利用DVH图比较鼻咽癌两种放疗方法对正常组织受量的影响

1、利用DVH图比较鼻咽癌两种放疗方法对正常组织受量的影响         07-08-27 10:07:00     编辑：studa20         作者：原锦，程惠华，傅志超，林贵山，朱锦锋 【关键词】  鼻咽肿瘤    DVH comparison of threedimensional conformal and conventional radi

2、otherapies in normal tissues of patients with nasopharyngeal carcinoma【Abstract】 AIM: To investigate the effect of threedimensional conformal radiotherapies (3DCRT) and conventional radiotherapies on normal tissues in patients with nasopharyngeal carcinoma by comparing the dose distribution in norma

3、l tissues so as to pick out the better method. METHODS:  Forty cases of nasopharyngeal carcinoma (18 cases at stage T1 and 22 at stage T2, according to 92 Fuzhou staging) underwent conventional radiotherapy and 3DCRT respectively. Treatment planning system (TPS) was used to mark the dose distri

4、bution and quantity in normal tissues (bilateral lens, optic nerves, brain stem, spinal cord, parotid glands and temporomandibular joints) and the data obtained were analyzed with dosevolume histogram (DVH). The major fields in conventional radiotherapy were bilateral neckconjoined horizontal field

5、and preauricular field, the prenasal. The tophead fields were respectively added in the first and second phases in 3DCRT and 3 to 5 conplane or nonconplane fields were designed in the third phase. The prescribed dose of the two groups was 70Gy respectively. RESULTS:  3DCRT had satisfactory dose

6、 coverage of target volume of nasopharyngeal carcinoma compared with conventional radiotherapy. 3DCRT plans spared more parotid glands and twoside lens than conventional treatment （P<0.05）, the conventional treatment spared a little more brain stem and bilateral optic nerves than 3DCRT（P<0.05）

7、 and the received dose in other organs was similar in the two plans（P>0.05）. CONCLUSION:  3DCRT not only satisfies the dose coverage of target volume, especially in subclinical lesion region, but also spares more normal tissues compared with conventional radiotherapy.【Keywords】 nasopharyngea

8、l neoplasms; radiotherapy; dosevolume histogram【摘要】 目的：两种鼻咽癌放疗方法对比，应用剂量体积直方图(DVH)对正常组织的受量进行分析，确定最佳治疗方案. 方法：鼻咽癌40例，按92福州分期法确定为T1期18例和T2期22例，分别采用常规放疗法和三维适形放疗(3DCRT)法，通过治疗计划系统(TPS)进行布野、给量、优化并计算，最后用DVH图对正常组织（两侧晶体、视神经、脑干、脊髓、腮腺及颞颌关节）进行受量分析，两种方法均分三阶段进行. 常规放疗法以两侧水平面颈联合野和耳前野为主（2野照射），3DCRT法第一阶段加设鼻前野（3野照射），第二阶

9、段加设一头顶野（3野照射），第三阶段设35个共面或非共面野. 两种放疗方法总剂量DT 70 Gy. 结果： 三维适形法脑干、两侧视神经受量略高于常规方法，脊髓剂量相仿，而双侧晶体及腮腺受量明显低于常规方法（P<0.05）. 结论： 用3DCRT治疗鼻咽癌靶区适合度更好，能更好地保护正常组织或器官.【关键词】 鼻咽肿瘤；放射疗法；剂量体积直方图0引言鼻咽癌的首选治疗手段为放射治疗，但正常组织或器官的损伤较重. 我们对T1T2期鼻咽癌进行三维适形放疗（threedimensional conformal radiotherapies, 3DCRT）的同时用治疗计划系统(treatment p

10、lanning system, TPS)进行常规方法布野，剂量计算，剂量体积直方图（dosevolume histogram, DVH）分析两种方法治疗后的正常组织受量变化.1对象和方法1.1对象200307/200406收治鼻咽癌患者40（男32，女8）例，按福州分期法（1992），确定为T1T2期，其中T1期18例，T2期22例，年龄2868岁. 仪器采用以色列进口双螺旋CT（包括可移动三维激光定位系统一套），美国CMS进口治疗计划系统，美国瓦里安公司进口600C/D直线加速器.1.2方法患者仰卧于治疗床上，进行体模制作，用头颈肩固定，同时在体模上进行皮肤标记，确定参考点，然后进行CT扫描

11、，范围从头顶至胸骨切迹，病灶区层厚2.5 mm，其余为5 mm，通过网络将CT图像传输至治疗计划系统，进行三维重建，确定靶区及重要器官，在BEV窗口下进行布野、设定剂量，通过优化最后确定治疗方案，两种方法均分三阶段进行. 常规放疗方案：设左右两侧对穿照射，第一阶段以CTV为中心，设面颈联合野+颈切野（DT 36 Gy/2.0 Gy/3+W），第二阶段复查CT根据肿瘤消退情况，确定CTV，避开脊髓，颈部改电子线，DT 20 Gy/2.0 Gy/2 W，第三阶段：再查CT，针对鼻咽部肿瘤大小缩野加量，DT 14 Gy/2.0 Gy/1+W. 3DCRT方案：第一阶段以CTV为中心，设面颈联合野+鼻前野+颈切野，DT 36 Gy/2.0 Gy/3+W，第二阶段复查CT确定新的CTV，避开脊髓，颈部改用电子线，设两水平野+头顶野，DT 20 Gy/2.0 Gy/2 W，第三阶段再查CT，以鼻咽部肿瘤为中心，设非共面4野照射，DT 14 Gy/2