A large area, silicon photomultiplier-based PET detector module

Abstract

The introduction of silicon photomultipliers (SiPM) has facilitated construction of compact, efficient and magnetic field-hardened positron emission tomography (PET) scanners. To take full advantage of these devices, methods for using them to produce large field-of-view PET scanners are needed. In this investigation, we explored techniques to combine two SiPM arrays to form the building block for a small animal PET scanner. The module consists of a 26 × 58 array of 1.5 × 1.5mm2 LYSO elements (spanning 41 × 91mm2) coupled to two SensL SiPM arrays. The SiPMs were read out with new multiplexing electronics developed for this project. To facilitate calculation of event position with multiple SiPM arrays it was necessary to spread scintillation light amongst a number of elements with a small light guide. This method was successful in permitting identification of all detector elements, even at the seam between two SiPM arrays. Since the performance of SiPMs is enhanced by cooling, the detector module was fitted with a cooling jacket, which allowed the temperature of the device and electronics to be controlled. Testing demonstrated that the peak-to-valley contrast ratio of the light detected from the scintillation array was increased by ∼45% when the temperature was reduced from 28 °C to 16 °C. Energy resolution for 511 keV photons improved slightly from 18.8% at 28 °C to 17.8% at 16 °C. Finally, the coincidence timing resolution of the module was found to be insufficient for time-of-flight applications (∼2100 ps at 14 °C). The first use of these new modules will be in the construction of a small animal PET scanner to be integrated with a 3T clinical magnetic resonance imaging scanner.

Timing Results Using an FPGA-Based TDC with Large Arrays of 144 SiPMs

“…It should be pointed out that the CRT values obtained with the SiPM array are significantly better than those values reported so far in the literature for smaller ( and ) SiPM arrays [17] [22] and for the similar array dimensions [23].…”

“…For a black painted crystal, a 6.79 ns FWHM CRT was achieved for both (SiPM and PMT) in coincidence. Recent publications such as [22] and [23] also use SiPM matrices. The aim of the first work consists in demonstrating the ability to resolve time and energy resolution with an array of SiPMs coupled to pixelated LYSO crystals.…”

Preclinical positron emission tomography scanner based on a monolithic annulus of scintillator: initial design study

“…First, performance of the SiPM arrays is enhanced by cooling. 81 Normally, cooling would be accomplished with Peltier coolers, but the heat removed from the SiPMs by these devices must then be dissipated. Often this process is accomplished by circulating air or fluid over the Peltier coolers.…”

Detector block based on arrays of 144 SiPMs and monolithic scintillators: A performance study

“…Since then, there has been suggested to design wide SiPM arrays with dimensions nearing those of standard Position Sensitive PMTs of 5 cm  5 cm. Several experiments have been carried out with SiPMs arrays (and also Avalanche Photodiodes arrays) with sizes hardly extending beyond 3 cm  3 cm [1][2][3][4][5][6][7][8][9]. The major reasons for designs that do not exceed these dimensions are principally the integrated dark noise that nevertheless depends on the readout strategy, but also on its implementation complexity.…”