Huang He, Zhang Lian, Bian Yunfei, Dong Yang, Lin Hongyu, Xu Hui, Li Ying
Department of Oncology, The First Hospital of Hebei Medical University, Shijiazhuang, China.
Department of Radiation Oncology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin's Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin, China.
Front Oncol. 2024 Nov 27;14:1458158. doi: 10.3389/fonc.2024.1458158. eCollection 2024.
This study investigates the impact of non-standard positioning on the accuracy of 6D-skull tracking using dual-panel imaging systems. It explores whether positioning patients' heads at various angles during intracranial lesion treatment affects the accuracy of the CyberKnife 6D-skull tracking system.
A heterogeneous density skull phantom was used to simulate various patient skull positioning angles. To accurately compare 6D-skull tracking and fiducial tracking, their center coordinates were pre-set to be identical in the treatment plan. The phantom was positioned using fiducial tracking, and the offset value recorded. The system was then switched to 6D-skull tracking to observe the corresponding offset. The difference between the two tracking methods was calculated, and a paired-sample T-test was conducted to assess statistical significance across different angles. Additionally, the gamma passing rate (criteria: 3%/3mm) was employed to quantitatively delineate dosimetric disparities attributable to positional variations.
Paired sample T-tests on the deviations between rotational and translational parameters of fiducial tracking and skull tracking under identical conditions revealed no statistically significant differences between the methods across all selected angles. The minimal deviations and lack of statistical significance demonstrate that both tracking methods are equivalent in skull positioning. Furthermore, the gamma passing rate analysis showed that in all tested conditions, the rates exceeded 95%, which aligns with clinical requirements. This high passing rate indicates a high degree of dosimetric accuracy and consistency between the two tracking methods, providing robust assurance of treatment precision in skull positioning.
Since fiducial tracking is not affected by patient or phantom positioning, this study compares the registration results of 6D-skull tracking with fiducial tracking under the same conditions. The results show minimal deviations and no statistically significant differences, indicating that 6D-skull tracking is not dependent on the skull's positioning angle. Furthermore, the gamma passing rate analysis was conducted to quantitatively assess the dosimetric differences arising from variations in patient positioning. Our results demonstrated that under all tested conditions, the gamma passing rates exceeded the clinically accepted threshold of 95%, confirming the clinical adequacy of both tracking methods in maintaining treatment precision. In clinical practice, patients do not need to maintain a strict supine position; the algorithm can accurately perform registration even if patients need to rotate their heads or lie prone. Clinical recommendations should prioritize patient comfort and safety without imposing overly strict requirements.
本研究调查非标准定位对使用双面板成像系统进行6D颅骨跟踪准确性的影响。探讨在颅内病变治疗期间将患者头部置于不同角度是否会影响射波刀6D颅骨跟踪系统的准确性。
使用异质密度颅骨模型模拟各种患者颅骨定位角度。为了准确比较6D颅骨跟踪和基准标记跟踪，在治疗计划中将它们的中心坐标预先设置为相同。使用基准标记跟踪对模型进行定位，并记录偏移值。然后将系统切换到6D颅骨跟踪以观察相应的偏移。计算两种跟踪方法之间的差异，并进行配对样本T检验以评估不同角度下的统计学显著性。此外，采用伽马通过率（标准：3%/3mm）来定量描述因位置变化导致的剂量差异。
在相同条件下对基准标记跟踪和颅骨跟踪的旋转和平移参数偏差进行配对样本T检验，结果显示在所有选定角度下，两种方法之间均无统计学显著差异。最小偏差和缺乏统计学显著性表明两种跟踪方法在颅骨定位方面等效。此外，伽马通过率分析表明，在所有测试条件下，通过率均超过95%，符合临床要求。这种高通过率表明两种跟踪方法之间具有高度的剂量准确性和一致性，为颅骨定位中的治疗精度提供了有力保证。
由于基准标记跟踪不受患者或模型定位的影响，本研究在相同条件下比较了6D颅骨跟踪与基准标记跟踪的配准结果。结果显示偏差最小且无统计学显著差异，表明6D颅骨跟踪不依赖于颅骨的定位角度。此外，进行了伽马通过率分析以定量评估因患者定位变化产生的剂量差异。我们的结果表明，在所有测试条件下，伽马通过率均超过临床可接受的95%阈值，证实了两种跟踪方法在维持治疗精度方面的临床适用性。在临床实践中，患者无需保持严格的仰卧位；即使患者需要转动头部或俯卧，算法也能准确进行配准。临床建议应优先考虑患者的舒适度和安全性，而无需施加过于严格的要求。
