TY - JOUR
T1 - Quantitative analysis with the optoacoustic/ultrasound system OPUS
AU - Haisch, Christoph
AU - Zell, Karin
AU - Sperl, Jonathan
AU - Vogel, Mika W.
AU - Niessner, Reinhard
PY - 2009
Y1 - 2009
N2 - The OPUS (Optoacoustic plus Ultrasound) system is a combination of a medical ultrasound scanner with a high-repetition rate, wavelength-tunable laser system and a suitable triggering interface to synchronize the laser and the ultrasound system. The pulsed laser generates an optoacoustic (OA), or photoacoustic (PA), signal which is detected by the ultrasound system. Alternatively, imaging in conventional ultrasound mode can be performed. Both imaging modes can be superimposed. The laser light is coupled into the tissue laterally, parallel to the ultrasound transducer, which does not require for any major modification to the transducer or the ultrasound beam forming. This was a basic requirement on the instrument, as the intention of the project was to establish the optoacoustic imaging modality as add-on to a conventional standard ultrasound instrument. We believe that this approach may foster the introduction of OA imaging as routine tool in medical diagnosis. Another key aspect of the project was to exploit the capabilities of OA imaging for quantitative analysis. The intention of the presented work is to summarize all steps necessary to extract the significant information from the PA raw data, which are required for the quantification of local absorber distributions. We show results of spatially resolved absorption measurements in scattering samples and a comparison of four different image reconstruction algorithms, regarding their influence on lateral resolution as well as on the signal to noise ratio for different sample depths and absorption values. The reconstruction algorithms are based on Fourier transformation, on a generalized 2D Hough transformation, on circular back-projection and the classical delay-and-sum approach which is implemented in most ultrasound scanners. Furthermore, we discuss the influence of a newly developed laser source, combining diode and flash lamp pumping. Compared to all-flash-lamp pumped systems it features a significantly higher pulse-to-pulse stability, which is required for sensitive and precise quantitative analyses.
AB - The OPUS (Optoacoustic plus Ultrasound) system is a combination of a medical ultrasound scanner with a high-repetition rate, wavelength-tunable laser system and a suitable triggering interface to synchronize the laser and the ultrasound system. The pulsed laser generates an optoacoustic (OA), or photoacoustic (PA), signal which is detected by the ultrasound system. Alternatively, imaging in conventional ultrasound mode can be performed. Both imaging modes can be superimposed. The laser light is coupled into the tissue laterally, parallel to the ultrasound transducer, which does not require for any major modification to the transducer or the ultrasound beam forming. This was a basic requirement on the instrument, as the intention of the project was to establish the optoacoustic imaging modality as add-on to a conventional standard ultrasound instrument. We believe that this approach may foster the introduction of OA imaging as routine tool in medical diagnosis. Another key aspect of the project was to exploit the capabilities of OA imaging for quantitative analysis. The intention of the presented work is to summarize all steps necessary to extract the significant information from the PA raw data, which are required for the quantification of local absorber distributions. We show results of spatially resolved absorption measurements in scattering samples and a comparison of four different image reconstruction algorithms, regarding their influence on lateral resolution as well as on the signal to noise ratio for different sample depths and absorption values. The reconstruction algorithms are based on Fourier transformation, on a generalized 2D Hough transformation, on circular back-projection and the classical delay-and-sum approach which is implemented in most ultrasound scanners. Furthermore, we discuss the influence of a newly developed laser source, combining diode and flash lamp pumping. Compared to all-flash-lamp pumped systems it features a significantly higher pulse-to-pulse stability, which is required for sensitive and precise quantitative analyses.
KW - Imaging
KW - Optoacoustic
KW - Photoacoustic
KW - Quantification
KW - Reconstruction
KW - Ultrasound
UR - http://www.scopus.com/inward/record.url?scp=66249135988&partnerID=8YFLogxK
U2 - 10.1117/12.810739
DO - 10.1117/12.810739
M3 - Conference article
AN - SCOPUS:66249135988
SN - 1605-7422
VL - 7177
JO - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
JF - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
M1 - 717702
T2 - Photons Plus Ultrasound: Imaging and Sensing 2009
Y2 - 25 January 2009 through 28 January 2009
ER -