How Digital Photon Counting works


The Digital Photon Counter (DPC) converts scintillating light directly to a digital signal.

Chip animation
The DPC detector tile consists of an array of 64 pixels. Each pixel couples directly to a single scintillation crystal.
Exploratorium animation
Each pixel contains thousands of microcells that enable detection of single photons. Each photon is converted directly into a pure binary output signal.

Advantages of digital detection

In conventional analog PET scanning, photomultipliers that are used to detect light output from the scintillator are limited in counting capabilities due to size and processing capabilities. To count photon events, light emitted from the scintillator is dispersed to multiple photomultiplier detectors. This sharing of information limits the capability of the PET detector to accurately process count rate information and location of the origin of the photon.


The Philips difference is digital. Unlike analog PET/CT scanners that use photomultipliers to detect light, the Vereos PET/CT scanner uses proprietary Digital Photon Counting (DPC) technology. It detects photons emitted from radiotracers individually by converting the scintillating light that collects them directly into a digital signal. This 1:1 coupling of crystals to light sensors provides faster time-of-flight than analog,* and approximately twice the sensitivity gain, volumetric resolution and quantitative accuracy.

Analog photon counter vs. Digital photon counter
Each scintillating light crystal is converted to a single digital pixel for approximately twice the sensitivity, volumetric resolution and quantitative accuracy of analog.*

Digital that's really digital

Analog SiPM

Analog SiPM

● Limited integration
● Analog signals to be digitized
● A/D converted needed
All digital photon counting Digital SiPMs

Digital photon counting Digital SiPMs

●●● Fully integrated
●●● Fully digital signals
●●● No A/D converted

Philips Digital Photon Counting

Redefine light detectors with digital SiPMs


Digital SiPMs create a new class of light detectors for ultra-low light levels down to single photons, by integrating both the sensor and the data processing into a single silicon chip.

Photomultiplier Tube

Avalanche Photodiode

Analog SiPM

Digital photon counting Digital SiPMs

TOF capability*
●● analog, time-of-flight
● N/A
●● analog, time-of-flight
●●● digital, time-of-flight
Operational stability
●● medium
● low
●● medium
●●● high
Signal amplification
●● 106
● 102-3
●● 106
●●● not needed
Level of integration
● low
●● medium
●● medium
●●● high
Signal readout
● analog
● analog
● analog
●●● digital

Performance data*

Number of Detectors
System spatial resolution
Effective system sensitivity

> 23.4 kcps/MBq at center

> 23.4 kcps/MBq at 10 cm

Effective peak NECR
> 687 kcps @ 50 kBq/mL
Maximum trues
>800 kcps
System timing resolution
310 ps
Quantitative accuracy
+/- 5%
*Preliminary performance is subject to change