Du Huini, Yang Yongfeng, Cherry Simon R
Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, CA 95616, USA.
Phys Med Biol. 2007 May 7;52(9):2499-514. doi: 10.1088/0031-9155/52/9/011. Epub 2007 Apr 10.
We are attempting to develop a laboratory PET scanner for mouse imaging that utilizes far fewer detectors and channels of electronics, thus reducing cost, whilst retaining state-of-the-art performance. The detectors are based on LSO arrays read out by wavelength shifting (WLS) fibres placed on the top and the bottom of the arrays. Depth of interaction information will be obtained from the ratio of the signals at either end of the array. For acceptable performance, it is critical to maximize collection of light photons from the ends of the fibres and to minimize the optical crosstalk between adjacent fibres. Factors which can affect the light collection and crosstalk were studied, including coupling materials between fibres and crystals, reflectors wrapped around the fibre sides and ends, fibre size and shape, and number of layers of fibre cladding. Properties of WLS fibres such as the transmission attenuation and transverse absorption were also studied. The light yield from 2 x 2 x 10 mm(3) LSO crystals collected from the end of a 2 x 2 x 30 mm(3) WLS fibre was up to 24% (typical values 16-20%) of that obtained by direct coupling of the LSO crystal. This light collection efficiency appears to be sufficient for decoding interaction position in these detectors.
我们正在尝试开发一种用于小鼠成像的实验室正电子发射断层扫描（PET）扫描仪，该扫描仪使用的探测器和电子通道要少得多，从而降低成本，同时保持最先进的性能。探测器基于硅酸镥（LSO）阵列，由放置在阵列顶部和底部的波长转换（WLS）光纤读出。相互作用深度信息将从阵列两端信号的比率中获得。为了获得可接受的性能，关键是要最大限度地收集来自光纤末端的光子，并尽量减少相邻光纤之间的光学串扰。研究了可能影响光收集和串扰的因素，包括光纤与晶体之间的耦合材料、包裹在光纤侧面和末端的反射器、光纤的尺寸和形状以及光纤包层的层数。还研究了WLS光纤的特性，如传输衰减和横向吸收。从2×2×30 mm³ WLS光纤末端收集的2×2×10 mm³ LSO晶体的光产额高达通过LSO晶体直接耦合获得的光产额的24%（典型值为16 - 20%）。这种光收集效率似乎足以解码这些探测器中的相互作用位置。
