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目的:探讨腹腔镜直肠癌根治术后应用仰卧臀高腹低与俯卧垫有孔泡沫板2种放疗体位对小肠及膀胱照射体积及剂量的影响。方法:选取2010-06-01-2012-12-31我科收治腹腔镜下直肠癌根治术患者37例,分别在2种不同体位下进行CT模拟定位,勾画治疗靶区和正常器官,进行3野适形计划的设计,比较2种体位下小肠及膀胱的平均剂量,以及在20、30、40和45Gy等剂量水平小肠和膀胱受照体积V20、V30、V40及V45。结果:采用仰卧臀高腹低位和俯卧位垫有孔泡沫板位时,小肠在20Gy剂量水平受照体积分别为76.22和156.27cm3,t=-3.352;30Gy处分别为31.26和56.35cm3,t=-3.412;40Gy处分别为21.22和45.35cm3,t=-4.072;45Gy处分别为21.22和45.35cm3,t=-3.768;均仰卧高于俯卧位,P值均<0.05。膀胱在40Gy剂量水平受照体积分别为132.46和202.57cm3,显著低于俯卧位垫有孔泡沫板位的57.52和100.35cm3,t值分别为-4.072和-3.768,P值均<0.05。但在20和30Gy剂量水平两组患者间差异无统计学意义,t值分别为-1.739和0.218,P值均>0.05。结论:直肠癌术后放疗,应用仰卧臀高腹低体位能减少小肠的受照体积及剂量,也能减少高剂量区膀胱的受照体积。
Objective: To investigate the effects of two radiotherapy positions on the size and dose of small bowel and bladder irradiation after laparoscopic resection of rectal cancer. METHODS: From 2010-06-01-2012-12-31, 37 patients underwent laparoscopic radical resection of rectal cancer in our department. The CT simulations were performed in 2 different postures to delineate the target area and normal organs. The Wild Conformal Plan was designed to compare the mean dose of the small intestine and bladder under two postures and the volume of small intestine and bladder irradiated V20, V30, V40, and V45 at dose levels of 20, 30, 40, and 45 Gy. RESULTS: When the supine hips were placed in the low-lying ventral position and the prone position cushioned with foamed holes, the irradiated volume of the small intestine at the 20 Gy dose level was 76.22 and 156.27 cm3, t=-3.352; 30 Gy was 31.26 and 56.35 cm3, respectively. -3.412; 40Gy were 21.22 and 45.35cm3, t =-4.072; 45Gy were 21.22 and 45.35cm3, t = -3.768; both supine was higher than the prone position, P values were <0.05. The irradiated volume of the bladder at the dose of 40 Gy was 132.46 and 202.57 cm3, respectively, which was significantly lower than the 57.52 and 100.35 cm3 of the foamed plate in the prone position. The t values were -4.072 and -3.768, respectively, and the P values were all <0.05. However, there was no significant difference between the two groups at the doses of 20 and 30 Gy. The t values were -1.739 and 0.218, respectively, and the P values were all >0.05. Conclusion: The postoperative radiotherapy of rectal cancer, the application of supine buttocks and high abdominal low position can reduce the volume and dose of small intestine, and can also reduce the irradiated volume of bladder in high dose area.