Dose Comparison of Treatment Plans Using Different Ir-192 Sources and Treatment Planning Systems for Intracavitary HDR Brachytherapy / 의학물리

ABSTRACT

For HDR intracavitary brachytherapy with ovoids and a tandem, we compared the dose discrepancy of treatment plans using two different Ir-192 sources (microSelectron, Varian) and generated on two different treatment planning systems (PLATO, BrachyVision). The treatment plans of ten patient treated from Oct. 2007 to Jan. 2008 were selected for these comparisons. For the comparison of dose calculation using different sources, the average discrepancies were -0.91+/-0.09%, 0.27+/-0.07%, 0.22+/-0.39%, and 0.88+/-0.37% in total treatment time and at B-point and ICRU bladder and rectum reference point, respectively. Comparing the two systems, the average dose discrepancies between treatment planning programs were -0.22+/-0.42%, -0.25+/-0.29%, -0.23+/-0.63%, and -0.17+/-0.76%, and the average dose discrepancies between positioning methods (PLATO with film and BrachyVision with digitial image) were -0.61+/-0.59%, -0.77+/-0.45%, -0.72+/-1.70%, and 0.35+/-2.82% at A-point, B-point, and ICRU bladder and rectum reference points, respectively. The rectal dose discrepancies between two systems were reached 5.87%. The difference in the dwell position expected by each TPS are mainly affected by the differences in the positioning method in TPSs and have an effect on dose calculations of rectal and bladder located in AP direction.