Erik Fredenberg MSC, Abstract Co-Author: Research collaboration, Sectra AB, Stockholm, Sweden

Magnus Aslund PhD, Presenter: Stockholder, Sectra AB Employee, Sectra AB

Felix Diekmann MD, Abstract Co-Author: Research grant, Bayer AG Research grant, General Electric Company Research grant, Sectra AB

Magnus Hemmendorff MSc, Abstract Co-Author: Employee, Sectra AB

Björn Cederström PhD, Abstract Co-Author: Stockholder, Sectra AB

Mats Danielsson PhD, Abstract Co-Author: Stockholder, Sectra AB, Linkoping, Sweden Employee, Sectra AB, Linkoping, Sweden

To evaluate the benefit of material decomposition using a photon counting spectral detector for breast imaging.

A photon counting spectral detector has been developed within the EU funded Highrex project based on the scanning multislit geometry from Sectra (Smidesvägen 5, Sweden). It is used in clinical trials to evaluate: photon counting tomosynthesis; spectral tomosynthesis; and contrast-enhanced spectral tomosynthesis. The detector has a high- and a low-energy photon counter, which allow for material decomposition in addition to standard absorption imaging. The imaging performance is characterized using MTF and NNPS. The energy resolution is measured by scanning the energy thresholds over several bremsstrahlung spectra. A theoretical model of the detector's spectral performance has been developed, which uses the measured MTF, NNPS and threshold scans as input. The model is used to predict the system performance using an ideal observer and a generalized form of the DQE that includes the anatomical noise. Contrast-detail images of an anatomical clutter phantom with iodinated contrast agent are investigated and related to the model in a two-dimensional geometry.  

Using IEC 62220-1-2 methodology the DQE(0) was 73% with the counters summed. Model prediction of the iodine contrast in subtracted images deviated less than 20%, which is within the experimental uncertainties, e.g. the actual iodine concentration. For a 5 mm diameter iodine cylinder, ideal observer performance with the generalized DQE is superior in the decomposed image compared to the absorption image, which is in agreement with phantom images.  

The standardized DQE measurements show that the spectral detector is highly efficient with low electronic noise, which combined with the efficient scatter rejection makes it suitable for spectral imaging. The model agrees well with experimental data. Contrast-enhanced spectral imaging is feasible in the investigated two-dimensional geometry. This motivates extending model and experiments, e.g. to the tomosynthesis geometry.          

Spectral breast imaging may increase sensitivity and specificity at lower radiation dose compared to absorption imaging in projection or tomosynthesis geometry.

Fredenberg, E, Aslund, M, Diekmann, F, Hemmendorff, M, Cederström, B, Danielsson, M, Evaluation of Photon Counting Spectral Breast Imaging Performance.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8010781.html