- The Short Answer: What the Name Actually Says
- Who Awards This Credential
- What It Is Not: Clearing Up Look-Alikes
- Anatomy of the Written Exam
- The Eighteen Published Topic Entries
- The Oral Stage and Its Ten Subject Headings
- Eligibility and Fee Mechanics
- After Certification: Continuing Certification
- Sequencing Your Preparation by Domain
- Frequently Asked Questions
- This credential is Primary Certification in Diagnostic Radiology, awarded by the American Osteopathic Board of Radiology (AOBR).
- The written exam has 300 multiple-choice questions in three 100-minute sections: about 50 physics and 250 imaging.
- The written passing score is a scaled 500 on a 200-800 scale.
- Written and oral fees are $800 each, totaling $1,600 for the two standard initial stages.
The Short Answer: What the Name Actually Says
When candidates search for what "Diagnostic Radiology" stands for, they are usually looking for one of two things: a definition of the medical discipline, or an explanation of the credential tied to it. On this site, the term refers to Primary Certification in Diagnostic Radiology, the board certification pathway administered by the American Osteopathic Board of Radiology. Read literally, the name tells you three things: it is the primary (initial) certification, it sits in the field of diagnostic imaging interpretation, and it belongs to the specialty of radiology.
The word "diagnostic" separates this pathway from interventional or therapeutic radiology work. Candidates are tested on how images from radiography, fluoroscopy, CT, mammography, ultrasound, MRI and nuclear medicine are produced, interpreted and kept safe for patients and staff. If you want the broader discipline-level definition, our explainers on what diagnostic radiology is and the meaning of diagnostic radiology cover it; this article stays focused on the credential itself.
Who Awards This Credential
The issuer is the American Osteopathic Board of Radiology (AOBR), operating with AOA certification approval. That matters for two reasons. First, the exam content, application process, fees and continuing-certification rules all come from AOBR's published pages rather than from any other radiology certifying organization. Second, when you research pass rates, study resources or fee schedules online, you must confirm the source is actually describing the AOBR pathway.
The candidate pool for this credential is osteopathic-pathway radiology residents and graduates working through approved training. Hiring contexts for certified diagnostic radiologists include hospital radiology departments, imaging groups, outpatient imaging centers and health systems; for current openings and role types, see our overview of diagnostic radiology jobs.
What It Is Not: Clearing Up Look-Alikes
Because the acronym-style name overlaps with other credentials, it helps to lay out the distinctions plainly.
| Question | Primary Certification in Diagnostic Radiology (this site) | Common confusion |
|---|---|---|
| Certifying body | American Osteopathic Board of Radiology (AOBR) | Other boards and technologist registries have different issuers and rules |
| Who sits for it | Radiology residents in an approved diagnostic-radiology residency | Technologist credentials are for imaging professionals, not physicians |
| Written format | 300 multiple-choice questions, three 100-minute sections | Other exams use different formats, fees and content outlines |
| Second stage | Oral examination after written success | Other pathways structure their stages differently |
If you are weighing whether this is the credential you actually need, start with our page on what diagnostic radiology certification is and the broader diagnostic radiology certification overview.
Anatomy of the Written Exam
The written stage is a single combined examination built from two parts: Part I covers physics and Part II covers diagnostic imaging. The issuer indicates approximately 50 physics questions and 250 imaging questions, and it does not publish percentage weights, so any figure claiming to be the "official percentage" for a domain should be treated skeptically.
- Format: 300 multiple-choice questions.
- Structure: three sections of 100 minutes each, for five hours of testing.
- Breaks: optional ten-minute section breaks that fall outside the testing time.
- Scoring: scaled, with a passing score of 500 on a 200-800 scale.
- Delivery: remote delivery follows the MonitorEDU Secure Browser/PARADIGM instructions published by the board.
The practical consequence of the 50/250 split is that imaging interpretation dominates the exam by volume, but the physics block is a concentrated, calculation-and-concept-heavy segment that many candidates have not touched since early training. For detail on what the scaled score means for your preparation, read the passing score breakdown, and for a realistic read on workload see how hard the exam is.
The Eighteen Published Topic Entries
The exam content outline is published on the AOBR written-exam page. This site organizes it as eighteen topic entries: Domains 1-8 reproduce the Part I physics bullets, and Domains 9-18 reproduce the Part II diagnostic imaging bullets. Eighteen is the count of entries supplied here, not an issuer-declared "top-level domain count." Ultrasound and Nuclear Medicine appear twice on purpose, once in each part, because they are tested differently in physics than in clinical imaging.
Part I: Physics (Domains 1-8)
Domain 1: Biological effects and safety
Connects radiation exposure to patient and personnel outcomes.
- Biological consequences of exposure and the rationale for safety practice
Domain 2: Radiological Physics (radiation production and interaction with matter)
The foundation for every modality that follows.
- How radiation is produced and how it interacts with matter
Domain 3: Radiation Biology (health effects)
Health effects of ionizing radiation at the biological level.
Domain 4: Radiation Safety and Protection
Protection principles for patients, staff and the public.
Domain 5: Radiological Imaging (radiography, fluoroscopy, CT, mammography)
Physics of image formation across the ionizing-radiation modalities.
Domain 6: Ultrasound
Physics-side ultrasound content, distinct from the clinical ultrasound entry in Part II.
