One Specific Velocity Color Mapping of Flows with Complex Geometry Biomedical Engineering, Tambov State Technical University, Russia S.G.Proskurin, A.Yu.Potlov, K.E.S.Ghaleb

abstract Conventional OCT-systems has a bandpass filter centered at carrier frequency, f c Application of analog and digital tunable filters in the signal processing gives new possibilities By changing bands of the filters it is possible to distinguish Doppler shift in the spectrum of the signal

what wavelengths? red dotted ellipses show wavelengths with minimum absorption in tissues

SLD – superluminescent diode, FC1 and FC2 – fiber couplers, L – collimating and focusing optics, ODL – optical delay line, D1 and D2 – balanced detectors, α – the angle between incident light and the direction of the fluid flow velocity. Scanning is performed along X-axis experimental set-up ODL D1 D2 tunable filter

capillary entry hydrodynamic phantoms tilted capillary entry was used in the experiment tilted capillary entry

Doppler spectra of interference signal from a flow with parabolic velocity profile ΔV/V ~ 7% by choosing f c and Δ f c we could obtain equidvelocity images

processing the signal a new algorithm of color Doppler mapping of one specific velocity (OSV) of shuttle flows is applied it is realized using the separation of the raw data to two parts corresponding to positive and negative shifts of the carrier frequency it does not have 2π-ambiguity disadvantage of color Doppler OCT images

panel 1 of processing interference standard structural image final complexing Quantum Electronics (2013) submitted

panel 2 of processing interference positive direction OSV image negative direction OSV image Quantum Electronics (2013) submitted

processing the signal as a final result, the complexation of independently reconstructed structural image (green) and 2D color-coded OSV images (red and blue) is performed practical implementation of the algorithm was performed using the stream programming in the LabVIEW package

panel 3 of processing interference final structural image both OSV images Quantum Electronics (2013) submitted

image of subcutaneous human blood vessel and blood in vivo Proskurin S.G., Quantum Electronics (2012) p.495 the described approach is applicable to blood flow monitoring in subcutaneous human blood vessels it gives quantitative information about the chosen value of velocity determined by the Doppler angle and shift of the carrier

the described algorithm does not have disadvantage of 2π- ambiguity, as in a conventional qualitative color systems, where shift of adjacent A-scans is detected determined by the registered shift of the carrier OSV mapping gives quantitative information about the chosen velocity value and direction of the flow averaging over several consecutive A-scans reduces speckles noise, increases contrast and looses information about A- scan phase, but keeps information about Doppler shift itself conclusion

references Proskurin S.G. Potlov A.Yu., Frolov S.V., Doppler mapping of sign-variable flow with complex geometry using optical coherence tomography // Quantum Electronics, (2013) submitted Proskurin S.G., Raster scan and averaging for speckle reduction in optical coherence tomography // Quantum Electronics, Vol. 42 (6), p , 2012 Proskurin S.G., Frolov S.V., Visualization of blood vessels by means of optical coherence tomography // Biomedical Engineering, No.3, p.9-14, 2012 Proskurin S.G., Meglinski I.V., Optical coherence tomography imaging depth enhancement by superficial skin optical clearing // Laser Physics Letters, Vol. 4, No. 11, p , 2007

One Specific Velocity Color Mapping of Flows with Complex Geometry Biomedical Engineering, Tambov State Technical University, Russia S.G.Proskurin, A.Yu.Potlov, K.E.S.Ghaleb