|[Frontiers in Bioscience 1, b5-7, August 1, 1996]|
COMPARISON OF CONTRAST DETAIL CURVES OF FULL FIELD DIGITAL
WITH SCREEN FILM BREAST PHANTOM IMAGES
Aparna Visweswaran, M.D., Hong Liu, Ph.D., Laurie L. Fajardo, M.D., Gia A. DeAngelis, M.D.
Department of Radiology, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA
Received 05/15/96; Accepted 07/08/96; On-line 08/01/96
RESULTS & CONCLUSIONS
For both the analog and digital images, curves relating the detail diameters and the minimal detectable disk thickness are shown in Figure 3.The resulting curves demonstrate that the prototype digital mam-mography system imaged smaller and lower contrast phantom objects than the screen-film system. For example, at an object diameter of 3.2mm, the minimum thickness at which the object was detectable by the digital system was 0.08µm. At the same diameter, the object was not detected by the screen-film system until the thickness reached 0.10µm. At a diameter of 0.5mm, the minimal detectable thickness was 0.25µm for the digital system and 0.31µm for the screen-film system. For an object diameter of 0.16mm, the minimal detectable thickness for the digital system was 1.0µm and for the screen-film system it was 1.6µm.
Fig. 3. The contrast-detail curves of both the digital and the screen-film systems. Both the digital image and the analog screen-film images were acquired at 194 mRad mean glandular dose.
The prototype unit investigated in this study is one of the first full breast digital mammography systems undergoing clinical evaluation. The results of our preliminary technical evaluation show superior detectability using the digital mammography system, inspite of its lower spatial resolution (about 7 cycles per millimeter) compared with the screen-film system (about 16 cycles per millimeter). Early results from other development programs for digital mammographic detectors have also verified that spatial resolution is only one of several factors which determine the ability of an imaging system to resolve small objects (12). Thus, the superior contrast resolution and potentially lower noise characteristics of a well-designed digital breast imaging system may compensate for a lesser spatial resolution.
Many innovative approaches to full breast digital imaging are being pursued currently. Implementation of such systems will result in mammograms of higher quality than those presently available. The advantages of better image quality, real time display, ease of image management and access to digitally based image manipulation and transfer technologies may ultimately enable full breast digital mammography to replace screen-film mammography.
In light of the magnitude of the breast cancer problem and the improvement in prognosis associated with efficient, early detection, digital mammography may become the standard modality in the near future.