Abstract：
Objective.In diffusing alpha-emitters radiation therapy (\'Alpha DaRT\'), the diffusion-leakage (DL) model is used to determine the spatial distributions of the emitters and the corresponding alpha dose, critical for a successful treatment. This work first introduces a finite volume (FV) approach to develop numerical schemes to simulate the DL model in one, two and three dimensions then presents how variations over realistic ranges of the DL model parameters related to desorption, diffusion and leakage processes affect the alpha dose distribution and the position of the clinically significant alpha particle10Gy isodose. This work also presents the effects of three modeling approximations: two source geometry approximations (solid cylinder instead of hollow, pixelized cross section instead of circular), and one dosimetric approximation (single-source dose superposition instead of multiple-sources direct dose calculation).Approach.The introduced FV approach was used to obtain spatial distributions of the emitters, from which the corresponding alpha dose distributions were calculated under the assumption of a local deposition of the alpha particles\' energies. Variation ranges of the DL model parameters were based on previously published data. For each modeling approximation studied, the error and relative error on the alpha dose distribution were calculated and the displacement of the10Gy isodose was evaluated.Main results.Over realistic ranges, the desorption probabilities, diffusion lengths, and leakage probabilities affect the position of the alpha particle10Gy isodose by∼0.1mm,∼1.5mm and∼0.5mm, respectively. The three modeling approximations studied have a negligible effect on the alpha particle10Gy isodose position, with displacements⩽0.01mm.Significance.This work quantitatively evaluates the relative importance of different parameters and approximations in Alpha-DaRT alpha dose calculations based on their impact not only on the dose variation at a given distance from the source but also on the displacement of clinically significant isodoses.
摘要：
目标：在扩散α发射体放射治疗（DaRT）中，扩散-泄漏（DL）模型用于确定发射器的空间分布和相应的α剂量，对于成功的治疗至关重要。这项工作介绍了与解吸相关的DL模型参数在实际范围内的变化，扩散和泄漏过程会影响α剂量分布和临床意义的α粒子10Gy等剂量的位置。这项工作还介绍了三种建模近似的效果：两种源几何近似（实心圆柱体代替空心，像素化横截面而不是圆形)，和单源剂量叠加（而不是多源直接剂量计算）。
方法。使用有限体积方法来开发数值方案，以模拟DL模型，二维和三维，并获得发射器的空间分布。在假设α粒子能量局部沉积的情况下，计算了相应的α剂量分布。DL模型参数的变化范围基于先前发布的数据。对于所研究的每个建模近似，计算了α剂量分布的误差和相对误差，并评估了10Gy等剂量的位移。
主要结果。在现实范围内，解吸概率，扩散长度,和泄漏概率分别影响阿尔法粒子10Gy等剂量的位置，约0.1毫米，1.5毫米和0.5毫米。所研究的三个建模近似对α粒子10Gy等剂量位置的影响可以忽略不计，位移≤0.01mm。
意义。这项工作定量评估了DaRTα剂量计算中不同参数和近似值的相对重要性，这些参数和近似值不仅对距来源给定距离的剂量变化的影响，而且对临床显着等剂量的位移。
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