Accelerating photon transport in Monte Carlo simulation using octree structure

使用八叉树结构加速蒙特卡罗模拟中的光子传输

基本信息

批准号：
07457204
负责人：
OGAWA Koichi
金额：
$ 3.07万
依托单位：
Hosei University, College of Engineering
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07457204/
关键词：
Monte Carlo simulation Photon transport Object modeling Octree coding Single photon emission CT Acceleration Radiology Image Processing オクトツリーモンテカルロ計算放射線治療 SPECT PET 核医学

项目摘要

The study was carried out to develop a high-speed calculation method in photon/electron transportation using a Monte Carlo simulation. Object description is important in performing the photon transport efficiently. In order to describe an object, three methods have been proposed : a shape-based (SV) approach, a voxel-based (VB) approach, and a solid geometry based approach. However, these three methods have some shortcoming (e.g., accuracy of boundaries, calculation time, amount of memory, manual instructions). To the problems we introduced an octree representation of an object to the photon transport using a Monte Carlo method. The representation of the object yields accurate boundaries of each medium and fast calculation of the photon transport with the same accuracy as the VB method using the finest voxels. Moreover, the octree structure for any object can be formed systematically.Our Monte Carlo code, first, establishes the simulation geometry by reading "octree string, " which is produced by forming an octree structure from a set of serial sections for the object before the simulation automatically, and then it transports photons in the geotry. Using the code, if the user just prepares a set of serial sections for the object in which he wants to simulate photon trajectories, he can perform the simulation automatically using the suboptimal geometry simplified by the octree representation without forming the optimal geometry by handwriting. The accuracy and ability of our code were confirmed by comparison with Electron Gamma Shower code system (EGS4) and simulations using a head phantom, respectively. Moreover, we examined our code using Zubal's digital phantoms (head and thorax) by comparing the results of the VB approach. In summary, the proposed method is efficient in the Monte Carlo simulation of any object.

进行了研究以使用蒙特卡洛模拟在光子/电子传输中开发高速计算方法。对象描述对于有效地执行光子传输很重要。为了描述一个对象，已经提出了三种方法：一种基于形状的方法（SV）方法，一种基于体素的（VB）方法和基于固体几何的方法。但是，这三种方法具有一些缺点（例如，边界的准确性，计算时间，内存量，手动指令）。对于问题，我们使用Monte Carlo方法引入了对象的OCTREE表示光子传输。物体的表示会产生每种培养基的准确边界，并使用最优质的体素以与VB方法相同的精度进行光子传输的快速计算。此外，可以系统地形成任何对象的OCTREE结构。我们的Monte Carlo Code首先，通过读取“ OctRee String”来确定模拟几何形状，该几何是通过从模拟前的对象组成串行段来形成OCTREE结构，然后自动传输geotry中的光子。使用代码，如果用户只是为他想要模拟光子轨迹的对象准备了一组串行部分，则可以使用OCTREE表示简化的次优几何形状自动执行模拟，而无需通过手写形成最佳的几何形状。通过与电子伽马淋浴代码系统（EGS4）和使用头幻影进行比较，确认了我们代码的准确性和能力。此外，我们使用Zubal的数字幻像（头部和胸部）进行了比较VB方法的结果来检查代码。总而言之，所提出的方法在任何对象的蒙特卡洛模拟中都是有效的。