背景:室性心动过速是一种使用侵入性心脏导管消融和药物治疗的不规则心跳。然而,当标准治疗已经用尽时,心脏SABR为这种高死亡率疾病提供了最终的治疗选择。复杂的诊断映射和规划扫描可实现25Gy单个分数的多学科目标描绘。然而,目标附近的危险器官(OAR)使得这种治疗计划和交付具有挑战性。心脏病学家的出版物报道了心脏SABR的疗效,然而,关于这种复杂手术的治疗和图像匹配的数据有限。
方法:四位在心脏SABR方面有经验的专业放射治疗医师回顾了在英国接受治疗的10例患者的40个CBCT。每位放射治疗师进行了五次图像匹配:一次手动匹配(manual),与心脏结构的自动匹配(自动)和自动匹配,然后手动调整PTV(PTV),全部仅使用三个自由度(DoF)。还使用6DoF重复自动和PTV匹配。使用来自改良的Bland-Altman分析的95%一致性极限来量化观察者间变异性。
结果:自动匹配中的一致性极限最小,这表明该算法是可靠的。从自动匹配到PTV的手动调整在临床上适合于优化目标覆盖。在6DoFPTV匹配1.06mm中,协议限制较小,1.24mm,1.68毫米比3DoFPTV匹配1.57毫米,2.06mm,2.11mm(横向,垂直,纵向)。
结论:6DoFCBCT图像匹配的变异性较小,因此建议使用6DoF沙发进行治疗。
结论:治疗时心脏SABRCBCT图像匹配很复杂,在实施之前,优化CBCT采集参数和放射治疗技师培训至关重要。
BACKGROUND: Ventricular tachycardia is an irregular heartbeat conventionally treated using invasive cardiac catheter ablation and medication. However, when standard treatments have been exhausted, cardiac SABR provides a final treatment option to this high-mortality condition. Complex diagnostic mapping and planning scans enable multi-disciplinary target delineation for a 25Gy single fraction. However, organs at risk (OAR) near the target make this treatment challenging to plan and deliver. Publications from cardiologists report the efficacy of cardiac SABR, however there is limited data on the treatment delivery and image matching of this complex procedure.
METHODS: Four specialist therapeutic radiographers experienced in cardiac SABR reviewed 40 CBCTs from 10 patients treated in the UK. Each therapeutic radiographer conducted five image matches: a manual match (manual), an automatic match to the heart structure (auto) and the auto match followed by manual adjustment to the PTV (PTV), all using three degrees of freedom (DoF) only. The auto and PTV matches were also repeated using 6DoF. Inter-observer variability was quantified using 95% limits of agreement from a modified Bland-Altman analysis.
RESULTS: The limits of agreement were smallest in the automatic matches suggesting the algorithm is reliable. A manual adjustment from the auto match to the PTV is clinically appropriate to optimise target coverage. The limits of agreement were smaller in the 6DoF PTV match 1.06 mm, 1.24 mm, 1.68 mm than the 3DoF PTV match 1.57 mm, 2.06 mm, 2.11 mm (lateral, vertical, longitudinal).
CONCLUSIONS: The 6DoF CBCT image match has less variability and therefore suggest using a 6DoF couch for treatment delivery.
CONCLUSIONS: Cardiac SABR CBCT image matching at treatment delivery is complex, optimisation of CBCT acquisition parameters and therapeutic radiographer training is essential prior to implementation.