发表机构
Université Laval; CHU de Québec Université Laval; Elekta Instrument AB（拉瓦尔大学; 魁北克大学医院研究中心; Elekta仪器公司）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究提出一种线-弧-线扫描轨迹，通过模拟验证其能有效减少伽玛刀CBCT图像的锥束伪影，且与现有系统兼容，有望替代当前200度单弧扫描。
AI 中文摘要
目的。伽玛刀锥束计算机断层扫描（CBCT）图像因锥束伪影而质量下降，这些伪影的幅度沿上方向增加。在本研究中，优化了一种与伽玛刀CBCT系统兼容的新型扫描轨迹以减少锥束伪影，旨在替代当前的200度单弧扫描。方法。利用断层扫描不完整性图进行数据采样分析，基于系统和扫描轨迹的几何形状评估视场内的欠采样水平。此外，使用沿轴向排列的圆盘虚拟体模以及立体定向端到端验证（STEEV）体模的CT重建进行CBCT模拟。针对给定扫描轨迹，通过多色前向投影模型（含添加噪声和散射）模拟CBCT投影，然后使用最小化加权最小二乘的迭代算法重建CBCT图像。主要结果。不完整性分析和CBCT模拟均表明，在当前单弧轨迹上添加线比添加更多弧更有效地减少锥束伪影，无论是在额外投影数量还是新伪影方面。具有3.5毫米源轴向步长的线-弧-线轨迹几乎消除了所有锥束伪影。圆盘产生的锥束伪影宽度显示伪影幅度与不完整性值之间存在正相关。意义。线-弧-线扫描轨迹有望减少伽玛刀CBCT图像的锥束伪影，同时对于当前系统设计而言是兼容且合理的轨迹。
英文摘要
Objective. Gamma Knife cone-beam computed tomography (CBCT) images are deteriorated by cone-beam artifacts whose magnitude increases along the superior direction. In this study, a novel scan trajectory compatible with the Gamma Knife CBCT system is optimized to reduce cone-beam artifacts, with the aim to replace the current 200-degree single-arc scan. Approach. Data sampling analysis with tomographic incompleteness maps indicates the level of undersampling across the field of view based on the geometry of the system and of a scan trajectory. Moreover, CBCT simulations are performed from a virtual phantom with disks aligned along the axial direction and from a CT reconstruction of a stereotactic end-to-end validation (STEEV) phantom. CBCT projections are simulated for a given scan trajectory through a polychromatic forward projection model with added noise and scatter, then the CBCT image is reconstructed using an iterative algorithm which minimizes weighted least squares. Main results. Both the incompleteness analysis and the CBCT simulations indicate adding lines to the current single-arc trajectory is more efficient to reduce cone-beam artifacts than adding more arcs, both in terms of number of additional projections and new artifacts. A line-arc-line trajectory with source axial steps of 3.5 mm removes virtually all cone-beam artifacts. The widths of the cone-beam artifacts created by the disks show a positive correlation between the artifact magnitude and the incompleteness value. Significance. A line-arc-line scan trajectory is promising to reduce cone-beam artifacts of the Gamma Knife CBCT images while being a compatible and reasonable trajectory for the current system design.
CommentsThis paper is 18 pages in length, including 7 figures and 1 table. The content of this paper was presented at ESTRO2026, with the reference to the conference abstract as follows: Alain-Beaudoin, A. et al. (2026). Radiother. Oncol., 218, S2059-S2061. The manuscript has been submitted to Physics in Medecine & Biology
