基于单片LYSO探测器的长轴视野PET系统性能的蒙特卡罗模拟。

Monte Carlo simulation of the system performance of a long axial field-of-view PET based on monolithic LYSO detectors.

作者信息

Abi-Akl Maya, Dadgar Meysam, Toufique Yassine, Bouhali Othmane, Vandenberghe Stefaan

机构信息

Department of Electronics and Information Systems, Medical Image and Signal Processing, Ghent University, Ghent, Belgium.

Division of Arts and Sciences, Texas A&M University at Qatar, Doha, Qatar.

出版信息

EJNMMI Phys. 2023 Jun 13;10(1):37. doi: 10.1186/s40658-023-00559-2.

DOI:10.1186/s40658-023-00559-2

PMID:37311926

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC10264335/

Abstract

BACKGROUND

In light of the milestones achieved in PET design so far, further sensitivity improvements aim to optimise factors such as the dose, throughput, and detection of small lesions. While several longer axial field-of-view (aFOV) PET systems based on pixelated detectors have been installed, continuous monolithic scintillation detectors recently gained increased attention due to their depth of interaction capability and superior intrinsic resolution. As a result, the aim of this work is to present and evaluate the performance of two long aFOV, monolithic LYSO-based PET scanner designs.

METHODS

Geant4 Application for Tomographic Emission (GATE) v9.1 was used to perform the simulations. Scanner designs A and B have an aFOV of 36.2 cm (7 rings) and 72.6 cm (14 rings), respectively, with 40 detector modules per ring each and a bore diameter of 70 cm. Each module is a 50 × 50 × 16 mm monolithic LYSO crystal. Sensitivity, noise equivalent count rate (NECR), scatter fraction, spatial resolution, and image quality tests were performed based on NEMA NU-2018 standards.

RESULTS

The sensitivity of design A was calculated to be 29.2 kcps/MBq at the centre and 27 kcps/MBq at 10 cm radial offset; similarly, the sensitivity of design B was found to be 106.8 kcps/MBq and 98.3 kcps/MBq at 10 cm radial offset. NECR peaks were reached at activity concentrations beyond the range of activities used for clinical studies. In terms of spatial resolution, the values for the point sources were below 2 mm for the radial, tangential, and axial full width half maximum. The contrast recovery coefficient ranged from 53% for design B and 4:1 contrast ratio to 90% for design A and 8:1 ratio, with a reasonably low background variability.

CONCLUSIONS

Longer aFOV PET designs using monolithic LYSO have superior spatial resolution compared to current pixelated total-body PET (TB-PET) scanners. These systems combine high sensitivity with improved contrast recovery.

摘要

背景

鉴于目前PET设计已取得的进展，进一步提高灵敏度旨在优化诸如剂量、通量和小病灶检测等因素。虽然基于像素化探测器的几种长轴向视野（aFOV）PET系统已安装使用，但连续单片闪烁探测器最近因其相互作用深度能力和卓越的固有分辨率而受到更多关注。因此，本研究的目的是展示和评估两种基于单片LYSO的长aFOV PET扫描仪设计的性能。

方法

使用Geant4断层发射应用程序（GATE）v9.1进行模拟。扫描仪设计A和B的aFOV分别为36.2 cm（7环）和72.6 cm（14环），每环有40个探测器模块，孔径为70 cm。每个模块是一个50×50×16 mm的单片LYSO晶体。基于NEMA NU - 2018标准进行灵敏度、噪声等效计数率（NECR）、散射分数、空间分辨率和图像质量测试。

结果

设计A在中心处的灵敏度计算为29.2 kcps/MBq，在径向偏移10 cm处为27 kcps/MBq；同样，设计B在径向偏移10 cm处的灵敏度分别为106.8 kcps/MBq和98.3 kcps/MBq。NECR峰值在超出临床研究使用的活度范围的活度浓度下达到。在空间分辨率方面，点源在径向、切向和轴向半高宽的值均低于2 mm。对比恢复系数范围从设计B在4:1对比度时的53%到设计A在8:1对比度时的90%，背景变化相当低。