A variable speed translating couch technique for total body irradiation.

We have developed a variable speed translating patient couch system for the delivery of total body irradiation (TBI). For a whole body Rando-type phantom, dose variation at mid-plane relative to the prescription point (navel) can be as high as 15% (neck or legs) with a constant velocity. By taking into account variations in body thickness, the intensity modulation radiation therapy, resulting from variable velocities, effectively delivers a uniform dose distribution at mid plane. The couch control user interface, technical aspects and dose planning optimization procedure for determining velocity distribution are described.