论文部分内容阅读
目的 分析摆位误差对肿瘤计划靶体积(PTV)及危及器官受照剂量的影响,探讨前列腺癌调强放疗中摆位误差在线校正的必要性. 方法 16例前列腺癌患者调强放疗中行治疗机下的锥形束CT(CBCT)扫描共214次,其图像与计划CT图像融合配准获得x、y、z轴方向平移摆位误差.将上述误差引入治疗计划系统中重新计算得到PTV、膀胱、直肠等的剂量和体积参数并与原计划行配对t检验. 结果 214次摆位误差再计划的PTV 95％体积剂量D95(7 613.73 cGy比7764.25 cGy,t=2.494,P=0.025)和最小剂量Dmin(80.20±9.83比86.80±5.05,t=5.536,P＜0.001)小于原计划,但未超过可接受偏差范围.膀胱接受50Gy剂量体积(V50)和30％膀胱体积剂量(D30)以及直肠接受50Gy剂量体积(V50)和25％直肠体积剂量(D25)与原计划差异不明显. 结论 平移摆位误差导致PTVD95下降但可接受,膀胱、直肠总体受量变化不明显,前列腺癌放疗过程中在线误差纠正能提高治疗精确性.“,”Objective To analyze the impact of set-up errors on planning target volume (PTV) for tumors and radiation dose distributions,then to investigate the necessity of on-line set-up error correction for prostate cancer during IMRT.Methods Cone-beam CT (CBCT) scanning images in 16 patients with prostate cancer were acquired with a total of 214 times during IMRT.The CBCT images and the original planning CT images were matched to acquire the translational errors of the x,y and z axis.The dose distributions were recalculated based on the data of each set-up error.The PTV,radiation dose distribution in organs at risk including bladder and rectum,and dose volume parameters were calculated in the re-planning,and then compared with the original planning by paired t-test.Results The PTV 95％ dose volume (D95) and PTV minimal dose volume (Dmin) were lower in the re-planning than in the original planning after 214 times set-up (7613.73 cGy vs.7764.25 cGy,80.2％ vs.86.8％,t=2.494 and 5.536,P=0.025 or ＜0.001),but it could be acceptable.Bladder received 50 Gy dose volume (V50),30％ bladder volume dose (D30),rectume received 50 Gy dose volume (V50) and 25％ rectume volume dose (D25) in the re-planning had no statistical differences with those in the original planning.Conclusions The set-up errors lead to the decrease of PTV D95 but be acceptable.The radiation dose received by bladder and rectum has no obvious changes in the re-planning as compared with the original planning.The on-line set-up error correction for prostate cancer may improve the treatment accuracy during IMRT.