Sassaroli Angelo, Tommasi Federico, Cavalieri Stefano, Martelli Fabrizio
Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA 02155, USA.
Dipartimento di Fisica e Astronomia dell'Università degli Studi di Firenze, via Giovanni Sansone 1, 50019 Sesto Fiorentino, Italy.
Biomed Opt Express. 2022 Dec 13;14(1):148-162. doi: 10.1364/BOE.477339. eCollection 2023 Jan 1.
In biomedical optics, the mean fluence rate of photons, assessed in a sub-volume of a propagating medium, is classically obtained in Monte Carlo simulations by taking into account the power deposited by the absorbed photons in the sub-volume. In the present contribution, we propose and analytically demonstrate an alternative method based on the assessment of the mean pathlength traveled by all the photons inside the sub-volume. Few practical examples of its applications are given. This method has the advantage of improving, in many cases, the statistics and the convergence of the Monte Carlo simulations. Further, it also works when the absorption coefficient is nil and for a non-constant spatial distribution of the absorption coefficient inside the sub-volume. The proposed approach is a re-visitation of a well-known method applied in radiation and nuclear physics in the context of radiative transfer, where it can be derived in a more natural manner.
在生物医学光学中，在传播介质的子体积中评估的光子平均通量率，传统上是通过在蒙特卡罗模拟中考虑被吸收光子在子体积中沉积的功率来获得的。在本论文中，我们提出并通过分析证明了一种基于评估子体积内所有光子传播的平均路径长度的替代方法。给出了其应用的一些实际例子。该方法的优点是在许多情况下可以改善蒙特卡罗模拟的统计特性和收敛性。此外，当吸收系数为零以及子体积内吸收系数的空间分布不均匀时，该方法也适用。所提出的方法是对辐射和核物理中在辐射传输背景下应用的一种著名方法的重新审视，在该背景下它可以以更自然的方式推导出来。
