摘要
目的比较容积旋转调强(volametric modulated arc therapy,VMAT)与静态调强(intensity-modulated radiotherapy,IMRT)在胸上段食管癌放疗计划中的剂量学差异。方法选取安阳市肿瘤医院2012-04-10-2013-11-05收治的20例T2-4N0-1M0胸上段食管癌患者,使用患者定位CT图像与靶区分别制定VMAT和IMRT两套放疗计划。利用Oncentra 4.1计划系统,每位患者均给予PTV 5 040cGy,PGTV推量900cGy,总量为5 940cGy;通过剂量体积直方图统计PTV及GTV相关剂量参数、适形指数(conformal index,CI)、均匀指数(homogeneity index,HI)、脊髓及肺剂量体积参数,以及机器跳数(monitor unit,MU)、总治疗时间。记录正常身体V5来评估低剂量辐射增加的健康组织体积。结果两组计划均能满足治疗要求。GTV:VMAT计划的D2、D98、Dmean、V100低于IMRT计划,差异有统计学意义,P<0.05;VMAT计划的适形指数CI更接近于1,适形度优于IMRT计划,P<0.05;两组计划的靶区均匀性差异无统计学意义,P>0.05。PTV:VMAT计划的D2、HI低于IMRT计划,差异有统计学意义,P<0.05;VMAT计划的D98、CI高于IMRT计划,差异有统计学意义,P<0.05;VMAT计划的HI和CI均优于IMRT计划,差异有统计学意义,P<0.05;两种计划的Dmean、V100比较差异无统计学意义,P>0.05。两组计划的脊髓D1差异无统计学意义,P>0.05。两组计划的双肺V5、V15、V20和MLD比较差异有统计学意义,P<0.05;V10和V30比较差异无统计学意义,P>0.05,VMAT计划的双肺V15、V20低于IMRT计划,双肺V5、MLD高于IMRT计划。VMAT计划中External的V5、V10、V15和V30相对IMRT计划较高,差异有统计学意义,P<0.05,V20差异无统计学意义,P>0.05,VMAT计划中正常身体的V5较IMRT增加了约12%。VMAT计划的MU和治疗时间均低于IMRT计划,差异有统计学意义,P<0.001。结论 VMAT计划在胸上段食管癌治疗中可以达到或优于IMRT计划的靶区剂量分布,具有缩短总治疗时间和减少MU的优势,能够更好地降低危及器官的受照剂量。
OBJECTIVE To compare the dosimetry difference between volumetric modulated arc therapy （VMAT） and static intensity-modulated radiotherapy （IMRT） for upper-thoracic esophageal cancer. METHODS From April 10, 2012 to November 5, 2013, twenty patients with T2-4 N0-1 M0 upper-thoracic esophageal cancer were given VMAT and IMRT plans,using the same CT image and target. The treatment planning system was version 4. 1 of the Oncentra. VMAT and IMRT treatment plans were generated for each case, and both techniques were used to deliver 5 040 cGy to the planning target volume （PTV） and then provided a 900 cGy boost （PGTV）, and the total was 5 940 cGy. Dosimetric comparisons between VMAT and IMRT plans were analyzed to evaluate coverage, homogeneity index（ HI）, conformity index（CI） ,sparing of spinal cord and lung, total accelerator output monitor units（MU） and total treatment time. Body V5 was recorded to evaluate the increased volume of healthy tissue irradiated by low doses. RESULTS Two plans could meet the requirements. The dose parameters D2, D98, D , V100 of GTV for VMAT were lower than those in IMRT. The CI of GTV for VMAT was higher than that in IMRT, showing significant differences （P〈0.05）; there was no significant difference in HI between the two plans （P〈0.05）. The D2, HI of VMAT were lower than those in IMRT, showing significant differences （P〈0.05）. The D98 ,CI of VMAT were higher than those in IMRT, showing significant differences （P〈0.05） ; there were no significant difference in D and V100 between the two plans （P〈0.05）. The D1 of spinal cord for VMAT and IMRT was no significant difference （P〉0.05） ; there were significant differences in V5 ,V15, V20, MLD of lung （P〈0.05）, the V15 , V20 of lung for VMAT were lower, and the V5, MLD were higher, there was no significant difference for V10 ,Va0 （P〈0.05）. Compared to IMRT, the V5, V10, V15, V30 of external for VMAT were higher, showing significant differences （P〈0.05）, there was no significant difference for V20 （P〈0.05）, the V5 of external for VMAT increased about 12 %. The number of monitor units and treatment time in VMAT were lower than those in IMRT（P〈0. 001）. CONCLUSION Compared to IMRT, VMAT shows similar or better effects in the target dose distribution, it has the advantages in less monitor units add less total treatment time, it is better in reducing the irradiation doses on organs at risk.
出处
《中华肿瘤防治杂志》
CAS
北大核心
2014年第23期1902-1906,1910,共6页
Chinese Journal of Cancer Prevention and Treatment
基金
国家自然科学基金〔青年科学基金项目(81201945)〕
天津医科大学科学基金(2011KY08)
关键词
食管癌
容积旋转调强
静态调强
剂量学
esophageal cancer
volumetric modulated arc therapy
step-and-shoot intensity-modulated radiotherapy
Dosimetry
