TY - GEN
T1 - Simultaneous multispectral coded excitation using periodic and unipolar M-sequences for photoacoustic imaging
AU - Zhang, Haichong
AU - Kondo, Kengo
AU - Yamakawa, Makoto
AU - Shiina, Tsuyoshi
PY - 2013
Y1 - 2013
N2 - Photoacoustics (PA) enables optical-absorption imaging such as functional imaging with depth information by combining ultrasonics and optics. The issue with PA is to increase the signal-to-noise ratio (SNR) because excitation light is attenuated with depth. Repeating irradiation degrades the frame rate, and it will be worse to acquire multispectral information. In previous research, we proposed the m-sequence family such as gold codes, which provide better SNR images than the ensemble average. However, the sending procedure is so complex that it was essential to send sequences twice aperiodically since the negative codes of bipolar sequences must be sent separately, and the decoding artifacts of those bipolar sequences cannot be minimized in aperiodic sending, unlike periodic sending. This study proposes periodic and unipolar m-sequences (PUM): a unipolar sequence consisting of {1, 0}, selected from positive codes of bipolar msequences. Signals can be enhanced by decoding periodically sent PUM using bipolar sequences, and there are no coding artifacts at all for a single wavelength. Moreover, in multispectral simultaneous irradiation, the crosstalk in PUM remains low, which is inherited from m-sequences. We demonstrated that PUM's improved SNR is superior to that of aperiodic m-sequence family codes or orthogonal Golay codes. Furthermore, the frame-rate, which is normally limited by acoustic time-of-flight, can be maximized up to the pulse repetition frequency since the decoding start point can be set in any code in periodic irradiation.
AB - Photoacoustics (PA) enables optical-absorption imaging such as functional imaging with depth information by combining ultrasonics and optics. The issue with PA is to increase the signal-to-noise ratio (SNR) because excitation light is attenuated with depth. Repeating irradiation degrades the frame rate, and it will be worse to acquire multispectral information. In previous research, we proposed the m-sequence family such as gold codes, which provide better SNR images than the ensemble average. However, the sending procedure is so complex that it was essential to send sequences twice aperiodically since the negative codes of bipolar sequences must be sent separately, and the decoding artifacts of those bipolar sequences cannot be minimized in aperiodic sending, unlike periodic sending. This study proposes periodic and unipolar m-sequences (PUM): a unipolar sequence consisting of {1, 0}, selected from positive codes of bipolar msequences. Signals can be enhanced by decoding periodically sent PUM using bipolar sequences, and there are no coding artifacts at all for a single wavelength. Moreover, in multispectral simultaneous irradiation, the crosstalk in PUM remains low, which is inherited from m-sequences. We demonstrated that PUM's improved SNR is superior to that of aperiodic m-sequence family codes or orthogonal Golay codes. Furthermore, the frame-rate, which is normally limited by acoustic time-of-flight, can be maximized up to the pulse repetition frequency since the decoding start point can be set in any code in periodic irradiation.
KW - coded excitation
KW - photoacoustic imaging
KW - simultaneous multispectral measurement
UR - http://www.scopus.com/inward/record.url?scp=84878080548&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84878080548&partnerID=8YFLogxK
U2 - 10.1117/12.2003319
DO - 10.1117/12.2003319
M3 - Conference contribution
AN - SCOPUS:84878080548
SN - 9780819493507
T3 - Progress in Biomedical Optics and Imaging - Proceedings of SPIE
BT - Photons Plus Ultrasound
T2 - Photons Plus Ultrasound: Imaging and Sensing 2013
Y2 - 3 February 2013 through 5 February 2013
ER -