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In compact systems, precise measurement in the projection space may be compromised due to minification. The objective of this work is to investigate the impact of the magnification factor in a model-based calibration procedure. This has direct relevance to the geometrical calibration of the clinical INSERT camera. Projection data from three point sources were simulated for a single pinhole collimator...
In the context of the development of a simultaneous SPECT/MRI system, we have previously proposed a multi-mini-slit-slat (MSS) collimator, with multiple sections of short slits in order to improve the angular sampling. The data can be reconstructed using a 3D reconstruction algorithm that models the collimator geometry. One drawback, however, is that the projection data obtained with this collimator...
The objective of this work is to evaluate the shielding requirements of a SPECT insert for installation in the Siemens Biograph mMR in order to perform simultaneous SPECT/MR imaging of the human brain. We intend to use the radionuclides 99mTc, 123I and 111In. The main photopeaks of these radionuclides have the following energies: 140.5, 159.0, 171.3 and 245.4 keV. There is also about ∼3% of emission...
This project’s goal is to design a SPECT insert for a clinical MRI system for simultaneous brain SPECT/MR imaging, with a high-sensitivity collimator and high-resolution detectors. We have compared eight collimator designs, four multi-pinhole and four multi-slit slit-slat configurations. The collimation was designed for a system with 2 rings of 25 detectors. We introduce the concept...
The aim of this work is to develop an optimal collimator design for a stationary, compact SPECT insert for an MRI system, intended to perform simultaneous brain SPECT/MRI in humans. The SPECT insert will consist of a single ring of 25 SiPM-based detectors, insensitive to magnetic fields (5 by 10cm, 0.8mm intrinsic resolution). Compactness is needed due to limited space inside the MRI bore. Here we...
In this paper we propose a Gaussian decomposition approach to compute the SPECT imaging system matrix. The flexibility of our method allows the implementation of a wide range of imaging systems. With the system matrix, we predict the variance in reconstructed images using the Fisher information matrix and local block circulant approximation. We present results of noise prediction for 3 multi-pinhole...
Multi-modality scanners have become increasingly popular in recent years. While PET/CT, SPECT/CT and PET/MRI systems are now commercially available, SPECT/MRI systems are still in a development phase. The aim of this work was to design a SPECT insert for a conventional MRI scanner in order to perform simultaneous SPECT/MRI studies. The SPECT system will consist of a stationary ring of detectors equipped...
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