National Cancer Center, National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, 518116, China.
Department of Radiation Oncology, National Clinical Research Center for Cancer/Cancer Hospital, National Cancer Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100021, China.
Radiat Oncol. 2023 Apr 17;18(1):69. doi: 10.1186/s13014-023-02259-8.
This study explored the application of four-dimensional cone beam computed tomography (4D CBCT) in lung cancer patients, seeking to improve the accuracy of radiotherapy and to establish a uniform protocol for the application of 4D CBCT in radiotherapy for lung cancer.
4D CBCT was applied to evaluate tumor volume response (TVR), motion, and center coordinates during radiotherapy in 67 eligible individuals with lung cancer diagnoses. The differences between 4D CBCT and 3D CBCT in different registration methods were compared.
TVR was observed during treatment in 41% of patients (28/67), with a mean volume reduction of 41.7% and a median time to TVR of 19 days. Tumor motion was obvious in 16 patients, with a mean value of 0.52 cm (0.22 to 1.34 cm), and in 3 of 6 tumors close to the diaphragm (0.28 to 0.66 cm). Gray value registration based on mean density projection could still achieve close results to the 4D gray value registration. However, when the registration was based on bone alone, partial off-targeting occurred in the treatment in 41.8% of cases. The off-target rate was 19.0% when the tumor motion was ≤ 0.5 cm and 52.2% when the motion was > 0.5 cm.
Tumor volume and motion of intrapulmonary lesions in individuals diagnosed with lung cancer varied significantly in the third week of radiotherapy. 4D CBCT may be more advantageous for isolated lesions without reference to relative anatomical structures or those near the diaphragm. Grayscale registration based on mean density projection is feasible.
本研究旨在探讨四维锥形束 CT（4D CBCT）在肺癌患者中的应用，旨在提高放疗的准确性，并为肺癌放疗中 4D CBCT 的应用建立统一的方案。
对 67 例经病理诊断为肺癌的患者，应用 4D CBCT 评估肿瘤体积变化（TVR）、运动和放疗期间的中心坐标。比较了不同注册方法下 4D CBCT 与 3D CBCT 的差异。
41%（28/67）的患者在治疗过程中出现 TVR，平均体积减少 41.7%，TVR 中位时间为 19 天。16 例患者肿瘤运动明显，平均为 0.52cm（0.221.34cm），其中 3 例靠近膈肌的肿瘤（0.280.66cm）。基于平均密度投影的灰度值注册仍能获得与 4D 灰度值注册接近的结果。然而，当仅基于骨进行注册时，41.8%的病例在治疗中出现部分靶区外移。当肿瘤运动≤0.5cm 时，靶区外移率为 19.0%，当运动>0.5cm 时，靶区外移率为 52.2%。
肺癌患者在放疗的第三周，肺内病变的肿瘤体积和运动变化显著。4D CBCT 可能更有利于孤立的无参照相对解剖结构或靠近膈肌的病变。基于平均密度投影的灰度值注册是可行的。
