前列腺癌三维适形放疗中体位对靶区和正常组织体积及照射剂量的影响  

The effect of treatment positioning on volume and dose of target and critical organs in three-dimensional conformal radiotherapy of prostate cancer

作　　者：刘跃平[1] 刘新帆[1] 李晔雄[1] 金晶[1] 关莹[1] 

机构地区：[1]中国医学科学院中国协和医科大学肿瘤研究所肿瘤医院放疗科,北京100021

出　　处：《中华放射肿瘤学杂志》2005年第5期422-426,共5页Chinese Journal of Radiation Oncology

基　　金：首都医学发展科研基金资助项目(2002-3042)

摘　　要：目的对比研究仰、俯卧体位下前列腺癌三维适形放疗对靶区和周边重要器官体积改变和照射剂量变化.方法临床穿刺细胞学证实的分期为T1～T2N0M0期的前列腺癌8例,行对称六野三维适形放疗.定位前1 h排空膀胱,定位前1.0、0.5 h口服造影剂各400ml,每例病例同一时间分别行前列腺癌仰、俯卧位CT定位扫描,定位后勾画靶区及盆腔重要器官结构,三维计划设计.分别评估CTV、PTV、直肠、膀胱、股骨头和盆腔小肠体积,CTV、PTV、直肠、膀胱、股骨头、盆腔小肠平均照射剂量,50Gy膀胱、直肠和30Gy股骨头受照体积及盆腔小肠最大照射剂量,对比仰、俯卧位各器官结构体积变化以及照射剂量差别.结果无论是仰卧位还是俯卧位,靶区均能得到均匀理想的剂量分布.直肠体积在不同体位下变化较大.仰、俯卧位各正常组织的平均体积分别为:膀胱(306±58)、(325±69)cm3,直肠(59±20)、(144±96)cm3,小肠(94±51)、(75±18)cm3.CTV、PTV、股骨头体积变化不明显.CTV、PTV、膀胱、股骨头、小肠平均照射剂量在不同治疗体位下差别不大.仰、俯卧位直肠平均照射剂量分别为(3364±995)、(2221±1176)cGy.DVH分析显示直肠在俯卧位保护最好,仰、俯卧位50Gy直肠体积分别占总体积的39.5%±19.7%、19.8%±15.7%.俯、仰卧位小肠最大照射剂量分别为(234±143)、(275±220)cCy.结论前列腺癌俯卧位三维适形放疗使直肠体积明显增大,可因减少直肠照射而起一定保护作用.Objective To prospectively assess the effect of supine vs. prone treatment position on the voltune and dose to the target and surrounding critical organs in prostate cancer being treated with the three-dimensional conformal technique. Methods Eight patients with early prostate cancer diagnosed by puncture cytology received three-dimensional conformal radiotherapy （3DCRT） to the prostate and inferior seminal vesicle. The stage of disease were either T1N0M0 or T2N0M0. One hour before CT simulation, the bladder was voided, and then 400 ml of oral contrast solution was given every half hour before the CT scan. Two sets of transverse images were taken for the whole pelvis in the supine and prone positions. A treatment plan of three-dimensional conformal radiotherapy was made using the CMS Focus-Xio treatment planning system. The volume of CTV, PTV, rectum, bladder, head of femur, and small bowel in both the supine and prone position were evaluated, as well as the mean dose to CTV, PTV, rectum, bladder, head of femur, and pelvic small bowel. The percentage of volumes of 50 Gy received in the rectum and bladder, 30 Gy in the femoral heads, and the maximal dose in the pelvic small bowel were also assessed. The variability of volume and dose of these targets or organ structures were compared in the supine position and prone position. Results An even and satisfactory target dose distribution was obtained both for the supine and prone position through opposing 6-field 3DCRT. The alteration of volume was found in organs of bladder, rectum and small bowel when comparing the supine position to prone position. Their mean values were （306 ± 58） cm^3 and （325±69） cm^3 for the bladder, （59±20） cm^3 and （144 ± 96） cm^3 for the rectum, and （94 ± 51） cm^3 and （ 75 ± 18） cm^3 for the small bowell.The volume change of the rectum was obvious, with a P value of 0. 027. Little volume change was observed between different positions for CTV, PTV, and head of femur. No obvious differencewas found for the mea

关 键 词：前列腺肿瘤/放射疗法 放射疗法 适形 体位影响 三维适形放疗 照射剂量 体积变化 前列腺癌 俯卧体位 正常组织 

分 类 号：R737.25[医药卫生—肿瘤]