High-Resolution L(Y)SO Detectors Using PMT-Quadrant-Sharing for Human and Animal PET Cameras

Ramirez, Rocio; Kim, Soonseok; Zhang, Yuxuan; Liu, Shitao; Baghaei, H.; Li, Hongdi; Wang, Yu; Liu, Jiguo; Wong, Wai-Hoi

doi:10.1109/tns.2008.922832

Cited by 37 publications

(14 citation statements)

References 26 publications

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“…The PET component of the MuPET/CT system uses small ceriumdoped lutetium yttrium oxyorthosilicate (LYSO) crystals (Crystal Photonics, Inc.) and is based on the low-cost photomultiplierquadrant-sharing (PQS) method that we have developed and refined over several years (4)(5)(6)(7)(8). MuPET comprises 180 blocks of 13 · 13 LYSO crystals and 210 photomultipliers.…”

Section: Pet Camera Descriptionmentioning

confidence: 99%

Engineering and Performance (NEMA and Animal) of a Lower-Cost Higher-Resolution Animal PET/CT Scanner Using Photomultiplier-Quadrant-Sharing Detectors

Wong

Baghaei

et al. 2012

J Nucl Med

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The dedicated murine PET (MuPET) scanner is a high-resolution, high-sensitivity, and low-cost preclinical PET camera designed and manufactured at our laboratory. In this article, we report its performance according to the NU 4-2008 standards of the National Electrical Manufacturers Association (NEMA). We also report the results of additional phantom and mouse studies. Methods: The MuPET scanner, which is integrated with a CT camera, is based on the photomultiplier-quadrant-sharing concept and comprises 180 blocks of 13 · 13 lutetium yttrium oxyorthosilicate crystals (1.24 · 1.4 · 9.5 mm 3 ) and 210 low-cost 19-mm photomultipliers. The camera has 78 detector rings, with an 11.6-cm axial field of view and a ring diameter of 16.6 cm. We measured the energy resolution, scatter fraction, sensitivity, spatial resolution, and counting rate performance of the scanner. In addition, we scanned the NEMA image-quality phantom, Micro Deluxe and Ultra-Micro Hot Spot phantoms, and 2 healthy mice. Results: The system average energy resolution was 14% at 511 keV. The average spatial resolution at the center of the field of view was about 1.2 mm, improving to 0.8 mm and remaining below 1.2 mm in the central 6-cm field of view when a resolution-recovery method was used. The absolute sensitivity of the camera was 6.38% for an energy window of 350-650 keV and a coincidence timing window of 3.4 ns. The system scatter fraction was 11.9% for the NEMA mouselike phantom and 28% for the ratlike phantom. The maximum noise-equivalent counting rate was 1,100 at 57 MBq for the mouselike phantom and 352 kcps at 65 MBq for the ratlike phantom. The 1-mm fillable rod was clearly observable using the NEMA image-quality phantom. The images of the Ultra-Micro Hot Spot phantom also showed the 1-mm hot rods. In the mouse studies, both the left and right ventricle walls were clearly observable, as were the Harderian glands. Conclusion: The MuPET camera has excellent resolution, sensitivity, counting rate, and imaging performance. The data show it is a powerful scanner for preclinical animal study and pharmaceutical development. Smal l-animal PET has been widely used in a broad range of applications in the field of biology and pharmaceutical development (1). Because of the small physical dimensions of rodents, achieving spatial resolution and detection sensitivity adequate to study small structures and the low concentration of receptors is challenging. In addition, to make the in vivo molecular imaging capability of PET accessible to more biology and genetics laboratories, thus facilitating the integration of biologic research and clinical medicine, lower camera-production costs are also needed.A preclinical dedicated murine PET (MuPET) camera has been designed and constructed at the University of Texas M.D. Anderson Cancer Center (2). It has been integrated with a CT camera into a compact gantry. The MuPET camera combines the advantages of a lower production cost with high resolution and high sensitivity. In this work, we report on the scanner's perfor...

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Section: Pet Camera Descriptionmentioning

confidence: 99%

Engineering and Performance (NEMA and Animal) of a Lower-Cost Higher-Resolution Animal PET/CT Scanner Using Photomultiplier-Quadrant-Sharing Detectors

Wong

Baghaei

et al. 2012

J Nucl Med

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“…In high-resolution PMT-quadrant-sharing (PQS) position-sensitive PET block detectors [11], [12] that we have been working with for many years, one PMT channel involves a large decoding area of four detector blocks, which increases the count-rate for each channel. Our high light-output PQS detectors have a large decoding ratio of 256 crystals/PMT for LYSO (4 to 15 times higher decoding resolution than that of current PET manufacturers).…”

Section: Methodsmentioning

confidence: 99%

A New Statistics-Based Online Baseline Restorer for a High Count-Rate Fully Digital System

Wang

Baghaei

et al. 2010

IEEE Trans. Nucl. Sci.

