Showing papers on "Digital mammography published in 1989"

Characterization Of Mammographic Parenchymal Pattern By Fractal Dimension

Abstract: Mammographic parenchymal pattern has been associated with risk of developing breast cancer. Currently, these patterns are classified subjectively by radiologists according to "Wolfe grade", as N, P1, P2, or DY. Such broad classifications have limited applicability for the assessment of subtle changes which may occur, for example, in long term studies of women at high risk for breast cancer. For such work, a consistent, quantitative, observer-independent method of characterization is required. We have been developing such a method based on the use of "fractals". We have applied techniques of calculating fractal dimension to digitized mammograms. To evaluate our technique, we are measuring the degree of correlation between the fractal classification of images and their mammographic patterns as assessed by radiologists. Preliminary results have shown significant correlation between the fractal-based and radiologist-based assessments.

Detection of early breast cancer: an overview and future prospects.

Abstract: Detection and treatment of breast cancer at an early stage is the only method with proven potential for lowering the death rate from this disease Detection of early breast cancer is promoted by the American Cancer Society, American College of Radiology, and Canadian Association of Radiologists by encouraging the regular use of three types of screening: breast self-examination, clinical breast examination, and mammography When all factors are considered, it has been convincingly demonstrated that the potential benefits of mammography far outweigh the minimal, clinically undetected radiation risk incurred by the examination New technologies, such as computed tomography, magnetic resonance imaging, transillumination diaphanography, ultrasound, thermography, and digital subtraction angiography might offer a wide selection for patient examination However, none of these procedures, in its present form, is expected to replace mammography as the first-line imaging technique for the detection and diagnosis of benign and malignant breast lesions Breast cancer is detected now, in most cases, via casual or informed breast self-examination This first-line of detection is not sufficient, since most tumors may metastasize before they reach a palpable size Mammography generally shows up tumors no smaller than 1-cm diameter, which in many cases have already metastasized The more advanced imaging modalities in their current forms suffer from a number of drawbacks that give them a lower overall detection rate than mammography Understandably, improving breast imaging modalities is a great challenge to diagnostic radiology The purpose of this article is to provide a comprehensive overview of the detection of early breast cancer It briefly discusses the understanding of breast cancer, its incidence, and the mortality and survival of patients with breast cancer, as well as screening programs for breast cancer We review the developments in mammography and other breast imaging modalities over the last several years Prospects for digital mammography, digital image enhancement, and three-dimensional digital subtraction mammography, which may someday supplant film mammography, are also discussed

Automatic Detection Of Microcalcifications In Digital Mammograms Using Local Area Thresholding Techniques

Abstract: In this study the automatic detection of clusters of microcalcifications in digital mammograms was investigated. A local area thresholding technique was employed to segment all potential microcalcifications from the normal breast structure. These objects were then analysed using size, shape and gradient measures to extract clusters of microcalcifications. The results for a set of 25 mammographic regions, each 5.76 X 5.76 cm2 in area, show that the computer system can achieve 100% true positive cluster detection with a false positive rate of 12%. 1 INTRODUCTION Breast cancer is the commonest cancer affecting women, and the United Kingdom has the highest mortality rate for breast cancer in the world.Mammography is an X-ray technique which has been specially developed for taking images of the breast and is able to detect clinically occult early breast cancer. On mammograms between 30 and 50% of breast carcinomas exhibit microcalcifications (1) and between 60 and 80% of breast carcinomas show calcifications upon histologic analysis (2). Following the publication of the Forrest report in 1986 (3), the Department of Health and Social Securuity in the U.K. is setting up a National Breast Screening Programme for all women aged between 50 and 64. The report recommends that single-view mammography, with an interval of three years between consecutive mammograms, is the best method to employ for basic screening in a mass population screening programme. This could result in 1,440,000 screening mammography patients per year and double this number of films to be reported. The success of the screening programme may be enhanced if an automatic computer method could be employed to detect microcalcifications. Other workers in this field, in particular Chan et al (4,5), have developed a computer system which can achieve a true positive

Digital mammography. A comparison of two digitization methods.

Abstract: A preliminary study of 40 different radiodense breasts digitized with a Fuji high resolution BAFBr:EU2+ imaging plate enabled us to establish acceptable enhancement procedures with a Fuji Computer Radiology 201 system. Screen-film images of 36 of these breasts were also digitized and enhanced on a Damon DETECT TV system. Three radiologists specializing in mammography reviewed each pair of images. For the 20 normal examinations, both digital methods were considered equivalent in image quality, while for the 16 cases containing pathology (masses and/or calcifications) the TV system was considered to provide the best image quality twice as often as the laser scanned system. The radiologists rejected both methods of enhancement for 8% of the images. Despite cost differences between the two systems, both have equal capability in penetrating dense breasts. However, both systems have several significant deficiencies which preclude their clinical use. At the present time, there is no objective justification for using either system for breast imaging other than in an experimental capacity.

Slot-Beam Digital Mammography Using A Time-Delay Integration (TDI) CCD

Abstract: We have developed an experimental digital mammography system which incorporates a beryllium-window x-ray image intensifier (XRII), allowing efficient detection of low-energy diagnostic x rays. The optical image produced by the XRII is recorded by a low-noise charge-coupled device (CCD) operating in the time-delay integration (TDI) mode. Images are obtained by translating a 7 mm x 15 cm slot of radiation across the breast and integrating the signal over 96 image lines. By using a 7 mm slot-beam, we are able to obtain a scatter-to-primary photon fluence ratio of 0.1 for a 4 cm compressed breast. At the same time, the TDI approach results in more efficient usage of available x-ray fluence than a line-scan system, so that imaging times of about 4 seconds are possible. Detector noise is minimized by cooling the CCD to about 5° C. We report on measurements of physical parameters such as modulation transfer function, noise power spectrum and detective quantum efficiency. Our results are compared with equivalent measurements on screen-film systems. Although high-contrast spatial resolution with our digital system is currently limited to 4 mm-1, the improved signal-to-noise ratio allows better low-contrast detectability than screen-film systems.

Diagnostic accuracy of new imaging techniques in breast diseases.

Abstract: During the last decade, the hypothetical carcinogenic effects of mammography have lead to new technical developments in X-ray diagnosis and to the use of other imaging techniques such as ultrasonography (US), transillumination, magnetic resonance imaging (MRI). Many preliminary studies were published but few clinical trials are really convincing. According to the definition of a diagnostic tool, none of these new modalities is supposed to supplant mammography in the diagnosis of breast cancer. Improvements are expected by digital mammography in the near future.