A self-sufficient method for calibration of Varian electronic portal imaging device

8th International Conference on 3D Radiation Dosimetry

Sun, Baozhou^1 ; Yaddanapudi, Sridhar^1 ; Goddu, Sreekrishna M.^1 ; Mutic, Sasa^1

Department of Radiation Oncology, Washington University in St. Louis, St. Louis

MO, United States^1

关键词: Additional equipment;    Calibration method;    Calibration procedure;    Conventional methods;    Dosimetric response;    Electronic portal imaging devices;    Equipment requirements;    Robust calibration;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/573/1/012041/pdf
DOI  :  10.1088/1742-6596/573/1/012041

来源: IOP

【 摘 要 】

Electronic portal imaging device (EPID) is currently used for dosimetric verification of IMRT fields and linac quality assurance (QA). It is critical to understand the dosimetric response and perform an accurate and robust calibration of EPID. We present the implementation of an efficient method for the calibration and the validation of a Varian EPID, which relies only on data collected with that specific device. The calibration method is based on images obtained with five shifts of EPID panel. With this method, the relative gain (sensitivity) of each element of a detector matrix is calculated and applied on top of the calibration determined with the flood-field procedure. The calibration procedure was verified using a physical wedge inserted in the beam line and the corrected profile shows consistent results with the measurements using a calibrated 2D array. This method does not rely on the beam profile used in the flood-field calibration process, which allows EPID calibration in 10 minutes with no additional equipment compared to at least 2 hours to obtain beam profile and scanning beam equipment requirement with the conventional method.