A 10-mc/s, 0.5-/spl mu/m CMOS constant-fraction discriminator having built-in pulse tail cancellation

Binkley, D.M.; Puckett, B.S.; Swann, B.K.; Rochelle, Jonathan; Musrock, M.S.; Casey, Michael

doi:10.1109/tns.2002.1039626

Cited by 23 publications

(9 citation statements)

References 13 publications

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“…A short delay did not provide good timing resolution because of the high noise associated with the signal. We are therefore exploring other techniques, including non-cable delay CFD (Binkley et al , 2002) and other signal processing techniques, for these large-area PSAPDs.…”

Section: Discussionmentioning

confidence: 99%

A study of the timing properties of position-sensitive avalanche photodiodes

Yang

et al. 2009

Phys. Med. Biol.

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In this paper we study position-dependent timing shifts and timing resolution in position sensitive avalanche photodiodes (PSAPDs) and their effect on the coincidence window used in positron emission tomography (PET) systems using these devices. There is a delay in PSAPD signals that increases as the excitation position moves from the corner to the center of the device and the timing resolution concurrently worsens. The difference in timing between the center and corner can be up to 30.7 ns for a 14×14 mm2 area PSAPD. This means that a PSAPD-based PET system could require a very wide coincidence timing window (>60 ns) if this effect is not corrected, although the individual crystal pairs still have full-width half-maximum (FWHM) timing resolutions better than 7.4 ns. In addition to characterizing the timing properties of PSAPDs, two correction methods were developed and applied to data from a pair of PSAPD detectors. These two timing offset corrections reduced the timing shift of a crystal pair from 52.4 ns to 9.7 ns or 1.3 ns, improved FWHM timing resolution of the detector pair from 24.6 ns to 9.5 ns or 6.0 ns and reduced the timing window (sufficient to cover at least twice the FWHM for all crystal pairs) from 65.1 ns to 22.0 ns or 15.2 ns respectively. A two-step timing alignment method is proposed for a PET system consisting of multiple PSAPDs. Lastly, the effect of PSAPD size on the timing performance was also evaluated.

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Section: Discussionmentioning

confidence: 99%

A study of the timing properties of position-sensitive avalanche photodiodes

Yang

et al. 2009

Phys. Med. Biol.

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“…In the Accel camera, the constant fraction discriminator is part of the CPS Analog ASIC [34][35][36]. The main components of this ASIC are variable-gain preamplifiers, analog summing circuits, gated integrators, and a non-delay line CFD, and it internally terminates each PMT input with 50Ω.…”

Section: Constant Fraction Discriminatormentioning

confidence: 99%

Factors influencing timing resolution in a commercial LSO PET camera

Moses

Ullisch

2006

IEEE Trans. Nucl. Sci.

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Abstract--The CPS Accel is a commercial PET camera based on a block detector with 64 LSO scintillator crystals (each 6.75 x 6.75 x 25 mm) read out with 4 photomultiplier tubes. The excellent timing resolution of LSO suggests that this camera might be used for time-of-flight (TOF) PET, thereby reducing the statistical noise significantly. Although the Accel achieves 3 ns coincidence resolution (a factor of two better than BGObased PET cameras), its timing resolution is nearly an order of magnitude worse than that demonstrated with individual LSO crystals. This paper quantifies the effect on the timing of each component in the Accel timing chain to identify which components most limit the camera's timing resolution. The components in the timing chain are: the scintillator crystal, the photomultiplier tube (PMT), the constant fraction discriminator (CFD), and the time to digital converter (TDC). To measure the contribution of each component, we construct a single crystal test system with high-performance versions of these components. This system achieves 221 ps fwhm coincidence timing resolution, which is used as a baseline measurement. One of the high-performance components is replaced by a production component, the coincidence timing resolution is remeasured, and the difference between measurements is the contribution of that (production) component. We find that the contributions of the TDC, CFD, PMT, and scintillator are 2000 ps, 1354 ps, 422 ps, and 326 ps fwhm respectively, and that the overall timing resolution scales like the square root of the amount of scintillation light detected by the PMT. Based on these measurements we predict that the limit for the coincidence timing resolution in a practical, commercial, LSO-based PET camera is 528 ps fwhm.

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“…They are block detector modules, with an 8 8 array of 30 mm deep BGO crystals that cover a 50 mm 50 mm area. The electronics are a modified version of the electronics used for the CTI HRRT camera [9]- [13], with the main difference being that the ASIC used for processing the detector module signal is designed for BGO-based block detectors [14] rather than LSO-based block detectors [15]- [17]. For this work, the pertinent features are that the arrival time of each annihilation photon is quantized in 2 ns steps and that the electronics support an additive time delay correction factor for each crystal that is also quantized in 2 ns steps.…”

Section: B Prostate-specific Pet Cameramentioning

confidence: 99%

Timing Calibration in PET Using a Time Alignment Probe

Moses

Thompson

2006

IEEE Trans. Nucl. Sci.

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A"#tract--We evaluate the Scanwell Time Alignment Probe for performing the timing calibration for the LBNL ProstateSpecific PET Camera. We calibrate the time delay correction factors for each detector module in the camera using two methods-using the Time Alignment Probe (which measures the time difference between the probe and each detector module) and using the conventional method (which measures the timing difference between all module-module combinations in the camera). These correction factors, which are quantized in 2 ns steps, are compared on a module-by-module basis. The values are in excellent agreement-of the 80 correction factors, 62 agree exactly, 17 differ by 1 step, and 1 differs by 2 steps. We also measure on-time and off-time counting rates when the two sets of calibration factors are loaded into the camera and find that they agree within statistical error. We conclude that the performance using the Time Alignment Probe and conventional methods are equivalent.Inde, .er/#-calibration, positron emission tomography (PET), timing.

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A 10-mc/s, 0.5-/spl mu/m CMOS constant-fraction discriminator having built-in pulse tail cancellation

Cited by 23 publications

References 13 publications

A study of the timing properties of position-sensitive avalanche photodiodes

A study of the timing properties of position-sensitive avalanche photodiodes

Factors influencing timing resolution in a commercial LSO PET camera

Timing Calibration in PET Using a Time Alignment Probe

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