“Inter-fractional error and intra-fractional motion of prostate and dosimetry comparisons of patient position registrations with versus without fiducial markers during treatment with carbon-ion radiotherapy”
Abstract (extract): In 2020, data from 15 patients with prostate cancer who received carbon-ion beam radiotherapy (CIRT) with gold markers were investigated. We checked marker positions before and during irradiation to calculate the inter-fractional positioning and intra-fractional movement and evaluated the CIRT dose distribution by adjusting the planning beam isocenter and clinical target volume (CTV) position.
Introduction (extract): Previous studies reported that image-guided irradiation using fiducial markers reduced late toxicity and improved biochemical tumor control. To enable patients with prostate cancer to receive these benefits at our institute, we introduced the fiducial marker Gold Anchor (0.4×10.0 mm; Naslund Medical AB, Huddinge, Sweden) for image-guided irradiation in October 2020.
Results (extract): The average variation in inter-fractional marker position for all patients was 1.68 ± 1.11 mm (mean ± standard deviation). The average variation in intra-fractional marker position, expressed as the Euclidean distance, in all patients was 0.76 ± 0.54 mm (95th percentile = 1.65 mm).
Conclusion (extract): Our study not only highlights the importance of considering inter-fractional and intra-fractional errors in treatment planning but also demonstrates the superior efficacy of fiducial marker matching in enhancing CTV coverage.