Sci-Fri AM: Imaging - 05: Cone-beam computed tomography for breast biopsy analysis: Simulations

To determine the feasibility and potential utility of cone beam CT on breast biopsies.

CBCT simulations were done with a setup which emulates an MX-20 digital specimen radiography system (Faxitron X-Ray Corporation, Chicago, IL), albeit a DQE = 1 was assumed. The phantom consisted of a 5mm diameter cylinder with a length of 5mm, made up of a homogeneous 50:50 mixture of fibrous and fatty tissue. Small cancerous spheres (lesions) with diameters ranging from 5 to 500 μm were embedded. Projections were acquired at magnification 5 using 26 kV-0.3 mA-3.8 sec beams. Images were reconstructed using a varied number of projections (50, 100, 150, 300). Values of contrast and SNR were calculated between the lesions and nearby regions. Noise was estimated by generating 10 images for each task. Scatter was found to be negligible.

The 50 μm spheres were only visible when at least 150 projections were used, but the 100 μm ones were visible regardless of the number. SNR increased with the number of projections, whereas contrast was insensitive. For ≥100 μm spheres contrast ranged from 0.26 on the outer radial edge to 0.28 nearer the center. The SNRs for 100 μm spheres were above 5 for reconstructions composed of ≥100 projections. Cancerous lesions within a fibrous biopsy may be detectable.

The findings from this simulation study suggest that CBCT for breast biopsy characterization via the MX-20 system could be of potential use to see structures on the order of 100 μm.