The ABR included therapeutic radiology and radium therapy in its diagnostic certification from its outset in 1934. However, in 1944, some voiced concerns about inadequate training in therapeutic radiology [1], and, as late as 1952, certification limited to therapeutic radiology was given to candidates that failed the diagnostic portion of the test [2]. In 1974, the ABR enlarged its Board of Trustees to accommodate representatives of the American Society of Therapeutic Radiology and Oncology (ASTRO). The ABR then announced that trainees starting their training after July 1, 1976, would be offered certification in either diagnostic radiology or radiotherapy [1].
For years, the examination for therapeutic radiology was primarily oral [1], but the ABR subsequently recognized the need for changes, which included a written examination as a prerequisite for the oral examination, starting in 1965. Content for this examination covered physics, radiation biology, clinical oncology, anatomy, pathology, physiology and chemotherapy [3]. The ABR began to issue time-limited certificates in radiation oncology in 1995 [4].
The three ABR board examinations for radiation oncology, including the qualifying/written examinations and certifying (oral) examination, were historically administered in a single session from 1978 through 2004, but concerns about undue examinee stress prompted splitting it into multiple sessions [5]. The separation and timing of the written examinations were also based on requests by department leaders who were concerned about residents’ conflicting priorities between examination preparation and clinical training during their final year of residency. Smaller training programs also advocated splitting the examinations and moving them earlier into training, as they often alternated years of training in vital educational domains such as physics and radiation and cancer biology [5].
Currently, the initial certification in radiation oncology is administered in two steps: 1) the qualifying examinations in medical physics for radiation oncology and radiation and cancer biology are available to residents after 32 months of training; and 2) the qualifying examination in clinical oncology (radiation and general) is available to residents after 48 months of training. These examinations are currently administered in Pearson VUE test centers throughout the country. When candidates have passed all three qualifying examinations, they are eligible to sit for the certifying (oral) examination, which until the 2020 pandemic was administered at a single site (Louisville, KY, until 2018, then Tucson, AZ, in 2019). Because of the global COVID-19 pandemic, the ABR announced its intent to discontinue administration of a single-site, face-to-face examination. Some have again proposed a combined single written examination of about 10 hours, comparable to other specialties [6]. Of the 24 ABMS boards, only radiation oncology and anesthesia require that residents take more than one written qualifying examination.
On the 2018 ABR Radiation Oncology Medical Physics and Radiation and Cancer Biology written qualifying examinations, there was an atypically low pass rate (dropping from 90% to 70% for physics and 74% for biology). ASTRO convened workgroups that made recommendations, including that the ABR study guide and topic blueprint should be replaced by the ASTRO physics core curriculum [7]. Others have suggested reorientation of the examinations to be more clinically oriented, practical, and relevant, and that subject areas be represented more proportionally [8].