Cone-beam artifact reduction in Gamma Knife CBCT images using a line-arc-line scan trajectory

Alexandra Alain-Beaudoin; Håkan Nordström; Luc Beaulieu; Joakim da Silva

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arXiv · 2609.30169

Cone-beam artifact reduction in Gamma Knife CBCT images using a line-arc-line scan trajectory

Alexandra Alain-Beaudoin·Håkan Nordström·Luc Beaulieu·Joakim da Silva

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Abstract

Objective. Gamma Knife cone-beam computed tomography (CBCT) images suffer from distinct cone-beam artifacts for some patients, due to the conical X-ray beam which is oriented to intersect the detector perpendicularly at its inferior edge. The use of an exotic scan trajectory which provides more complete sampling across the field of view than the current arc can reduce cone-beam artifacts. In this study, the feasibility of a line-arc-line scan trajectory for the Gamma Knife CBCT is assessed through a proof of concept. Approach. Using a customized research Gamma Knife, a Catphan 503 and an anthropomorphic head phantom are imaged for different exotic scan trajectories, consisting of combinations of arcs and lines. The CBCT images for each trajectory are then reconstructed with an iterative algorithm. Main results. A line-arc-line trajectory provides the largest image quality improvement among the investigated trajectories, with no noticeable cone-beam artifacts in the CBCT images: the axial interfaces between modules of the Catphan are well defined, and the superior edge of the phantom on the axial axis is sharper by 92\%, compared with the current arc trajectory. For the head CBCT images, the proposed trajectory removes most of the cone-beam artifact on the superior side of the skull, characteristic of the current Gamma Knife CBCT images. The artifact reduction also leads to a visual improvement in terms of uniformity in both phantoms. Significance. A line-arc-line CBCT scan trajectory would be feasible on the Gamma Knife with limited changes to the current configuration, and could produce images with improved image quality.

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Alexandra Alain-Beaudoin, Håkan Nordström, Luc Beaulieu, Joakim da Silva. 2026-09-24. Cone-beam artifact reduction in Gamma Knife CBCT images using a line-arc-line scan trajectory. https://arxiv.org/abs/2609.30169

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