Recent advances and future trends in medical computed tomography
Dr. Thomas Koehler (Philips Technologie GmbH, Forschungslaboratorien, Hamburg / Rudolf Diesel Industry Fellow, TUM IAS)
X-ray Computed Tomography (CT) is a versatile and widely used medical imaging modality that generates three-dimensional images of the linear x-ray attenuation coefficient. Current CT scanners suffer from a poor contrast-to-noise ratio (CNR) in the soft tissue regime, which demands the additional use of contrast agent and/or rather high x-ray dose for soft-tissue protocols. Strategiesto mitigate this issue will be reviewed; in particular the use of photon counting detectors and iterative reconstruction.
An alternative to improve CNR is the usage of x-ray interferometry (phase contrast imaging) that measures the x-ray deflection rather than its attenuation. Since the first demonstration of the feasibility of using a Talbot-Lau interferometer in the x-ray regime by Franz Pfeiffer in 2006,this technology gained tremendous interest in the medical imaging community. Compared to other interferometric methods, it has the main advantage that a conventional x-ray tube can be used, which is a pre-requisite for a wide use in medical imaging. A further advantage that will be discussed is the simultaneous detection of the deflection, the attenuation, and the loss of coherence of the x-ray beam.