A dosimetric method of total body irradiation

The determination of the dose delivered to the body during Total Body Irradiation (TBI) is not easy, as direct measurements are impossible. This article presents the intention to develop a systematic and simple method for absorbed dose determination in 60Co TBI using mid plane dose factors (MDF) and external measurements, i.e. entrance and exit dose readings by semiconductor detectors. In order to perform the radiation field analysis prior to TBI treatment, a special silicon n-type detector with increased sensitivity (1200 nC/Gy) was used. The dependence of the calibration factor of this detector exposed to different dose rates in standard and TBI conditions was investigated. A theoretical model of anthropomorphic phantoms of cylindrical ellipsoid shape was established. The software made it possible to generalize the applicability of TBI dosimetry to any individual case of real patient data. A quality assurance analysis of dosimetric results of 350 patients, who underwent TBI during a 17-year period, was performed.