Room: AAPM ePoster Library
Purpose: To quantify the impact of sparse-view (96 views) non-uniform angular sampling in short-scan (192-degree) acquisition in upright-position dedicated cone-beam breast computed tomography (UBCT), compared to the conventional 360-degree full-scan (300 views) prone-position dedicated cone-beam breast CT (PBCT).
Methods: In UBCT, the dimensions of the breast in the coronal plane is expected to be asymmetric. Ten cases (four with calcified lesions) with asymmetric dimensions in the coronal plane were selected from an existing de-identified database of PBCT exams to simulate the breasts in upright position with a breast support. Feldkamp-Davis-Kress (FDK) reconstruction of the full-scan PBCT data served as the reference. Projection data encompassing 192-degree short-scan acquisition with non-uniform angular sampling (96 views) were selected retrospectively such that the view sampling is finer for rays traversing along the longer dimension of the breast. An improved version of GPU-based adaptive steepest descent-projection onto convex sets (ASD-POCS) algorithm was used for incomplete data reconstructions. The ASD-POCS hyper-parameters were tuned to match the variance of FDK images. Image quality was quantified by the full-width at half-maximum (FWHM) of calcifications in two orthogonal directions, bias and root-mean-squared-error (RMSE) computed with respect to reference.
Results: The FWHM of calcifications in short-scan, sparse-view, non-uniform sampling UBCT were similar to reference (median difference of 0%), indicating comparable spatial resolution. Regarding RMSE and bias, the observed median of 11.95x10^-6 cm^-1 and 12.02x10^-3 cm^-1 correspond to approximately 0.004% and 4%, respectively, for the range of linear attenuation coefficients expected for breast tissue. The computational time (40 iterations) was less than 7 minutes.
Conclusion: This study indicates the feasibility of a non-uniform angular undersampling acquisition schemes applied to UBCT using compressed sensing-based iterative reconstruction. Therefore, shorter scan times and reduced radiation dose without sacrificing image quality are potentially achievable. Reader studies are planned in the future.
Funding Support, Disclosures, and Conflict of Interest: Supported in part by National Cancer Institute (NCI) of the National Institutes of Health (NIH) grants R01 CA241709 and R21 CA134128. The contents are solely the responsibility of the authors and do not necessarily reflect the official views of the NCI or the NIH.