A breast-specific, negligible-dose scatter correction technique for dedicated cone-beam breast CT: a physics-based approach to improve Hounsfield Unit accuracy

Abstract

The purpose of this research was to develop a method to correct the cupping artifact caused from x-ray scattering and to achieve consistent Hounsfield Unit (HU) values of breast tissues for a dedicated breast CT (bCT) system. The use of a beam passing array (BPA) composed of parallel-holes has been previously proposed for scatter correction in various imaging applications. In this study, we first verified the efficacy and accuracy using BPA to measure the scatter signal on a cone-beam bCT system. A systematic scatter correction approach was then developed by modeling the scatter-to-primary ratio (SPR) in projection images acquired with and without BPA. To quantitatively evaluate the improved accuracy of HU values, different breast tissue-equivalent phantoms were scanned and radially averaged HU profiles through reconstructed planes were evaluated. The dependency of the correction method on object size and number of projections was studied. A simplified application of the proposed method on five clinical patient scans was performed to demonstrate efficacy. For the typical 10-18 cm breast diameters seen in the bCT application, the proposed method can effectively correct for the cupping artifact and reduce the variation of HU values of breast equivalent material from 150 to 40 HU. The measured HU values of 100% glandular tissue, 50/50 glandular/adipose tissue, and 100% adipose tissue were approximately 46, -35, and -94, respectively. It was found that only six BPA projections were necessary to accurately implement this method, and the additional dose requirement is less than 1% of the exam dose. The proposed method can effectively correct for the cupping artifact caused from x-ray scattering and retain consistent HU values of breast tissues.

Characterization of CT Hounsfield Units for 3D acquisition trajectories on a dedicated breast CT system

“…3), and compared to the Yang et al reported values [27]. Yang et al reported that the measured HU values of 100% glandular, 50:50 glandular: adipose and 100% adipose tissue were approximately 46, −35 HU, and −94 HU, respectively; note that the variability of their system was not reported.…”

“…Yang et al [27] have characterized the performance of a new scatter correction method for BCT, wherein they also investigate HU accuracy for different breast tissue compositions. Although those HU values are specific to their BCT system, the individual HU values can be used for comparison with the water:methanol HU values measured on our system (Table 5).…”

“… Average measured HU for glandular: adipose (G:A) breast tissue compositions, measured by Yang et al [27] are also reported here for comparison. …”

Augmented Reality: Advances in Diagnostic Imaging

“…Tissue segmentation and subtraction can isolate the tumor's outer shell for precise characterization of how the tumor changes over time as compared to its previous appearance. Improvements in the breast CT's spatial resolution [30,31] and contrast resolution [32] are foreseeable and will provide larger databases and an even greater importance of image optimization, possibly with AR/VR imaging.…”

Library-based scatter correction for dedicated cone beam breast CT: a feasibility study

“…Researchers have developed similar methods in CBBCT for image quality improvement. For example, Ioannis [3] and Yang [4] proposed to insert a beam stop array between the x-ray source and the object for scatter measurement, in a scan additional to the conventional CBBCT scan. Chen [5] demonstrated accurate scatter estimation via Monte Carlo (MC) simulation and thus showed the potential of MC-based scatter correction at the cost of intensive computation.…”