certification in Diagnostic Radiology, as discussed on this page, is the osteopathic board certification pathway administered by the American Osteopathic Board of Radiology (AOBR), with AOA certification approval. It is the credential a radiology resident earns by passing a combined written examination followed by an oral examination. It is not the ABR Core examination, it is not an ARRT technologist registry credential, and it has nothing to do with radiation oncology. If you have landed here searching for one of those, the exam content, fees, and eligibility rules differ entirely.
The structure is distinctive: a single written exam covers both radiological physics and diagnostic imaging, and a later oral exam tests case-based reasoning across ten subject areas. For a broader orientation to the term itself, see What Is Diagnostic Radiology Certification?, and for the training that precedes the exam, Diagnostic Radiology Training.
Eligibility and the Training Pathway
Eligibility is built around a specific training sequence. According to the AOBR, candidates need:
- A qualifying medical degree, or a valid ECFMG pathway for international graduates
- One year of approved internship
- A four-year diagnostic radiology residency that includes 700 hours of nuclear medicine training
- Active licensure
- Ethics and training approval
The 700-hour nuclear medicine requirement is worth noticing early. It signals that nuclear medicine is not a peripheral topic for this board: it appears twice in the exam outline, once in the physics portion and again in the clinical imaging portion.
A Wrinkle in the Published Timing Rules
The AOBR written-exam page contains a bullet referencing second-year eligibility, but the same page explicitly restricts the combined written examination to third-year or later residents. These statements sit in tension, and this article does not try to smooth them over. If you are a second-year resident planning ahead, confirm directly with the AOBR which rule applies to your application cycle before building a schedule around it. For a fuller discussion of prerequisites, see Diagnostic Radiology Requirements: Eligibility, Prerequisites & How to Qualify.
The Written Exam: Format and Scoring
The written component is a single combined examination with a fixed structure:
| Feature | Detail |
|---|---|
| Question type | Multiple choice |
| Total questions | 300 |
| Sections | Three, each 100 minutes |
| Total testing time | Five hours |
| Breaks | Optional ten-minute breaks between sections, outside the testing clock |
| Physics content | Approximately 50 questions (Part I) |
| Imaging content | Approximately 250 questions (Part II) |
| Passing score | Scaled 500 on a 200-800 scale |
The issuer publishes approximate question counts but no percentage weights, and this article does not convert those counts into percentages. What the counts do tell you plainly is where the volume sits: the imaging portion dwarfs physics in raw question count, though physics questions can still decide a borderline result.
Pacing matters at this scale. Three 100-minute blocks of 100 questions each means roughly a minute per item on average, which rewards candidates who recognize classic imaging patterns quickly rather than reasoning from scratch each time. For perspective on how this structure feels in practice, read How Hard Is the Diagnostic Radiology Exam? and the breakdown of what the passing score means.
The Oral Examination
The oral exam is the second stage and is open only to candidates who have passed the written exam and have reached fourth-year or later training. The AOBR oral page states a 4.5-hour examination, eight cases, 20 minutes per case, and that candidates must pass all ten stations. Those statements do not reconcile neatly into a single case count or timer, and this article does not attempt to derive one. What is clear is the ten-subject structure, which maps onto the clinical imaging domains below.
The oral format changes how you prepare. Written preparation rewards recognition; oral preparation rewards structured verbal reasoning under observation: describing findings, building a differential, recommending the next study, and defending your reasoning. Practice presenting cases aloud, not just reading them.
The AOBR's overview timeline lists oral application dates that conflict with the relative application windows given on the oral page itself. Rather than trusting either in isolation, check both pages and confirm current deadlines with the board. Our guide to exam dates, testing windows, and scheduling covers how to approach this.
Fees, Registration, and Remote Delivery
The fee structure is straightforward compared with many credentials:
- Written examination fee: $800
- Oral examination fee: $800
- The two standard initial-stage fees add up to $1,600
- The listed corresponding reexamination fees are included in the board's stated figures
That $1,600 is the sum of the two standard stage fees by simple addition; it does not include study materials, travel, licensure costs, or annual maintenance fees that come later. Review the full picture in Diagnostic Radiology Certification Cost: Complete Pricing Breakdown.
Written delivery can be remote. The AOBR directs candidates to its remote-proctored exam instructions, which involve the MonitorEDU Secure Browser and PARADIGM platform. Remote delivery makes technical readiness part of your preparation: run the system checks well ahead of exam day, and do not assume a home setup that works for ordinary tasks will satisfy a secure-browser environment.
Content Outline: Physics First, Imaging Second
The AOBR content outline reproduces two parts: Part I (Physics) and Part II (Diagnostic Imaging). The eighteen domains used throughout this site are the published topic entries, not an issuer-declared count of top-level domains. Ultrasound and Nuclear Medicine each appear twice on purpose, because they show up in both parts with different emphasis. For a domain-by-domain walkthrough, see Diagnostic Radiology Exam Domains: Complete Guide to All 18 Content Areas.
Part I: Physics (Domains 1-8)
Domain 1: Biological Effects and Safety
Connects physical exposure to patient and worker consequences.
- Expect questions that bridge physics and clinical consequence rather than isolated definitions
Domain 2: Radiological Physics (Radiation Production and Interaction with Matter)
The foundation for everything downstream.
- How x-rays are produced and how they interact with tissue
- Why those interactions determine image contrast and dose
Domain 3: Radiation Biology (Health Effects)
Health effects of radiation exposure, essential for risk-benefit reasoning in everyday practice.
Domain 4: Radiation Safety and Protection
Practical protection principles that apply to patients, staff, and the public.
