Digital Mammography

All studies related to development of breast imaging, breast cancer, early detection, and in so doing to contribute to the minimal possible harm is intended to be given to patients. That is the target, increase the rate of early diagnosis, it is to use less x-ray. For this purpose, which was developed digital mammography, in 1992 by the National Cancer Institute, "the treatment of breast cancer with the highest potential impact on the developing technology," defined as.



Digital X-rays absorbed by the detector is an electronic signal for each pixel generates an electric signal and an analog-digital converter that translated into a digital value. Then the digital values ​​are stored in computer memory. Digital images at any time be recalled from memory. During evaluation of the images according to image contrast and all kinds of requests are subject to change radiologist. This is the most important advantages of digital mammography.


Many of analog mammography, digital mammography systems. Digital mammography systems, image acquisition, presentation and storage is done independently, and each of these three elements can be adjusted according to the optimal conditions. However, the limits of the masses, the high resolution required for detection of microcalcifications and their characters, not provided enough digital mammography devices. The earliest sign of breast cancer and 30-50% of the cases followed microcalcifications, microcalcifications appear overkill extends to the evaluation is critical to have high spatial resolution and high contrast sensitivity. The use of digital imaging in the breast it was delayed due to technical difficulties in obtaining.


The first studies on clinical uses of computed radiographs were published in the first half of the 90s. Digitized films, the experience obtained by conventional, full-field digital mammography images, the spot has been integral to the transition. Spot or spot transactions stereotactic digital images since 1992 Full field digital mammography, the routine use of magnification used in imaging has been possible only recently.



Advantages of the conventional mammogram with the digital mammographic


1. Expose wider range can be made.

2. Even the smallest differences in contrast can be easily detected and amplified, exposure errors can be minimized.

3. Computer manipulation can be done all kinds of images have been digitized.

4. Images can be more easily stored and transferred between centers.

5. The patient is less than 30-50% of the radiation.

6. Allows for computer-aided diagnosis.


Digital mammography, dense breast tissue of the superior features:


a) Has a wide dynamic range. Thus, without loss of image information of a lower dose can increase the contrast resolution. With this method, without loss of diagnostic information in 50-70% of dose savings can be achieved. Does not need to re-exposure.

b) the processing of data is possible to have different options. Different gray values, contrast, density, noise, such as the use provides many options. In other words, a variety of data presentation can be the same.

c) Digital systems are "dual energy subtraction" (DES) studies of the development is suitable. This system develops more easily, and diagnostic accuracy rate of detection of calcifications by subtraction will be higher. DES directly show calcification. High-and low-energy when the two images subject calcification is monitored only.

d) Again, the contrast of digital subtraction method, which is difficult to follow because of the heavy-heterogeneously dense parenchyma feature benefit-risk patients.

e) The real digital systems, identification of suspicious calcification clusters and the detection and diagnosis of lesions noncalcification help radiologist and artificial intelligence systems to improve the quality of the image allows you to increase the diagnostic power.


Disadvantages:


a) Limited spatial resolution. Digital mammography has been exceeded in recent years, technical difficulties encountered in clinical practice and promising opportunities provided. Superiority of the method accepted in many centers, routine has been introduced (89).

b) And the contrast of neighboring structures, the display of artifacts that can occur if too much difference.

c) Yet the system cost is high. Evidence of two primary breast cancer, microcalcifications and irregular bordered mass


lesions. The entire breast area in order to detect microcalcifications and mass lesions 00:15 calcifications smaller than the background to distinguish it from the complex pattern of breast tissue should be superior contrast resolution. They have been provided to 4.5 cm thick compressed, 50/50 ratio of glandular / adipose tissue patterns in the breast of a given dose of radiation must be less than 3.0.