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We are developing a time-of-flight (TOF) positron emission tomography (PET) scanner for brain imaging using SiPMs. In our development, we have adopted a strip-line based signal multiplexing method for efficient channel reduction for SiPMs; the method is using a single strip-line on which multiple SiPMs are connected for sharing readout, and the position of hit SiPM is decoded from the arrival time...
Spatial resolution is one of the most important performance in PET system. Higher spatial resolution can give more information about the region of interest in animal PET imaging. In this work, we implement a high resolution (approximate 0.7 mm) all digital animal PET system using improved Trans-PET detectors. The improved detector module uses 24×24 crystal array for higher intrinsic spatial resolution...
Measuring system response matrix (SRM) by Monte Carlo method is time and resource consuming, even with high performance computer nodes. In this paper, we exploited symmetry properties available to drastically reduce the complexity in computing SRM of panel PET, which has two parallel panel detectors. By extending the original system and simulating 4 voxels every slice parallel to the PET detector,...
With high specificity of tumor necrosis, hypoxia tissues and subclinical lesions, PET may have great potential for tumor surgery guidance. PET images in surgery will tell us how tissues change during the operation and whether the lesion has been cleared. We did research on panel PET guided therapy, and we have developed 3-dimensional reconstruction methods for panel PET systems. However we meet the...
In recent years, panel PET is an interesting field in medical imaging. But the major obstacle of panel PET is the limited view problem. Images reconstructed by traditional algorithms will suffer serious artifacts. Time-of-flight (TOF) information can be incorporated into the image reconstruction to remove the artifacts. However, the best system timing resolution available in current commercial PET...
Recently, there is growing interest in directly digitizing the scintillation pulses in PET detectors. With digital pulse samples, in principle one can apply nontrivial signal analysis software algorithms to either yield better detection performance or more flexibility in detector design. Previously, we have proposed the MVT method for direct scintillation pulse sampling and developed several kinds...
A combined Cerenkov Luminescence Imaging (CLI) and Positron Emission Tomography (PET) scanner for in-vivo imaging of small animals is conceptually designed via all event-by-event readout and multiple-coincidence processing. Strategies and concepts for the design of the combined CLI/PET scanner based on the list-mode scheme are analyzed and modeled in terms of Monte Carlo approach. This allows for...
WE have previously demonstrated a stripline readout for TOFPET detectors that can achieve significant reduction in the number of readout channels while maintaining good detection performance [1-3]. The principle of this time-based multiplexing readout is depicted in Figs. 1(a) and 1(b). As shown, a stripline receives the outputs of several photodetectors (PD). When a PD produces a signal at time t...
High-accuracy time synchronization is one of the most important issues for basic detector modules (BDMs) in the all-digital PET. The existing synchronization solutions are hard to extend as strict requirement to the wires and interfaces. Once the number of BDM changed, the whole system's synchronization should be rebuilt from the beginning. In this paper, a new high-accuracy time-sync solution based...
Based on the multi-voltage threshold (MVT) method, we have proposed the FPGA-only implementation for positron emission tomography (PET) detectors. It realizes required comparators and time-to-digital convertors (TDCs) on FPGAs. Thus, its performance can be easily enhanced by optimizing the inside algorithm without hardware modifications or improved with the development of FPGA technologies. In this...
Digitizing scintillation pulses with the Multi-voltage threshold (MVT) method shows great potentials for building all-digital positron emission tomography (PET). In this paper, we introduce the MVT method into gamma-ray spectroscopy. An accurate scintillation pulse model used in pulse fitting is especially important to get precise energy when implementing the MVT in gamma-ray spectroscopy, since a...
Nowadays, time-of-flight (TOF) PET detectors and systems are becoming increasingly common since scintillators, photodetectors and electronics has made significant progress. It has been well recognized that TOF PET imaging can increase the image signal-to-noise ratio (SNR) and yield other benefits; and the degree of these enhancements is higher as the timing resolution improves. Previously we have...
As digital signal has abilities like immunity for transmit distortion and feasibility to calibrate, digital architecture that samples the event waveform at the earliest possible stage shows promising potential for building next generation PET system. Multi-voltage threshold (MVT) is a digital sampling method that take time samples when pulses cross predefined thresholds and extracts event information...
We proposed a novel Event Pulses Classification (EPC) method to reject scatter directly from Multi-Voltage Threshold (MVT) samples data. This study is motivated by the emerging demand for the MVT-digitalized scintillation pulses processing in the PET implementation. MVT is a sparse-quantization-level flash ADC which can digitize fast signals (such as scintillation pulses without shaper) with excellent...
The all digital PET system is attracting more and more attentions due to its flexibility, scalability, reusability and upgradability. Based on the Trans-PET formerly developed by us, we are trying to fulfill online parameter calibration of the all digital PET system. The ability of thorough and quick online parameter calibration will make the system well adaptive to application variation, environment...
We have explored, and continue exploring the potentials of the multi-voltage threshold (MVT) method that we previously proposed. By using of this method, we digitize PET event pulses by taking timing samples with respect to a number of predefined thresholds. Previous studies indicate that the MVT method is capable of obtaining sufficient accurate timing information for developing time-of-flight (TOF)...
Multi-voltage threshold (MVT) digitization is a cost-effective low-power sampling solution for fast scintillation pulse signal sampling, which has been proven to be practical in our preclinical scanner — Trans-PET BioCaliBurn. However, MVT digitization does not provide the amplitude information directly, while regular-time sampling (RTS) provides energy information as an integral form. This work focuses...
Multi-voltage threshold (MVT) is an amplitude-based sampling method. It takes timing samples when the event pulse crosses the user-defined thresholds. Only a few comparators and TDCs are required when implementing such digitizer. Previously, we have demonstrated an FPGA-only MVT digitizer based on this method. The FPGA-only MVT digitizer employs the differential I/Os in an FPGA as the required comparators...
Multi-voltage threshold (MVT) digitization is a low-power sampling solution with reasonable cost for fast scintillation pulse, which has been implemented in our preclinical scanner - Trans-PET® BioCaliBurn™. This digitizing scheme employs a few comparators with programmable reference voltage for determining the time points when the scintillation pulse crosses some of the user-defined voltage thresholds...
A Positron Emission Tomography (PET) system with local extremely high spatial resolution could be built with affordable costs by using extremely high spatial resolution detectors. The continuous scintillator/Silcon photomultiplier (CS/SiPM) detector shows the potential of providing the extreme spatial resolution without deteriorating the detect efficient (DE). However, the spatial resolution performance...
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