Domain 7: MRI
Physics of magnetic resonance imaging.
Domain 8: Nuclear Medicine
Physics-side nuclear medicine, distinct from the clinical entry in Part II.
Part II: Diagnostic Imaging (Domains 9-18)
These ten entries carry the bulk of the roughly 250 imaging questions: Neuroradiology (Domain 9), Vascular/Interventional Radiology (Domain 10), Cardiopulmonary (Domain 11), Genitourinary Tract (Domain 12), Ultrasound (Domain 13), Breast Radiology (Domain 14), Gastrointestinal Tract (Domain 15), Musculoskeletal (Domain 16), Pediatric Radiology (Domain 17) and Nuclear Medicine (Domain 18).
For a deeper walk through each entry, use the complete guide to all 18 content areas, and keep the one-page cheat sheet nearby for final review.
The Oral Stage and Its Ten Subject Headings
After written success, candidates with fourth-year or later training can proceed to the oral examination. The oral page states a duration of 4.5 hours, eight cases and 20 minutes per case, and says candidates must pass all ten stations. The ten oral subject headings are the same ten imaging topics listed above as Domains 9-18.
Practically, this means your Part II study does double duty: the same imaging domains you master for multiple-choice questions become the subject areas for the oral stage, where you must articulate findings and reasoning rather than select an answer.
Eligibility and Fee Mechanics
Eligibility essentials
- A qualifying medical degree or a valid ECFMG pathway
- One-year approved internship
- Four-year diagnostic-radiology residency that includes 700 nuclear-medicine training hours
- Active licensure
- Ethics and training approval
There is a published inconsistency to flag: the written page lists a second-year eligibility bullet but also explicitly restricts the combined written examination to third-year or later residents. We retain both statements rather than silently choosing one. Confirm your own timing with AOBR; our requirements guide tracks the details.
Fees
| Stage | Fee |
|---|---|
| Written examination | $800 |
| Oral examination | $800 |
| Two standard initial-stage fees combined | $1,600 (by addition) |
The listed fees include the corresponding reexamination fees. Scheduling is another area with a documented conflict: the timeline's oral application dates differ from the oral page's relative application windows, so verify current windows with the board. See our exam dates page and the full cost breakdown for planning.
After Certification: Continuing Certification
Certification is not the end of the obligation. Current Osteopathic Continuous Certification (OCC) includes automatic enrollment for time-limited diplomates and a $300 annual fee. The component guidance for 2025-2027 includes:
- CME: 60 credits per three-year cycle, with no category or specialty quota (this current guidance takes precedence over older specialty-credit wording in the overview)
- Self-assessment: 15 SAMs/SA-CME per three-year cycle, which also count toward CME
- 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 caution on older sources: the 2013 AOBR Policies and Procedures document describes a historical separate-exam structure, additional physics headings and legacy ten-year certificates. It is not a verified current combined-exam blueprint, and this article does not assert a validity term for newly issued certificates. If you are weighing long-run value, see the ROI analysis and the salary guide.
Sequencing Your Preparation by Domain
Because the exam leads with physics and then moves to a large imaging block, a domain-ordered plan works better than an even split. One reasonable sequence follows.
Physics foundation (Domains 1-4)
- Radiation production, interaction, biological effects, safety and protection
- Do this first so later modality physics builds on it
Modality physics (Domains 5-8)
- Radiography, fluoroscopy, CT, mammography, then ultrasound, MRI and nuclear medicine
- Keep ultrasound and nuclear medicine physics separate from their clinical entries
High-volume imaging (Domains 9-12, 15, 16)
- Neuroradiology, vascular/interventional, cardiopulmonary, genitourinary, GI and musculoskeletal
- Practice these in oral-style verbal reasoning as well as multiple choice
Focused imaging and review (Domains 13, 14, 17, 18)
- Clinical ultrasound, breast, pediatric and clinical nuclear medicine
- Finish with timed three-section, 100-minute practice blocks
For a fuller method, see the study guide, and when you are ready to test yourself under realistic conditions, use the Diagnostic Radiology practice test.
Key Takeaway
Rehearse the five-hour endurance format. Three 100-minute sections is a long sitting, so practice in full blocks on the main practice test site before exam day rather than only drilling short quizzes.
Frequently Asked Questions
It refers to Primary Certification in Diagnostic Radiology, the initial board certification pathway offered by the American Osteopathic Board of Radiology. For related phrasing, see what diagnostic radiology stands for and what it means.
There are 300 multiple-choice questions delivered in three 100-minute sections, with approximately 50 physics questions and 250 imaging questions. No percentage weights are published.
The written passing score is a scaled 500 on a 200-800 scale.
The written and oral fees are $800 each, so the two standard initial-stage fees total $1,600 by addition. The listed fees include the corresponding reexamination fees.
No. This is the AOBR pathway specifically. It is not ABR Core, not an ARRT technologist credential and not radiation oncology certification, so fees, content and policies from those programs do not apply.
In short, the name describes a physician-level, initial board certification in diagnostic imaging interpretation, earned through a written exam covering physics and eighteen published topic entries, followed by an oral stage drawn from ten imaging subject headings. Confirm every current detail against the AOBR pages, and build your preparation around the specific domains the board actually publishes.