基于XVI系统探讨鼻咽癌PTV外放范围及对放疗剂量的影响  

Planning target volume margin and its effect on radiotherapy dose for nasopharyngeal cancer：a study based on XVI system

作　　者：李明[1] 吴志军[1] 曹顾飞 曹飞[1] 曹旻昱[1] 

机构地区：[1]南通市肿瘤医院放疗科,江苏南通226361

出　　处：《中华生物医学工程杂志》2015年第2期141-144,共4页Chinese Journal of Biomedical Engineering

摘　　要：目的：应用医科达Synergy自带XVI系统直线加速器对鼻咽癌患者摆位误差进行测量，计算鼻咽癌患者计划靶区（PTV）外放范围，并探讨不同外放范围对放疗剂量的影响。方法对入组鼻咽癌放疗患者的摆位误差进行统计，依据PTV外放公式计算外放范围，将算好的外放范围导入患者计划，比较与常规外放范围的剂量学差异。结果鼻咽癌患者三维方向上摆位误差分别为X轴向（-0.3±1.5）mm、Y轴向（1.7±1.9）mm、Z轴向（-1.7±1.1）mm，计算得出PTV外放在X、Y、Z轴分别为3.6 mm、3.6 mm、3.1 mm。PTV外放3.6 mm时，脑干D1cc为（5080±108.3）cGy、D2%为（5164±93.5）cGy；脊髓D-max为（4382±212.4）cGy、D1cc为（4010±72.2）cGy；晶体D-max左侧为（532±32.2）cGy、右侧为（550.9±37.2）cGy；左腮腺V35左侧为（51.63±3.2）%、右侧为（53.15±2.7）%。PTV外放5 mm时，脑干D1cc为（5240±103.1）cGy、D2%为（5380±95.2）cGy；脊髓D-max为（4398±187.4）cGy、D1cc为（4070±68.9） cGy；晶体D-max左侧为（564.5±33.3）cGy、右侧为（554.6±28.8）cGy；左腮腺V35左侧为（51.04±3.8）%、右侧为（53.12±3.2）%。PTV外放3.6 mm与常规外放5 mm的放疗剂量比较，脑干D1CC、脑干-D2%、脊髓D-max、脊髓-D1CC、右眼晶体D-max及PTV1剂量差异有统计学意义（P〈0.05）；左眼晶体D-max、腮腺V35%、PGTVnd、PGTVnx、PTV2剂量差异无统计学意义（P〉0.05）。结论在鼻咽癌的放疗中，计算出放疗患者的PTV外放范围，并将其应用于临床治疗中，有利于提高放疗增益比。Objective To measure setup errors and calculate planning target volume（PTV）margin for patients with nasopharyngeal cancer（NPC）by using Elekta linear accelerator,and to investigate the effects of different PTV margins on radiotherapy dose. Methods The setup errors of the included NPC patients,who received radiotherapy,were statistically analyzed,and the margins were calculated by PTV margin formula. Then,the calculated PTV margins were imported into patient plan to compare the dosimetric difference with the conventional PTV margins. Results The setup error of NPC patients on the three-dimensional direction,X,Y and Z axis,was （-0.3 ± 1.5）mm,（1.7 ± 1.9）mm and （-1.7 ± 1.1）mm, respectively. The calculated PTV margin on the X,Y and Z axis was 3.6 mm,3.6 mm,3.1 mm,respectively. When the PTV margin was 3.6 mm,the D1cc[（5 080 ± 108.3）cGy]and D2%[（5 164 ± 93.5）cGy]of brainstem,D-max[（4 382±212.4）cGy]and D1cc[（4 010±72.2）cGy]of spinal cord,left crystal D-max [（532±32.2）cGy]and right crystal D-max[（550.9±37.2）cGy],left parotid gland V35[（51.63±3.2）%] and right parotid gland V35[（53.15±2.7）%]were found. When the PTV margin was 5mm,the D1cc无nbsp;[（5 240±103.1）cGy]and D2%[（5 380±95.2）cGy]of brainstem,D-max[（4 398±187.4）cGy]and D1cc [（4 070 ± 68.9）cGy]of spinal cord,left crystal D-max[（564.5 ± 33.3）cGy]and right crystal D-max [（554.6 ± 28.8）cGy],left parotid gland V35[（51.04 ± 3.8）%]and right parotid gland V35[（53.12 ± 3.2）%] were found. There were statistically significant differences in the radiotherapy dose of brainstem D1CC and D2%,spinal cord D-max and D1CC,right eye crystal D-max between the PTV margin of 3.6 mm and the conventional margin of 5 mm（P〈0.05）,whereas no statistically significant differences were found in the dose of left eye crystal D-max,parotid gland V35%,PGTVnd,PGTVnx and PTV2 （P〉0.05）. Conclusion Calculating the PTV margin for NPC patients in radiotherapy and applying it to clinical treatmen

关 键 词：鼻咽癌 锥形束CT 摆位误差 计划靶区外放 X线容积成像 

分 类 号：R739.63[医药卫生—肿瘤]