Review of techniques for improving the uniformity of dose distribution in total body irradiation (TBI) with parallel – opposed anterior and posterior geometry

      Total body irradiation (TBI) is a kind of external beam radiotherapy which is used in conjunction with chemotherapy with the purpose of immunosuppression before bone marrow transplantation. As recommended by AAPM dose distribution uniformity in TBI is very important and dose variation must be within ±10% of prescription dose. Patients treatment geometry for TBI techniques fall into two common categories: parallel-opposed anterior/posterior lateral total body irradiation and parallel-opposed lateral total body irradiation. So far several techniques such as use of tissue compensator, dynamic TBI delivery, etc. where implemented in different department around the world to improve dose distribution uniformity. The propose of this paper is to review several techniques that are used around the world for dose uniformity improvement in parallel opposed anterior posterior TBI.