CAREDose4D在鼻咽癌放疗定位中的应用

Application of CARE Dose 4D in radiotherapy localization of nasopharyngeal carcinoma

目的:探讨CARE Dose 4D技术在鼻咽癌放疗定位中的应用价值。方法:将60例拟放疗的鼻咽癌患者随机分为A组和B组,每组30例。A组管电压120 kV固定300 mAs行常规扫描,B组管电压120 kV并开启CARE Dose 4D设置预设值为500 mAs进行扫描。在这两种不同扫描方式下扫描CIRS 064M电子密度模体,验证CT-RED转换曲线是否有差异。客观评价两组图像的噪声(SD)、信噪比(SNR)、对比噪声比(CNR)、GTV的CT值、剂量长度乘积(DLP)、容积CT剂量指数(CTDI_(vol))及有效辐射剂量(ED)。并由两位高年资医师对图像进行主观评分。结果:两种扫描方式下,CT值及CT-RED转换曲线无明显差异,保证了靶区剂量计算的精确性;B组与A组比较CTDI_(vol)降低35%,DLP、ED均降低43%,差异有统计学意义(P<0.001);客观评价中两组图像的SNR、CNR、GTV的平均CT值之间的差异无统计学意义(P>0.05)。两组图像在三角肌平面,A组SD高于B组,差异有统计学意义(t=30.809,P<0.001);两组图像主观评价有显著性差异(z=-2.445,P<0.05)。A组图像中由于肩部横断面内颈部淋巴引流区噪声较大,对医生勾画该层面的靶区造成了一定困扰,从靶区勾画角度来说,B组图像要优A组。结论:在鼻咽癌放疗定位中应用CARE Dose 4D技术是可行的,可提高图像质量,同时大幅降低患者的有效辐射剂量。

Objective To investigate the application value of CARE Dose 4D technique in radiotherapy localization of nasopharyngeal carcinoma.Methods Sixty patients with nasopharyngeal carcinoma scheduled for radiotherapy were randomly divided into groups A and B,with 30 cases in each group.The patients in group A received routine CT examination with a tube voltage of 120 kV and a fixed value of 300 mAs,and those in group B were scanned with a tube voltage of 120 kV and CARE Dose 4D set at a preset value of 500 mAs.CIRS 064M electron density phantom was scanned by two different methods,thereby verifying if there was a difference in CT-RED conversion curve.The noise(SD),signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR),CT value at GTV,dose length product(DLP),volumetric CT dose index(CTDI_(vol))and effective radiation dose(ED)were objectively evaluated for 2 groups of images.The images were also scored subjectively by two senior physicians.Results There were no significant differences in CT values and CT-RED conversion curve between the two scanning methods,which guaranteed the accuracy of target area dose calculation.CTDI_(vol) was 35%lower,and DLP and ED were both 43%lower in group B compared with group A,with statistically significant differences(P<0.001).The results of objective evaluation revealed that the differences in SNR,CNR and the mean CT values at GTV between two groups were trivial,without statistical differences(P>0.05),but the SD in the deltoid section in group A was higher than that in group B,with statistical differences(t=30.809,P<0.001).Moreover,there was significant difference in the subjective evaluation between two groups(z=-2.445,P<0.05).In the images of group A,the large noise in the cervical lymphatic drainage area within the shoulder cross-section caused some troubles for the physician to outline target areas on the section,thus the images in group B were superior to those in group A in terms of target area segmentation.Conclusion The application of CARE Dose 4D technique in radiotherapy localization of nasopharyngeal carcinoma is feasible,and it can improve image quality while significantly reducing the effective radiation dose to the patient.