A novel approach to total skin irradiation using helical TomoTherapy

PURPOSE: To describe our experience with a novel technique for total skin irradiation using helical TomoTherapy (Accuray, Sunnyvale, CA). METHODS AND MATERIALS: An infant with refractory acute myelogenous leukemia with extensive cutaneous involvement was given total skin irradiation using inverse-planned helical tomotherapy. Quality assurance tests to determine the deliverability of the technique and the accuracy of dose estimation at the superficial skin level were devised and performed. Daily megavoltage imaging, tomotherapy plan adaptive evaluation, in vivo skin dose measurements, and cumulative dose summation were tools employed to assess the quality of treatment and positioning reproducibility on a daily basis. RESULTS: The quality assurance checks showed that tomotherapy can indeed be used for total skin irradiation in cases where conventional electron treatment delivery is not possible. However, the overestimation of absorbed dose near surface by the treatment planning software must be quantified and taken into account using in-phantom and in vivo dosimetry techniques with appropriate detectors. Daily imaging allows for superior positioning, while daily plan adaptive and dose summations based on the plan adaptive calculations allow for evaluation of the treatment delivery. CONCLUSIONS: An infant has been treated successfully using helical TomoTherapy for total skin irradiation prior to allogeneic stem cell transplant. The course of treatment was uncomplicated and the patient is doing well more than 15 months following therapy.