评估放射治疗期间呼吸运动估计的差异：单一计划 4DMRI 与每日 4DMRI,Radiation Oncology

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评估放射治疗期间呼吸运动估计的差异：单一计划 4DMRI 与每日 4DMRI
Radiation Oncology ( IF 3.3 ) Pub Date : 2021-09-26 , DOI: 10.1186/s13014-021-01915-1
Duncan den Boer ₁ , Johannes K. Veldman ₁ , Geertjan van Tienhoven ₁ , Arjan Bel ₁ , Zdenko van Kesteren ₁

Affiliation

在放射治疗中，呼吸诱发的肿瘤运动通常使用单个四维计算机断层扫描采集 (4DCT) 进行测量。不规律的呼吸会导致不准确的运动估计，可能导致对肿瘤的治疗不足和对健康组织的不必要剂量。该研究的目的是确定与单一计划的 4DMRI（有或没有异常值拒绝）相比，每日预处理 4DMRI 策略是否能显着改善运动估计。获得了来自 10 名健康志愿者的 4DMRI 数据集。第一次采集模拟了计划中的 MRI，将呼吸运动估计（由呼吸信号构建，即 1D 导航器）与后续扫描中的呼吸信号（模拟 5-29 个治疗部分）进行比较。使用每天的第一次采集作为当天后续采集的估计值（每天 2 次，每位志愿者 4-20 次）执行相同的程序，模拟每日 MRI 策略。这是针对三种异常值策略完成的：无异常值拒绝（NoOR）；排除 5% 的呼吸信号，同时最小化范围 (Min95) 并排除平均吸气末和呼气末位置 (MeanIE) 之外的数据点。NoOR 的计划 MRI 中位运动估计值为 27 mm，Min95 为 18 mm，MeanIE 为 13 mm。NoOR 的每日 MRI 中位运动估计值为 29 mm，Min95 为 19 mm，MeanIE 为 15 mm。运动估计之外的时间百分比用于计划 MRI：NoOR、Min95 和 MeanIE 分别为 2%、10% 和 32%。这些值随着每日 MRI 策略而降低：0%、6% 和 17%。与 NoOR 相比，应用 Min95 使运动估计减少了 30%。与单个 4D（计划）MRI 相比，每日 MRI 显着改善了对呼吸运动的估计。将 Min95 技术与每日 4DMRI 相结合，包括时间减少 6%，运动减少 30%。单独在计划 MRI 上的异常拒绝通常会导致对运动的低估，并可能导致剂量不足。试验注册：协议W15_373#16.007 单独在计划 MRI 上的异常拒绝通常会导致对运动的低估，并可能导致剂量不足。试验注册：协议W15_373#16.007 单独在计划 MRI 上的异常拒绝通常会导致对运动的低估，并可能导致剂量不足。试验注册：协议W15_373#16.007

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Evaluating differences in respiratory motion estimates during radiotherapy: a single planning 4DMRI versus daily 4DMRI

In radiotherapy, respiratory-induced tumor motion is typically measured using a single four-dimensional computed tomography acquisition (4DCT). Irregular breathing leads to inaccurate motion estimates, potentially resulting in undertreatment of the tumor and unnecessary dose to healthy tissue. The aim of the research was to determine if a daily pre-treatment 4DMRI-strategy led to a significantly improved motion estimate compared to single planning 4DMRI (with or without outlier rejection). 4DMRI data sets from 10 healthy volunteers were acquired. The first acquisition simulated a planning MRI, the respiratory motion estimate (constructed from the respiratory signal, i.e. the 1D navigator) was compared to the respiratory signal in the subsequent scans (simulating 5–29 treatment fractions). The same procedure was performed using the first acquisition of each day as an estimate for the subsequent acquisitions that day (2 per day, 4–20 per volunteer), simulating a daily MRI strategy. This was done for three outlier strategies: no outlier rejection (NoOR); excluding 5% of the respiratory signal whilst minimizing the range (Min95) and excluding the datapoints outside the mean end-inhalation and end-exhalation positions (MeanIE). The planning MRI median motion estimates were 27 mm for NoOR, 18 mm for Min95, and 13 mm for MeanIE. The daily MRI median motion estimates were 29 mm for NoOR, 19 mm for Min95 and 15 mm for MeanIE. The percentage of time outside the motion estimate were for the planning MRI: 2%, 10% and 32% for NoOR, Min95 and MeanIE respectively. These values were reduced with the daily MRI strategy: 0%, 6% and 17%. Applying Min95 accounted for a 30% decrease in motion estimate compared to NoOR. A daily MRI improved the estimation of respiratory motion as compared to a single 4D (planning) MRI significantly. Combining the Min95 technique with a daily 4DMRI resulted in a decrease of inclusion time of 6% with a 30% decrease of motion. Outlier rejection alone on a planning MRI often led to underestimation of the movement and could potentially lead to an underdosage. Trial registration: protocol W15_373#16.007

更新日期：2021-09-28

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