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The goal of this work is to develop a novel, accurate, real-time digital baseline restorer using online statistical processing for a high count-rate digital system such as positron emission tomography (PET). In high count-rate nuclear instrumentation applications, analog signals are DC-coupled for better performance. However, the detectors, pre-amplifiers and other front-end electronics would cause a signal baseline drift in a DC-coupling system, which will degrade the performance of energy resolution and positioning accuracy. Event pileups normally exist in a high-count rate system and the baseline drift will create errors in the event pileup-correction. Hence, a baseline restorer (BLR) is required in a high count-rate system to remove the DC drift ahead of the pileup correction. Many methods have been reported for BLR from classic analog methods to digital filter solutions. However a single channel BLR with analog method can only work under 500 kcps count-rate, and normally an analog front-end application-specific integrated circuits (ASIC) is required for the application involved hundreds BLR such as a PET camera. We have developed a simple statistics-based online baseline restorer (SOBLR) for a high count-rate fully digital system. In this method, we acquire additional samples, excluding the real gamma pulses, from the existing free-running ADC in the digital system, and perform online statistical processing to generate a baseline value. This baseline value will be subtracted from the digitized waveform to retrieve its original pulse with zero-baseline drift. This method can self-track the baseline without a micro-controller involved. The circuit consists of two digital counter/timers, one comparator, one register and one subtraction unit. Simulation shows a single channel works at 30 Mcps count-rate with pileup condition. 336 baseline restorer circuits have been implemented into 12 field-programmable-gate-arrays (FPGA) for our new fully digital PET system.

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“…For the crystal finishing, 4 μ m (roughness) on five crystal surfaces and polished smoothly (less than 1 μ m) on one end was selected. This specific surface finish, together with the reflective patterns placed between adjacent crystals optimizes the light sharing in the detectors for PQS-PET system, [25]. …”

Section: Methodsmentioning

confidence: 99%

A Lower-Cost High-Resolution LYSO Detector Development for Positron Emission Mammography (PEM)

Ramirez

Zhang

Liu

et al. 2009

IEEE Trans. Nucl. Sci.

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In photomultiplier-quadrant-sharing (PQS) geometry for positron emission tomography applications, each PMT is shared by four blocks and each detector block is optically coupled to four round PMTs. Although this design reduces the cost of high-resolution PET systems, when the camera consists of detector panels that are made up of square blocks, half of the PMT's sensitive window remains unused at the detector panel edge. Our goal was to develop a LYSO detector panel which minimizes the unused portion of the PMTs for a low-cost, high-resolution, and high-sensitivity positron emission mammography (PEM) camera. We modified the PQS design by using elongated blocks at panel edges and square blocks in the inner area. For elongated blocks, symmetric and asymmetrical reflector patterns were developed and PQS and PMT-half-sharing (PHS) arrangements were implemented in order to obtain a suitable decoding. The packing fraction was 96.3% for asymmetric block and 95.5% for symmetric block. Both of the blocks have excellent decoding capability with all crystals clearly identified, 156 for asymmetric and 144 for symmetric and peak-to-valley ratio of 3.0 and 2.3 respectively. The average energy resolution was 14.2% for the asymmetric block and 13.1% for the symmetric block. Using a modified PQS geometry and asymmetric block design, we reduced the unused PMT region at detector panel edges, thereby increased the field-of-view and the overall detection sensitivity and minimized the undetected breast region near the chest wall. This detector design and using regular round PMT allowed building a lower-cost, high-resolution and highsensitivity PEM camera. NIH Public Access

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High-Resolution L(Y)SO Detectors Using PMT-Quadrant-Sharing for Human and Animal PET Cameras

Cited by 37 publications

References 26 publications

Engineering and Performance (NEMA and Animal) of a Lower-Cost Higher-Resolution Animal PET/CT Scanner Using Photomultiplier-Quadrant-Sharing Detectors

Engineering and Performance (NEMA and Animal) of a Lower-Cost Higher-Resolution Animal PET/CT Scanner Using Photomultiplier-Quadrant-Sharing Detectors

A New Statistics-Based Online Baseline Restorer for a High Count-Rate Fully Digital System

A Lower-Cost High-Resolution LYSO Detector Development for Positron Emission Mammography (PEM)

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