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目的:比较直肠癌术前放疗计划中6、10及15MV-X射线的剂量学差异。方法:选择18例直肠癌术前放疗患者,在医科达计划系统中分别采用6、10及15MV-X射线予相同的3个野形成3个放疗计划,比较3个计划的靶区剂量学特点以及小肠、膀胱、股骨头等正常组织的平均受照剂量及体积。结果:6、10及15MV-X射线均能满足计划要求,靶区剂量分布及适形指数、均匀性指数均无明显差异(P>0.05);正常组织中除股骨头中15MV的V30明显小于6MV的V30(P<0.05)外,其余指标无明显差异。结论:6、10及15MV-X射线均能满足计划要求,考虑到放射防护因素,尽量不使用15MV-X射线。
OBJECTIVE: To compare the dosimetric differences of 6, 10, and 15 MV-X rays in preoperative radiotherapy plans for rectal cancer. METHODS: Eighteen patients with preoperative radiotherapy for rectal cancer were selected. Three radiotherapy plans were generated using the same three fields as 6, 10, and 15 MV-X radiation in the Edarach system. The dosimetric characteristics of the three planned targets were compared. The average dose and volume of normal tissues such as the small intestine, bladder, and femoral head. RESULTS: All of the 6, 10, and 15 MV-X rays were able to meet the requirements of the plan. There was no significant difference in dose distribution, conformal index, and uniformity index between the target area (P>0.05). The V30 of 15MV in the femoral head was significantly smaller than that in the normal tissue. 6MV V30 (P<0.05), there was no significant difference in other indicators. Conclusion: 6, 10, and 15 MV-X-rays can meet the requirements of the plan, taking into account the radiation protection factors, try not to use 15MV-X rays.