Development of light and radiation fields coincidence test toolkit for LINAC quality assurance

The coincidence of light and radiation fields is an important quality assurance test for accurate beam delivery in a linear accelerator (LINAC), and is recommended to be checked monthly by the American Association of Physicists in Medicine (AAPM). The test-related conventional tools may yield different results, especially without a commercial software, depending on the user, even if the tolerance suggested by the AAPM is very tight. This study was conducted to develop a semiautomatic film analyzer, called FSChecker, for a simple, easy, and consistent quantitative evaluation of the LINAC light and radiation field coincidence, without commercial tools. The FSChecker has two components, a dedicated grid paper and an analyzing software based on MATLAB. Comparing the results obtained from the FSChecker with those of a commercial software revealed that the FSChecker could provide a reasonable and reliable analysis for the coincidence test of light and radiation fields in a LINAC with various scan parameters, including an office-level configuration.