Timing resolution improvement using DOI information in a four-layer scintillation detector for TOF-PET

Shibuya, Kengo; Nishikido, Fumihiko; Tsuda, Tomoaki; Kobayashi, Tetsuya; Lam, Chih Fung; Yamaya, Taiga; Yoshida, Eiji; Inadama, Naoko; Murayama, Hideo

doi:10.1016/j.nima.2008.05.020

Cited by 32 publications

(18 citation statements)

References 41 publications

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“…10 Unfortunately TOF and DOI precision are somewhat mutually exclusive, therefore whenever one improves the former, the latter worsens and vice versa. [11][12][13][14][15][16][17] In this paper, we show that the choice of a suitable treatment of the scintillator surfaces, along with suitable photodetectors and specific algorithms for raw data analysis, can allow to achieve an interesting tradeoff between detector element size, energy, time, and DOI resolution, thus strongly supporting the feasibility of a TOF-PET probe with the required features and performance. In numbers, we are going to show that a detector array whose individual elements are 1.5 mm × 1.5 mm × 10 mm in size, might achieve at the same time energy resolution around 11.5%, coincidence resolving time (CRT) below 300 ps and DOI resolution below 1 mm.…”

Section: Introductionmentioning

confidence: 77%

Characterization of a scintillating mini-detector for time-of-flight positron emission tomography with depth-of-interaction

Coséntino

Finocchiaro

Pappalardo

et al. 2012

Review of Scientific Instruments

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By exploiting a suitable treatment of the scintillator surfaces, along with silicon photomultiplier photodetectors and specific algorithms for raw data analysis, we achieved a remarkable tradeoff between energy, time, and depth-of-interaction (DOI) resolution, thus supporting the feasibility of a prostate time-of-flight positron emission tomography probe, magnetic resonance imaging compatible, with the required features and performance. In numbers this means a detector element of 1.5 mm × 1.5 mm × 10 mm, promising to achieve at the same time energy resolution around 11.5%, coincidence resolving time around 300 ps corresponding to a space resolution<5 cm along the line of response, and DOI resolution even below 1 mm. We stress that such a time resolution allows to increase significantly the noise equivalent counting rate, and consequently improve the image quality and the lesion detection capability.

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Section: Introductionmentioning

confidence: 77%

Characterization of a scintillating mini-detector for time-of-flight positron emission tomography with depth-of-interaction

Coséntino

Finocchiaro

Pappalardo

et al. 2012

Review of Scientific Instruments

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“…The increased scatter and longer transport lead to more light attenuation, which causes the photo-peak in the energy spectrum to decrease as the distance between the DOI position and the PMT surface increases (figure 5(b)). In addition, the time walk between the 2 and 18 mm DOI positions was estimated to be relatively longer (340 ps) than when polished crystals were used (100-200 ps) (Shibuya et al 2008, Vinke et al 2010, Spanoudaki and Levin 2011. This time walk information as a function of DOI position can be utilized for elevating the timing performance of this detector at the system level as the time resolution at each DOI position ranges from 320 to 356 ps (Ito et al 2011).…”

Section: Discussionmentioning

confidence: 98%

Continuous depth-of-interaction measurement in a single-layer pixelated crystal array using a single-ended readout

Ito

Lee

2013

Phys. Med. Biol.

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We propose a depth-of-interaction (DOI)-encoding method to extract continuous DOI information using a single-layer scintillation crystal array with single-ended readout for cost-effective high-resolution positron emission tomography (PET). DOI information is estimated by different light dispersions along the x- and y-directions tailored by the geometric shape of reflectors around the crystals. The detector module comprised a 22 × 22 array of unpolished LGSO crystals (2.0 × 2.0 × 20 mm(3)). A multi-anode photomultiplier tube with 64 anodes measured light dispersion in the crystal array. Gain non-uniformity of each anode was corrected by an analogue gain compensation circuit. DOI information was determined from peaks in the x and y anode-signal distributions normalized by the total energy of the distribution. Average DOI resolution (full width at half maximum, FWHM) over all crystals and depths was estimated to be 4.2 mm. Average energy resolution from the 2 to 18 mm DOI positions was 11.3% ± 0.79%, with 13% difference in photo-peak positions. Average time resolutions (FWHM) were 320-356 ps. Energy, time and DOI resolutions were uniform over all crystal positions except at the array's edge. This DOI-PET detector shows promise for applications that require high resolution and sensitivity at low cost.

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“…A PET system using long crystals will also have an increased parallax error, leading to a radial degradation in image spatial resolution. Therefore, detector designs based on LaBr 3 /CeBr 3 can potentially benefit more by including techniques to measure DOI, as this information can be used to correct for timing uncertainties caused by the use of longer length crystals (Shibuya et al 2008, Spanoudaki and Levin 2011), as well as reduce parallax error in the reconstructed images.…”

Section: Introductionmentioning

confidence: 99%

Characterization of stacked-crystal PET detector designs for measurement of both TOF and DOI

2015

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A PET detector with good timing resolution and two-level depth-of-interaction (DOI) discrimination can be constructed using a single-ended readout of scintillator stacks of Lanthanum Bromide (LaBr3), with various Cerium dopant concentrations, including pure Cerium Bromide (CeBr3). The stacked crystal geometry creates a unique signal shape for interactions occurring in each layer, which can be used to identify the DOI, while retaining the inherently good timing properties of LaBr3 and CeBr3. In this work, single pixel elements are used to optimize the choice of scintillator, coupling of layers, and type of photodetector, evaluating the performance using a fast, single-channel photomultiplier tube (PMT) and a single 4×4 mm2 silicon photomultiplier (SiPM). We also introduce a method to quantify and evaluate the DOI discrimination accuracy. From signal shape measurements using fast waveform sampling, we found that in addition to differences in signal rise times, between crystal layers, there were also differences in the signal fall times. A DOI accuracy of 98% was achieved using our classification method for a stacked crystal pair, consisting of a 15-mm long LaBr3(Ce:20%) crystal on top of a 15-mm long CeBr3 crystal, readout using a PMT. A DOI accuracy of 95% was measured with a stack of two, identical, 12-mm long, CeBr3 crystals. The DOI accuracy of this crystal pair was reduced to 91% when using a SiPM for readout. For the stack of two, 12-mm long, CeBr3 crystals, a coincidence timing resolution (average of timing results from the top and bottom layer) of 199 ps was measured using a PMT, and this was improved to 153 ps when using a SiPM. These results show that with stacked LaBr3/CeBr3 scintillators and fast waveform sampling nearly perfect DOI accuracy can be achieved with excellent timing resolution—timing resolution that is only minimally degraded compared to results from a single CeBr3 crystal of comparable length to the stacked crystals. The interface in the stacked crystal geometry itself plays a major role in creating the differences in signal shape and this can be used to construct stacked DOI detectors using the same scintillator type, thereby simplifying and broadening the application of this technique.

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Timing resolution improvement using DOI information in a four-layer scintillation detector for TOF-PET

Cited by 32 publications

References 41 publications

Characterization of a scintillating mini-detector for time-of-flight positron emission tomography with depth-of-interaction

Characterization of a scintillating mini-detector for time-of-flight positron emission tomography with depth-of-interaction

Continuous depth-of-interaction measurement in a single-layer pixelated crystal array using a single-ended readout

Characterization of stacked-crystal PET detector designs for measurement of both TOF and DOI

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