Ideally, the gray level changes in a Contrast-Enhanced Digital Mammography (CEDM) sequence reflect the uptake and wash-out of contrast medium in the breast. While insignificant in standard mammography, gray level variations with time caused both by patient and system related factors, have been observed in clinical CEDM sequences.
We have acquired phantom image series on digital mammography systems using a Mo/Cu anode-filter combination and a tube voltage between 45 and 49 kVp, in order to derive a model for gray level change with time as a function of system parameters. The gray level variation exhibits a fair degree of inter-series repeatability, and strongly depends on the dose received by the detector and timing of the image acquisition series. Moreover, for tissue-equivalent compositions, the relative gray level change with respect to the first image does not depend on the composition.
We designed a calibration procedure that can be used to compensate for the tiny system-dependent signal variation that has been observed. A global reduction of 80-93% of the variation has been demonstrated in sequences acquired on a breast shaped phantom. Local improvement is effective across the whole field of view. When imaging iodine inserts (0.5-2 mg/cm2 concentration), the calibration increases the constancy with time of iodine signal on subtracted sequences by a factor of 4 (median value).
Although screen-film mammography is the current standard for detecting abnormalities in the breast, the sensitivity can range from 40-95 percent. One of the reasons this occurs is because surrounding dense tissues obscure the visualization of cancers. To address this issue, we are investigating contrast digital mammography (CDM), which involves imaging the uptake of a non-ionic iodinated contrast agent with full-field digital mammography to detect and characterize masses in the breast. The technical aspects, including spectral optimization and image processing, for the implementation of CDM have been investigated and a clinical trial is being carried out to study the technique. This article describes an experimental study using an iodine detail phantom in combination with various breast equivalent plastics to evaluate technique parameters used when imaging patients. It is desirable to find the technique parameters that will maximize iodine contrast while delivering a reasonably low dose to the patient. It was found that the contrast can be increased up to 53 percent for thinner breasts by increasing the dose to a level that still remains lower than the dose that would be received by the breast from conventional screening images.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.