Comparison of dose distributions in different treatment positions with 10 MV and 6 MV photon energies in total body irradiations

In this study, effects of dose distribution have been examined in different treatment positions (two sides, front-back) with (TVI), 10 MV and 6 MV photon energies in Total Body Irradiations. Gantry angle was adjusted to 270o, collimator angle to 45o, collimator gap to 40x40 cm2 in order to create a wide area geometry needed in irradiation and source axis distance (SAD=350 cm) technique was used in treatment. Dosimetric parameters such as dose efficiency, deep-dose data, profile smoothness, usable area width required for Total Body Irradiation were measured in same geometric conditions with Total Body Irradiation and with a Solid Water phantom material. Deep dose equivalent percentages were measured by an ion chamber with parallel plates. TLD?s used in measurements have been calibrated in the same conditions with Total Body Irradiation. Midsection was chosen as the calculation point and the center of area was laid such that it is in the midsection level in both lateral and front-back irradiations. Middle line dose was calculated and concord between measured dose values was compared. Lateral dose distributions were also measured in shoulder, thorax, abdomen and hip cross-sections for lateral irradiations in addition to middle line dose distribution. Consequently, it was detected that dose distribution in front back irradiations for both energies were more homogenous than those in lateral irradiations and also dose distributions at 6MV were more homogenous than 10 MV.