Design goal: Photon Counting CT engineered with Deep Silicon technology to enable advanced CT Imaging

CT detects cancers at early, more treatable stages and effectively evaluates many heart conditions. Photon counting technology could be a substantial step forward for millions of patients worldwide.

Deep Silicon technology* could allow for the realization of the full potential of photon counting CT oncology, cardiology, neurology, and more.

For nearly 50 years, CT has proven to be a vital imaging tool used by clinicians for the diagnosis of disease, trauma, or abnormality and for planning, guiding, and monitoring therapy. Photon counting CT technology has the potential to enable a significant increase in imaging performance for oncology, cardiology, neurology, and many other clinical CT applications.


Photon counting CT technology engineered to enable higher contrast-to noise ratio, improved spatial resolution, and optimized spectral imaging.

Photon counting CT technology is designed to use new, energy-resolving x-ray detectors to count the number of incoming photons and quantify photon energy for higher contrast-to-noise ratio, improved spatial resolution, and optimized spectral imaging compared to conventional energy-integrating techniques.¹

Traditional Energy Integrating Detector (EID) lacks specific energy level information of each photon

In a traditional Energy Integrating Detector (EID) system, the x-ray photon first hits a scintillator where it is turned into visible light. A photodiode then measures this light to create an electrical charge that becomes the CT signal. With an EID detector, the photons that hit the detector at the same time are added up (or integrated) to create the signals that are used to generate a CT image. This process provides no specific information about the energy level of each individual photon.

Photon counting is engineered to use semiconducting material to help enable the generation of images with more accurate signals and the production of high quality spectral information.

A photon counting detector is made from a semiconducting material that allows for the direct conversion of the x-ray photon to an electrical signal. In this case, the many photons hitting the detector can be counted individually, enabling a more accurate signal to generate images. In addition, the energy level of each photon can be quantified, enabling the production of high quality spectral information.

Design goals: Engineering a photon counting CT that enables capabilities for improved spectral and spatial resolutions, reduced radiation and enhanced contrast to-noise ratio

From the first x-ray machines to the first Silicon-based photon counting prototype, GE HealthCare is committed to pioneering next generation imaging technology. GE’s researchers began studying photon counting CT in 1993 and developed the world’s first photon counting CT prototype using cadmium-based detectors in 2006.

Photon counting CT technology could significantly increase imaging performance for oncology, cardiology, neurology, and many other clinical CT applications. It has the potential to enable improved spectral and spatial resolutions, reduced radiation, and an enhanced contrast-to-noise ratio to help provide more detailed images of small blood vessels, vascular pathologies, and malignant changes at an earlier stage.

“Our research shows Deep Silicon is the best detector solution for photon counting CT to meet clinical requirements,” says Mats Danielsson, PhD.

“Silicon is by far the purest material produced for use in detectors. Alternative materials, including cadmium-based, may face limitations as x-ray detector materials due to their imperfect crystal structure and contaminations.

GE HealthCare’s unique approach after three decades of R&D: Deep Silicon as the semiconductor material for its intended photon counting CT detector to help clinicians realize the full potential of spectral CT.

The effective depth of the detector is determined not by the thickness of the silicon, but by its length – allowing the detector to have as long an absorption length as necessary. This is why we call it “Deep Silicon.”

Advantages of Silicon as a semi-conductor material

Silicon has a number of advantages as a semi-conductor material, including its purity, abundance, length, and broad manufacturing infrastructure.

Historic Challenges of Silicon as a Semi-Conductor Material

The main challenge has been that it has a relatively low atomic number such that when placed in a “face on” position, it is too thin to stop and collect a sufficient number of x-ray photons.

GE HealthCare Overcomes the Challenge with Patented Novel “Edge On” Positioning

Our approach puts silicon sensors edge on so the detector is deep enough to absorb high energy photons and fast enough to count and quantify energies of hundreds of millions of CT photons per second.


Exploring the full potential of photon-counting CT technology

Computed tomography (CT) plays a key role in clinical radiology today, assisting clinicians in the diagnosis of disease, trauma, and clinical abnormalities.

May 16, 2023

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UW–Madison To Perform the First U.S. Evaluation of GE HealthCare’s Photon Counting

GE HealthCare’s design for Deep Silicon detectors for a photon counting CT (PCCT) is engineered with the goal of achieving breakthroughs in both CT spatial and spectral resolution at the same time and increasing imaging performance across care areas Researchers at the University of Wisconsin–Madison

Nov 21, 2022

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Karolinska Institutet & MedTechLabs Kickoff The World’s First Clinical Evaluation of GE HealthCare’s Photon Counting CT Technology with Deep Silicon Detectors

Photon counting CT has the promise to further expand the capabilities of traditional CT Karolinska Institutet and MedTechLabs’ pilot study represents the first of its kind to test pure silicon CT detector technology for photon counting CT in a clinical setting The project is the result of close collaborations between healthcare, academia and business

Nov 17, 2021

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GE HealthCare Pioneers Photon Counting CT with Prismatic Sensors Acquisition

GE HealthCare invests in a unique approach to cutting-edge CT technology and acquires Prismatic Sensors AB, a leader in Deep Silicon detector technology for photon counting computed tomography (PCCT)

Nov 20, 2020

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Silicon Dreams: A Technological Breakthrough To Let Doctors Peer Inside The Body With Startling Clarity

Wilhelm Röntgen had no inkling that he was about to revolutionize how doctors diagnose and treat injuries and disease

Nov 20, 2020

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Technology in development that represents ongoing research and development efforts. These technologies are not products and may never become products. Not for sale. Not cleared or approved by the U.S. FDA or any other global regulator for commercial availability. This is neither an offer nor an agreement to supply the technologies. Cannot be placed on the market or put into service until it has been made to comply with the Medical Device Regulation requirements for CE marking.


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