Canon Medical Systems is developing a Photon Counting CT (PCCT) with the potential to significantly improve resolution, provide more precise imaging, and reduce radiation exposure compared to conventional CT.

Late last year Canon Medical installed our first PCCT system at Japan’s National Cancer Center (NCC) and recently received regulatory clearance to begin clinical scanning in Japan. Initial research based on patient data has now begun, marking a very exciting stage in the development process. In collaboration with Canon Medical, NCC has started a clinical research program to explore the benefits of PCCT for both new clinical applications, as well as for routine scanning.

One area in which we expect PCCT to have a significant impact is clinical care in oncology. Canon Medical is working with the NCC’s Exploratory Oncology Research & Clinical Trial Center (EPOC) and the NCC Hospital East, in Kashiwa, Japan, to explore new diagnostic methods with PCCT and investigate their clinical value for oncology.

As this research continues, the anticipated advantages of PCCT include significantly reduced radiation exposure at higher spatial resolution levels compared to conventional CT detectors. This increased precision, combined with spectral information, could lead to improved detectability of pathological changes, improved discrimination and identification of various materials in the body, as well as tissue characterization and malignancy assessment based on quantitative image analysis. Advances in these areas would lead to improved diagnostic accuracy throughout all phases of patient care in the field of oncology, from prevention to diagnosis, to evaluation of treatment effects, and to long-term prognosis.

PCCT systems are similar in many aspects to conventional CT except they use a photon-counting detector instead of a conventional, energy-integrating detector (EID). Unlike EIDs, which only measure the total amount of x-ray energy deposited, PCCT detectors record the energy of each individual photon striking the detector and group them into specified energy bins. These energy bins allow the reconstruction process to take optimal advantage of the beam spectra to form higher quality images than EIDs. In addition, the energy bins can be used to perform routine material decomposition for every scan, with no additional scan time or dose. Finally, because the energy bin thresholds can be tailored for multiple energy ranges, novel reconstruction and material decomposition approaches are possible, opening the door to new clinical applications.

Canon has been in a strong position as a developer of PCCT technology since it welcomed Redlen Technologies as a group company in 2021. Redlen is the global leader in photon counting detector design and manufacturing, suppling photon counting detectors not just for medical imaging, but also for aerospace and security applications.

As we have already begun to see firsthand through our research with NCC, PCCT has the potential to deliver considerable benefits beyond what’s possible with conventional CT detectors. Improved spatial resolution is one of the key benefits of photon-counting detectors. PCCT uses much smaller detector pixels than conventional detectors and also doesn’t require extra septa between detector pixels to prevent cross talk. As a result, PCCT images are fundamentally sharper than conventional CT detectors. PCCT also opens the door to routine Ultra-High Resolution (UHR) scanning.

PCCT is also able to disregard electronic noise, which creates a pulse too low in energy to be counted as signal. Therefore, noise properties, particularly for large patients and low dose applications like screening, are improved with PCCT relative to conventional CT detectors. Alternatively, this noise reduction can be used to significantly reduce radiation exposure to the patient.

In terms of clinical applications, the energy bins of the PCCT system readily enable material decomposition with every scan. This includes routine dual energy applications but also allows for pioneering new clinical applications that can take advantage of multiple energy bins. The spectral capabilities of PCCT, particularly when combined with novel contrast agents, can lead to new diagnostic imaging techniques and treatment evaluation methods.

Our new PCCT detector is constructed using Cadmium Zinc Telluride (CZT), which increases the detector’s ability to capture photons compared to Cadmium Telluride alone, for greater dose efficiency. In addition, Redlen has maximized the active area of the detector to further increase dose efficiency. Finally, because our PCCT detector is compatible with the geometry of Canon Medical’s CT platform, it is straightforward to combine the CZT detector with Canon’s existing CT features and workflow enhancements for maximum utility.

Canon Medical also has unique experience with Ultra-High Resolution CT, having a significant install base of our UHR scanner Aquilion Precision, which provides a wealth of knowledge to best take advantage of PCCT’s UHR capabilities. And, as the industry leader in reconstruction, Canon is in a unique position to best leverage PCCT acquisition advantages in the reconstruction process.