Counting Every Photon: How Photon-Counting CT Is Redefining Clarity in Radiology
Standard CT scanners have continued to be relevant in the practice of radiologists in many regions. But the normal detectors convert X-ray images to light that takes two steps of transformation. This way causes the presence of the electronic noise and prevents achieving the clear images. Photon counting CT (PCCT) can be called the most prominent advancement in the domain of CT technology since it allows converting X-ray pictures immediately into electric signals providing an opportunity to record the energy of each photon separately.
Ordinary detectors require a septum between the elements of the detector, adding the electronic noise. The detectors based on photon-counting technology do not need a septum and eliminate subthreshold noise making them more efficient and allowing the use of more compact pixel sizes in the installation of detectors. Hence the good spatial resolution has been achieved without the significant rise of noise in the images.
Thanks to the efficiency of the dose used, PCCT can achieve the same image quality as the conventional CT but with a lesser dose of radiation. One study reported that the
contrast-enhanced abdominal CT resulted in 32% lower radiation dose while maintaining comparable image quality (Onishi et al., 2024). For patients with bigger body types, PCCT has
shown a reduction in contrast volume by 27% and a maximum dose decrease of up to 34% in terms of radiation received.
In ultra-high resolution mode, PCCT can yield images as thin as 0.2mm, which is very helpful in visualizing very small structures like tiny blood vessels, pancreatic tumors, and tiny stones in the kidneys. It can also produce monochromatic virtual images from 40 keV to 190 keV in a single scan. Lower energies of keV enhance the contrast between a tumor and surrounding tissues and can be used to search for very small or low-contrast tumors in the liver and pancreas.
PCCT is hardly clinically available, and optimal scan settings are being evaluated, while more evidence still has to be provided to show PCCT's advantages in comparison with conventional CT for detecting disease (Onishi et al., 2024). Radiology departments will cautiously adopt it through various carefully devised protocols with ongoing research on it.
In conclusion, Photon-counting CT demonstrates a huge leap in diagnostic imaging since it offers sharp detail, better contrast as well as lower doses of radiation and contrast. As research grows, PCCT may become a routine tool that helps radiologists see better while keeping patients safer.
References
Onishi, H., Tsuboyama, T., Nakamoto, A., Ota, T., Fukui, H., Tatsumi, M., Honda, T., Kiso, K.,
Matsumoto, S., Kaketaka, K., Enchi, Y., Kawabata, S., Nakasone, S., & Tomiyama, N. (2024). Photon-counting CT: Technical features and clinical impact on abdominal imaging. Abdominal Radiology, 49(12), 4383–4399. https://doi.org/10.1007/s00261-024-04414-5
Schwartz, F. R., Sodickson, A. D., Pickhardt, P. J., Sahani, D. V., Lev, M. H., & Gupta, R. (2025).
Photon-counting CT: Technology, current and potential future clinical applications, overview of approved systems and those in various stages of research and development.
Comments