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It turns out that the iterative approach is very attractive for image reconstruction in positron emission tomography (PET). Its reconstruction quality heavily depends on the accuracy of the measurement model, which consists of the projection matrix and the statistics of noise. Almost all of iterative approaches require that the projection matrix is exactly known a prior, which conflicts with the fact...
In designs of PET detectors, PMT-Quadrant-Sharing(PQS) technique has some remarkable advantages, such as lower production cost, higher efficiency in packing fraction, uniform signal pulse-heights at the edge of the block and the fewer number of PMTs. But it also brings a problem that the events at the edge of scintillators array would be recorded twice, both in this sector and in the neighboring sector...
Recent developments in the area of Positron Emission Tomography (PET) detectors using Silicon Photomultipliers (SiPMs) have demonstrated the feasibility of higher resolution PET scanners due to a significant reduction in the detector form factor. However, reduced size implies a corresponding increase in the detector density, resulting in a proportional rise in the number of channels interfacing a...
Positron Emission Tomography (PET) combined with Magnetic Resonance Imaging (MRI) as a hybrid imaging modality is about to become the next-generation imaging technique in the field of molecular imaging. The integration of PET detectors into an MR-gantry enabling simultaneous acquisitions with unaffected performance of PET and MRI is challenging, as PET detectors need to be unaffected by the MR operation,...
Based on the VIP-PIX architecture [1], the results of an integrated time to digital converter (TDC), a temperature sensor, and a 4 × 4 pixels readout integrated circuit (ROIC) for pixelated Cadmium Telluride (CdTe) gamma-ray detectors are presented. The developed circuits are the proof of concept of the 10×10 pixels array readout ASIC for positron-emission tomography (PET) scanners and Compton gamma...
A 144 channel measurement IC for CZT detectors, used for PET, is presented. Each channel consists of a charge sensitive amplifier, a fast and a slow signal shaper, a peak sampler for the energy acquisition and an event detector based on a time to digital converter to generate an accurate time stamp for each event. The channels are multiplexed to a fast pipeline ADC on demand. Measurement results for...
We present a PET image reconstruction approach that aims for accurate quantitation through model-based physical corrections and rigorous noise control with clinically acceptable image properties. We focus particularly on image generation chain components that are critical to quantitation such as physical system modeling, scatter correction, patient motion correction and regularized image reconstruction...
Patient movement during SPECT and PET data acquisition makes serious distortions in reconstructed images. In most conventional methods a correction of this movement is conducted in the sinogram space. However, the direction of movement occurs at an angle that is parallel to collimator holes, making it is difficult to detect the movement of an object. This paper proposes a new correction method of...
We describe a new exact analytical algorithm for estimating the single event rates in detectors from random coincidence data (for randoms variance reduction), and detector efficiencies from true coincidence data (for normalization), in positron emission tomography (PET). The estimates are derived from the ratios of the co-fan sums of coincidence events between individual detectors. The co-fan for...
Photo-sensor sharing (multiple blocks or crystals) can achieve high-resolution position-sensitive detectors but it also increases the dead time and pileups for scintillation event detection. Several methods such as pulse-clipping and HYPER (high-yield-pileup-event-recovery) have been introduced to minimize the dead time and pileups with a trade-off of less scintillation light collection. However,...
The scintillator is one of the key building blocks that critically determine the physical performance of PET detectors. The quest for scintillation crystals with improved characteristics has been crucial in designing scanners with superior imaging performance. Recently, it was shown that the decay time constant of high lutetium content Lu1.8Gd0.2SiO5:Ce (LGSO) scintillators can be adjusted between...
In many medical imaging applications (e.g., SPECT, PET), the data are a count of the number of photons incident on a detector array. When the number of photons is small, the measurement process is best modeled with a Poisson distribution. The problem addressed in this paper is the estimation of an underlying intensity from photon-limited projections where the intensity admits a sparse or low-complexity...
A 16 channel front-end IC dedicated to small animal positron emission tomography has been developed for cross-strip CdTe detectors. Each channel, designed to handle up to 20 pF detector capacitance, includes both low voltage (2 nV/Hz1/2) and low current (40 fA/Hz1/2) noise, high bandwidth (50 MHz at 20 pF detector capacitance) current amplifier with a gain of 100 for a power consumption of 4.7 mW...
Small animal PET imaging requires both high resolution and high sensitivity in order to detect small amounts of radiopharmaceutical with precision. Semiconductor detector such as cadmium telluride (CdTe) makes it possible to localize gamma ray interactions in 3D at submillimetric scale, enabling the design of PET system architectures with innovative geometries. Indeed, thank to a good knowledge of...
In time-of-flight (TOF) measurements, or positron emission tomography (PET) experiments where two gamma rays are emitted in coincidence, the time resolution of the photon detector is of primary importance. SIPMs are very promising devices for these applications, since their intrinsic response time is very short, typically less than 1ns. In practice, the actual timing resolution of SIPMs is affected...
The combination of SiPMs with fast and bright scintillators, such as LaBr3:Ce, seems very promising for application in time-of-flight (TOF) PET. We therefore conducted a series of experiments with the goal of obtaining the best possible timing resolution with SiPM-based scintillation detectors in order to establish a bench mark for future experiments with different detector designs. The detectors...
The performance characteristics of a monolithic crystal PET detector utilizing a novel sensor on the entrance surface (SES) design is reported. To facilitate this design, we propose to utilize a 2D silicon photomultiplier (SiPM) array device. SiPMs are a form of Geiger-Muller mode avalanche photodiodes (GMAPD) that can provide signal gain similar to a photomultiplier tube (PMT). Since these devices...
The relatively new inorganic scintillator LaBr3:Ce is well suited for time-of-flight positron emission tomography (TOF-PET), since it has short scintillation decay time, high light yield and very good energy resolution. Silicon photomultipliers (SiPMs) show low noise, high gain and small transit-time jitter, and are thus well suited for fast timing applications. The work presented here focuses on...
Higher count rate detectors are needed for high sensitivity positron emission tomography (PET) scanners. However, the maximum count rate of the detectors is limited due to the large pileup quantity in the high count rate situation, in which pileups are rejected conventionally. In this paper, we investigate the development of a method for digitally sampling scintillation pulses for PET. We focus on...
A detector pulse simulator was recently developed to simulate digital output signals from LabPET, an APD-based small animal Positron Emission Tomography (PET) scanner developed at Universite?? de Sherbrooke. The main goal of the simulator was to validate the digital crystal identification (CI) and timing algorithms implemented in the LabPET. The pulse simulator uses information generated by Monte...
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