Quality control for multileaf collimator leaf position accuracy using amorphous silicon electronic portal imaging devices

Abstract

The multi-leaf collimator (MLC) leaf position deviation of the linear accelerator (LINAC) can result in dose distribution errors during intensity modulated radiotherapy (IMRT), which would cause treatment failure and serious injury to the patients. This study was to develop a simple method to control the MLC leaf position accuracy. Elekta LINAC, Elekta iView aSi electronic portal imaging devices (EPIDs) and an 8MV photon beam were used. A digital image designed by a treatment planning system (TPS) was acquired using the EPIDs and was analyzed to compute the MLC leaf position coordinates. The position error was thus obtained by comparing the coordinates in the image with those in the TPS DicomRT file, which was used to quickly adjust the MLC leaf position. The leaf deviation of leaf position accuracy was kept less than 1 mm. Quality control for MLC leaf position accuracy using EPIDs is simple and adequate.