摘要
目的通过对宫颈癌二维与三维近距离治疗中点剂量与体积剂量的对照研究,评估二者在靶区、直肠及膀胱剂量学上的差异及联系。方法选取2014年7月至2015年12月,在我院诊治的初发宫颈癌患者52例,临床分期为ⅡB~ⅢB期。入组患者均完成全盆腔三维适形外照射(10MV-X线DT 50Gy/2Gy/25F)。于放疗开始后第2周给予同步化疗,方案为:顺铂25mg/m2 d1~3,氟尿嘧啶300mg/m2 d1~5。外照射结束后即开始后装治疗。治疗采用高剂量率192铱后装治疗机,施源器采用宫腔管和阴道球三管施源器。模拟机下模拟定位,将图片传输至计划系统,后行CT定位,数据传输至CT模拟系统工作站(CT-SIM)。按照ICRU38号文件勾画GTV、HR CTV、IR CTV及直肠、膀胱等危及器官。应用PLATO治疗计划系统,设定A点及直肠、膀胱参考点,同时将各点坐标导入到CT影像中,根据已勾画完成的靶区及危及器官分别按照A点及HRCTV 500cGy的处方剂量设计二维近距离计划和三维近距离计划,通过DVH图及各参考剂量点来评价计划。结果 (1)二维、三维计划中左、右A点的剂量变化比较无统计学差异。(2)三维近距离治疗计划直肠、膀胱点剂量均大于二维近距离治疗计划,但二者无统计学差异(P>0.05)。(3)直肠二维近距离治疗计划点剂量与三维近距离治疗2cc的体积剂量有相关性;膀胱二维近距离治疗计划点剂量与三维近距离治疗2cc的体积剂量无相关性。(4)三维近距离治疗计划的HR CTV-D100、HRCTV-D90、IR CTV-D100、和IR CTV-D90比分别为处方剂量的99.9%、119.3%、66.9%、84.9%,三维适形近距离治疗的靶区等剂量线覆盖能够满足治疗要求。结论 (1)三维近距离治疗靶区等剂量线满足治疗要求,危及器官剂量未见明显增加,但是在CT定位时,由于对靶区认识的不准确性,可能使对三维治疗计划的评价具有主观性;(2)直肠与膀胱二维点剂量评价不能替代三维体积剂量评价,但点剂量评价为主的二维后装适形治疗亦能够较好地反映危及器官辐射受量。
Objective To compare point dose and volume dose in 2D-and 3D-brachytherapy for cervical cancer so as to evaluate their differences in target area,rectum and bladder dosimetry as well as their association.Methods We selected 52 cases of initial cervical cancer diagnosed in our hospital from July 2012 to December 2012 in clinical stageⅡB-ⅢB period.All the enrolled patients completed the three-dimensional conformal external beam(10 MV-x-ray DT 50 Gy/2 cGy/25 F).At the second week after radiotherapy,we started to give one cycle of chemotherapy.The planning was as follows:Cisplatin 25 mg/m 2 d1-3,fluorouracil 300 mg/m 2 d1-5.The brachytherapy began immediately after the end of external beam.The brachytherapy machine used was Micro-Selectron HDR 192Ir.The uterine tube adopted source control facilities while vaginal ball three facilities.We simulated the positioning of the simulator and transferred the image to the planning system.After the data were reconstructed,we transferred them to the CT simulation system work-station(CT-SIM).According to ICRU38 file delineated GTV,HR CTV,IR CTV and the OAR included rectum and bladder.We applied PLATO treatment planning system to set point A and rectum,bladder reference point.At the same time,we entered all points into the CT image coordinates.According to the completed target and OAR,we designed the two-dimensional and three-dimensional plans by A point and HRCTV under 500 cGy,respectively.We evaluated all reference doses by using DVH.Results ①The left and right Point A between two-dimensional plan and three-dimensional plan showed no significant difference.②Rectum and bladder point doses in three-dimensional brachytherapy planning were better than those in two-dimensional brachytherapy planning,but they had no significant difference(P>0.05).③Point of rectal dose in two-dimensional plan and the volume of 2 cc dose in three-dimensional plan were related;however,there was no correlation between point of bladder dose and the volume of 2 cc dose.④The prescribed dose of three-dimensional brachytherapy HR CTV-D100,HRCTV-D90,IR CTV-D100,and IR CTV-D90 was 84.9%,119.3%,66.9%,and 99.9%.Three-dimensional conformal brachytherapy for target isodose coverage could meet the treatment requirements.Conclusion ①Three-dimensional brachytherapy could meet the treatment requirements of isodose target area coverage in cervical cancer without significant increase in OAR dose.But by CT simulator,inaccuracy of the target area may result in subjectivity of the evaluation of three-dimensional treatment plan.②two-dimensional point dose evaluation of rectum and bladder cannot replace three-dimensional volume dose.However,two-dimensional brachytherapy evaluated by point dose can also reflect the OAR by the amount of radiation.
作者
苏进
李毅
刘孜
SU Jin;LI Yi;LIU Zi(Department of Oncology Radiotherapy,the First Affiliated Hospital of Xi’an Jiaotong University,Xi’an 710061,China)
出处
《西安交通大学学报（医学版）》
CAS
CSCD
北大核心
2018年第3期409-413,共5页
Journal of Xi’an Jiaotong University（Medical Sciences）
基金
国家自然科学基金资助项目(No.81071838)~~
关键词
宫颈癌
二维近距离治疗
三维近距离治疗
剂量学
cervical cancer
two-dimensional brachytherapy
three-dimensional brachytherapy
dosimetry
