Showing papers on "Digital mammography published in 1992"
TL;DR: The author proposed to form the National Digital Mammography Development Group, which will stimulate research in digital mammography and its integration with related technologies: image processing for improved lesion contrast, automated computer-aided diagnosis for enhanced breast cancer detection and characterization, and teleradiology for facilitated radiologic consultation with recognized experts in the field.
Abstract: The National Cancer Institute held a workshop entitled "Breast Imaging: State-of-the-Art and Technologies of the Future" in September 1991. This article describes some of the presentations given at the workshop as well as relevant data in the literature and discusses their implications. The workshop faculty identified digital mammography as the evolving technology with the greatest potential impact on management of breast cancer. On the basis of the workshop findings and literature review, the author proposed to form the National Digital Mammography Development Group, which will stimulate research in digital mammography and its integration with related technologies: image processing for improved lesion contrast, automated computer-aided diagnosis for enhanced breast cancer detection and characterization, and teleradiology for facilitated radiologic consultation with recognized experts in the field. It is expected that the National Digital Mammography Development Group will facilitate transfer of advanced ...
112 citations
TL;DR: The results show that computerized parenchymal classification of digitized mammograms is possible and independent of exposure.
67 citations
TL;DR: Observer performance tests were conducted to study the visibility of malignancies in digital mammography, and no statistical differences were found between judgements based on conventional and digitized mammography.
Abstract: Observer performance tests were conducted to study the visibility of malignancies in digital mammography. Detectabilities of tumours and of microcalcifications were studied separately. For this purpose two sets of images were used, one for tumours consisting of 150 mammograms and one for microcalcifications containing 120 mammograms. Images were digitized at a resolution of 2048 × 2048 pixels using a 12-bit CCD camera. Conventional film mammograms were read on a lightbox, whereas digital mammograms were viewed on a high-resolution monitor. Two experienced radiologists read both sets independently, and ranked their judgements about the presence or absence of tumours or microcalcifications on a confidence-rating scale. Results were evaluated using receiver operating characteristic (ROC) analysis. No statistical differences were found between judgements based on conventional and digitized mammography.
37 citations
22 Sep 1992
TL;DR: It is shown that efficient (nonredundant) representations may be identified from digital mammography and used to enhance specific mammographic features within a continuum of scale space.
Abstract: This paper introduces a novel approach for accomplishing mammographic feature analysis through multiresolution representations We show that efficient (nonredundant) representations may be identified from digital mammography and used to enhance specific mammographic features within a continuum of scale space The multiresolution decomposition of wavelet transforms provides a natural hierarchy in which to embed an interactive paradigm for accomplishing scale space feature analysis Similar to traditional coarse to fine matching strategies, the radiologist may first choose to look for coarse features (eg, dominant mass) within low frequency levels of a wavelet transform and later examine finer features (eg, microcalcifications) at higher frequency levels In addition, features may be extracted by applying geometric constraints within each level of the transform Choosing wavelets (or analyzing functions) that are simultaneously localized in both space and frequency, results in a powerful methodology for image analysis Multiresolution and orientation selectivity, known biological mechanisms in primate vision, are ingrained in wavelet representations and inspire the techniques presented in this paper Our approach includes local analysis of complete multiscale representations Mammograms are reconstructed from wavelet representations, enhanced by linear, exponential and constant weight functions through scale space By improving the visualization of breast pathology we can improve the chances of early detection of breast cancers (improve quality) while requiring less time to evaluate mammograms for most patients (lower costs)© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering Downloading of the abstract is permitted for personal use only
26 citations
Journal Article•
TL;DR: Two improvements in mammography equipment during the last 4 years will greatly affect the practice of mammography during the next decade: dose reduction and improved testing equipment for monitoring the quality of Mammography.
26 citations
02 Apr 1992
TL;DR: In this article, the authors propose a method to solve the problem of unstructured data. But it requires not available data sets, which is not available in this paper, and
Abstract: Abstract not available.
19 citations
01 Jun 1992
TL;DR: The applied kilovoltage for molybdenum and tungsten target x-ray sources with various spectral filters and average breast composition has been optimized with respect to signal-to-noise ratio and absorbed dose and was found to vary between 19 and 29 kVp as breast thickness increased from 4 to 8 cm.
