The comparison of physical and biological plan optimization alghorthims of eclipse treatment planning system for static imrt treatments of early stage prostate cancers

Compare the results which were obtained using biological optimization algorithm with conventional dose/dose-volume based approach (DVTP) in the Eclipse Treatment Planning System and to assess the feasibility of this developing method for the patients who were in early stage prostate cancers. CT images of 20 early stage prostate cancer patients were taken from the archive of the Eclipse Treatment Planning System in the department of Radiation Oncology of Dokuz Eylul University. IMRT plans which were acquired on the CT images were optimized using physical and biological optimization algorithms. In the physical optimization approach, DVTP plans were prepared in accordance with the physical dose and volume criteria for the determined target and organs at risk. In the biological optimization approach, BORT plans and TCP/NTCP plans which depend on the tumor control probability and normal tissue complication probability were calculated. Thus three different treatment plans were acquired according to those optimization models. And, the results of those plans were compared for the PTV78, rectum, bladder and femoral heads. The data was analyzed on the SPSS v20 statistic program. The values of CI and HI were calculated and found as 0,95(±0,09), 0,90(±0,31), 0,58(±0,36) and 0,03(±0,01), 0,05(±0,02), 0,26(±0,07) for the DVTP, BORT, TCP/NTCP plans. The values of maximum dose were found as 103,47(±0,92), 104,40(±1,30), 111,06(±7,81) for the DVTP, BORT, TCP/NTCP plans. In the BORT plans, it was seen that V30, V50, V65 and V75 parameters had 10% lower values compared with DVTP plans for the bladder and rectum. Also, in the TCP/NTCP plans, calculated rectum and bladder complication probabilities were 90% lower than the other plans, averagely. The target dose homogeneity and conformity in the TCP/NTCP plans were decreased, the TCP/NTCP plans were improved sparing of normal tissues with lower NTCP values. In the DVTP and BORT plans were evaluated in terms of the maximum dose, and it was seen that these values are within the acceptable limits compared with ICRU83 report. The evaluation of all results shows there are no meaning differences among target coverage, target conformity BORT and DVTP approaches, but in the BORT plans were provided better sparing of normal tissues. Consequently, Biologically-based Optimization could be an alternative to the dose/dose-volume approach in terms of critical structures to early stage prostate cases.