Influence of anode/filter material and tube potential on contrast, signal-to-noise ratio and average absorbed dose in mammography: a Monte Carlo study

• The comparative performance of mammographic X-ray systems that use different anode/filter combinations has been assessed for screen±®lm and digital imaging. Monte Carlo techniques have been used to calculate average glandular dose as well as contrast and signal-tonoise ratio for imaging two test details. Five anode/filter combinations have been studied to establish the potential for dose saving or image quality improvement. For screen±film mammography, it was found that little bene®t is gained by changing from a standard 28 kV molybdenum/molybdenum spectrum for breasts up to 6 cm thick. For thicker breasts, where the tube potential for the standard technique might be increased, 20% improvement in contrast can be achieved without dose penalty using molybdenum/rhodium or rhodium/rhodium spectra, whereas dose savings of more than 50% can be attained whilst maintaining contrast using tungsten/rhodium or rhodium/aluminium spectra. In digital mammography, a molybdenum/ molybdenum spectrum delivers the lowest dose for a 2 cm breast, but gives the highest dose for thicker breasts. Tungsten/rhodium or rhodium/aluminium spectra provide the lowest doses at greater thicknesses. It is concluded that for screen±film mammography, molybdenum/ molybdenum is the spectrum of choice for all but the thickest or most glandular breasts. In digital mammography, an alternative spectrum is preferable for breasts thicker than 2 cm.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Radiologi och bildbehandling (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Radiology, Nuclear Medicine and Medical Imaging (hsv//eng)

Nyckelord

Mammography Radaition Dosimetry

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