非小细胞肺癌精确放疗中三种CT扫描方法的研究

目的 比较自主呼吸控制(ABC)、自由呼吸(FB)状态下慢速CT扫描(SS)和常规轴位扫描在周围型非小细胞肺癌(NSCLC)精确放疗中减小放射性肺损伤方面的作用差异。方法 10例周围型NSCLC患者在适形放疗定位时分别采集3种CT图像:1FB时常规轴位扫描;2ABC螺旋CT快速扫描;3FB时慢速CT扫描。将3套图像传输至计划系统,分别制定3个适形放疗计划,比较3个计划的大体肿瘤靶区(GTV)、临床靶区(CTV)、计划靶区(PTV)、受照剂量>20 Gy的正常肺组织占全肺体积的百分比(V₂₀)及全肺平均受照剂量(D_mean)。结果 3个计划的GTV、CTV体积以慢速扫描似乎最大,ABC计划似乎最小,但差异无统计学意义(F=1.513,P=0.238;F=1.376,P=0.270);FB常规轴位计划的PTV体积最大,且分别与另2个计划间差异有统计学意义(F=26.148,P=0.000);V₂₀、D_mean在FB常规轴位计划均最大,且FB计划和另2个计划间差异有统计学意义(F=7.623,P=0.002;F=18.217,P=0.000)。结论 相对于FB状态,使用ABC或慢速CT扫描可有效减少周围型NSCLC精确放疗中正常组织的受照体积和剂量,减小放射性肺损伤的发生率。

Comparison of three CT scan methods used in precise radiotherapy of non-small cell lung cancer

Objective To compare the difference of decreasing radiation-induce lung injure among CT scans including active breathing control (ABC), slow CT scan and general axial CT scan under free breathing (FB) in precise radiotherapy of peripheral non-small cell lung cancer (NSCLC). Methods Ten patients of peripheral NSCLC were included. For each patient, three CT scans were obtained: (1) the general axial CT scans under FB; (2) the fast spiral CT scans under ABC; (3) the slow CT scans under FB. Three treatment plans based on three CT scans were optimized. Gross tumor volume (GTV), clinical target volume (CTV) and planning target volume (PTV) along with V₂₀ (lung volume accepted >20Gy/all lung volume×100%) and D_mean (average dosage accepted irradiation of all lung)of three treatment plans were calculated and compared. Results The GTV and CTV of the slow CT plan seem in largest, and those of ABC plan in smallest, but no statistics signification among the three plans (F=1.513,P=0.238;F=1.376,P=0.270). However, The PTV of the FB plan was largest, and the difference of PTV between plans of ABC and FB, plans of slow CT scans and FB were statistics significant (F=26.148,P=0.000). The differences of V₂₀ and D_mean between plans of FB and ABC, plans of FB and slow CT scans were statistics significant yet (F=7.623,P=0.002; F=18.217,P=0.000).Conclusion Compared with FB conditions, ABC or the slow CT scan method in precise radiotherapy of peripheral NSCLC can decrease radiation volume and dose to normal tissues as well as the probability of decreasing radiation-induce lung injure.