Development of capacitive multiplexing circuit for SiPM-based time-of-flight (TOF) PET detector

Abstract

There has been great interest in developing a time-of-flight (TOF) PET to improve the signal-to-noise ratio of PET image relative to that of non-TOF PET. Silicon photomultiplier (SiPM) arrays have attracted attention for use as a fast TOF PET photosensor. Since numerous SiPM arrays are needed to construct a modern human PET, a multiplexing method providing both good timing performance and high channel reduction capability is required to develop a SiPM-based TOF PET. The purpose of this study was to develop a capacitive multiplexing circuit for the SiPM-based TOF PET. The proposed multiplexing circuit was evaluated by measuring the coincidence resolving time (CRT) and the energy resolution as a function of the overvoltage using three different capacitor values of 15, 30, and 51 pF. A flood histogram was also obtained and quantitatively assessed. Experiments were performed using a [Formula: see text] array of [Formula: see text] mm SiPMs. Regarding the capacitor values, the multiplexing circuit using a smaller capacitor value showed the best timing performance. On the other hand, the energy resolution and flood histogram quality of the multiplexing circuit deteriorated as the capacitor value became smaller. The proposed circuit was able to achieve a CRT of [Formula: see text] ps FWHM and an energy resolution of 17.1[Formula: see text] with a pair of [Formula: see text] mm LYSO crystals using a capacitor value of 30 pF at an overvoltage of 3.0 V. It was also possible to clearly resolve a [Formula: see text] array of LYSO crystals in the flood histogram using the multiplexing circuit. The experiment results indicate that the proposed capacitive multiplexing circuit is useful to obtain an excellent timing performance and a crystal-resolving capability in the flood histogram with a minimal degradation of the energy resolution, as well as to reduce the number of the readout channels of the SiPM-based TOF PET detector.

Analog and digital signal processing method using multi‐time‐over‐threshold and FPGA for PET

“…Additional energy spectra were acquired using different point sources ( 57 Co, 22 Na, and 137 Cs) and energy linearity performance was assessed by photopeak position measured from energy spectra . In addition, the energy calibration was performed by plotting the nonlinear curve of the pulse height distributions, by fitting with the exponential function below and by solving for the unknown parameters of a and b where x and y are the energy and upcounter values, respectively.…”

“…26,27 In addition, the energy calibration was performed by plotting the nonlinear curve of the pulse height distributions, by fitting with the exponential function below and by solving for the unknown parameters of a and b. 28,29 y ¼ að1 À e Àbx Þ where x and y are the energy and upcounter values, respectively.…”

Sensors for Positron Emission Tomography Applications

“…In the application of PET, the detected signal from the analog SiPM needs a readout ASIC to get the timing and energy information of the detected photons, as shown in Figure 14a. The number of the output channels of analog SiPM can be reduced by employing resistive [100] or capacitive [101] multiplexing circuits. This feature reduces the efforts involved in designing the readout electronics for the analog SiPMs.…”

Proposal for a PET scanner with 4π formula steradian span

“…Some groups have came up with ways to solve this problem by using data processing or simply by using a different equation for finding the pixel position [53]. There are different ways of implementing an Anger multiplexing scheme, some use only capacitors and no biasing resistor for each pixel, others use resistors instead of capacitors, and some others use the network along with a biasing resistor [54], [55]. In our experience all of this solutions suffer from the two problems stated above.…”