Module 3.1: Data Fitting

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Module 3.1Data Fitting
Wendy Tanamai Albert Cerussi Beckman Laser
Institute University of California, Irvine
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Outline

• How data is fit
• Data file summary
• Using the GUI

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How Data is Fit

• FDPM Data
• Data inputs
• phase and amplitude vs. modulation frequency
• sample (tissue) and reference (phantom)
• Calibration for
• FDPM amplitude (ratio)
• FDPM phase (difference)

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Raw FDPM
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How Data is Fit

• FDPM Data (continued)
• Conversion to Real Imaginary
• lsqcurvefit function in MATLAB using both real
  and imaginary together
• Some weighted fitting options
• Done for each laser diode ?

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Processed FDPM
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How Data is Fit

• Broadband Data
• Dark count subtraction (usually done in
  acquisition)
• Spectral calibration

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Spectral Calibration
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Spectral Calibration
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How Data is Fit

• Broadband Data
• Power Law fit to FDPM scattering
• Scattering removed from broadband reflectance
• FDPM absorption used to scale broadband
  reflectance
• Solve for absorption using MATLAB fzero

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How Data is Fit

• Physiological Fitting
• Assume 4-chromophores
• Non-zero least squares
• Usually fit with baseline

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Processed Spectra
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Data Files (Acquired)

• All files are ASCII
• FDPM data has dcswitch tag
• for all modulation frequencies
• one for each location
• SPEC data has tis tag
• for all wavelengths
• one for each location
• Cal files named phantom/standard

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Data Files (Processed)

• _dBSUM file has all processed results for both
  FDPM (only) and FDPM-Broadband for all spatial
  locations
• _MUA file has broadband absorption spectra and
  chromophore fits for all spatial locations
• _MUS file has broadband reduced scattering
  spectra for all spatial locations

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Data Files (Processed)

• _dBMU file has all FDPM values for each
  wavelength and all spatial locations
• _specR has the calibrated/scaled broadband
  reflectance spectra for all spatial locations
• _gbfi (coming soon) quality of fit data for all
  fits and all spatial locations

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Data Files (Processed)

• Other processing options
• Gridimager program (Visualization)
• Double differential analysis (can download)
• Bound Water/Temperature analysis

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Using the GUI

• Demo of the GUI