High density trans-admittance mammography development and preliminary phantom tests
<p>Abstract</p> <p>Background</p> <p>Malignant breast tumor tissue has a significantly different electrical impedance spectrum than surrounding normal tissues. This has led to the development of impedance imaging as a supplementary or alternative method to X-ray mammogr...
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| Format: | Article |
| Language: | English |
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BMC
2012-09-01
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| Series: | BioMedical Engineering OnLine |
| Subjects: |
| _version_ | 1818394593581858816 |
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| author | Zhao Mingkang Wi Hun Mostofa Kamal Abu McEwan Alistair Woo Eung Oh Tong |
| author_facet | Zhao Mingkang Wi Hun Mostofa Kamal Abu McEwan Alistair Woo Eung Oh Tong |
| author_sort | Zhao Mingkang |
| collection | DOAJ |
| description | <p>Abstract</p> <p>Background</p> <p>Malignant breast tumor tissue has a significantly different electrical impedance spectrum than surrounding normal tissues. This has led to the development of impedance imaging as a supplementary or alternative method to X-ray mammography for screening and assessment of breast cancers. However low spatial resolution and poor signal to noise ratio has limited the clinical application.</p> <p>Methods</p> <p>In order to improve spatial resolution we developed a trans-admittance mammography (TAM) system including an array of 60×60 current sensing electrodes. We adopted a similar setup to X-ray mammography where the breast is situated between two holding plates. The top plate is a large solid metal electrode for applying a sinusoidal voltage over a range of frequencies from 50 Hz to 500 kHz. The bottom plate has 3600 current sensing electrodes that are kept at the ground potential. Currents are generated from the top voltage-applying electrode and spread throughout the breast, entering the TAM system through the array of current sensing electrodes on the bottom plate. The TAM system measures the exit currents through 6 switching modules connected to 600 electrodes each. Each switching module is connected to 12 ammeter channels which are switched sequentially to 50 of the 600 electrodes each measurement time. Each ammeter channel is comprised of a current-to-voltage converter, a gain amplifier, filters, an analog to digital converter, and a digital phase sensitive demodulator.</p> <p>Results</p> <p>We found an average noise level of 38 nA, amplitude stability of less than 0.2<it>%</it>, crosstalk of better than -60 dB and 70 dB signal to noise ratio over all channels and operating frequencies. Images were obtained in time difference and frequency difference modes in a saline phantom.</p> <p>Conclusion</p> <p>We describe the design, construction, and calibration of a high density TAM system in detail. Successful high resolution time and frequency difference images showed regions of interest with the expected admittivity changes in the frequency spectrum.</p> |
| first_indexed | 2024-12-14T06:03:40Z |
| format | Article |
| id | doaj.art-90ee4a8d884f457492b8f23dbe186bd4 |
| institution | Directory Open Access Journal |
| issn | 1475-925X |
| language | English |
| last_indexed | 2024-12-14T06:03:40Z |
| publishDate | 2012-09-01 |
| publisher | BMC |
| record_format | Article |
| series | BioMedical Engineering OnLine |
| spelling | doaj.art-90ee4a8d884f457492b8f23dbe186bd42022-12-21T23:14:22ZengBMCBioMedical Engineering OnLine1475-925X2012-09-011117510.1186/1475-925X-11-75High density trans-admittance mammography development and preliminary phantom testsZhao MingkangWi HunMostofa Kamal AbuMcEwan AlistairWoo EungOh Tong<p>Abstract</p> <p>Background</p> <p>Malignant breast tumor tissue has a significantly different electrical impedance spectrum than surrounding normal tissues. This has led to the development of impedance imaging as a supplementary or alternative method to X-ray mammography for screening and assessment of breast cancers. However low spatial resolution and poor signal to noise ratio has limited the clinical application.</p> <p>Methods</p> <p>In order to improve spatial resolution we developed a trans-admittance mammography (TAM) system including an array of 60×60 current sensing electrodes. We adopted a similar setup to X-ray mammography where the breast is situated between two holding plates. The top plate is a large solid metal electrode for applying a sinusoidal voltage over a range of frequencies from 50 Hz to 500 kHz. The bottom plate has 3600 current sensing electrodes that are kept at the ground potential. Currents are generated from the top voltage-applying electrode and spread throughout the breast, entering the TAM system through the array of current sensing electrodes on the bottom plate. The TAM system measures the exit currents through 6 switching modules connected to 600 electrodes each. Each switching module is connected to 12 ammeter channels which are switched sequentially to 50 of the 600 electrodes each measurement time. Each ammeter channel is comprised of a current-to-voltage converter, a gain amplifier, filters, an analog to digital converter, and a digital phase sensitive demodulator.</p> <p>Results</p> <p>We found an average noise level of 38 nA, amplitude stability of less than 0.2<it>%</it>, crosstalk of better than -60 dB and 70 dB signal to noise ratio over all channels and operating frequencies. Images were obtained in time difference and frequency difference modes in a saline phantom.</p> <p>Conclusion</p> <p>We describe the design, construction, and calibration of a high density TAM system in detail. Successful high resolution time and frequency difference images showed regions of interest with the expected admittivity changes in the frequency spectrum.</p>Trans-admittanceConductivity spectrumBreast cancerLesion detectionAdmittance measurement84.37. + <it>q</it> Mammography in computer-aided diagnosis87.57<it>.rh</it> Electric impedance measurement84.37. + <it>q</it> |
| spellingShingle | Zhao Mingkang Wi Hun Mostofa Kamal Abu McEwan Alistair Woo Eung Oh Tong High density trans-admittance mammography development and preliminary phantom tests BioMedical Engineering OnLine Trans-admittance Conductivity spectrum Breast cancer Lesion detection Admittance measurement 84.37. + <it>q</it> Mammography in computer-aided diagnosis 87.57<it>.rh</it> Electric impedance measurement 84.37. + <it>q</it> |
| title | High density trans-admittance mammography development and preliminary phantom tests |
| title_full | High density trans-admittance mammography development and preliminary phantom tests |
| title_fullStr | High density trans-admittance mammography development and preliminary phantom tests |
| title_full_unstemmed | High density trans-admittance mammography development and preliminary phantom tests |
| title_short | High density trans-admittance mammography development and preliminary phantom tests |
| title_sort | high density trans admittance mammography development and preliminary phantom tests |
| topic | Trans-admittance Conductivity spectrum Breast cancer Lesion detection Admittance measurement 84.37. + <it>q</it> Mammography in computer-aided diagnosis 87.57<it>.rh</it> Electric impedance measurement 84.37. + <it>q</it> |
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