• Journal of radiological science and technology
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• v.31 no.1
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• pp.61-69
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• 2008

Diagnosis of breast ultrasound is better than mammography in the early detection of breast cancer, but, it is difficult to detect microcalcification. We studied on detection for calcification of breast tissue using acoustic resonance and power doppler with 7.5 MHz linear probe in breast ultrasound. We first constructed breast tissue phantom made of gelatin and saw breast, and then observed calcification by the change of external vibration. Calcification injected breast tissue phantom visualized the difference for brightness and region of color in ROI regions of power doppler. Acoustic resonance almost never visualized in low frequency regions, plateau constituted in about 300-400 Hz and colors vanished according to the increase of frequency.

• The Journal of the Acoustical Society of Korea
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• v.27 no.2
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• pp.80-86
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• 2008

Breast ultrasound has many advantages over mammography but suffers from a shortcoming of being not suitable in detecting microcalcification. We studied on a method based on acoustic resonance and power Doppler to detect calcification of breast tissue using a typical 7.5 MHz linear probe used in breast ultrasound examination. We first constructed a breast tissue phantom made of gelatin and then observed calcified legions as external vibrations varied. Calcification injected to the breast tissue phantom being resonated different from the surrounding medium, and its acoustic resonance driven by external vibrations was visualized by differences for color brightness and area in ROI of power doppler. In low frequency regions, the acoustic resonance almost not appeared and showed a plateau in $300{\sim}600\;Hz$ and the color vanished as the frequency further increased.

• Journal of radiological science and technology
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• v.30 no.1
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• pp.13-23
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• 2007

In recent years, mammography system is changed rapidly from conventional screen-film system to digital system for application to screening and diagnosis. Digital mammography system provides several advantages over screen-film mammography system. According to the information provided by the manufacturer, digital mammography system offers radiation dose reduction in comparison with screen-film mammography system, because of digital detector, particularly direct digital detector has higher x-ray absorption efficiency than screen-film combination or imaging plate(IP). We measured average glandular doses(AGD) in screen-film mammography(SFM) system with slow screen-film combination, computed mammography(CM) system, indirect digital mammography(IDM) system and direct digital mammography(DDM) system using brest tissue-equivalent phantom(glandularity 30%, 50% and 70%). The results were shown as follows : AGD values for DDM system were highest than those for other systems. Although automatic exposure control(AEC) mode was selected, the curve of the AGD values against thickness or glandularity increased significantly for the SFM system with the uniform target/filter(Mo/Mo) combination. Therefore, the AGD values for the high energy examinations were highest in the SFM system, and those for the low energy examinations were highest in the DDM system. But the curve of the AGD values against thickness and glandularity increased gently for CM system with the automatic selection of the target/filter combination (from Mo/Mo to Mo/Rh or from Mo/Rh to Rh/Rh), and the AGD values were lowest. Consequently, the parameters in mammography for each exposure besides detection efficiency play an important role in oder to estimate a patient radiation dose.