Background: We aimed to develop a new tumor response assessment method for lung SBRT. Methods: In total, 132 lung cancer patients with 134 tumors who received SBRT treatment with daily CBCT were included in this study. The information about tumor size (area), contrast (contrast-to-noise ratio (CNR)), and density/attenuation (μ) was derived from the CBCT images for the first and the last fractions. The ratios of tumor area, CNR, and μ (RA, RCNR, Rμ) between the last and first fractions were calculated for comparison. The product of the three rations was defined as a new parameter (R) for assessment. Tumor response was independently assessed by a radiologist based on a comprehensive analysis of the CBCT images. Results: R ranged from 0.27 to 1.67 with a mean value of 0.95. Based on the radiologic assessment results, a receiver operation characteristic (ROC) curve with the area under the curve (AUC) of 95% was obtained and the optimal cutoff value (RC) was determined as 1.1. The results based on RCachieved a 94% accuracy, 94% specificity, and 90% sensitivity. Conclusion: The results show that R was correlated with early tumor response to lung SBRT and that using R for evaluating tumor response to SBRT would be viable and efficient.
背景：本研究旨在开发一种新的肺部立体定向放射治疗（SBRT）肿瘤反应评估方法。方法：共纳入132例接受每日锥形束CT（CBCT）引导下SBRT治疗的肺癌患者，共计134个肿瘤。从首次和末次治疗分次的CBCT图像中提取肿瘤大小（面积）、对比度（信噪比）及密度/衰减系数信息，计算末次与首次分次间肿瘤面积比、信噪比比及衰减系数比，并定义三者的乘积为新型评估参数R。由放射科医师基于CBCT影像综合分析结果独立评估肿瘤反应。结果：R值范围为0.27-1.67，均值为0.95。基于影像学评估结果绘制受试者工作特征曲线，曲线下面积达95%，确定最佳截断值RC为1.1。采用RC评估的准确率达94%，特异性94%，敏感性90%。结论：研究结果表明R值与肺部SBRT早期肿瘤反应具有相关性，将其应用于SBRT疗效评估具有可行性与高效性。
A Novel Method for Evaluating Early Tumor Response Based on Daily CBCT Images for Lung SBRT
肿瘤(癌症)患者之家