Room: Exhibi Hall | Forum 6
Purpose: Cone beam computerized tomography (CBCT) has been widely used in modern linacs for patient positioning and tumor localization. Iterative CBCT (iCBCT) can improve image quality, allowing better patient positioning and targeting as well as advanced application on adaptive radiotherapy. In this study, we evaluated the image quality of a commercial iCBCT algorithm and its application for clinical use.
Methods: The iCBCT was installed and accept tested on a linac (Truebeam, Varian, Palo Alto) last first. ICBCT was used for all patients treated using this linac for below sites: Head & Neck, Brain, Pelvis and other disease sites where motion is minimal. Regular CBCT was reconstructed retrospectively, using the Advanced Reconstruction function provided by the linac. The reconstruction time for both regular and iterative CBCT images were compared. Both CT images were compared and evaluated by a physicist and physician in terms of image quality and tumor localization accuracy. Its potential application for adaptive planning for Head and Neck and other sites was also evaluated.
Results: iCBCT has been used for over 30 patients on one linac at our center. Preliminary study indicates a better image quality for the majority of patients, and no clear difference for the rest. The reconstruction time for iCBCT ranged from about 15 for a head & neck case to 50 seconds for a pelvic cases, about 10 to 20 seconds longer compared to regular CBCT. Whether the better image quality of iCBCT would lead to better tumor localization in being investigated. The application of iCBCT on adaptive planning for Head and Neck will be carried out in the future.
Conclusion: The iCBCT offers better image quality and can lead to better tumor visualization and localization. The improved image quality may lead potential application for adaptive planning.