Automated Analysis of Film Checks for QA of Stereotactic Treatment Setup

Abstract

Stereotactic radiotherapy with high doses per treatment strongly depends among other factors on the mechanical accuracy of the setup of the patient at the linear accelerator. A commonly used quality assurance tool for radiosurgery with circular collimators is a film check introduced by Winston and Lutz [1] to evaluate the positional accuracy of the gantry and couch rotation around a radiopaque target ball that is positioned in the isocenter by means of the stereotactic setup. There are different manual methods to determine the shift between the center of the exposures of the circular collimator and the sometimes hardly recognizable target ball on the film that naturally depend on the individual skills of the analyzing person to estimate the appropriate centers. Since stereotactic radiotherapy as well as radiosurgery steadily gain importance in cancer treatment, an automated tool to speed up and standardize the analysis of Winston-Lutz film QA checks would be very helpful.