Development of four-dimensional CT acquisition and tumor detection system during volumetric modulated arc therapy.

在本研究中，我们利用投影图像的基于图像的相位识别技术，在体积调制电弧治疗（VMAT）期间开发了治疗中千伏四维锥束CT（治疗中千伏四维CBCT）采集。利用治疗中kV 4D CBCT，首次定量评价肺肿瘤的呼吸运动，并对治疗方案中应用的切缘进行回顾性再分析。此外，利用VMAT光束的入口图像及其四维版本（4D VMAT CBCT）进行了CBCT重建。4D VMAT CBCT目测肿瘤位置及运动情况。将4D VMAT CBCT与治疗中kV 4D CBCT相结合，期望达到合适的切缘设置，降低正常组织的辐射外剂量。

In this study, we have developed in-treatment kilo-voltage four-dimensional cone-beam CT (in-treatment kV 4D CBCT) acquisition during volumetric modulated arc therapy (VMAT) by use of the image-based phase recognition technique of projection images. With the in-treatment kV 4D CBCT, the respiratory motion of lung tumors has been quantitatively evaluated for the first time, and the margin applied in treatment planning has been retrospectively reanalyzed. In addition, the CBCT reconstruction using the portal images of VMAT beam and its four dimensional version (4D VMAT CBCT) have been developed. With the 4D VMAT CBCT, the tumor location and movement were visually observed. Combining 4D VMAT CBCT with in-treatment kV 4D CBCT, it is expected that the appropriate margin setting and the reduction of the extra-radiation dose for normal tissue are achieved.