Total body irradiation practice patterns: insights from a national survey

Despite the expansion of hematopoietic stem cell transplantation (HSCT) services, contemporary Total Body Irradiation (TBI) practices remain insufficiently characterized in many healthcare settings. This study aimed to establish a national baseline for TBI practice to support benchmarking, standardization, and quality improvement.

A cross-sectional online survey was distributed between May and June 2026 to seven Saudi centers that provided TBI services. The questionnaire collected data on service capacity, patient populations, dose fractionation, treatment techniques and delivery, planning methods, and quality assurance. A census sampling approach was used, inviting Radiation Oncologists, Medical Physicists, and Therapists. Data were analyzed using descriptive statistics in Python (v3.11).

All seven centers responded. One center (C) submitted two responses covering conventional extended source-to-surface distance (SSD) and volumetric-modulated arc therapy (VMAT) practices. Commissioned between 1980 and 2020, the TBI programs manage an estimated 386 annual cases (range: 12-120). Fractionated TBI (10-12 Gy, six twice-daily fractions) predominated. The extended SSD opposed-beam technique remained in use at six centers, with the umbilicus as the most common prescription point. At two centers, extended-SSD TBI was used alongside Intensity-modulated radiation therapy (IMRT)-TBI (VMAT and Tomotherapy. IMRT-TBI-based centers reported volumetric target-coverage objectives of 90% and explicit organ-at-risk (OAR) dose planning constraints, particularly for the lungs and kidneys. Treatment planning for IMRT-TBI involved treatment planning systems (TPS), whereas extended-SSD techniques used varied planning approaches, including in-house spreadsheets, pre-calculated templates, and, in some cases, TPS-assisted planning. In vivo dosimetry was performed at all centers. The absorbed dose-rate at the prescription point ranged from <10 to 30 cGy/min for conventional techniques. Three centers planned their initial implementation of IMRT-TBI within three years. The ability to control OARs was the main driver, while linear accelerator availability and staff training were key barriers.

Although conventional extended SSD TBI remains the most widely used technique, TBI practice is transitioning toward IMRT-based delivery. National practice guidelines based on existing international recommendations may help standardize care, address implementation barriers, and support the delivery of high-quality TBI services across treatment centers.