Abstract
Small microcalcifications essential to the early detection of breast cancer may be obscured by overlapping tissue structures. Dual-energy digital mammography (DEDM), where separate low-and high-energy images are acquired and synthesized to cancel the tissue structures, may improve the ability to detect and visualize microcalcifications. The investigation of DEDM began with a signal-to noise ratio analysis to estimate and relate the noise level in the dual-energy calcification signals to the x-ray spectra, microcalcification size, tissue composition and breast thickness. We investigated various inverse-mapping functions, both linear and non-linear, to estimate the calcification thickness from low- and high-energy measurements. Transmission (calibration) measurements made at two different kVp values for variable aluminum thickness (to simulate calcifications) and variable glandular-tissue ratio for a fixed total tissue thickness were used to determine the coefficients of the inverse-mapping functions by a least-squares analysis. We implemented and evaluated the DEDM technique under narrow-beam geometry. Phantoms, used in the evaluation, were constructed by placing different aluminum strips over breast-tissue-equivalent materials of different compositions. The resulting phantom images consisted of four distinct regions, each with a different combination of aluminum thickness and tissue composition. DEDM with non-linear inverse-mapping functions could successfully cancel the contrast of the tissue-structure background to better visualize the overlapping aluminum strip. We are currently in the process of translating our DEDM techniques into full-field imaging. We have designed special phantoms with variable glandular ratios and variable calcification thicknesses for evaluation of the full-field dual-energy calcification images.
Original language | English (US) |
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Pages (from-to) | 751-760 |
Number of pages | 10 |
Journal | Proceedings of SPIE - The International Society for Optical Engineering |
Volume | 5368 |
Issue number | 2 |
DOIs | |
State | Published - 2004 |
Event | Medical Imaging 2004: Physics of Medical Imaging - San Diego, CA, United States Duration: Feb 15 2004 → Feb 17 2004 |
Keywords
- Calcifications
- Digital imaging
- Dual-energy
- Inverse-mapping
- Mammography
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering