A fast scatter field estimator for digital breast tomosynthesis

Abstract

Digital breast tomosynthesis (DBT) is a promising alternative approach to overcome the limitations of tissue superposition found in full-field 2D digital mammography. However, due to the absence of anti-scatter grids in DBT, accurate scatter estimation for each projection is necessary for modelling the image reconstruction stage. In this work we identify the limitations associated with scatter estimation using spatial invariant scatter kernels, in particular at the edge region where such methods result in scatter overestimation. Such approaches show an overestimation of scatter-to-primary ratio of over 50% at the edges when compared with results from direct Monte Carlo simulation. This problem was found to increase with projection angle. Simulation work presented here shows that this overestimation in scatter is largely due to air gap between the lower curved breast edge and the detector. We propose a new fast, accurate scatter field estimator for use in DBT which not only considers the breast thickness and primary incidence angle, but also accounts for scatter exiting the breast edge region and traversing an air gap prior to absorption in the detector. The new proposed scatter estimator represents an alternative approach to this problem which reduces discrepancies at the edge of a breast phantom. Moreover, the time required for generating scatter has dropped from approximately 12 hours using Monte Carlo simulations for 10 10 photons to just a few minutes per projection. The insertion of scatter from the compression paddle to aforementioned methodologies is also discussed.

Simulation of 3D DLA masses in digital breast tomosynthesis

“…The scatter to primary ratio used here was calculated using the validated Monte Carlo Model of Diaz et al 17 for the Hologic Selenia Dimension Tomosynthesis system geometry for a set of breast thicknesses, glandularity and different projection angles. The resulting values were tabulated so that the SPR for any breast thickness, glandularity, and projection angle could be found by interpolation (block 13,14).…”

A Modelling Framework for Evaluation of 2D-Mammography and Breast Tomosynthesis Systems

“…One mammogram and 15 tomosynthesis primary projections were acquired using the ray tracing tool [9], Beer's law and attenuation coefficients [10] corresponding to the appropriate X-ray spectrum [11], at different angles in accord with the Hologic specification. The information such as thickness, glandularity, and air gap that is required for the selection of appropriate scatter kernels [12] was extracted from the ray tracing results and fed into the tool, for addition of scatter to the primary images. Using the MTF and noise model [13], a system MTF was applied to the projections corresponding to the detector and system, and noise was added to the projections corresponding to a specific dose.…”

Breast CT image simulation framework for optimisation of lesion visualisation

“…flat panel detector), scattered radiation can be added at this point. Due to the large computational time required by MC simulations, a kernel-based approach is proposed to estimate the scattered radiation [6]. On the other hand, when simulating a slit detector geometry (e.g.…”