摆位误差对鼻咽癌容积旋转调强放疗剂量的影响  

Effect of Setup Error on the Irradiation Dose of Volumetric Modulated Arc Therapy for Nasopharyngeal Carcinomas

作　　者：林家帆 袁星星[1] 张雯楠 龚晓昌[1] 张云[1] LIN Jiafan;YUAN Xingxing;ZHANG Wennan(Jiangxi Cancer Hospital,Nanchang,330029)

机构地区：[1]江西省肿瘤医院,330029

出　　处：《实用癌症杂志》2023年第10期1624-1628,共5页The Practical Journal of Cancer

摘　　要：目的探讨摆位误差在鼻咽癌容积旋转调强放疗方式中对靶区和正常组织照射剂量的影响。方法随机挑选15例接受容积旋转放疗的鼻咽癌患者,在Eclipse计划系统分别模拟患者前后方向、头脚方向和左右方向摆位3 mm和6 mm的误差。在其他计划参数保持不变的情况下重新计算患者的受照剂量,通过剂量-体积直方图分析存在移位误差的计划与初始计划的靶区和正常组织剂量差异。采用配对t检验方法验证差异是否具有统计学意义。结果不同方向的摆位误差对GTV和CTV的剂量有一定的影响,但临床上这部分影响可以忽略不计。对于危机器官,摆位误差对腮腺、视神经和视交叉的影响最大。腮腺对X方向(左右方向)摆位误差最为敏感,等中心向左或向右偏移3 mm和6 mm,相应方向的腮腺的V 30Gy将增大9%、19.4%和10%、21.2%。视交叉和左右视神经对Z+方向(头方向)的偏差最为敏感,3 mm与6 mm的偏差,D_(max)分别增加15.5 Gy、15.3 Gy、15.5 Gy和23 Gy、25 Gy、23 Gy。晶体的D_(max)、颞叶的D_(mean)和V 60Gy同样受Z+方向偏差影响较大,只是没有视神经和视交叉那么明显。脑干的D mean和V 54Gy受Y+方向(后方向)影响较大,脊髓的D_(max)受Y+和Z-方向(后方向和脚方向)影响较大。结论摆位误差对GTV和CTV影响较小,临床上可以忽略。然而对正常组织影响较大,在计划设计和放疗实施时需重点关注。Objective To investigate the effect of the setup error on the irradiation dose to the target area and normal tissues in volumetric modulated arc therapy(VMAT)for nasopharyngeal carcinomas(NPC).Methods 15 NPC patients who had been treated with VAMT were randomly selected.The setup errors of 3 mm and 6 mm of the patient's pose in the anterior-posterior,head-foot,and left-right directions were simulated in the Eclipse planning system,respectively,and the irradiation doses were recalculated while other parameters of the plan were kept unchanged.The dosimetry differences in the planned target area and normal tissue between the initial plan and post-shift plan were analyzed by Dose volume histogram.Paired t-test was used to verify whether the differences were statistically significant.Results The setup error in different directions had a definite effect on the doses of GTV and CTV,but this part of the effect is negligible in clinical practice.For the organ of risk(OAR),the setup error had the greatest effect on the parotid gland,optic nerve,and optic chiasm.The parotid gland is most sensitive to the setup error in the X-direction(left and right directions).A 3mm and 6mm shift of the isocenter to the left or right will increase the V 30Gy of the parotid gland by 9%,19.4%,and 10%,21.2%in the corresponding directions,respectively.The optic chiasm and the right/left optic nerves are most sensitive to deviations in the Z+direction(head direction),and D max increases by 15.5 Gy,15.3 Gy,15.5 Gy,and 23 Gy,25 Gy,23 Gy for 3mm versus 6mm deviations,respectively.The D_(max)of the lens,D_(mean),and V 60Gy of the temporal lobe were also greatly affected by deviations in the Z+direction,but not as obvious as the optic nerve and optic chiasm.D_(mean)and V 54Gy of the brainstem were more affected by the Y+direction(posterior direction),and D_(max) of the spinal cord was more influenced by the Y+and Z-directions(posterior and pedal directions).Conclusion The effect of the setup error on GTV and CTV is small and clinically negligible.Ho

关 键 词：鼻咽癌 容积旋转调强放疗 摆位误差 剂量学差异 

分 类 号：R739.63[医药卫生—肿瘤]