TY - GEN

T1 - Image reconstruction in optoacoustic tomography accounting for frequency-dependent attenuation

AU - La Rivière, Patrick J.

AU - Jin, Zhang

AU - Anastasio, Mark A.

PY - 2005/12/1

Y1 - 2005/12/1

N2 - In this work, we show how to incorporate attenuation into the optoacoustic tomography (OAT) imaging equation and develop a strategy for compensating for this attenuation during image reconstruction. In OAT, one exposes a sample to pulses of electromagnetic radiation that cause small amounts of heating in the specimen. The heating engenders thermal expansion which, in turn, gives rise to acoustic waves. The resulting acoustic pressure signal is generally measured by transducers arrayed around the object, and these data may be used to reconstruct images of the original electromagnetic absorption. Frequency-dependent absorption of the acoustic waves can lead to blurring and distortion in reconstructed images. We show that in the temporal frequency domain, the optoacoustic wave equation incorporating attenuation is equivalent to the inhomogeneous Helmholtz equation with a complex wave number. While some work has been done in other fields on directly solving Helmholtz equations with complex wave numbers, these are generally computationally intensive numerical approaches. We pursue a different approach, deriving an integral equation that relates the temporal optoacoustic signal at a given transducer location in the presence of attenuation to the ideal signal that would have been obtained in the absence of attenuation. This equation is readily discretized and the resulting linear system of equations involves a matrix that need only be inverted once, at which point the inverse can be used to correct all of the measured time signals prior to reconstruction by conventional methods.

AB - In this work, we show how to incorporate attenuation into the optoacoustic tomography (OAT) imaging equation and develop a strategy for compensating for this attenuation during image reconstruction. In OAT, one exposes a sample to pulses of electromagnetic radiation that cause small amounts of heating in the specimen. The heating engenders thermal expansion which, in turn, gives rise to acoustic waves. The resulting acoustic pressure signal is generally measured by transducers arrayed around the object, and these data may be used to reconstruct images of the original electromagnetic absorption. Frequency-dependent absorption of the acoustic waves can lead to blurring and distortion in reconstructed images. We show that in the temporal frequency domain, the optoacoustic wave equation incorporating attenuation is equivalent to the inhomogeneous Helmholtz equation with a complex wave number. While some work has been done in other fields on directly solving Helmholtz equations with complex wave numbers, these are generally computationally intensive numerical approaches. We pursue a different approach, deriving an integral equation that relates the temporal optoacoustic signal at a given transducer location in the presence of attenuation to the ideal signal that would have been obtained in the absence of attenuation. This equation is readily discretized and the resulting linear system of equations involves a matrix that need only be inverted once, at which point the inverse can be used to correct all of the measured time signals prior to reconstruction by conventional methods.

UR - http://www.scopus.com/inward/record.url?scp=33846604352&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33846604352&partnerID=8YFLogxK

U2 - 10.1109/NSSMIC.2005.1596689

DO - 10.1109/NSSMIC.2005.1596689

M3 - Conference contribution

AN - SCOPUS:33846604352

SN - 0780392213

SN - 9780780392212

T3 - IEEE Nuclear Science Symposium Conference Record

SP - 1841

EP - 1845

BT - 2005 IEEE Nuclear Science Symposium Conference Record -Nuclear Science Symposium and Medical Imaging Conference

T2 - Nuclear Science Symposium Conference Record, 2005 IEEE

Y2 - 23 October 2005 through 29 October 2005

ER -