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Presentation Information     2006-09-25 (15:15)   •  The seminar room at Vi2

Speaker Åsa Berglund
Type Master thesis presentation
Title The impact of NEQ on detectability of microcalcifications in mammography
Abstract In mammography it is very important to be able to identify so called microcalcifications in the breast, since they may be an early sign of cancer. This work investigates how the visibility of microcalcifications is affected when certain parameters in the mammography system are changed.

An existing model of the Sectra MDM D40 system was further developed and verified against experimental measurements. Software was developed for simulating mammography images with microcalcifications, based on the system model. Different system settings were investigated to obtain the best system parameters for detection of 100 micrometer microcalcifications.

To evaluate the visibility of microcalcifications a human observer study was performed, and a mathematical model observer was implemented and compared to human performance.

The studies showed that increasing the slit width resulted in better visibility of the microcalcifications, if maximum dose was used for all slit widths. However, the clinical benefit has to be weighed against the dangers with increased dose to the patient. A slit width of around 100 micrometer is proposed as the best trade-off between image quality and patient dose.

The use of a micro focal spot results in somewhat better visibility, if the same dose as for the normal focal spot is achieved. But the time needed for the image acquisition then becomes so long that this approach is not recommended. Using a system with normal focal spot and narrower slit width results in the same visibility without increasing the scan time as much.