Bridging Precision and Practice: A Systematic Approach to Total Body Irradiation in Routine Clinical Settings

To evaluate the feasibility of delivering total body irradiation (TBI) in a standard linear accelerator bunker using a treatment planning system (TPS) and a conventional multileaf collimator assembly. The aim was to address dose homogeneity and lung shielding within practical clinical constraints.

TBI was performed using conventional anterior-posterior beam delivery, dividing the whole-body irradiation into three to four sections with patients positioned on the treatment couch. Whole-body computed tomography images, acquired with Vac-Loc immobilization, were used for planning in the TPS. The source-to-surface distance was maintained between 120 and 135 cm. The moving-junction technique provided uniformity at section junctions, and the multileaf collimator (MLC) was employed for customized lung shielding. Patient setup and shield positioning were verified with an electronic portal imaging device.

The plan resulted in ≥ 92% of the target volume received ≥ 90% of the prescribed dose while V110 remained <7%. The mean lung dose was kept below 8 Gy. The prescribed dose rate at the mid-plane was approximately 1.8 Gy/min. Point dose measurements showed agreement with the TPS calculations within 2%, indicating high dosimetric accuracy and reliable dose delivery.

Conventional linac setups, combined with TPS-guided planning, MLC-based lung shielding, and moving-junction delivery approaches, provide a practical solution for TBI with acceptable dose uniformity and lung sparing, supporting implementation in standard radiation oncology practice.