IntroductionThe Clinical Specialist Radiation Therapist (CSRT), is a new advanced practice (AP) role for radiation therapists (RTTs). Following training, education and evaluation, the CSRT performs specific duties in autonomous ways, making advanced clinical decisions in their area of specialization. This case study examines the CSRT's impact on quantity (i.e., increasing capacity), improving quality and stimulating research and innovation.MethodsBetween 2007 and 2016, 23 CSRTs worked in 10 cancer centres in various AP position. A standardised metrics package, focusing on wait‐times, patient volumes, patient throughput, time‐savings, quality initiatives, satisfaction, research and innovation was developed and used to collect qualitative and quantitative data. Data were self‐reported by the CSRTs but electronic databases, pre/post‐studies, surveys and interviews were also used.ResultsQuantity projects (n = 76) related to patient volumes, wait‐times, patient throughput and time‐savings increased capacity and allowed more patients to enter the system. The presence of a CSRT allowed, on average, 13 additional patients (either new or re‐treated) to be seen, at their respective cancer centre, per month. An average of 1.4 yearly quality improvement initiatives were led by each CSRT, which contributed to improvements in quality of care and satisfaction. CSRTs demonstrated a high level of involvement in research, innovation and knowledge translation activities, either as leaders or part of interprofessional teams.ConclusionCSRTs positively impact quantity (capacity of the system), quality, research and innovation. Future efforts include permanent and sustainable team integration, practice standards, formal and comprehensive educational preparation, and approaches to consistent, valid assessment of AP in radiation therapy.