A maximum likelihood proton path formalism for application in proton computed tomography
A maximum likelihood proton path formalism for application in proton computed tomography
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DOI：
10.1118/1.2986139
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发表时间：
2008-11-01
期刊：
影响因子：
3.8
通讯作者：
Schubert, K. E.
中科院分区：
文献类型：
--
作者：
Schulte, R. W.;Penfold, S. N.;Schubert, K. E.
与X射线CT相比，质子计算机断层扫描（pCT）中有限的空间分辨率与成像对象内的多次库仑散射（MCS）有关。当前一代pCT设计利用硅探测器来测量单个质子在穿过患者之前和之后的位置和方向，以最大限度地了解成像对象内质子的路径。为了利用所提出的pCT系统进行有效重建，需要开发紧凑且灵活的数学形式，其对质子穿过成像对象时MCS的影响进行建模。在这篇文章中，一个紧凑的，基于矩阵的最可能路径（MLP）的形式主义采用贝叶斯统计和高斯近似MCS。使用GEANT 4模拟在一个均匀的20厘米水立方，MLP表达式被发现能够预测的Monte Carlo轨道的200 MeV的质子平均在0.6毫米内时，采用3西格玛削减的相对出口角和出口能量。发现这些切割消除了大多数不符合MLP推导中使用的MCS高斯模型的事件。(C)2008年美国医学物理学家协会。[DOI 10.1118/1.2986139]
The limited spatial resolution in proton computed tomography (pCT) in comparison to x-ray CT is related to multiple Coulomb scattering (MCS) within the imaged object. The current generation pCT design utilizes silicon detectors that measure the position and direction of individual protons prior to and post-traversing the patient to maximize the knowledge of the path of the proton within the imaged object. For efficient reconstruction with the proposed pCT system, one needs to develop compact and flexible mathematical formalisms that model the effects of MCS as the proton traverses the imaged object. In this article, a compact, matrix-based most likely path (MLP) formalism is presented employing Bayesian statistics and a Gaussian approximation of MCS. Using GEANT4 simulations in a homogeneous 20 cm water cube, the MLP expression was found to be able to predict the Monte Carlo tracks of 200 MeV protons to within 0.6 mm on average when employing 3 sigma cuts on the relative exit angle and exit energy. These cuts were found to eliminate the majority of events not conforming to the Gaussian model of MCS used in the MLP derivation. (C) 2008 American Association of Physicists in Medicine. [DOI: 10.1118/1.2986139]