Paul Jijo, Yang Cungeng, Wu Hui, Tai An, Dalah Entesar, Zheng Cheng, Johnstone Candice, Kong Feng-Ming, Gore Elizabeth, Li X Allen
Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin.
Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin; The Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou, China.
Int J Radiat Oncol Biol Phys. 2017 Jun 1;98(2):463-472. doi: 10.1016/j.ijrobp.2017.02.032. Epub 2017 Feb 21.
To investigate early tumor and normal tissue responses during the course of radiation therapy (RT) for lung cancer using quantitative analysis of daily computed tomography (CT) scans.
Daily diagnostic-quality CT scans acquired using CT-on-rails during CT-guided RT for 20 lung cancer patients were quantitatively analyzed. On each daily CT set, the contours of the gross tumor volume (GTV) and lungs were generated and the radiation dose delivered was reconstructed. The changes in CT image intensity (Hounsfield unit [HU]) features in the GTV and the multiple normal lung tissue shells around the GTV were extracted from the daily CT scans. The associations between the changes in the mean HUs, GTV, accumulated dose during RT delivery, and patient survival rate were analyzed.
During the RT course, radiation can induce substantial changes in the HU histogram features on the daily CT scans, with reductions in the GTV mean HUs (dH) observed in the range of 11 to 48 HU (median 30). The dH is statistically related to the accumulated GTV dose (R > 0.99) and correlates weakly with the change in GTV (R = 0.3481). Statistically significant increases in patient survival rates (P=.038) were observed for patients with a higher dH in the GTV. In the normal lung, the 4 regions proximal to the GTV showed statistically significant (P<.001) HU reductions from the first to last fraction.
Quantitative analysis of the daily CT scans indicated that the mean HUs in lung tumor and surrounding normal tissue were reduced during RT delivery. This reduction was observed in the early phase of the treatment, is patient specific, and correlated with the delivered dose. A larger HU reduction in the GTV correlated significantly with greater patient survival. The changes in daily CT features, such as the mean HU, can be used for early assessment of the radiation response during RT delivery for lung cancer.
通过对每日计算机断层扫描（CT）图像进行定量分析，研究肺癌放射治疗（RT）过程中肿瘤组织和正常组织的早期反应。
对20例肺癌患者在CT引导下的放射治疗过程中，使用轨道CT获取的每日诊断级CT图像进行定量分析。在每日的CT图像上，勾画出大体肿瘤体积（GTV）和肺组织的轮廓，并重建所给予的放射剂量。从每日CT图像中提取GTV及其周围多个正常肺组织区域的CT图像强度（亨氏单位[HU]）特征变化。分析平均HU变化、GTV、放疗期间累积剂量与患者生存率之间的相关性。
在放疗过程中，放射可导致每日CT图像的HU直方图特征发生显著变化，GTV的平均HU（dH）下降范围为11至48 HU（中位数为30）。dH与GTV累积剂量在统计学上相关（R>0.99），与GTV变化的相关性较弱（R = 0.3481）。GTV中dH较高的患者，其生存率在统计学上有显著提高（P = 0.038）。在正常肺组织中，GTV近端的4个区域从首次分割到末次分割期间HU有统计学显著下降（P<0.001）。
每日CT图像的定量分析表明，在放疗过程中肺肿瘤及周围正常组织的平均HU降低。这种降低在治疗早期即可观察到，具有患者个体特异性，且与所给予的剂量相关。GTV中HU降低幅度越大，患者生存率越高。每日CT特征的变化，如平均HU，可用于肺癌放疗过程中放射反应的早期评估。
