One photon at a time

Cost-effective thyroid screening device relies on single photon counting

A team of European researchers has developed a point-of-care device that could lead to more efficient and cost-effective thyroid cancer screening. The device uses near-infrared time-resolve spectroscopy (TRS) and diffuse correlation spectroscopy (DCS), and features a time-correlated single photon counting module that has helped to lower the cost of the system.

Funded under Horizon 2020, the technique could lead to faster diagnosis and prevent unnecessary surgeries.

Early diagnosis in thyroid cancer can improve a patient’s likelihood of recovery, but current screening methods use instruments with poor sensitivity and can yield inaccurate results, according to the researchers involved.

‘The poor specificity of the current approaches leads to a significant number of unnecessary biopsies and surgeries,’ said Turgut Durduran, the project coordinator and professor at the Institute of Photonic Sciences (ICFO), Barcelona, Spain. ‘Current imaging or screening modalities are not able to distinguish malignant nodules from benign nodules with a good specificity.’

Under the H2020 project, called Laser and Ultrasound Co-Analyser for thyroid nodules (LUCA), a device is being developed to improve data acquisition for medical professionals by probing chemical constitution, water concentration, structure and haemodynamics – like blood flow and oxygenation – of tissue simultaneously. This device builds on the current ultrasound standard with a hybrid optics/ultrasound probe.

The instrument uses near-infrared time-resolve spectroscopy (TRS) and diffuse correlation spectroscopy (DCS) to collect the tissue data, each independently a commercial-level technology already.

The optical module also collects data on chromophore concentrations, like water and lipids, through TRS. The TRS subsystem, which features photomultipliers and time-correlated single photon counting, cuts the cost of the system to five times lower than commercially available equivalents, the team has said.

Through the project, the research team designed an easy to use and compact (5 × 4 × 10cm) single photon counting module based on a 1mm2 active area silicon photomultiplier (SiPM) detector (commercially available from Excelitas). The module features a single-photon time-resolution of about 100ps FWHM; it embeds the high biasing voltage generation network and a thermoelectric cooler driver to stabilise the detector temperature, allowing both a very short – about 1 minute – warm-up time and a complete insensitivity to possible external thermal perturbations.

The module could become a reliable and cost-effective building block for time-correlated single-photon counting instruments, not just for their thyroid screening application, but for any application requiring high collection capability of isotropic light and detection efficiency, for example fluorescence decay measurements or time-domain diffuse optics systems.

Also in the thyroid screening module, the DCS laser subsystem features a fibre-coupled laser diode at 785nm and custom-developed driving and cooling electronics. This custom design cuts the device cost by 10 to 15 times that of a standard DCS laser system.

Because of the high prevalence of thyroid nodules, at up to 76 per cent of the population, the researchers believe that even modest strategy improvements for characterising lesions could have a major positive impact.

In addition to the ICFO, the research involved the European Institute for Biomedical Imaging Research (Austria), the Poitecnico di Milano (Italy), the University of Birmingham (UK), public research centre IDIBAPS (Spain), and private firms Hemophotonics (Barcelona), Echo Control Medical (France), and Vermom (France).

Latest single photon counting products

Hamamatsu Photonics - Featured product

Hamamatsu Photonics is the world’s leading manufacturer of optoelectronic components and systems. Since its inception in 1953 Hamamatsu has continued to push the boundaries of what is possible with optoelectronic technologies.

We develop, manufacture and customise Multi-Pixel Photon Counter ‘MPPC®’ detectors and modules in-house, using the latest silicon foundry technology. We deliver the industry’s most diverse sensor line-up, package types and accessories.

MPPCs, otherwise known as SiPMs, are a semiconductor photon counting device made up of multiple APD (avalanche photodiode) pixels operated in Geiger mode. The MPPC has excellent photon counting capabilities and other unique advantages such as low voltage operation, insensitivity to magnetic fields, high photon detection efficiency and high resistance to mechanical shocks.

Our comprehensive line-up offers various sizes, package types, associated evaluation boards and modules. This makes it simple to find the ideal match for your application from our standard products. We can also develop customised MPPCs and MPPC module solutions that integrate an MPPC, scintillator, circuitry and software.

In addition to MPPCs, we offer a wide range of solutions for single photon counting applications including our new range of peak-shifted MPPC and single pixel photon counters ‘SPPCs’ and modules. These detectors deliver low noise and high PDE in the visible to NIR region. We also have a world famous and unrivalled range of Photomultiplier Tubes and Modules.

If you are looking for the optimum solution for single photon counting, then look to Hamamatsu Photonics.


