Since its inception in 1971, the dramatic evolution of Computed Tomography (CT) has led to the steady growth of CT’s role in patient care.
Canon Medical has pioneered many of the technological innovations defining the clinical expansion of CT, such as Area Detectors, Ultra-High Resolution, and Deep Learning Reconstruction. In partnership with Redlen Technologies Inc. (Redlen), a Canon group company, the global leader in photon counting detector design and manufacturing, Canon is currently developing a Photon Counting CT (PCCT) with the potential to improve visualization of small structures and enhance tissue characterization.
Our vision is to use Redlen’s state-of-the-art Photon Counting CT technology empowered by Canon Medical’s leading advancements in system, software, and image reconstruction to improve the quality of medical diagnosis for all patients worldwide.
CANON'S PHOTON COUNTING CT
Canon’s PCCT detector is uniquely constructed using Cadmium Zinc Telluride (CZT). The addition of Zinc to Cadmium Telluride increases the detector’s ability to effectively capture photons, for greater dose efficiency. In addition, Canon’s exclusive compact read out circuitry is designed to maximize the active area of the detector to achieve the highest geometric dose efficiency. With an optimized pixel size, fast read out, and sophisticated modelling algorithms, Canon’s CZT detector readily combats challenges such as pulse pileup and charge sharing to yield low noise, high-resolution images.
WHAT IS PHOTON COUNTING CT?
Photon counting CT uses a semiconductor material to directly convert each incident photon into an electric signal, which is then quickly read out by detector circuity to effectively “count” each photon individually. When an incident photon strikes the detector, it creates a charge cloud in the detector material proportional to the energy of incident photon. Based on their measured energy, the counted photons are sorted into energy bins that can be utilized by advanced reconstruction techniques to generate optimal image quality and spectral information.
WHAT IS THE MAIN DIFFERENCE OF PHOTON COUNTING FROM CONVENTIONAL CT?
A PCCT measures each photon and its energy directly, whereas with a conventional energy integrating detector (EID) the incident photons are not directly converted to signal. Rather, the absorbed energy of the photons is first converted to light by a scintillator, then that light is converted to an electrical signal by a photodiode. An EID’s output depends on the combined energy of the incident photons. Higher energy photons generate more light than lower energy photons, and thus contribute more heavily towards the EID’s output electrical signal.
BENEFITS OF CANON’S PCCT: IMAGE QUALITY
The key to achieving the best image quality PCCT can offer is reconstruction. Canon Medical’s long history of advances in reconstruction that have shattered the boundaries of image quality performance have led the way for Canon to optimize PCCT image quality for all patient shapes and sizes.
For more optimal dose efficiency, detectors should have as much active area capturing photons as possible. In conventional EIDs, light in one detector pixel can scatter into a neighboring pixel, a phenomenon called optical crosstalk that reduces spatial resolution. Because of this, EIDs require a reflector of finite thickness between the scintillator pixels to prevent crosstalk. However, the presence of this reflector reduces the active area of the detector and, thus, its dose efficiency, especially for small-sized detector pixels. Because PCCT doesn’t use a scintillator, there is no need for reflective material between detector pixels. This greatly improves the dose efficiency of the detector, allowing for smaller detector pixel sizes without dose penalty.
PCCT also overcomes a major disadvantage of EID: electronic noise. An EID’s electronic noise is unavoidably combined with true signal into the detector output. When the number of photons is low, electronic noise becomes dominant, degrading image quality. With PCCT, electronic noise from the detector registers below the threshold of lowest energy bin and is thus discarded. In this way, PCCT effectively eliminates electronic noise, which improves image quality.
BENEFITS OF CANON’S PCCT: SPECTRAL
PCCT enables Spectral Imaging with every scan for routine material decomposition. Canon’s exclusive advances in Spectral reconstruction have given Canon unique insight into minimizing noise and maximizing spectral information from PCCT. Because the thresholds for the energy bins are configurable, PCCT can also allow for imaging that targets specific K-edge energies, from common contrast agents, such as iodine and gadolinium, to novel nanoparticles such as gold.
BENEFITS OF CANON'S PCCT: ULTRA-HIGH RESOLUTION (UHR)
PCCT detectors permit the use of small detector pixels. In standard applications, these pixels can be combined to yield improved spatial resolution relative to conventional CT without noise or dose penalty. For applications where increased spatial resolution adds clinical value, these pixels can be read out individually for Ultra-High Spatial Resolution. Canon launched the Aquilion Precision Ultra-High Resolution (UHR) CT system in 2017 and has now obtained over half a decade of expertise in reconstruction and workflow optimization for UHR as well as achieved advances in tube design, table positioning, and gantry vibration to make the most effective use of UHR-CT. With these advances, Canon is posed to lead the way on UHR PCCT for maximum clinical utility and optimal workflow in a busy clinical environment.
THE ADVANTAGE OF REDLEN, A CANON GROUP COMPANY
Redlen has been developing photon counting detector manufacturing technology for over twenty years and is today a leading global supplier of photon counting imaging detectors. In addition to medical imaging, Redlen CZT technology is currently used globally in security scanning, non-destructive industrial scanning, and aerospace applications.
Redlen’s extensive manufacturing experience has resulted in a fully vertically integrated manufacturing system that spans CZT material growth, wafer processing, sensor fabrication, imaging module design, module assembly, module production testing and finally CZT material recycling, all under one roof. As a result, Canon can realize the stable production of the highly precise photon counting CT detectors. Combined with Canon Medical’s sophisticated CT manufacturing capabilities for gantry, tube, and table, the result is a revolutionary step forward in PCCT.
Note: Photon Counting CT technology is currently under development and the subject of ongoing research and development. Each technology is not yet commercialized and is not available for sale.
Due to medical device regulatory reasons, not all products/service displayed on this Canon Medical Systems global webpage are available in all countries, regions or markets. Future availability of the products/service cannot also be guaranteed. Please contact your local Canon Medical Systems representative for further details.