Mammography digital

Freedman M, Martin JS, O Gorman J, et al. Digitized mammography A clinical trial of postmenopausal women randomly assigned to receive raloxifene, estrogen, or placebo. J Natl Cancer Inst 2001 93 51-56. 

A well-optimized digital mammography system can provide the following benefits ... 

Properties of X-ray detectors for digital mammography will be discussed further in Chap. 2. 

The characteristic curve of a typical digital mammography detector is shown in Fig. 1.4b. The detector inherently produces a signal that is linearly proportional to the intensity of X-rays transmitted by the breast. It has a very large dynamic range, so that it is possible to produce a faithful representation of X-ray transmission for all parts of the breast Furthermore, unlike film, the shape of the chararteristic curve for these detectors is much less dependent on the level of radiation exposing the detector. Maintaining an adequate value of is still important however, both the... 

Fig. 1.4. (a) Characteristic (H and D) curve of a mam-mographic screen-film system. Optical density (OD) of the processed film is plotted versus the log of the relative X-ray exposure to the fluorescent intensifying screen, (b) Characteristic response of a detector designed for digital mammography (from Pisano et al. 2004. With permission)... 

Finally, recording the scatter adds statistical fluctuation without information, thereby reducing the SNR. This is probably the major detrimental effect of scatter in digital mammography. 

Before discussing the factors that affect spatial resolution in digital mammography, a brief introduction to the modulation transfer function, a valuable tool for quantifying resolution, is provided. 

Fig. 1.7. MTF of a modern screen-film system (after Bunch Fig. 1.8. Illustrating the concept of aliasing (from Pisano 1997) and of a typical detector used in digital mammography et al. 2004. With permission)...

Fig. 1.9. X-ray spectra produced with (a) Mo target and Mo filter at 26kV, (b) Rh target with Rh filter. With digital mammography the trend is toward use of more penetrating spectra...

The detector is one of the defining features of a digital mammography system. The detector produces an electronic signal that represents the spatial pattern of... 

Fig. 2.8. Digital mammogram (a) before and (b) after flat-field correction (from Digital Mammography, eds. ED Pisano,...

Several different types of detectors are used for digital mammography. These are briefly described here. 

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