摘要
背景与目的:调强放疗技术(intensity-modulated radiation therapy,IMRT)可以显著提高全乳放射治疗时乳房内的剂量分布,但全乳放疗中靶体积的确定和勾画存在一定的不确定性。本研究的目的是通过对正向调强方式下全乳放射治疗计划的剂量-体积直方图的分析,定量研究皮肤建成区效应对早期乳腺癌全乳放射治疗计划评估的影响。方法:22例Ⅰ、Ⅱ期乳腺癌保乳手术后需要做全乳放疗的患者,所有患者的治疗靶区均由一名有经验的放疗医师勾画,靶区的前界直接沿皮肤的轮廓勾画,后界沿胸壁的轮廓勾画,勾画的区域为临床靶区(clinical target volume,CTV),然后在前界和后界分别收缩0.5cm,形成另一个靶区CTV1。选择最佳角度的两个相对的切线野,用正向调强方式制定治疗计划,保证重要器官肺和心脏所接受的剂量体积比、每一层面的剂量分布都满足临床放疗要求。结果:CTV超过95%处方剂量的靶区体积百分比的平均值为(89.6±3.2)%,明显低于CTV1超过95%处方剂量的靶区体积百分比(96.5±2.0)%,(P<0.001);CTV的靶区剂量均匀性指数D99-01为(14.0±2.4)Gy,明显高于CTV1的D99-01(7.3±1.6)Gy,(P<0.001)。结论:皮肤建成区效应是早期乳腺癌全乳放疗中必须考虑的重要方面之一。定量认识建成区效应对治疗计划评估的影响,是有效实现乳腺癌全乳调强放疗技术在临床开展应用的一个重要环节。在调强治疗方式下,应该以扣除表面和建成区域的临床靶区体积来进行治疗计划的评估。
BACKGROUND ＆ OBJECTIVE： Intensity-modulated radiation therapy （IMRT） can improve the dose distribution in the breast irradiation for early stage breast cancer, but the definition and delineation for clinical target volume （CTV） are uncertain. This study was to investigate the impact of skin build-up region on evaluation of IMRT plan for early stage breast cancer by analyzing dose-volume histograms （DVHs）. METHODS： CTVs for 22 patients with early stage breast cancer were delineated on transversal CT images, which included the skin build-up region. The CTVs were contracted and modified to exclude 0.5 cm outer skin surface to form new target volumes （CTVls）. All plans were tailored by using step-and-shoot IMRT techniques. DVHs and dose distributions of these plans were evaluated. RESULTS： The percentage volume receiving more than 95% of the prescription dose （V95） for CTV was significantly lower than that for CTV1 [（89.6±3.2）% vs. （96.5±2.0）%, P〈0.0011. The homogeneity index of the dose distribution within targets （D99-01） for CTV was significantly higher than that for CTV1 [（14.0±2.4） Gy vs. （7.3±1.6） Gy, P〈0.001]. CONCLUSIONS： The surface effect of skin build-up region is important and must be considered in IMRT for breast cancer. It is better to use the CTV excluding surface and build-up region to evaluate such plans.
出处
《癌症》
SCIE
CAS
CSCD
北大核心
2008年第2期183-186,共4页
Chinese Journal of Cancer
关键词
乳腺肿瘤/放射疗法
全乳放疗
皮肤建成区
计划评估
靶区勾画
Breast neoplasm/radiotherapy
Intensity-modulated radiation therapy （IMRT）
Skin build-up region
Plan evaluation
Target delineation
作者简介
通讯作者：杨玉琼 Tel：86—28—85423270 E—mail：marsmensis@yahoo．com．cn
