Patient Setup Quality Assurance In External Beam Radiotherapy Using A Third-Party Treatment Setup Verification Software

Abstract

This study sought to assess the performance of a MATLAB algorithm (CORRO) as a quality assurance tool for the verification of treatment setup based on using megavoltage (MV) images from an Electronic Portal Imaging Device (EPID), and the treatment planning system's digitally reconstructed radiographs (DRRs) obtained from patients' three-dimensional (3D) computed tomography (CT) data sets. The individual treatment planning system's DRR was used as a reference radiograph to detect patient setup errors during radiotherapy treatment via the superimposition of the EPID Image on the DRR. Matching points on both images were placed on identical landmarks to facilitate the process. MV and kV (DRR) image pairs of thirty (30) anonymised patients who had received radiotherapy treatment on the Varian Medical System Clinac IX medical linear accelerator at the Komfo Anokye Teaching Hospital patients were employed in the study. Another Matlab algorithm (ASEMPA) was used to load the Anterior-Posterior (AP) and lateral (Lat) MV and kV image pairs for each patient at the same time, and the matching landmark spots on the image pairs were selected. The shifts' root mean square deviation was computed. The systematic error range for Prostate cases was determined to be 0.46 cm – 18.62 cm, while that for Head and Neck cases was found to be 1.57 cm – 11.56 cm. This revealed significant variances. These variables aided in calculating the setup variance and, as a result, the facility's setup accuracy.