The goal of this study was to evaluate the feasibility of recalculating the dose based on cone beam computed tomography (CBCT) images using an end-to-end thorax heterogeneous phantom. A CT simulator (SIEMENS, Sensation Open, Germany) was used for calibrating the curve of HU-to-density. The CBCT system evaluated in this study was assembled on an Electron Linear Accelerator (Varian Medical System, EDGE, USA). Image acquisitions of electron density phantom for both computed tomography (CT) and CBCTs were performed, and then the CT number to relative electron density calibration curve was obtained. The end-to-end heterogeneous phantom was scanned by CT simulation and the target volume was contoured to design a dummy treatment plan. The CBCT image was scanned before the simulated treatment, and registration between the CBCT and CT images was performed. The dummy treatment plan was transplanted to the CBCT images to recalculate the dose of the treatment plan. Then, differences of the dose volume histogram and three-dimensional isodose distribution were evaluated between the recalculated plan and the original dummy treatment plan. The HU-to-density curves for CBCT of the EDGE accelerator showed in principle a singe upward trend. The D-95, of the clinical target volume and planning target volume for the recalculated plan based on the CBCT images were lower than the original dummy treatment plan based on the CT images by 1.69% and 2.62%, respectively. On the premise of the CT number-relative density curve calibration of the CBCT images, the recalculated dose based on the high-quality CBCT images can be used as an important basis for replanning in lung cancer irradiation.
[1]Jilin Univ, Dept Radiat Oncol, China Japan Union Hosp, 126 Xiantai St, Changchun 130033, Jilin, Peoples R China.
[2]CNPC Jilin, Dept Radiat Oncol, Gen Hosp, Jilin 132022, Jilin, Peoples R China.
(8.0+极速模式)