Kim Tae Hyun, Chie Eui Kyu, Kim Dae Yong, Park Sung Yong, Cho Kwan Ho, Jung Kyung Hae, Kim Young Hoon, Sohn Dae Kyung, Jeong Seung-Yong, Park Jae-Gahb
Research Institute and Hospital, National Cancer Center, Goyang, Gyeonggi, South Korea.
Int J Radiat Oncol Biol Phys. 2005 Jul 1;62(3):769-75. doi: 10.1016/j.ijrobp.2004.11.015.
To determine the most effective method to reduce the irradiated small bowel volume when using a belly board device (BBD), a distended bladder (DB), or both in patients with rectal cancer undergoing preoperative pelvic radiotherapy (RT).
The study involved 20 patients with rectal cancer who were scheduled to receive preoperative pelvic RT. Patients were asked to empty their bladders and then drink 300 mL of water 2 h before the treatment planning computed tomographic (CT) scan. To identify the small bowel, an oral contrast solution (450 mL) was given 1 h before the CT scan. Two sets of transverse images were taken at 1-cm-thickness intervals with patients in the prone position with or without the BBD. After voiding, two additional sets of CT scans were obtained in prone positions with or without BBD. The conventional three-field treatment plan, composed of a 6-MV photon posterior-anterior field and 15-MV photon opposed lateral fields with wedges of 45 degrees, was made using a three-dimensional treatment planning system. The beam weights of the three-field plan were equal. The volume of irradiated small bowel was calculated for doses between 10% and 100% of the prescribed dose at 10% intervals. For each 10% dose increment, the effect of the BBD and the DB on the irradiated volume was analyzed using Kruskal-Wallis, Wilcoxon signed rank, and Wilcoxon rank-sum tests.
All patients underwent four sets of CT scan under the conditions of four different methods as follows: Group I = empty bladder without the use of belly board; Group II = empty bladder with the use of belly board; Group III = distended bladder without the use of belly board; Group IV = distended bladder with the use of belly board. We found that the volume of irradiated small bowel decreased in the order of Group I, Group II, Group III, and Group IV at all dose levels (p < 0.05). Compared with Group I, the mean volume reduction rate (reduced volume) of irradiated small bowel in Group II varied between 14.5% and 65.4% (15.5-80.4 cm(3)), in Group III it varied between 48.1% and 82.0% (21.6-163.1 cm(3)), and in Group IV between 51.4% and 96.4% (28.6-167.1 cm(3)).
The DB was more effective than the BBD for reducing the volume of irradiated small bowel in rectal cancer patients receiving pelvic RT. The combination of the BBD and DB showed an additive effect and was the most effective method for reducing the irradiated small bowel volume.
确定在接受术前盆腔放疗（RT）的直肠癌患者中，使用腹托装置（BBD）、充盈膀胱（DB）或两者结合时，减少小肠受照射体积的最有效方法。
本研究纳入20例计划接受术前盆腔放疗的直肠癌患者。患者在治疗计划计算机断层扫描（CT）前2小时排空膀胱，然后饮用300 mL水。为识别小肠，在CT扫描前1小时给予口服对比剂（450 mL）。患者俯卧位，有或没有使用BBD的情况下，以1 cm厚度间隔拍摄两组横向图像。排尿后，在有或没有BBD的俯卧位再进行两组CT扫描。使用三维治疗计划系统制定由6 MV光子前后野和15 MV光子对侧野加45度楔形板组成的常规三野治疗计划。三野计划的射束权重相等。计算处方剂量10%至100%之间，间隔10%剂量时的小肠受照射体积。对于每10%剂量增加，使用Kruskal-Wallis检验、Wilcoxon符号秩检验和Wilcoxon秩和检验分析BBD和DB对受照射体积的影响。
所有患者在以下四种不同方法条件下均接受了四组CT扫描：第一组 = 排空膀胱且不使用腹托；第二组 = 排空膀胱且使用腹托；第三组 = 充盈膀胱且不使用腹托；第四组 = 充盈膀胱且使用腹托。我们发现，在所有剂量水平下，小肠受照射体积按第一组、第二组、第三组和第四组的顺序递减（p < 0.05）。与第一组相比，第二组小肠受照射体积的平均减少率（减少体积）在14.5%至65.4%之间（15.5 - 80.4 cm³），第三组在48.1%至82.0%之间（21.6 - 163.1 cm³），第四组在51.4%至96.4%之间（28.6 - 167.1 cm³）。
在接受盆腔放疗的直肠癌患者中，充盈膀胱在减少小肠受照射体积方面比腹托装置更有效。腹托装置和充盈膀胱结合显示出相加效应，是减少小肠受照射体积的最有效方法。
