DigiMAM:A Sensitive Early Detection System for Breast Cancer

Institution: Nova R & D, Inc.
Investigator(s): Tumay Tumer, Ph.D. -
Award Cycle: 1996 (Cycle II) Grant #: 2RB-0103 Award: $126,280
Award Type: Research Project Awards
Research Priorities
Detection, Prognosis and Treatment>Imaging, Biomarkers, and Molecular Pathology: improving detection and diagnosis



Initial Award Abstract (1996)
Mammography has attained widespread acceptance as an important tool for the screening and diagnosis of breast cancer. In traditional mammography, the breast is x-rayed and the X-rays transmitted through the breast are detected and recorded by an 'image receptor". Current systems use phosphor screens and photographic film as the receptor. The image is then processed for display on a viewbox. In such film-based mammography, processing of the image is a chemical procedure carried out in a darkroom and there is little flexibility in how the film can be processed. The contrast of the image (which is one factor in determining how well different features within the breast may be seen) on film has a narrow range, which is fixed by the film type and processing conditions (time, temperature and chemical activity). Thus, a particular film image cannot be reprocessed to get a better image, and getting another (better) image requires re-exposure of the patient to X rays. We propose to build prototype solid state pixel detectors as part of a larger system that would replace film (by having the x-ray data go first into a computer in "digital form" which would then generate the image on screen instead of only creating a film image). In addition, we will study the pixel effectiveness for application to digital mammography.

Acquisition of mammograms in digital form offers the possibility of overcoming the limitations of film imaging since, once the image data is in the computer, it can be easily manipulated to obtain the best possible image. In fact, there are several ways in which the performance could be enhanced and the sensitivity of breast cancer detection and diagnosis improved. Such improvements may be in terms of higher contrast, better image resolution (enabling features in the breast to be more easily seen), and the reduction of "noise" (i.e., unwanted electrical signals) in the system. The computer-based images can also be sent through networks for expert consultation.

These improvements will initially come from acquisition of digital images using the more efficient and higher contrast solid state x-ray crystal detector. Detector elements will be laid down on these crystals so that an image of the X-rays passing through the patient's breast can be produced. These detectors directly convert x-ray energy into electrons (which are used to form the digital images) and can provide superior images with high resolution and low "noise". These detectors also absorb nearly 100% of the X-rays transmitted through the breast, compared to less than 50% for the x-ray films presently used for mammography. This offers the potential for sharper images of the structures in the breast at less than half the radiation dose than currently required. If development of the detectors is successful, we would, using other funding, then line these detectors into a narrow column to scan underneath the patient's breast.

In summary, the improved image resolution and exceptionally good contrast we expect to achieve would result in more accurate images of breast anatomy (using less than half the radiation dose), and therefore more accurate detection of breast cancer.


Final Report (1997)
Each year in the U.S., approximately 180,000 women are diagnosed with breast cancer and 46,000 women die of this disease. In all, 10% - 11% of all women can expect to be affected by breast cancer at some time during their lives. The causes of most breast cancers are not yet understood. Screening and early diagnosis are currently the most effective ways to reduce mortality from this disease.

Mammography has attained widespread acceptance as an important tool for the screening and diagnosis of breast cancer. Although mammography is quite effective in helping to detect breast cancer, there are several ways in which the performance could be improved to possibly increase the sensitivity of breast cancer detection and diagnosis. Such improvements may be in terms of higher contrast, better image resolution, and the reduction in the noise of the imaging system.

In mammography, an x-ray beam is directed at the breast and the X rays which pass through the breast are detected and recorded by an "image receptor". Traditional mammography systems use phosphor screens and photographic film as the receptor. The image is then processed as an x-ray film for display on a viewbox. In such film-based mammography, processing is a chemical procedure in the darkroom and flexibility of processing parameters is very limited. The contrast of the image on film has a narrow range, which is fixed with the film type and processing conditions (time, temperature and chemical activity). Should the image need to be altered, for example, should the contrast on the film not be the best for the physician viewing the film, altering the image requires re-exposure of the patient to x-rays to obtain another film. In a digitally recorded mammogram such alterations can be made on the computer and re-exposure of the patient to X rays is avoided.

Acquisition of mammograms in digital form offers the possibility of overcoming the limitations of film imaging. Improvements derive from digital acquisition of images (that is, as computer data and not a film) using a more efficient and higher contrast x-ray detector technology. Specifically, in this project we propose the development of a crystal detector made from the combination of cadmium, zinc and telluride materials. We are studying the fabrication of a two-dimensional array of detector elements on these crystals so that an image of the x-rays passing through the patient's breast can be produced. These detectors directly convert x-ray energy into electrons and is expected to provide an image with smaller visible detail, using less radiation, and showing less interference on the image from the imaging device itself ("noise") compared to the present x-ray films used for mammography.

These detectors will be lined into a narrow column to scan underneath the patientís breast. This geometry does not need a grid system used in present x-ray film mammography which requires about 3 times higher x-ray dose to the patient. The improved image resolution and exceptionally good contrast can produce more accurate images of breast anatomy, which in turn is expected to result in accurate detection of breast cancer, particularly in women with dense breasts which is a problem in present x-ray film based mammography systems. The higher sensitivity and the elimination of the grid is also expected to lead to the application of lower radiation dose to the patient.

If this study is successful NOVA expects to obtain funding for the development of pixel detectors from this material for a commercial digital mammography system called DigiMAMô. The DigiMAMô systems are expected to be used by doctors, medical centers and hospitals for high sensitivity and high contrast breast cancer screening and diagnosis.