252Cf中子后装治疗宫颈癌直肠钡灌肠与插铅丝监测直肠前壁受量的差异

目的观察宫颈癌锎(252Cf)中子后装治疗过程中直肠钡灌肠与插铅丝两种方法监测直肠前壁受量时的差异,分析直肠前壁受量的高低与急性期放射性直肠炎发生率的关系.方法30例宫颈癌用直肠插铅丝和钡灌肠的办法监测直肠前壁受量(各15例),分别拍摄等中心正交片.A点剂量均给予10Gy,分别计算直肠前壁和膀胱后壁最大受量以及按ICRU38号报告设定的直肠剂量参考点(R)的剂量,量取直肠前壁和膀胱后壁最大剂量点与官腔管中心的距离.统计所有病例及其中直肠前壁受量＞4Gy病例的急性放射性直肠炎的发生率.结果钡灌肠组直肠前壁最大剂量点与宫腔管中心的平均距离明显低于插铅丝组,钡灌肠组直肠前壁最大剂量点受量则明显高于插铅丝组,ICRU直肠剂量参考点(R)的剂量明显高于钡灌肠组,但其剂量的高低与钡灌肠时直肠前壁最大剂量点受量的高低无明显关系.而膀胱后壁最大剂量点与宫腔管中心的平均距离及膀胱后壁最大剂量点受量,两组均无明显差别.直肠前壁受量＞4 Gy病例的急性放射性直肠炎的发生率明显高于其他病例.结论宫颈癌中子后装治疗时直肠钡灌肠比插铅丝更能准确显示宫颈、阴道与直肠前壁的解剖关系,更能准确反映直肠前壁的真正受量.根据钡灌肠时直肠前壁最大剂量点受量的高低可大致预测宫颈癌放疗期间急性放射性直肠炎的发生率,且直肠钡灌肠对乙状结肠变异可起诊断作用.

In 252 Cf neutron brachytherapy for uterine cervical cancer: the comparison of absorbed dose at anterior rectal wall with shielding by barium enema or lead marker

Objective To show the relation between radiation proctitis and maximu m absorbed dose at anterior rectal wall in 252 Californium ( 252 Cf) n eutr on brachytherapy for uterine cervical cancer. Methods The absorbed dose at anterior rec tal wall of 30 patients was evaluated with shielding by barium enema or lead mar ker, 15 in each group. Perpendicular isocenter films were taken with the barium or lead marker in place. The dose given at reference point A was 10?Gy. The ma x imum absorbed dose (Dmax)of anterior rectal wall, posterior bladder wall and t he rectal reference point as proposed by ICRU Report 38 were calculated; The dis tance between the Dmax point at anterior rectal wall, posterior bladder wall and the center of uterine tube were measured by 252 Cf neutron after-lo ading treatme nt planning system. Radiation proctitis were analyzed both in the whole group an d in patients whose absorbed dose of anterior rectal wall was > 4?Gy. Results Th e Dmax at anterior rectal wall evaluated by barium enema was significantly highe r than those by lead marker.The distance between the Dmax point at anterior rec tal wall and the center of uterine tube was significantly lower by barium enema than those by lead marker. The dose of Dmax point at posterior bladder wall, the distance between the Dmax point at posterior bladder wall and the center of ute rine tube in these two groups were not significantly different. The morbidity of acute radiation proctitis in patients whose Dmax of anterior rectal wall >4?Gy were significantly higher than in those < 4?Gy patients. Concl usions Barium en em a, being able to show better the anatomic relation between cervix, vagina and an terior rectal wall than lead marker, is able to reflect the real absorbed dose a t the anterior rectal wall more accurately, Acute radiation proctitis can be pr edicted according to Dmax at anterior rectal wall. Moreover, the variation of s igmoid position can also be detected by barium enema at the same time.