Purpose Time-of-flight (TOF) capability of positron emission tomography (PET) can improve the signal-to-noise ratio (SNR) in the image reconstruction. A new high-density and compact front-end electronics design for TOF-enabled and position sensitive PET detectors was proposed and evaluated. Purpose The proposed readout scheme employs radio frequency (RF) amplifiers for timing readout and an FPGA-based dual-polarity charge-to-digital converter (FPGA-dQDC) for energy readout. The PET detector consists of a <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$15 \times 15$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>15</mn> <mo>×</mo> <mn>15</mn> </mrow> </math></EquationSource> </InlineEquation> array of <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$1 \times 1 \times 10~{\text {mm}}^3$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1</mn> <mo>×</mo> <mn>1</mn> <mo>×</mo> <mn>10</mn> <mspace width="3.33333pt" /> <msup> <mrow> <mtext>mm</mtext> </mrow> <mn>3</mn> </msup> </mrow> </math></EquationSource> </InlineEquation> LYSO crystals coupled to a <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$5 \times 5$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>5</mn> <mo>×</mo> <mn>5</mn> </mrow> </math></EquationSource> </InlineEquation> array of <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$3 \times 3~{\text {mm}}^2$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>3</mn> <mo>×</mo> <mn>3</mn> <mspace width="3.33333pt" /> <msup> <mrow> <mtext>mm</mtext> </mrow> <mn>2</mn> </msup> </mrow> </math></EquationSource> </InlineEquation> SiPMs through a light guide. All crystals are separated by enhanced specular reflector (ESR) films. The timing signals from the SiPM array are amplified and multiplexed with a 25:1 ratio, while the energy signals are multiplexed by row/column summation to form a "<InlineEquation ID="IEq5"> <EquationSource Format="TEX">$5+5$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>5</mn> <mo>+</mo> <mn>5</mn> </mrow> </math></EquationSource> </InlineEquation>" readout configuration. The FPGA-dQDC system consists of an analog board implementing the dQDC circuit and a digital board based on a Cyclone V FPGA for discharge control, data buffering, and digital processing. Results The system was evaluated using a dual-detector coincidence setup consisting of a single-crystal reference detector and the "<InlineEquation ID="IEq6"> <EquationSource Format="TEX">$5+5$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>5</mn> <mo>+</mo> <mn>5</mn> </mrow> </math></EquationSource> </InlineEquation>" PET detector. The average coincidence time resolution (CTR) obtained from the CTR map was measured to be <InlineEquation ID="IEq7"> <EquationSource Format="TEX">$381.68 \pm 9.80$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>381.68</mn> <mo>±</mo> <mn>9.80</mn> </mrow> </math></EquationSource> </InlineEquation> ps full width at half maximum (FWHM). After saturation correction, the average energy resolution of all crystals was <InlineEquation ID="IEq8"> <EquationSource Format="TEX">$10.83 \pm 0.68\%$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>10.83</mn> <mo>±</mo> <mn>0.68</mn> <mo>%</mo> </mrow> </math></EquationSource> </InlineEquation>. Conclusion The proposed RF-amplifier-based timing readout and FPGA-dQDC energy readout scheme enables compact and power-efficient front-end electronics for TOF-PET detector prototype development.

FPGA-based dual-polarity charge readout with fast timing for small-animal PET applications

期刊论文
发表日期：

2026年7月11日

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Bo Wang,
Chuijiang Meng,
Xiaohan Sun,
Kun Hu

摘要

Purpose

Time-of-flight (TOF) capability of positron emission tomography (PET) can improve the signal-to-noise ratio (SNR) in the image reconstruction. A new high-density and compact front-end electronics design for TOF-enabled and position sensitive PET detectors was proposed and evaluated.

Purpose

The proposed readout scheme employs radio frequency (RF) amplifiers for timing readout and an FPGA-based dual-polarity charge-to-digital converter (FPGA-dQDC) for energy readout. The PET detector consists of a $15 \times 15$ $15 \times 15$ array of $1 \times 1 \times 10~{\text {mm}}^3$ $1 \times 1 \times 10 {mm}^{3}$ LYSO crystals coupled to a $5 \times 5$ $5 \times 5$ array of $3 \times 3~{\text {mm}}^2$ $3 \times 3 {mm}^{2}$ SiPMs through a light guide. All crystals are separated by enhanced specular reflector (ESR) films. The timing signals from the SiPM array are amplified and multiplexed with a 25:1 ratio, while the energy signals are multiplexed by row/column summation to form a " $5+5$ $5 + 5$ " readout configuration. The FPGA-dQDC system consists of an analog board implementing the dQDC circuit and a digital board based on a Cyclone V FPGA for discharge control, data buffering, and digital processing.

Results

The system was evaluated using a dual-detector coincidence setup consisting of a single-crystal reference detector and the " $5+5$ $5 + 5$ " PET detector. The average coincidence time resolution (CTR) obtained from the CTR map was measured to be $381.68 \pm 9.80$ $381.68 \pm 9.80$ ps full width at half maximum (FWHM). After saturation correction, the average energy resolution of all crystals was $10.83 \pm 0.68\%$ $10.83 \pm 0.68 %$ .

Conclusion

The proposed RF-amplifier-based timing readout and FPGA-dQDC energy readout scheme enables compact and power-efficient front-end electronics for TOF-PET detector prototype development.