Accurate spatial dose delivery in radiotherapy is frequently complicated due to changes in the patient’s internal anatomy during and in-between therapy segments. The recent introduction of hybrid MRI radiotherapy systems allows unequaled soft-tissue visualization during radiation delivery and can be used for dose reconstruction to quantify the impact of motion. To this end, knowledge of anatomical deformations obtained from continuous monitoring during treatment has to be combined with information on the spatio-temporal dose delivery to perform motion-compensated dose accumulation (MCDA). Here, the influence of the choice of deformable image registration algorithm, dose warping strategy, and magnetic resonance image resolution and signal-to-noise-ratio on the resulting MCDA is investigated. For a quantitative investigation, four 4D MRI-datasets representing typical patient observed motion patterns are generated using finite element modeling and serve as a gold standard. Energy delivery is simulated intra-fractionally in the deformed image space and, subsequently, MCDA-processed. Finally, the results are substantiated by comparing MCDA strategies on clinically acquired patient data. It is shown that MCDA is needed for correct quantitative dose reconstruction. For prostate treatments, using the energy per mass transfer dose warping strategy has the largest influence on decreasing dose estimation errors.

由于在治疗段期间和治疗段之间患者内部解剖结构的变化，放射治疗中的准确空间剂量输送通常很复杂。最近引入的混合 MRI 放射治疗系统允许在放射输送过程中实现无与伦比的软组织可视化，并可用于剂量重建以量化运动的影响。为此，必须将在治疗期间从连续监测中获得的解剖变形知识与时空剂量输送信息相结合，以执行运动补偿剂量累积 (MCDA)。在这里，研究了可变形图像配准算法、剂量扭曲策略以及磁共振图像分辨率和信噪比的选择对所得 MCDA 的影响。对于定量调查，代表典型患者观察到的运动模式的四个 4D MRI 数据集是使用有限元建模生成的，并用作黄金标准。在变形的图像空间中对能量传递进行分数内模拟，然后进行 MCDA 处理。最后，通过比较临床获得的患者数据的 MCDA 策略来证实结果。结果表明，正确的定量剂量重建需要 MCDA。对于前列腺治疗，使用每传质能量剂量翘曲策略对减少剂量估计误差的影响最大。通过比较临床获得的患者数据的 MCDA 策略来证实这些结果。结果表明，正确的定量剂量重建需要 MCDA。对于前列腺治疗，使用每传质能量剂量翘曲策略对减少剂量估计误差的影响最大。通过比较临床获得的患者数据的 MCDA 策略来证实这些结果。结果表明，正确的定量剂量重建需要 MCDA。对于前列腺治疗，使用每传质能量剂量翘曲策略对减少剂量估计误差的影响最大。