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Researcher's view Patient dose & breast compression Ken Young Patient dose in mammography "Modern mammography X-ray sets have much greater flexibility in tailoring the energy of X-rays used to form mammograms. This has the advantage that higher energies can be selected for larger breasts where penetration is more difficult, or lower energies used to increase the contrast in the image. The decision on the best energy to use for each woman is usually taken automatically by the X-ray set. The main radiation dose saving observed when using these modern systems are reductions in doses for women with relatively large breasts." "Digital mammography systems are in a few places replacing traditional film screen technology. There are currently several different types of digital system and these hold out the possibility of much lower doses. One means of reducing radiation dose is to use a scanned collimated beam of X-rays to eliminate scattered X-rays rather than the more traditional moving grid. Another means is to use higher energy X-rays with the digital receptors." "Although the above technical developments can reduce the radiation dose per image the NHS Breast Screening Programme is currently implementing a change in its procedures, which will increase the number of images, recorded for each woman. Until recently it was policy to record two views of each breast only on a woman’s first visit to a screening centre. However since there is a large body of research evidence to show that more and smaller cancers are detected if two views are recorded on every screening visit this technique is becoming standard practice at all NHS Breast Screening Centres. It has been shown that the extra clinical benefits substantially out-weigh the risk of the extra radiation dose. Where mammography is used on women with symptoms, such as a lump, two views are already routinely recorded." Compression in mammography "It has been realised for many years that effective breast compression is important to enhance image quality and minimise radiation dose in mammography. However these desirable objectives involve some discomfort. Traditionally the amount of compression applied is under the control of the operator up to a specified maximum. One manufacturer has implemented automatic compression setting on its models of X-ray set. However no data is available to demonstrate whether this is in practice better than manual control by the operator." "A small proportion of mammograms is affected by patient movement, which suggests that the compression was not effective in keeping the breast still during the exposure. A few manufacturers have attempted to reduce the incidence of such blurring and make compression more comfortable by redesigning the compression mechanism to allow some tilting of compression plates. It is too early to say whether these modifications will prove successful – but it is clear that there is room to improve on the traditional design of compression systems." Woman's view | Radiologist's view | Researcher's view | Research process |