Total Body Irradiation (TBI) using Helical Tomotherapy in children and young adults undergoing stem cell transplantation

Background: Establishing Total Body Irradiation (TBI) using Helical Tomotherapy (HT) to gain better control over dose distribution and homogeneity and to individually spare organs at risk. Because of their limited body length the technique seems especially eligible in juvenile patients. Patients and methods: The cohort consisted of 10 patients, 6 female and 4 male, aged 4 - 22 y with acute lymphoblastic- (ALL) or acute myeloic leukemia (AML). All patients presented with high risk disease features. Body length in treatment position ranged from 110-180 cm. Two Gy single dose was applied BID to a total dose of 12 Gy. Dose volume constraint for the PTV was 95% dose coverage for 95% of the volume. The lungs were spared to a mean dose of [less than or equal to] 10 Gy. Patients were positioned in a vac-loc bag in supine position with a 3-point head mask. Results: Average D95 to the PTV was 11.7 Gy corresponding to a mean coverage of the PTV of 97.5%. Dmean for the lungs was 9.14 Gy. Grade 3-4 side effects were not observed. Conclusions: TBI using HT is feasible and well tolerated. A benefit could be demonstrated with regard to dose distribution and homogeneity and the selective dose-reduction to organs at risk.