Evaluation and Comparison of Prostate & Rectum Radiation Absorbed dose in 3D Conformal treatments using Cobalt-60 Unit & Linac

OBJECTIVE: Radiation therapy is a good option for treating this cancer and new radiotherapy techniques has an essential role in prostate treatment. This Study was designed to evaluate the dosimetric parameters such as rectum dose, bladder dose, Integral dose (ID), Homogeneity Index (HI) and Conformity Index (CI) in both Conventional and 3D Conformal Radiotherapy (3D CRT) at three different energies: Cobalt-60, 6 MV and 18 MV . Materials and Methods: Computed tomography (CT) scans of pelvis of 27 patients were acquired and transferred to the RTDosePLAN treatment planning system. For each patient, 8 Conventional plans (3, 4, 5 and 6 Fields) and one 3D CRT plan were planned by in Cobalt-60 photon Energy, and then the same plans were performed by 6 MV and 18 MV Photon Energies . Results: By increasing the energy of beam relative to Cobalt-60 energy, rectum’s and bladder’s Dmean were decreased by 3 to 4% and 4 to 6%, respectively, bladder’s D3/3 and D2/3 to bladder were decreased by 26% and 8% for 6 MV and 58% and 20% for 18 MV. Increasing the photon beam energy decreased CI to 7% and 10%, 10% and 20% for ID and 3% to 4% for Dmax. CI and ID in 3D CRT decreased to 50% and 33% in comparison of Conventional RT . Conclusions: Compared with conventional treatment techniques, Conformal RT offered the most conformity in delivery of tumoricidal doses to the prostate while sparing dose to critical, uninvolved structures with Lower Integral Dose .

کلیدواژه ها:

Prostate Cancer ، Absorbed dose ، Rectum ، Linac ، Cobalt-60