John W. Garrett MS, Presenter: Nothing to Disclose

Wei Zhao PhD, Abstract Co-Author: Nothing to Disclose

Yongshuai Ge, Abstract Co-Author: Nothing to Disclose

Ke Li PhD, Abstract Co-Author: Nothing to Disclose

Guang-Hong Chen PhD, Abstract Co-Author: Research funded, General Electric Company Research funded, Siemens AG Research funded, Varian Medical Systems, Inc Research funded, Hologic, Inc

Grating-based X-ray differential phase contrast imaging (DPCI) has the potential to add two additional imaging contrasts (in addition to x-ray attenuation) to digital breast tomosynthesis (DBT): differential phase contrast and dark field. An analyzer grating used in this method is characterized by a high aspect ratio and essentially acts as a one-dimensional anti-scatter grid. The purpose of this work is to determine the impact of this grating on scatter rejection and overall image quality of absorption DBT images.

Monte-Carlo modelling (GATE 6.2.0 simulation toolkit) was used to predict the scatter performance of a DBT system (Hologic Selenia Dimensions, Hologic, Inc.) with and without an analyzer grating present. A novel in-house design for the G2 grating was used; for simulation, a 40% duty cycle was used for the grating with a depth of 50 µm Au. The width of the gold septa was 2.12 µm. A 5 cm-thick phantom simulating 50/50 adipose/glandular breast tissue was placed on the breast support 2.5 cm above the detector. The scatter-to-primary ratio (SPR) and contrast-to-noise ratio (CNR) were quantified with and without the presence of the analyzer grating in the x-ray beam. Experimental validation with the same system setup was performed to validate the SPR and CNR values without the gratings.

The Monte-Carlo prediction for the SPR in the 5 cm thick breast matched the measured values within about 10% across the image field of view. The introduction of the analyzer grating stopped about 37% of post-phantom photons while reducing the SPR from 0.45 to 0.20. This resulted in an equivalent CNR to that without the grating for a given exposure. No grid lines were observed in the measured image due to the ultra-fine pitch of the grating when compared with the detector pixel size. The one-dimensional grating structure that was aligned parallel to the chest wall so as not to block additional x-rays incident from oblique angles during the DBT data acquisition.

A carefully designed Talbot-Lau interferometer can be introduced in existing DBT systems to provide two additional imaging contrast mechanisms without degradation the imaging performance of absorption contrast DBT imaging.

The introduction of a Talbot-Lau interferometer in a digital breast tomosynthesis system provides additional diagnostic information without degrading imaging performance for a fixed exposure.

Garrett, J, Zhao, W, Ge, Y, Li, K, Chen, G, Grating Based Differential Phase Contrast Imaging in Digital Breast Tomosynthesis: Imaging Performance with an Analyzer Grating.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14008229.html