在线红外定位系统对37例鼻咽癌患者减少放疗摆位误差观察

On-line infrared positioning system was used to reduce the radiotherapy positioning error in 37 patients with nasopharyngeal carcinoma

目的探讨在线红外定位系统在鼻咽癌放射治疗中对摆位误差的控制及不同计划靶区(planning target volume,PTV)外放对危及器官剂量的影响。方法选取2017-04-03-2018-11-20南通市肿瘤医院放疗科进行治疗的鼻咽癌患者74例。患者随机分为常规摆位组(n=37)与在线红外定位系统摆位组(n=37),比较2种不同摆位方式对摆位误差的影响。依据测量的摆位误差数据,通过PTV外放公式计算2组患者PTV外放范围,将算好外放范围导入患者计划,比较不同外放范围危及器官剂量学的差异。采用独立样本t检验进行统计学分析。结果常规摆位组患者摆位误差在X轴向为(1.11±1.04)mm、Y轴向为(1.47±0.84)mm、Z轴向为(1.14±0.90)mm;在线红外定位系统摆位组患者摆位误差在X轴向为(0.83±0.70)mm、Y轴向为(1.11±0.67)mm、Z轴向为(0.75±0.61)mm;常规摆位组与在线红外定位系统摆位组患者摆位误差比较在X轴向差异无统计学意义(t=1.29,P=0.206),Y、Z轴向差异有统计学意义(t=2.29,P=0.028;t=2.34,P=0.025)。在线红外定位系统摆位组计算得出PTV外放2.8mm与常规摆位组(3mm)对靶区内危及器官剂量比较可见,在脑干D-max、晶体D-max、腮腺V35(%)、左侧视神经D-max、颞叶、右侧颞颌关节差异有统计学意义,均P<0.05;在脊髓D-max、右侧视神经D-max、左侧颞颌关节差异无统计学意义,均P>0.05。结论借助在线红外定位系统对鼻咽癌患者进行摆位能够减小摆位误差,通过减少摆位误差来降低PTV外放从而减少危及器官受量,有利于患者的治疗。

Objective To investigate the control of the online infrared positioning system in the radiotherapy of nasopharyngeal carcinoma on the positioning error and the effect of different planning target volumes(PTV)on the dose of the organs at risk.Methods Totally 74 patients with nasopharyngeal carcinoma were selected from the Department of radiotherapy,Nantong cancer hospital from April 3,2017 to November 20,2018.The selected patients were randomly divided into the conventional positioning group(n=37)and the online infrared positioning system positioning group(n=37),and the influence of two different positioning methods on the positioning error was compared.According to the measured positioning error data,calculate the PTV extention range of the two groups of patients through the PTV radiation formula,then introduce the calculated range into the patient plan,to compare dosimetry differences of organs endangered by different external ranges.Statistical analysis by using independent sample t-test.Results We found that the positioning errors of the patients in the conventional positioning group were(1.11±1.04)mm on the X axis,(1.47±0.84)mm on the Y axis,and(1.14±0.90)mm on the Z axis.The positioning error of patients in the online infrared positioning system positioning group were(0.83±0.70)mm on the X axis,(1.11±0.67)mm on the Y axis,and(0.75±0.61)mm on the Z axis.There was no significant difference in the positioning error between the conventional positioning group and the online infrared positioning system positioning group on the X axis(t=1.29,P=0.206),and the difference between the Y and Z axes was statistically significant(t=2.29,P=0.028;t=2.34,P=0.025).The dose of PTV 2.8 mm calculated by online infrared positioning system was significantly different from that of conventional positioning group(3 mm).It can be seen in the brainstem D-max,crystal D-max,parotid gland V35(%),the left optic nerve D-max,the temporal lobe,and the right temporomandibular joint had statistically significant differences,all P<0.05);D-max in spinal cord,right optic nerve There was no significant difference in D-max and left temporomandibular joint,all P>0.05).Conclusions The positioning of patients with nasopharyngeal carcinoma with the help of the online infrared positioning system can reduce the positioning error.By reducing the positioning error,the PTV radiation can be reduced tand thus reduce the amount of organs at risk,which is conducive to the treatment of patients.