Domain 5: Radiological Imaging (Radiography, Fluoroscopy, CT, Mammography)
The physics of image formation across the ionizing-radiation modalities, including image quality and dose tradeoffs.
Domain 6: Ultrasound
Physics of sound in tissue, transducers, and image artifacts.
Domain 7: MRI
Magnetic resonance physics, contrast mechanisms, and safety considerations specific to the magnet environment.
Domain 8: Nuclear Medicine
Radioactive decay, radiopharmaceuticals, and detection instrumentation, the physics counterpart to the clinical nuclear medicine domain later in the outline.
Part II: Diagnostic Imaging (Domains 9-18)
Part II carries the bulk of the questions and aligns with the ten oral subject headings.
| Domain | What it demands |
|---|---|
| 9: Neuroradiology | Brain, head and neck, and spine imaging patterns |
| 10: Vascular/Interventional Radiology | Vascular anatomy, pathology, and procedural reasoning |
| 11: Cardiopulmonary | Chest radiography and cross-sectional thoracic imaging |
| 12: Genitourinary Tract | Kidneys, urinary tract, and reproductive organs |
| 13: Ultrasound | Clinical sonographic diagnosis (distinct from Domain 6 physics) |
| 14: Breast Radiology | Mammographic and breast imaging interpretation |
| 15: Gastrointestinal Tract | Luminal and solid-organ abdominal imaging |
| 16: Musculoskeletal | Bone, joint, and soft-tissue imaging |
| 17: Pediatric Radiology | Age-specific anatomy, pathology, and dose consciousness |
| 18: Nuclear Medicine | Clinical scintigraphic and molecular imaging interpretation (distinct from Domain 8 physics) |
Key Takeaway
Do not treat the repeated headings as redundancy. Domain 6 and Domain 13 are both Ultrasound, and Domain 8 and Domain 18 are both Nuclear Medicine, but one tests how the technology works while the other tests how you interpret what it shows. Study each pair as two separate skills.
Sequencing Your Preparation by Domain
Because the exam is combined, a sensible plan front-loads physics while it can still anchor everything else, then spends most of the calendar on imaging. Here is one domain-driven sequence; adjust it to your rotation schedule and weak areas.
Physics Foundation (Domains 1-5)
- Radiation production and interaction first, since dose, contrast, and safety all derive from it
- Radiation biology and protection next, tied to clinical risk reasoning
- Radiography, fluoroscopy, CT, and mammography image formation
Non-Ionizing and Nuclear Physics (Domains 6-8)
- Ultrasound physics and artifacts
- MRI physics and magnet safety
- Nuclear medicine physics, linking decay and detection to later clinical interpretation
High-Volume Imaging Domains (9, 11, 15, 16)
- Neuroradiology, cardiopulmonary, gastrointestinal, and musculoskeletal, where the 250-item imaging section concentrates your exposure
- Pattern recognition first, then differential building
Remaining Imaging Domains (10, 12, 13, 14, 17, 18)
- Vascular/interventional, genitourinary, clinical ultrasound, breast, pediatric, and clinical nuclear medicine
- Finish with timed sets of 100 questions to rehearse one 100-minute section
If you want a fuller preparation framework, the Diagnostic Radiology Study Guide goes deeper, and the one-page cheat sheet is useful for last-week review. When you are ready to test yourself against realistic multiple-choice items, the practice test platform lets you drill by domain.
Staying Certified: OCC Requirements
Certification is not a one-time event for time-limited diplomates. The AOBR's Osteopathic Continuous Certification (OCC) program includes automatic enrollment and a $300 annual fee. Its components, as currently described, include:
- CME: For 2025-2027, 60 CME credits per three-year cycle, with no category or specialty quota. This current component guidance takes precedence over the overview page's older specialty-credit wording.
- Self-assessment: 15 SAMs/SA-CME per three-year cycle, which also count toward the CME total.
- Licensure and practice performance: Maintain active licensure and complete one practice-performance assessment per cycle.
- Cognitive assessment: The current cognitive assessment replaces the former ten-year OCC examination.
A historical AOBR policies document revised in September 2013 describes an older structure, including separate examinations, additional physics headings, and legacy ten-year certificates. That document is not a verified blueprint for the current combined exam, and this article does not assert a validity term for newly issued certificates. If you need that detail for contract or credentialing purposes, get it in writing from the board.
What to Verify Before You Commit
Several points in the published materials are in tension or are intentionally left open, so a careful candidate confirms them directly:
- Whether second-year residents may sit the combined written exam, given the conflicting statements on the written page
- Current oral application dates, given the mismatch between the timeline and the oral page
- The exact oral case count and timing, since the published statements cannot be reconciled into one number
- The validity term of a newly issued certificate
Frequently Asked Questions
The American Osteopathic Board of Radiology (AOBR), with AOA certification approval. It is distinct from ABR Core, ARRT credentials, and radiation oncology certification.
There are 300 multiple-choice questions delivered in three 100-minute sections, for five hours of testing. The issuer describes approximately 50 physics questions and 250 imaging questions, without publishing percentage weights.
The written passing score is a scaled 500 on a 200-800 scale. A scaled score is not the same as a raw percentage correct, so avoid converting it into one.
The written and oral fees are $800 each, and the two standard initial-stage fees total $1,600 by addition. Study materials, licensure, and the $300 annual OCC fee are separate.
Remote delivery follows the AOBR's MonitorEDU Secure Browser and PARADIGM instructions. Review the technical requirements well before your exam date.
For a wider look at the certification and its terminology, you may also find Diagnostic Radiology Certification and What Is Diagnostic Radiology? helpful, and you can begin timed domain practice at Diagnostic Radiology Exam Prep.