Simple Automated Verification of Field Size Indicator for Quality Assurance of Medical Linear Accelerator

Abstract

Purpose: The purpose of this study is to automate the field size verification to facilitate mechanical check aspect medical linear accelerator (linac) quality assurance in a MATLAB-based algorithm on electronic portal imaging device (EPID) images. Methods: A total of 5 reference datasets (i.e. field sizes of 5 cm × 5 cm, 10 cm × 10 cm, 15 cm × 15 cm, 20 cm × 20 cm, and 25 cm × 25 cm) and 15 test datasets (i.e. reference field sizes plus 1 mm, 3 mm, and 5 mm increments) acquired by 6 MV Elekta Linac were used in this study. The proposed algorithm implemented a full automatic threshold with a value of 230 as a segmentation technique. The automated results were compared with manual results obtained using a ruler. Results: The automated results are comparable to manual results (i.e., the difference of both is within 2% or equal to 3 mm). The range of minimum to maximum difference between automated and manual was 0 - 3 mm and the maximum difference found in the 15.3 cm field size setting. Conclusions: We have successfully developed an automated procedure of field size verification and confirmed that the proposed algorithm provide a fast and accurate results.