ET Enterprises Ltd - Featured product

ET Enterprises Ltd has been a leading supplier of photomultiplier tubes and associated electronics for a number of years. The ever expanding product portfolio of ET Enterprises now includes high QE and compact photomultiplier tubes, low noise, low power consumption high voltage power bases and photodetector modules.

Our market-leading, high-performance low background photon counting modules can be supplied customised for specific applications. A variety of options are available with most units. The rectangular shaped modules offer a more cost-effective solution without affecting performance.

Some of our rectangular modules also offer an over light detection flag. We have recently introduced a dual output photon counting module with both a TTL output directly from the amplifier-discriminator and a USB output from the built-in-counter.

We have a range of high-gain photomultiplier tubes specifically designed for single photon counting applications.

Please visit our website, for further information on any of these products or contact us at with your specific requirement.


Becker and Hickl - Featured product

Becker and Hickl’s suite of TCSPC-based fluorescence lifetime imaging solutions now includes fast-acquisition TCSPC FLIM with <25ps optical timing resolution (<7ps IRF electrical), FLIM up to 2,048 x 2,048 pixels and up to 4,096 time channels per pixel.

Operating at frame rates of those of a galvanometric scanner, yet with the very high timing accuracy and channel resolution necessary for accurate metabolic imaging, B&H’s new single photon counting fast-acquisition FLIM is suited to both fast FLIM and to precision FLIM applications.

Time correlated single photon counting (TCSPC) FLIM delivers the best time-resolution and photon efficiency of all FLIM techniques. B&H’s SPC-150NX single photon counting card has the highest available temporal resolution, time channel width down to 407fs and electrical timing resolution down to 3.3ps FWHM.

In combination with ultra-fast hybrid detectors, the SPC-150NXC has been successfully used for metabolic imaging of NADH FLIM with high accuracy separation of the fluorescence decay components of the bound and the unbound fraction of NAD(P)H. The fast response of the detector-TCSPC combination rise of the NADH fluorescence occurs almost instantaneously. Further, due to the unmatched channel width of the SPC-150NX, it can record the data into a sufficient number of sufficiently small time channels so that multi-exponential decay analysis is possible. Separation of the decay components and the accuracy of the amplitudes and lifetimes improve substantially with the combination of SPC-150NX with ultra-fast hybrid detector.


Excelitas’ self-contained single photon counting modules (SPCMs) meet the low light level analytical detection demands of confocal microscopy, fluorescence, luminescence and TCSPC applications. Excelitas SPCMs deliver excellent photon counting performance featuring high photon detection efficiency (PDE), low after pulsing, high uniformity over an active area, high linear dynamic range, and low dark counts.

Designed and built to be fully RoHS-compliant, Excelitas SPCMs use an APD developed specifically to operate in so-called Geiger-mode, so that a single incoming photon triggers an avalanche of electrons already large enough to be detected and counted as an electronic pulse.

Excelitas SPCMs also use a unique silicon avalanche photodiode with a circular active area intended for peak photon detection efficiency.

The photodiode is both thermoelectrically cooled and temperature controlled, ensuring stabilised performance despite ambient temperature changes.


Laser Components’ Count series of photon counting modules has been developed to offer a combination of high quantum efficiency, wide dynamic range and ease of use for photon counting applications.

Combining ultra-low-noise avalanche photodiodes with specially developed quenching and signal processing electronics, the Count series offers everything needed for single photon detection from 350nm to 1,000nm.

From the original Count module, offering excellent detection efficiency in the red, the family has grown to include the Count Blue and the Count NIR, with the former offering detection efficiency in the blue and green and the latter offering high performance at 810nm.

Also available in the Count family is the Count S – a passively quenched module featuring a larger active area for a low cost alternative to the original Count module, and the Count T, designed for time-correlated single photon counting applications. The Count T both detects and records the time of detection from a reference signal.


Princeton Instruments’ ProEM-HS:1024BX3 is an advanced EMCCD camera, utilising low-noise readout electronics and a 1,024 x 1,024 EMCCD. This camera delivers single photon sensitivity and the best fringe suppression with patented eXelon3 technology.


This  2-in-1 camera features 30 MHz readout speed with the EM gain mode to deliver 25fps, a slow scan normal CCD readout mode with very low read noise for precision photometry applications, as well as other advanced features including solid baseline stability and linear EM gain control.

The ultra-fast custom CCD readout mode is specially designed to deliver greater than 4,400 fps with reduced ROI, whereas the special spectra kinetics mode delivers > 300,000 spectra / sec. The ProEM-HS: 1024BX3 camera is cooled to below -65°C, and the all-metal, hermetic vacuum seals have a lifetime warranty. Ideal for demanding, low-light level applications such as astronomy and Bose-Einstein Condensate (BEC) imaging.