ABR Radiation Oncology study guide
ABR Radiation Oncology · Work through your exam, one topic at a time.
ABR Radiation Oncology initial certification is the American Board of Radiology's credential for physicians who treat cancer and other conditions with ionizing radiation. Candidates must complete a year of accredited clinical training, finish a four-year ACGME- or RCPSC-accredited radiation oncology residency (or the International Medical Graduate Alternate Pathway), hold a valid state or provincial license (a training license is acceptable during residency), and demonstrate ethical standards. Certification requires passing two exams. The Qualifying Exam is computer-based and has three separately scored parts: Medical Physics for Radiation Oncology, Radiation and Cancer Biology, and Clinical Radiation Oncology. Topics on this exam: Medical Physics for Radiation Oncology, Radiation and Cancer Biology, and Clinical Radiation Oncology. The ABR Radiation Oncology study guide has 3 sections and about 815 words.
01Medical Physics for Radiation Oncology
A candidate must be fluent in photon and electron interactions, dosimetry formalisms (TG-51/TG-21 calibration, absorbed dose to water), and treatment-planning physics. Know the difference between percent depth dose and tissue-air ratio , and how field size, SSD, energy, and depth shift each. Understand inverse-square falloff, buildup region, and why dmax moves shallower with higher energy. For brachytherapy, know TG-43 formalism, dose-rate constant, and anisotropy.
296 words, about 1 min02Radiation and Cancer Biology
Master the 4 R's (repair, reassortment, repopulation, reoxygenation) and how fractionation exploits them. Know the linear-quadratic model : survival = e^−(αD+βD²), the α/β ratio, and how BED = nd(1 + d/(α/β)) converts schedules. Understand DNA damage and repair (HR/NHEJ), the oxygen effect (OER ~2.5–3), and cell-cycle radiosensitivity (M most sensitive, late S most resistant). Know clinically relevant α/β values: ~10 Gy for tumors/early effects, ~3 Gy for late effects.
267 words, about 1 min03Clinical Radiation Oncology
Know site-specific indications, target volumes (GTV/CTV/PTV), dose/fractionation, and normal-tissue constraints for the major diseases: head/neck, lung (NSCLC, SCLC), breast, prostate, GI (esophagus, rectum, anal), CNS, gynecologic, lymphoma, and palliation. Understand concurrent chemoradiation rationale, elective nodal coverage, and when SBRT/SRS is appropriate. Be able to name classic dose levels (e.g., 60 Gy/30 for definitive NSCLC, 50 Gy/25 postoperative breast, 78 Gy prostate, 50.4 Gy anal with mitomycin/5-FU) and key constraints (spinal cord, brachial plexus, parotids, lung V20). Questions test whether you know elective vs involved nodal dosing and the difference between definitive and adjuvant intent.
252 words, about 1 min