arXiv subjects

Yuemeng Feng

Publications and source records attributed to Yuemeng Feng.

5 recordsLinked to original sources

arXiv2026

Novel Asymmetrical High-Resolution and High-Sensitivity Brain Dedicated PET system: Design optimization and performance evaluation

Objective. This study investigates the best achievable performance of a brain-dedicated PET system with high resolution and sensitivity by evaluating different detector configurations, while maintaining a practical system design suitable for dynamic brain Imaging. Approach. Monte Carlo simulations were performed to evaluate system sensitivity and image quality under various timing resolutions (200 ps, 100 ps and 50 ps). The PET scanner geometry was optimized for human head imaging, featuring an elliptical cylindrical configuration with a neck cut-out, and front/back panels to enhance sensitivity and line of response (LOR) sampling. Detector configurations using LYSO:Ce crystals of varying thicknesses (15 mm and 20 mm) and depth of interaction (DOI) levels were simulated. Sensitivity was calculated using a point-like 511 keV back-to-back gamma source simulated at multiple locations within the field of view (FOV). Image reconstruction was conducted using list mode Maximum Likelihood Expectation Maximization (MLEM), assessing both a Derenzo-type phantom and a voxelated digital brain phantom. Main results. A location-dependent sensitivity ranging from 35.04% to 13.59% was achieved using a 20 mm thick LYSO:Ce crystal. Spatial resolution ranged from 0.8 mm to 1.5 mm within the FOV without applying resolution recovery techniques, measured using the FWHM of reconstructed hot rods. Previous results using 15 mm crystals with three DOI levels showed sensitivity between 23.42% and 15.99%, confirming the performance benefits of increased detector thickness and DOI capability. Significance. This study demonstrates the potential of a practical, brain-optimized PET system to achieve superior resolution and sensitivity for brain imaging. The findings offer valuable insights into optimal detector configurations, supporting the development of next-generation high-performance brain PET technologies.

physics.med-ph↗

arXiv2024

Collimator-less SPECT System Design for Dynamic Whole-body Imaging

In this study, we introduce a Compton SPECT system for whole-body imaging of Actinium-225 (225Ac), one of the trending radionuclides for targeted alpha therapy (TAT). The Compton SPECT system enables multi-energy gamma photon detection with higher efficiency compared to mechanically collimated SPECT. The system consists of two detectors, providing a field of view (FOV) adequate for whole-body imaging, while achieving high sensitivity and clinically usable imaging resolution within a reasonable scanning time. This work focuses on the system design and evaluation using the Monte Carlo simulation toolkit Gate. The imaging performance is evaluated at two energy peaks (218 keV, 440 keV), representing the major detectable gamma energies generated from 225Ac. We explore the possibility of using the Compton SPECT system for treatment response monitoring in TAT. Results demonstrate an image resolution of 1.0 cm using a NEMA IQ phantom with 5.7 MBq of 225Ac simulated in a cold background. An image resolution of 1.3 cm can be achieved with a hot to background ratio of 30:1, and a resolution of 3.7 cm can be achieved with an activity ratio of 12:1. The best achievable sensitivity at 10 cm distance to the detector is 0.5% with the two energy windows (211-225 keV, 430-450 keV) selected. The proposed system may serve as an alternative imaging tool for TAT scanning in clinical settings.

physics.med-ph↗

arXiv2024

Limited-angle TOF-PET for intraoperative surgical applications: Simulation Study

In this work, we present modeling and imaging performance of a dual panel limited-angle TOF-PET system for intraoperative surgical applications using GATE monte carlo toolkit. Several detector parameters such as detector pixel dimensions, timing resolution and depth of interaction resolution along with tumor uptake ratio and phantom dimension are varied. Ultimately TOF-PET detector properties to achieve a specific imaging task are presented. To assess image resolution, we employed Simple Back Projection (SBP) reconstruction due to its fast speed compared to list-mode Maximum Likelihood Expectation Maximization (MLEM). We evaluated the quality of the reconstructed images using metrics contrast-to-noise ratio (CNR), contrast recovery coefficient (CRC), and signal-to-noise ratio (SNR). The purpose is to show effects of different detector parameters on the resolution of reconstructed images.

physics.med-ph↗

arXiv2023

Application of Spherical Convolutional Neural Networks to Image Reconstruction and Denoising in Nuclear Medicine

This work investigates use of equivariant neural networks as efficient and high-performance frameworks for image reconstruction and denoising in nuclear medicine. Our work aims to tackle limitations of conventional Convolutional Neural Networks (CNNs), which require significant training. We investigated equivariant networks, aiming to reduce CNN's dependency on specific training sets. Specifically, we implemented and evaluated equivariant spherical CNNs (SCNNs) for 2- and 3-dimensional medical imaging problems. Our results demonstrate superior quality and computational efficiency of SCNNs in both image reconstruction and denoising benchmark problems. Furthermore, we propose a novel approach to employ SCNNs as a complement to conventional image reconstruction tools, enhancing the outcomes while reducing reliance on the training set. Across all cases, we observed significant decrease in computational cost by leveraging the inherent inclusion of equivariant representatives while achieving the same or higher quality of image processing using SCNNs compared to CNNs. Additionally, we explore the potential of SCNNs for broader tomography applications, particularly those requiring rotationally variant representation.

eess.IV↗

arXiv2022

Resolution recovery on list mode MLEM reconstruction for Dynamic Cardiac SPECT system

The Dynamic Cardiac SPECT (DC-SPECT) system is being developed at the Massachusetts General Hospital, featuring a static cardio focus asymmetrical geometry enabling simultaneous high resolution and high sensitivity imaging. Among 14 design iterations of the DC-SPECT with varying number of detector heads, system sensitivity and system resolution, the current version being fabricated features 10 mm FWHM geometrical resolution (without resolution recovery) and 0.07% sensitivity; this is 1.5x resolution gain and 7x sensitivity gain compared to a conventional dual head gamma camera. This work presents improvement in imaging resolution by implementing a spatially variant point spread function (SV-PSF) with list mode MLEM reconstruction. A resolution recovery method by PSF deconvolution is validated on list mode MLEM reconstruction for DC-SPECT. A spatial invariant PSF is included as an additional test to show the influence of the accuracy of PSF modelling on the reconstructed image quality. We compare the MLEM reconstruction with and without PSF deconvolution; an analytic model is used for the calculation of system response, and the results are compared to Monte Carlo (MC) based methods. Results show that with PSF modelling applied, the quality of the reconstructed image is improved, and the DC-SPECT system can achieve a 4.5 mm central spatial resolution with average 795 counts/(s*Mbq). The results show substantial improvement over the gold standard GE Discovery 570c performance (spatial resolution 7 mm with an average 460 counts/s*MBq, central resolution 5.8 mm). The impact of PSF deconvolution is significant, and the improvements of the reconstructed image quality is more evident compared to MC simulated system matrix with the same sampling size as in simulation.

physics.med-ph↗