Portsmouth Hospitals NHS Trust, Portsmouth, UK; University of Surrey, Guildford, UK.
Portsmouth Hospitals NHS Trust, Portsmouth, UK.
Radiother Oncol. 2017 Dec;125(3):453-458. doi: 10.1016/j.radonc.2017.09.033. Epub 2017 Oct 13.
External dosimetry audit is valuable for the assurance of radiotherapy quality. However, motion management has not been rigorously audited, despite its complexity and importance for accuracy. We describe the first end-to-end dosimetry audit for non-SABR (stereotactic ablative body radiotherapy) lung treatments, measuring dose accumulation in a moving target, and assessing adequacy of target dose coverage.
A respiratory motion lung-phantom with custom-designed insert was used. Dose was measured with radiochromic film, employing triple-channel dosimetry and uncertainty reduction. The host's 4DCT scan, outlining and planning techniques were used. Measurements with the phantom static and then moving at treatment delivery separated inherent treatment uncertainties from motion effects. Calculated and measured dose distributions were compared by isodose overlay, gamma analysis, and we introduce the concept of 'dose plane histograms' for clinically relevant interpretation of film dosimetry.
12 radiotherapy centres and 19 plans were audited: conformal, IMRT (intensity modulated radiotherapy) and VMAT (volumetric modulated radiotherapy). Excellent agreement between planned and static-phantom results were seen (mean gamma pass 98.7% at 3% 2 mm). Dose blurring was evident in the moving-phantom measurements (mean gamma pass 88.2% at 3% 2 mm). Planning techniques for motion management were adequate to deliver the intended moving-target dose coverage.
A novel, clinically-relevant, end-to-end dosimetry audit of motion management strategies in radiotherapy is reported.
外部剂量学审核对于保证放射治疗质量是有价值的。然而，尽管运动管理对于准确性很复杂且很重要，但它尚未经过严格审核。我们描述了首次针对非 SABR（立体定向消融体放射治疗）肺部治疗的端到端剂量学审核，测量移动靶区的剂量积累，并评估靶区剂量覆盖的充分性。
使用具有定制设计插件的呼吸运动肺部体模。采用三通道剂量测量法和不确定性降低技术，使用光致变色胶片测量剂量。使用主机的 4DCT 扫描、勾画和规划技术。在治疗输送时，使体模静态和移动的测量结果将固有治疗不确定性与运动效应分开。通过等剂量线叠加、伽马分析对计算和测量的剂量分布进行比较，并引入“剂量平面直方图”的概念，以便对胶片剂量学进行临床相关的解释。
审核了 12 个放疗中心和 19 个计划：适形、调强放疗（intensity modulated radiotherapy，IMRT）和容积旋转调强放疗（volumetric modulated radiotherapy，VMAT）。计划与静态体模结果之间显示出极好的一致性（3% 2mm 时平均伽马通过率为 98.7%）。在移动体模测量中，剂量模糊现象明显（3% 2mm 时平均伽马通过率为 88.2%）。运动管理的规划技术足以实现预期的移动靶区剂量覆盖。
报告了一种新的、与临床相关的放射治疗中运动管理策略的端到端剂量学审核。
