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In vivo imaging techniques applied to small animals are important tools in basic research. Scintigraphic planar and tomographic images allow in vivo functional expression of the protocol's effect on the animal's organs to be assessed. In that way, long term dynamical studies can be developed on the same animal, which can be used as its own control, helping to reduce statistical uncertainties, to cut...
Molecular breast imaging tomosynthesis (MBIT) provides 3D functional images of the breast. However, due to the asymmetrical and undersampled nature of the image acquisition process, artifacts may arise in the plane of the slices as well as in the orthogonal direction. In this paper, we explore image reconstruction parameters for MBIT using parallel-hole collimation and maximum likelihood expectation...
Pulse pile-up at high count rates is one factor that degrades spatial resolution of PET images. Most PET scanners with block detector designs suffer misidentification of event position, moving events from the edge to block center at high count rates. For the HRRT with LSO-LYSO phoswich detectors, there is an extra dimension of pile-up, i.e., inter-layer pile-up, which tends to push events to the LYSO...
A multiple-wavelength near-infrared (NIR) imaging device has been constructed. The scanner utilizes transmitted through the objects NIR light at five different wavelengths in the interval of 900nm-1600nm. The scanning is realized by a consecutive positioning of Hamamatsu G9203-256D InGaAs linear image sensor sliding close to the scanned object and results in a set of five object's images. The scanned...
Simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) can provide both functional and structural information about disease. However, for quantitative PET measurements all sources of scatter and absorption that photons undergo on their trajectory between source and detector must be assessed. In simultaneous PET/MR, this includes the scatter and absorption undergone in...
As the dimensions of crystal elements in modern PET systems is getting smaller, the fraction of events undergoing inter-crystal scattering (ICS) and penetration increases. This has deteriorative impact on the spatial resolution of images. However, with the utilization of statistical image reconstruction methods in PET, compensation for ICS and penetration impacts is feasible by accurately modeling...
Incorporation of the resolution modelling component of the scanner during statistical image reconstruction often produces images of improved signal-to-noise ratio (SNR). In our previous work we measured and parameterized the Hi-Rez PET/CT scanner's point spread function (PSF) in image space using printed point source arrays at multiple positions. Here we extend the work to the TruePoint PET/CT and...
We have previously reported that a brain PET using GAPD arrays was successfully developed. The brain PET consisted of 72 4 × 4 GAPD arrays combined with LYSO crystals (single pixel size: 3 mm × 3 mm). Each 4 GAPD arrays' output signals were sent to a 64:1 position decoder circuit (PDC) which detects the fastest gamma signal of 64 input channels. To further improve the PET system performance, several...
We are developing a high resolution and quantitative SPECT for the human brain. The SPECT has two types of detector, a large FOV detector with a parallel collimator and a small FOV detector with a pinhole collimator. A quantitative and high resolution image is reconstructed by the small FOV detector using a supporting image obtained by the large FOV detector. The large FOV detector consists of a Nal(Tl)...
Positron range depends on the materials in which positron propagates and on positron emitter isotope. As positron range limits the spatial resolution of PET images, good quantitative estimates of it should be included in any realistic simulation of PET acquisitions. In this work we compare positron range estimates obtained with PeneloPET to previous available simulations and experimental data. PeneloPET...
We have developed a CsI(Tl)/PIN detector module for high resolution SPECT and low dose photon-counting CT imaging. Using the detector modules with 6.1mm pixels, we built a cardiac SPECT system with three detector heads. The detector heads form a triple-head (each 20×15cm), geometry for emission scans and reconfigure to form a large transaxial field-of-view (FOV) geometry for transmission scans using...
High spatial resolution of multi-pinhole SPECT is often hampered by physical effects including collimator response, and pinhole edge penetration. The collimator response is related to the blurring effect varying with distance from source to the aperture, and caused by the non-ideal aperture diameter. Pinhole edge penetration is referred to penetration of gamma rays through the thin edge of the collimator,...
Several improvements of the k-nearest neighbor (k-NN) method for the determination of the entry point (x, y) of a gamma photon in a monolithic scintillator PET detector have been investigated with the aim to obtain better spatial resolution and/or to enable faster detector calibration by reducing the amount of required reference data and by allowing for calibrating with a line source. These methods...
SPECT scanners using multi-pinhole collimators benefit from modular detectors having a high spatial resolution. Such detectors can be placed closer to the collimator and perpendicular to the pinhole axis (thereby limiting DOI spatial resolution degradation). Current clinical gamma ray cameras have a large area and a poor spatial resolution. This proceeding describes the architecture of SPECTatress,...
High temporal resolution and high spatial resolution are required to image the coronary arteries without motion artifacts. Several approaches have been pursued to achieve better temporal resolution including faster rotational speeds, and dual tube systems. In this paper, we present an alternative approach using motion estimation and compensation. The results demonstrate that the proposed methods can...
Continuous miniature crystal element (cMiCE) detectors are a potentially lower cost alternative to high resolution discrete crystal PET detector designs. We report on performance characteristics of a prototype PET scanner consisting of two cMiCE detector modules. Each cMiCE detector is comprised of a 50 mm by 50 mm by 8 mm LYSO crystal coupled to a 64 channel multi-anode PMT. The cMiCE detectors use...
In classical x-ray CT the diameter of the field of measurement (FOM) must not fall below the transversal diameter of the patient or specimen. Thereby, the ratio of the the diameter of the FOM and the number of transversal detector elements typically defines the spatial resolution. We aim to improve the spatial resolution within a region of interest (ROI) by a factor of 10 to 100 while maintaining...
With the advance in PET technology and especially scintillating detectors, spatial resolution in the order of 2 mm FWHM are becoming a reality, allowing a more in-depth exploration of complex organs such as the human brain. Subject movement during imaging has always been a factor contributing to image degradation, but is becoming a major limitation in the achievement of the full spatial resolution...
In recent decades, magnetic resonance spectroscopic imaging (MRSI) has become an influential technique to provide information about metabolite distributions. However, long acquisition time is required in standard MRSI to achieve satisfactory resolution in both spatial and spectral dimensions. This limitation is a key challenge for MRSI applications. To overcome this problem, we propose to implement...
The goal of the HICAM project, supported by the European Community, is the development of a new Anger camera for clinical and research environments and specific applications where high overall spatial resolution and system compactness are required. The camera is based on a matrix of Silicon Drift Detectors (SDDs) coupled to a CsI(Tl) crystal. Two prototypes were developed during the project, with...
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