Nonlinear least-squares modeling of 3D interaction position in a monolithic scintillator block
Nonlinear least-squares modeling of 3D interaction position in a monolithic scintillator block
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DOI：
10.1088/0031-9155/55/21/012
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发表时间：
2010-11-07
影响因子：
3.5
通讯作者：
Vandersteen, G.
中科院分区：
文献类型：
--
作者：
Li, Zhi;Wedrowski, M.;Vandersteen, G.
本文提出了一种可能的模型来描述单片闪烁晶体中闪烁光的起始点和被测量的光电探测器像素信号之间的关系。根据这些模型，可以通过非线性最小二乘拟合同时估计X、Y和相互作用深度(DOI)坐标。该方法只依赖于单个事件信号中嵌入的信息，因此不需要任何事先的位置训练或校准。评估了三种可能的光源分布：精确的基于立体角的分布、近似的立体角分布和包括侧面和底面的内反射的扩展的近似立体角分布。利用2个滨松S8550雪崩光电二极管阵列读出的20×20×10 mm硅酸锂(Lu2SiO5或LSO)块的蒙特卡罗模拟数据，研究了使用这三种分布的一般模型的性能。近似的基于立体角度的模型在分辨率和简单性之间具有最好的折衷。通过在20x20x10 mm LSO块上的已知位置放置一束窄的1.2 mm全宽半高宽(FWHM)的511keV光子，对该模型进行了评估。对于覆盖整个区块的位置，X方向的平均固有分辨率为1.4 mm半高宽。本征DOI分辨率估计为2.6 mm半高宽。
This paper presents a study of possible models to describe the relation between the scintillation light point-of-origin and the measured photo detector pixel signals in monolithic scintillation crystals. From these models the X, Y and depth of interaction (DOI) coordinates can be estimated simultaneously by nonlinear least-square fitting. The method depends only on the information embedded in the signals of individual events, and therefore does not need any prior position training or calibration. Three possible distributions of the light sources were evaluated: an exact solid-angle-based distribution, an approximate solid-angle distribution and an extended approximate solid-angle- based distribution which includes internal reflection at side and bottom surfaces. The performance of the general model using these three distributions was studied using Monte Carlo simulated data of a 20 x 20 x 10 mm lutetium oxyorthosilicate (Lu2SiO5 or LSO) block read out by 2 Hamamatsu S8550 avalanche photo diode arrays. The approximate solid-angle-based model had the best compromise between resolution and simplicity. This model was also evaluated using experimental data by positioning a narrow 1.2 mm full width at half maximum (FWHM) beam of 511 keV photons at known positions on the 20 x 20 x 10 mm LSO block. An average intrinsic resolution in the X-direction of 1.4 mm FWHM was obtained for positions covering the complete block. The intrinsic DOI resolution was estimated at 2.6 mm FWHM.