PHYS1008 Study Guide - Final Guide: Mammography, Attenuation Coefficient
2 Aug 2018
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Document Summary
The breast needs to be held down to stop it from moving. Visualization systems are much more demanding need dark rooms and very high. It is very hard to get contrast between soft tissues, there is not much differentiation resolution monitors. Low kv energies are needed to differentiate tissues which have very similar linear attenuation co-efficient. Using low energy will allow you to differentiate between the fat tissue, glandular tissue and carcinoma by maximising the photo electric effect? kv ranges between 20-30 kvp. As kev increases, both the contrast and dose decrease. This is a problem as you want low contrast and low dose. At low kev there is mainly photo-electric effect which is responsible for the high dose. There is more x-ray absorption in thicker tissue. Tissue thickness must be reduced to increase the contrast of the image. Need to differentiate type of tissue as well as shape of lesion. Benign is dense, round, and well defined.
