A step and shoot intensity modulated technique for total body irradiation

INTRODUCTION: Total body irradiation (TBI) is a part of the conditioning regimen for bone marrow transplant. At the Royal Marsden (Sutton, UK) and Rigshospitalet (Copenhagen, Denmark), we introduced a step and shoot IMRT (SS IMRT) technique for TBI. This technique requires no equipment other than that used to deliver other external beam radiation. In this paper, we describe this technique and report on data from the two clinics. MATERIALS AND METHODS: The patients were positioned supine, supported by vacuum bag(s). The entire body of the patients were CT scanned with 5 mm slices. Multiple multi-leaf collimator (MLC) defined fields were used. In-vivo dosimetry was performed at the Royal Marsden for 113 patients. Calculated doses for 18 adult and 4 paediatric patients from Rigshospitalet were extracted. RESULTS: The in-vivo data from the Royal Marsden showed that the mean TLD measured dose difference was −1.9% with a standard deviation of 4.5%. SS IMRT plans for 22 patients from Rigshospitalet resulted in mean doses to the brain, lungs and kidneys all within the range of 11.1–11.8 Gy, while the V(12 Gy) was below 5% for the brain, 2% for the lungs and 0% for the kidneys. DISCUSSION: SS IMRT is feasible for TBI and can deliver targeted doses to the organs at risk.