Jan David Kuttig DIPLPHYS, Presenter: Nothing to Disclose

Christian Steiding MSc, Abstract Co-Author: Employee, CT Imaging GmbH

Daniel Kolditz PhD, Abstract Co-Author: Employee, CT Imaging GmbH

Willi A. Kalender PhD, Abstract Co-Author: Consultant, Siemens AG Consultant, Bayer AG Founder, CT Imaging GmbH Scientific Advisor, CT Imaging GmbH CEO, CT Imaging GmbH

To investigate and to motivate the application of cadmium telluride (CdTe) detector technology for dedicated breast CT (BCT).

We compared two detector technologies: a standard flat panel scintillation detector with 70 µm and 208 µm thick gadolinium oxysulfide (GOS) scintillators and a photon-counting cadmium telluride (CdTe) detector with 1000 µm sensor thickness. The GOS detector had a pixel size of 75 µm, the CdTe detector a pixel size of 100 µm. In order to evaluate the detective quantum efficiency (DQE) the modulation transfer function (MTF) and the noise power spectrum (NPS) were determined initially. A tantalum phantom providing a 10 µm slit was used for both MTF simulations and MTF measurements. To improve the reliability of the NPS estimates, the noise characteristics of difference images were evaluated by using two independent flat image stacks. All measurements and simulations were performed at a tube voltage of 60 kV, suitable for clinical breast CT.

The simulations for GOS scintillator thicknesses of 70 µm and 208 µm delivered 10% MTF values of 6.5 lp/mm and 3.1 lp/mm, and DQE values of 18% and 45%, respectively. The CdTe detector went beyond this: the 10% MTF value was 9.5 lp/mm and DQE values of 98% were reached in the simulations. The measured MTF and DQE values were in good agreement with the simulations. Depending on the scintillator thickness, the GOS detector is either optimized for resolution (70 µm GOS) or efficiency (208 µm GOS). In contrast, the detector with 1000 µm CdTe offered both improved spatial resolution and significantly higher efficiency.

The photon-counting CdTe detector allows for significant dose reduction compared to the intensity-integrating GOS scintillation detector as shown by simulations and measurements. Our comparative evaluation of both technologies indicates that a potential dose saving of up to 80% may be possible by using CdTe detectors.

The use of CdTe detector technology for BCT appears to be an important step to keep patient dose as low as reasonably achievable.

Kuttig, J, Steiding, C, Kolditz, D, Kalender, W, Detective Quantum Efficiency Investigation Demonstrates High Dose Saving Potential for Breast CT Using a Cadmium Telluride Detector.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14017066.html