Comprehensive quality assurance of a surface-guided radiotherapy system using a new anthropomorphic add-on phantom in a modular setup

PURPOSE: To demonstrate the suitability of a new anthropomorphic phantom add-on to an existing end-to-end phantom for the quality assurance (QA) of a surface-guided radiotherapy (SGRT) system following ESTRO-ACROP guidelines. METHODS: Tests were performed at C-arm linac equipped with a SGRT system. Positional accuracy QA for the SGRT system was assessed in 6 degrees-of-freedom by comparing against the cone-beam computed tomography registration as ground truth. Finally, the effectiveness in tracking and guiding dynamic dose delivery was tested completing end-to-end tests for a simulated sinusoidal and deep-inspiration breath hold (DIBH) treatment deliveries using the phantom-detector setup over a dynamic platform. RESULTS: Positioning accuracy of the SGRT system was within ±0.5mm/±0.5°. For gated delivery with a 5mm tolerance window, the 2%/3mm gamma metric (global gamma, 10% threshold) achieved pass rates of 100% for a sine waveform and 96.5% for a DIBH waveform. End-to-end tests with a 2%/1mm gamma criterion yielded passing rates of 100% for the single-target and 95.3% for the multi-metastasis target plan. CONCLUSIONS: A comprehensive QA of a SGRT system was successfully conducted using the new phantom, in accordance with ESTRO-ACROP guidelines. The newly developed anthropomorphic add-on facilitates the comprehensive evaluation of end-to-end positioning accuracy and delivery precision by integrating SGRT with widely adopted equipment in the field of stereotactic radiotherapy.