Commissioning and clinical outcome assessment of a novel surface-guided radiation therapy (SGRT) system at a C-Arm linear accelerator

TL;DR

This study details the commissioning and clinical validation of the LUNA 3D surface-guided radiation therapy system, demonstrating its accuracy and improvements in patient positioning in radiotherapy.

Contribution

The paper introduces a novel SGRT system, LUNA 3D, with advanced features and validates its performance against established standards and clinical datasets.

Findings

Temperature drift below 0.4 mm on all axes.

Agreement with CBCT within 1.0 mm.

Significant reduction in patient positioning errors after implementation.

Abstract

Surface-guided radiation therapy (SGRT) is now widely used for radiation-dose-free, marker-free patient positioning in modern radiotherapy. We commissioned and clinically implemented a novel SGRT system, LUNA 3D (LAP, Lueneburg, Germany), featuring browser-based operation, GPU-accelerated surface reconstruction, frame rates above 12 Hz, a large field of view, and virtual laser projection. Commissioning included tests of temperature drift, reproducibility, translational and rotational shift accuracy, gantry-related camera occlusion, agreement with cone-beam CT (CBCT), and end-to-end dosimetric performance. Results were evaluated using both an SGRT-acquired reference surface and a CT-derived external surface. Temperature drift remained below 0.4 mm on all axes. With the SGRT reference, maximum deviations were at most 0.3 mm translationally and 0.2 degrees rotationally; with the CT-derived reference, translational deviations increased to 0.8 mm, consistent with systematic bias from the reference surface. Agreement between LUNA 3D and CBCT was within 1.0 mm, and end-to-end testing showed CBCT residuals of 0.9-1.3 mm with 1.2% dosimetric deviation. All results satisfied ESTRO-ACROP guideline criteria. Clinical evaluation of 192 breast and 259 pelvic treatment datasets showed significant improvements after implementation: the breast 3D translational vector decreased by 28.7% from 7.00 +/- 4.35 mm to 4.99 +/- 2.75 mm, and the pelvic 3D rotational vector decreased by 24.0% from 2.31 +/- 0.96 degrees to 1.76 +/- 0.67 degrees (both p < 0.001). These results establish LUNA 3D as a reliable SGRT system that improves routine patient positioning accuracy.