الفهرس 
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Abstract
The present work is devoted to evaluate and compare the dosimetry results that were obtained by using convolution (CON), superposition (SUP), and fast superposition (FSUP) dose calculation algorithms in three-dimensional conformal radiotherapy (3D-CRT) and intensity modulated radiotherapy (IMRT) treatment planning techniques for two different sites (prostate and breast cancers). Ten patients with diagnosis of prostate cancer and ten patients with left-side breast cancer were selected for this study. Doses of 8000 cGy and 5000 cGy were prescribed to the planning target volume (PTV) of prostate and breast cases, respectively. For each patient, 3D-CRT and IMRT plans were created with photon beams of 6 MV quality using CON, SUP and FSUP algorithms. For each plan, dose-volume histogram (DVH) was generated. Dmin, Dmax, and Dmean were evaluated for the PTV and organs at risk (OARs). Maximum percent of variations between algorithms were recorded for the PTV, for all cases. The evaluation parameters include the homogeneity index (HI), and the conformity index (CI). For the evaluation of doses to the OARs, the maximum dose was used .The maximum percentage of variation recorded between the three algorithms for the PTV was 2.72% in average CI in 3D-CRT technique for breast cancer patients, and for the OARs was 11.47% in average Dmean in case of contralateral breast with 3D-CRT technique in breast cancer patients. Significant variations between the three algorithms were observed. According to this study as the results from the three different algorithms clearly differed, significant care should be taken when evaluating treatment plans, as the choice of the dose calculation algorithm may influence the treatment planning process as well as the end clinical results. We recommend to use the convolution algorithm with 3D-CRT technique in treatment planning (TP) of the prostate, to use the superposition algorithm with IMRT technique in TP of the prostate, and to use the convolution algorithm with both 3D-CRT and IMRT techniques in treatment planning of the left side breast.