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IMRT与3D-CRT治疗胸部食管癌的剂量学评价

IMRT与3D-CRT治疗胸段食管癌的剂量学评价

刘锐锋1, 张秋宁1 * 王小虎1 刘志强2 魏玺义2 魏世鸿1 罗宏涛1

1甘肃省肿瘤医院放疗科胸组,兰州 730000;

2甘肃省肿瘤医院放疗科物理组,兰州 730000.

通讯作者:张秋宁zqn168@http://www.wendangku.net/doc/927327420508763230121255.html

【摘要】

背景与目的:按照解剖部位不同,胸段食管癌可分为上、中、下三段。由于其淋巴引流有各自的特点,在放疗靶区勾画中有各自不同的区域。调强放疗(IMRT)技术,不仅在靶区形状上做到高度适形,而且能够有效地避开肿瘤邻近的正常组织,可同时对不同区域给出不同的放射剂量,同时更好地保护正常气管。本研究旨在比较分析IMRT和三维适形放疗(3D-CRT)计划在胸段食管癌治疗中的剂量学优劣,为IMRT在食管癌的临床应用提供参考。

方法:选择我院自开展调强放疗以来行根治性放疗的胸段食管癌20例进行研究,根据不同部位进行亚组分析,其中胸上段5例,中段10例,下段5例。瓦里安Eclipse治疗计划系统进行计划设计,靶区勾画按照不同部位食管癌的靶区勾画原则进行。上段:锁骨上淋巴结引流区、食管旁、2区、4区、5区、7区淋巴引流区。中段:食管旁、2区、4区、5区、7区淋巴引流区。下段:食管旁、4区、5区、7区和胃左、贲门周围的淋巴引流区。在实际治疗采用的3D-CRT 计划基础上,每一病例再设计一5野IMRT计划进行比较分析。处方剂量分别为:IMRT计划,CTV 51Gy/33F,GTV 66Gy/33F;3D-CRT 计划,CTV 50Gy/25F,GTV66Gy/33F。相关的剂量学参数包括:靶区剂量和危及器官百分体积受照射剂量。统计学分析采用配对样本t检验,显著性水平设定为0.05,采用SPSS16.0统计软件分析。

结果: IMRT 与3D-CRT相比,GTV平均剂量(cGy)分别为 6809±32和6848±100,p值为 0.289; CTV平均剂量(cGy)分别为5952±239 和6183±343 ,p值为 0.03;两肺受照射的平均剂量(cGy)分别为970±427和 1126 ±457,p值为 0.000;V30百分体积分别为6.25±3.61和9.75±6.25,p值为 0.033;V20百分体积分别为16.37±7.63和23±10.87,p 值为0.013;V10百分体积分别为 36.5±19.02和38±14.9,p值为 0.492 ;V5百分体积分别为50.5±24.9和50.5±18.7,p值为1.00;心脏V40百分体积分别为10.0±8.3和17.0±16.9,p 值为0.073;V30百分体积分别为19.5±17.4和26.1±23.1,p值为0.027;脊髓V0体积的剂量(cGy)分布为4096±441和4434±341,p值为0.042。

结论:IMRT与3D –CRT技术相比,靶区剂量均匀性方面两者相当,但IMRT具有更好的剂量适形性,特别是胸上段病变。在对正常组织的保护方面,IMRT能够显著降低脊髓最大受照剂量和双肺平均剂量,以及双肺>10 Gy剂量的受照体积。V5、V10的受照体积,二者相当。在实施IMRT的过程中,应考虑不同部位病变肺低剂量损伤的程度。

关键词:食管肿瘤/放射疗法; 三维适形放射治疗法; 调强放射疗法; 剂量学

The dosiology evaluation of IMRT vs. 3D-CRT for thoracic

esophageal cancer

LIU Rui-feng1, ZHANG Qiu-ning1*, WANG Xiao-hu1, LIU Zhi-qiang2, WEI Xi-yi2

WEI Shi-hong1, LUO Hong-tao1

1. Radiotherapy Department, the Tumor hospital of Gansu Province, Lanzhou 730050;

2. Physical Group, Radiotherapy Department, the Tumor hospital of Gansu Province, Lanzhou 730050

* The corresponding author: ZHANG Qiu-ning zqn168@http://www.wendangku.net/doc/927327420508763230121255.html

【Abstract】

Objective To assess the dosiology superiority of IMRT compared with 3D-CRT for thoracic esophageal cancer.

Methods To select 20 patients with esophageal cancer who were underwent radical radiotherapy, including superior segment 5 patients, middle segment 10 patents, inferior segment 5patients. Using Varian Ecelipse treatment planing system to devise IMRT and 3D–CRT treatment plan. According to the principle of target region sketching of different segment esophageal cancer, to sketch GTV and CTV respectively.The prescription dose of IMRT was 51Gy/30F/6w in CTV and 66Gy/30F/6w in GTV, the 3D –CRT was 50Gy/25F/5w in CTV and 66Gy/33F/7w in GTV. The SPSS 16.0 software was used for statistical analysis.

Results IMRT compared with 3D-CRT, the mean dose(cGy)of GTV respectively were 6809±32 and 6848±100,p value was 0.289, the mean dose of CTV(cGy)respectively were 5952±239 and 6183±343,p value was 0.03, the lung mean dose (MLD)(cGy)respectively were 940±427 and 1126 ±457,p value was 0.000;V30 of lung respectively were 6.25±3.61 and 9.75±6.25,p value was 0.033;V20 of lung respectively were 16.37±7.63 and 23±10.87,p value was 0.013;V10 of lung respectively were 36.5±19.02 and 38±14.9,p value was 0.05 ;V5 of lung respectively were 50.5±24.9 and 50.5±18.7,p value was 1.00;V40 of heart respectively were 10.0±8.3和17.0±16.9,p值为0.073;V30 of heart respectively were 19.5±17.4和26.1±23.1,p 值为0.027; the maximum dose(cGy)of spinal cord respective were 4096±441 and 4434±341,p value was 0.042.

Conclusions This study would suggest that IMRT compared with 3D –CRT,it is equivalent in dose uniformity, but IMRT is superior to 3D-CRT in dose gradiernt, especially to superior segment disease. Furthermore,IMRT could significantly reduce the maximum dose of spinal cord, MLD, and the lung volume of more than 10Gy,.To V5 and V10, IMRT was equal with 3D-CRT. We should cautiously consider the degree of low dose damage of lung in IMRT of esophageal cancer.

Key words:esophgeal tumor / radiotherapy; 3D-CRT; IMRT; dosiology.