Scanning thermoacoustic tomography in biological tissue

Ku, Geng; Wang, Lihong V.

doi:10.1118/1.598984

Cited by 141 publications

(103 citation statements)

References 36 publications

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“…Our group explored scanning microwave-induced thermoacoustic tomography. 18,19 Our approach is similar to the conventional ultrasonic B scan except that the ultrasound is produced internally inside the tissue by microwave pulses. This scanning approach can potentially provide real-time imaging and coregistration with ultrasonic B-scan images.…”

Section: Introductionmentioning

confidence: 99%

Scanning microwave-induced thermoacoustic tomography: Signal, resolution, and contrast

Ku¹,

Wang

2001

Med. Phys.

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155

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Scanning thermoacoustic tomography was explored in the microwave region of the electromagnetic spectrum. Short microwave pulses were used to induce acoustic waves by thermoelastic expansion in biological tissues. Cross sections of tissue samples were imaged by a linear scan of the samples while a focused ultrasonic transducer detected the time-resolved thermoacoustic signals. Based on the microwave-absorption properties of normal and cancerous breast tissues, the piezoelectric signals in response to the thermoacoustic contrast were investigated over a wide range of electromagnetic frequencies and depths of tumor locations. The axial resolution is related to the temporal profile of the microwave pulses and to the impulse response of the ultrasonic transducer. The lateral resolution is related to the numerical aperture of the ultrasonic transducer as well as to the frequency spectra of the piezoelectric signals in the time window corresponding to the axial resolution. Gain compensation, counteracting the microwave attenuation, was applied to enhance the image contrast.

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Section: Introductionmentioning

confidence: 99%

Scanning microwave-induced thermoacoustic tomography: Signal, resolution, and contrast

Ku¹,

Wang

2001

Med. Phys.

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155

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“…Linear scanning of the ultrasonic transducer yields multiple one-dimensional images, which can be combined to form a two-dimensional image of the sample. [8][9][10] In the two-dimensional images obtained with conventional LMTT, only boundaries that are nearly perpendicular to the axis of the ultrasonic transducer can be detected because most of the thermoacoustic waves travel in a small solid angle around the normals of boundaries; spherical or oblique boundaries of buried objects whose thermoacoustic waves have a large angle with the axis of the ultrasonic transducer cannot be imaged because the ultrasonic transducer receives little signal from these boundaries.…”

Section: Introductionmentioning

confidence: 99%

Microwave‐induced thermoacoustic tomography: Reconstruction by synthetic aperture

Feng

et al. 2001

Medical Physics

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We have applied the synthetic-aperture method to linear-scanning microwave-induced thermoacoustic tomography in biological tissues. A nonfocused ultrasonic transducer was used to receive thermoacoustic signals, to which the delay-and-sum algorithm was applied for image reconstruction. We greatly improved the lateral resolution of images and acquired a clear view of the circular boundaries of buried cylindrical objects, which could not be obtained in conventional linearscanning microwave-induced thermoacoustic tomography based on focused transducers. Two microwave sources, which had frequencies of 9 and 3 GHz, respectively, were used in the experiments for comparison. The 3 GHz system had a much larger imaging depth but a lower signal-noise ratio than the 9 GHz system in near-surface imaging.

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“…In photoacoustic tomography, 8 "" due to the use of short laser pulses-several nanoseconds in pulse width-and the strong attenuation of the laser light by tissues, the frequency spectrum of the acoustic signal from the buried object of several micrometers in size is estimated to have significant components up to 75 MHz, 9 which makes its axial resolution as good as 10 /xm. However, the maximum imaging depth in photoacoustic tomography is limited by the strong attenuation of the laser light and of the high-frequency acoustic waves.…”

Section: Introductionmentioning

confidence: 99%

Scanning Microwave Induced Acoustic Tomography

Wang¹

2001

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and AUTHOR(S)Lihong Wang, Ph.D. FUNDING NUMBERSDAMD17-00-1-0455 PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Texas Engineering Experiment Station College Station, Texas 77843-3000 E-Mail: LWang@tamu.edu Since the grant was awarded in October 2000, we have published three peer-reviewed journal articles, published one conference proceedings article, delivered 16 invited talks, and graduated one M.S. student. This research has been successful and rewarding. We are well prepared to continue the project with greater successes. PERFORMING ORGANIZATION REPORT NUMBER SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)UUntil cancer is eradicated by preventative measures, the grand challenge in cancer research is early-cancer detection because the cure rate of cancers is much improved if they are detected early. Cancerous breast tissues are found to be 2-5 times more strongly absorbing than surrounding normal breast tissues in the microwave, which has been attributed to an increase in bound water and sodium within malignant cells. The combination of ultrasound and microwave has provided us a unique opportunity for early-cancer imaging with high resolution and high contrast. We have made significant technical progress in thermoacoustic imaging including imaging configuration, data processing, and reconstruction. We have successfully imaged biological tissue with high resolution and high contrast. We look forward to meeting this grand challenge. Conclusions 8 SUBJECT TERMSReferences 9Appendices (21 pages) 9 IntroductionA novel imaging technology, scanning microwave-induced-acoustic tomography, will be developed for breast imaging. X-ray mammography and ultrasonography are the current clinical tools for breast-cancer screening and detection. Mammography is the "gold standard", however, uses ionizing radiation and has difficulties imaging pre-menopausal breasts, which are radiographically dense. Ultrasonography is an adjunct tool to x-ray mammography and cannot detect many of the nonpalpable tumors. The cure rate of breast cancers is improved if they are detected early. To provide a new non-invasive, non-ionizing diagnostic tool for detection of early breast cancers, we will develop real-time microwave-induced-acoustic tomography for breast imaging. Microwave-induced-acoustic tomography is based on the photoacoustic effect, generation of acoustic wave by deposition of short-pulse electromagnetic energy safely into biological tissues. Th...

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Scanning thermoacoustic tomography in biological tissue

Cited by 141 publications

References 36 publications

Scanning microwave-induced thermoacoustic tomography: Signal, resolution, and contrast

Scanning microwave-induced thermoacoustic tomography: Signal, resolution, and contrast

Microwave‐induced thermoacoustic tomography: Reconstruction by synthetic aperture

Scanning Microwave Induced Acoustic Tomography

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