Abstract: X-ray mammography is one of the most demanding radiological techniques, simultaneously requiring excellent image quality and low dose to the breast. In current mammographic practice, both image quality and dose are found to vary over a wide range of values. Previous attempts to define the optimum operating parameters for mammography systems have been limited due to the lack of realistic attenuation coefficients and absorbed dose data. These data are now available, and have been incorporated into an energy transport model which describes the image acquisition process. The model includes measured x-ray spectra and considers beam filtration, breast thickness and composition, lesion size and composition, scatter, grid transmission, and the production and propagation of light in a phosphor-based image receptor. The applied kilovoltage for molybdenum and tungsten target x-ray sources with various spectral filters and average breast composition (50% adipose, 50% fibroglandular) has been optimized with respect to signal-to-noise ratio and absorbed dose and was found to vary between 19 and 29 kVp as breast thickness increased from 4 to 8 cm. Preliminary results for various breast compositions and lesions, and experimental verification of the model are presented. The model may be extended to include either mammographic film or new detector designs for digital mammography.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
9 citations
18 Oct 1992
TL;DR: Computer-aided diagnosis schemes for the detection of breast lesions in digital mammograms are being developed and the authors plan to incorporate the schemes into a dedicated intelligent workstation for use as a second opinion in a mammographic screening program.
Abstract: Computer-aided diagnosis schemes for the detection of breast lesions in digital mammograms are being developed. The detection scheme employs a bilateral-subtraction technique that is based on the normal symmetry between the left and right breast images. The presence of asymmetries indicates a possible lesion. Feature-analysis techniques are then used to reduce the number of false-positive detections. In addition, characterization methods are being developed to aid in the benign/malignant decision. The authors plan to incorporate the schemes into a dedicated intelligent workstation for use as a second opinion in a mammographic screening program. Output from the computer would be displayed as an aid, leaving the final diagnostic decision to the radiologist. >
8 citations
TL;DR: A block adaptive coding algorithm based on the discrete cosine transform to compress digitized mammograms is described and it is shown that data compression with rather high compression rates is possible in the mammography field.
Abstract: The need for storage, transmission, and archiving of medical images has led researchers to develop adaptive and efficient data compression techniques. Among medical images, x-ray radiographs of the breast are especially difficult to process because of their particularly low contrast and very fine structures. A block adaptive coding algorithm based on the discrete cosine transform to compress digitized mammograms is described. A homogeneous repartition of the degradation in the decoded images is obtained using a spatially adaptive threshold. This threshold depends on the coding error associated with each block of the image. The proposed method is tested on a limited number of pathological mammograms including opacities and microcalcifications. A comparative visual analysis is performed between the original and the decoded images. Finally, it is shown that data compression with rather high compression rates (11 to 26) is possible in the mammography field.
4 citations
01 Nov 1992
TL;DR: A model of the breast imaging process is constructed and results show that molybdenum-anode, molyBdenum -filtered x-ray spectra are ill-suited for digital mammography.
Abstract: Screening mammography is a radiological procedure requiring the highest possible image quality at the lowest possible dose. It is widely recognized that digital image acquisition, computer assisted diagnosis, and scientific visualization can provide substantial improvement in mammography. For such systems, much of what is accepted as best practice with today`s film/screen/lightbox systems will become inappropriate. A complete system design is required. We have constructed a model of the breast imaging process. These results show that molybdenum-anode, molybdenum-filtered x-ray spectra are ill-suited for digital mammography. An x-ray spectrum rich in 22-to 25-keV photons is needed.
1 citations
11 Mar 1992
TL;DR: The aim of this project was to establish the specification for an effective digital mammography review station and investigate the suitability of some of the recent developments in both hardware and software for use in a clinical environment.
Abstract: The aim of this project was to establish the specification for an effective digital mammography review station and investigate the suitability of some of the recent developments in both hardware and software for use in a clinical environment. As the review station is still under development digital mammography images from the CR system are transferred to the laboratory on a weekly basis via a fibre optic data link. These images are then stored on erasable optical discs for reviewing at a later date. Eventually it is hoped to provide a clinical service via the review station.
25 Oct 1992
TL;DR: These four distinct methods for noise removal in mammography images, along with two general noise removal techniques, and the three standard techniques of mean, median, and k-nearest neighbors, are compared.
Abstract: Four distinct methods have recently been proposed for noise removal in mammography images: a tree-structured iterative selective median filter, a selective median filter, an improved median filter, and a weighted majority minimum range filter. These four methods, along with two general noise removal techniques, and the three standard techniques of mean, median, and k-nearest neighbors, are compared. A simulated mammography phantom to which varying levels of binary and Gaussian noise have been added is used. Two methods of measuring noise, a normalized root mean squared error and a signal-to-noise ratio, were used to compare and rank the nine different filters. There are no clear winners in all categories. Further research is needed to discover whether, by combining the best features of the best filters, one can produce a significantly improved method of noise removal. >