Exploring the spectrum: Advances and potential for Spectral CT
Global research and advanced development teams from Philips Healthcare, together with clinical investigators from around the world, are examining how to further enhance the diagnostic capabilities of CT in a new research area known as Spectral CT.
Just as any child with a prism can demonstrate, white light consists of a spectrum of colors. In other words, white light is polychromatic. The x-ray beam used in CT scanners is also polychromatic. Advances in CT detector technology can now take advantage of the polychromatic nature of the x-ray spectrum when creating CT images. Our goal is to use the additional information inherent in the full spectrum of an x-ray beam to add clinical value to CT. A number of potential clinical areas have already been identified and show early promise.
With prototype detector technology from Philips*, spectral CT can already facilitate better discrimination of tissues, making it easier to differentiate between materials, such as tissues containing calcium and iodine, that can appear similar on traditional, monochromatic CT techniques. It also can potentially increase diagnostic accuracy in a wide range of clinical applications, such as enhancing the conspicuity and detection of smaller vessels associated with sub-segmental pulmonary emboli.
Splitting the x-ray beam into its component energies, or spectrum, by advanced detection technology is the secret to Philips Spectral CT approach. A dual energy detection system depicted above has been in clinical operation since 2005. More advanced, multi-energy or photon counting detection systems are in prototype form. Note: The separation of the detection layers is for illustrative purposes only. In reality the detector layers are in physical contact, one with the other.
Spectral CT may have other advantages as well. Patients may benefit not only from images that facilitate more confident diagnosis, but potentially from decreased x-ray radiation dose. Using spectral information to create virtual non-contrast images may eliminate traditional non-contrast acquisitions in some studies. Eliminating these non-contrast images can also have an economic benefit, as it shortens exams and could lead to increased patient throughput.
Another important clinical and economic benefit is that spectral CT is hypothesized to increase imaging sensitivity to contrast agents, thereby enabling the detection of lower (more localized) concentrations and decreasing the injected volume. Improving the sensitivity of CT to low amounts of contrast agent may enable the use of novel contrast agents, allowing CT to provide molecular and physiological information.
As the number of clinically useful applications expands, the promise of spectral CT for simplified diagnosis and therapeutic guidance grows. Today, most experts agree that we are only beginning to understand its full potential.
To learn more, please click here to request white paper entitled “Exploring the Spectrum: Advances and potential for Spectral CT.” This paper provides a brief overview of spectral CT principles, discusses four techniques for acquiring spectral CT data, and summarizes a range of groundbreaking spectral CT advances and applications.
* Works-in-progress – pending commercial availability and regulatory approval.