摘要
目的探讨胸部增强CT扫描对勾画肺癌大体肿瘤体积(GTV)的影响。方法连续选择肿瘤紧邻纵隔或累及肺门、病理确诊的肺癌患者7例,在治疗体位下行全胸部平扫(C)和增强CT扫描(C+),扫描范围相同。将CT图像传人虚拟模拟计划工作站(AcQSim)中,每份图像传7次(C3次,C+4次)。3位年资相同的放疗科医生完全独立地在C与C+的CT图像上勾画GTV(GTV、GTV+),然后3位医生在另一份C+图像上共同勾画GTV(标准GTVco)。以GTVco形成的计划靶体积(PTV)为标准在治疗计划系统中进行剂量计算并优化,等中心点为剂量归一点(参考点),处方剂量为60Gy。通过图像融合技术将3位医生在C+、C图像上勾画的GTV复制到GTVco图像上,分别计算GTV、GTV+和GTVco共7份GTV体积、GTV三维最大径、90%等剂量线包括PTV的相对体积(V90)及PTV内最小剂量(Dmin),并计算GTV、GTV+与GTVco的比值R及R的变异系数CV,然后对GTV、GTV+两组数据进行配对样本t检验。结果GTV+、GTV体积R分别为1.04±0.16、1.25±0.52,GTV+体积、V90、Dmin的CV均小于GTV的(P值分别<0.01、0.05、0.05)。结论勾画肿瘤紧邻纵隔或累积肺门靶区时,增强CT扫描可明显提高GTV勾画的准确性和一致性,且费用较小容易实施。
Objective To study the impact of contrast CT scan on contouring of gross tumor volume (GTV) of lung cancer in three-dimensional conformal radiation therapy (3-DCRT). Methods Seven patients with pathological proven lung lesions close to mediastinum or with invasion of hilum had contrast(C+) and non-contrast(C-) CT scans at the radiotherapeutic position. Three radiation oncologists with similar-seniority contoured the GTV independently on both C+ (3copies) and C-(3copies) images, and then together on another copy of C+ image (standard, GTVco). The treatment planning based on GTVco was carried out and optimized with AcQSim plan. The reference dose point was normalized to the isocenter in PTV and prescription dose was 60?Gy. After the GTVs contoured by the three radiation oncologists on C+ and C-images were fused with GTVco, the ratios of these GTVs on C+, C-images (totally 6 copies) for each patient, the longest three dimensions of GTVs, the relative PTV volume covered by 90% isodose curve (V_ 90 ) and the minimum doses within PTV (D_ min ) to the GTVco were calculated, and so were the coefficients of variation (CV)of these ratios. T-test was used for detecting the difference of all parameters. Results The mean ratio of GTV on the C+ and C-images to standard GTVco were 1.04± 0.16,1.25±0.52, respectively. The CV of GTV, V_ 90 , D_ min on the C+ image was significantly smaller than those on C-images (P<0.01, P<0.05, P<0.05). Conclusion It is more accurate and consistent in contouring the GTV on contrast CT for lesion situated close to mediastinum or with invasion of hilum.
出处
《中华放射肿瘤学杂志》
CSCD
北大核心
2005年第4期321-325,共5页
Chinese Journal of Radiation Oncology
