Early in their technology collaboration, Siemens Healthineers asked CEA-Leti to design, integrate, manufacture and test a new generation of PCDM based on Cadmium Telluride (CdTe) to reach an enough maturity for being integrated into a X-ray computed tomography (CT) scanner prototype. Unlike conventional detector, which uses the total sum of the photons received to generate grey level images of the density of the anatomical structures being observed, CEA Leti's detector module counts in real time a large number of photons with very high spatial resolution and classifies them in two categories: low energy and high energy. And therein lies the advance!
CEA-Leti X-Ray Photon-Counting Detector Module (PCDM)
"The idea of Siemens Healthineers to integrate PCDMs into the future generation of X-ray CT scanners was new and no available technology existed when CEA Leti began working on this," said Loick Verger, the industrial partnership manager for X-ray imaging at CEA Leti. "The technical challenge – low noise at a very high counting rate, two energy classifications and sufficient maturity to be integrated in an X-ray CT scanner – was tremendous."
Photon-counting detector modules target improved medical diagnoses
Monochrome X-ray radiographic images that show the density of the body's organs are valuable. But adding color which can be used to diagnose very precisely certain diseases will make X-ray images even better. This is one of the novel features which might be offered by the new generation of X-ray detector currently being tested by the Mayo Clinic in the United States and built on a CEA Leti detector module technology.
- PCDMs photon counting feature improves the contrast-to-noise ratio of the image.
- The energy classification of the detected photons can be exploited to produce a "color" image that allows a precise determination of the atomic number of any chemical elements present in the body. This capability can also allow the use of contrast agents or nanoparticles, which are vital for screening and understanding of certain diseases.
- Finally, the very high spatial resolution of the detector modules generates more spatially resolved images of very fine structures, such as small airways in the lung, trabeculae in bones, and thin wires in coronary stents compared to current scanner technology
"The successful early collaboration with CEA-Leti allowed Siemens Healthineers to prototype what the med tech company sees as the future of detectors for whole-body CT," said Jean-Michel Casagrande, the project manager for medical X-ray imaging at CEA-Leti.
Researchers at the Mayo Clinic have evaluated the performance of X-ray CT scanner prototype built with CEA Leti's PCDM in phantoms, cadavers, animals, and humans. The initial feedback from physicians testing the detector has been very encouraging !
"Researchers at the Mayo Clinic in the U.S. have evaluated Siemens Healthineers' photon-counting detector system's performance in phantoms, cadavers, animals and humans. Images of more than 300 patients produced with this technology consistently demonstrated that the theoretical benefits of this type of detector technology yield a number of important clinical benefits," said Cynthia McCollough, professor of Medical Physics and Biomedical Engineering at the Mayo Clinic. Publications by our research team have shown improved spatial resolution, decreased radiation or iodine contrast dose requirements and decreased levels of image noise and artifacts. Additionally, the ability to simultaneously acquire multiple 150-micron-resolution datasets, each representing a different energy spectrum, is anticipated to lead to new clinical applications"
Recent publications* by the Mayo Clinic team highlight certain advantages for patients, such as the possibility of reducing the radiation dose received by up to 85% in the case of high spatial resolution imaging of the inner ear and surrounding bone. "It is extremely rewarding to look at the exquisite images that can be made using the technologies of the detector module that we developed," Verger said. "Seeing for ourselves the clinical benefits of all our R&D efforts motivates our entire team to continue our development of cutting-edge technologies that improve the lives of others."
*2020 Rajendran et al.