Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
Med Phys. 2011 Oct;38(10):5788-98. doi: 10.1118/1.3641827.
The Monte Carlo method is an accurate model for time-resolved quantitative fluorescence tomography. However, this method suffers from low computational efficiency due to the large number of photons required for reliable statistics. This paper presents a comparison study on the computational efficiency of three Monte Carlo-based methods for time-domain fluorescence molecular tomography.
The methods investigated to generate time-gated Jacobians were the perturbation Monte Carlo (pMC) method, the adjoint Monte Carlo (aMC) method and the mid-way Monte Carlo (mMC) method. The effects of the different parameters that affect the computation time and statistics reliability were evaluated. Also, the methods were applied to a set of experimental data for tomographic application.
In silico results establish that, the investigated parameters affect the computational time for the three methods differently (linearly, quadratically, or not significantly). Moreover, the noise level of the Jacobian varies when these parameters change. The experimental results in preclinical settings demonstrates the feasibility of using both aMC and pMC methods for time-resolved whole body studies in small animals within a few hours.
Among the three Monte Carlo methods, the mMC method is a computationally prohibitive technique that is not well suited for time-domain fluorescence tomography applications. The pMC method is advantageous over the aMC method when the early gates are employed and large number of detectors is present. Alternatively, the aMC method is the method of choice when a small number of source-detector pairs are used.
蒙特卡罗方法是一种用于时间分辨定量荧光层析的精确模型。然而，由于需要大量光子来进行可靠的统计，该方法的计算效率较低。本文对三种基于蒙特卡罗的时域荧光分子层析的计算效率进行了比较研究。
为生成时间门控雅可比矩阵，研究了三种方法：摄动蒙特卡罗（pMC）方法、伴随蒙特卡罗（aMC）方法和中间蒙特卡罗（mMC）方法。评估了影响计算时间和统计可靠性的不同参数的影响。此外，还将这些方法应用于一组实验数据进行层析成像应用。
在数值结果中建立了这些参数以不同的方式（线性、二次或不显著）影响三种方法的计算时间。此外，当这些参数发生变化时，雅可比矩阵的噪声水平也会发生变化。在临床前环境中的实验结果证明了在数小时内使用 aMC 和 pMC 方法对小动物进行时间分辨全身研究的可行性。
在这三种蒙特卡罗方法中，mMC 方法是一种计算上不可行的技术，不太适合用于时域荧光层析成像应用。当使用早期门时，pMC 方法比 aMC 方法更有利，并且存在大量探测器。相反，当使用少量源-探测器对时，aMC 方法是首选方法。
