Diffuse Optical Tomography - fiber-optic array - journal

Diffuse optical imaging (DOI) is a method of imaging using

near-infrared spectroscopy Near-infrared spectroscopy (NIRS) is a spectroscopic method that uses the near-infrared region of the electromagnetic spectrum (from 780 nm to 2500 nm). Typical applications include medical and physiological diagnostics and research inc ...

(NIRS) or fluorescence-based methods. When used to create 3D volumetric models of the imaged material DOI is referred to as diffuse optical tomography, whereas 2D imaging methods are classified as diffuse optical imaging. The technique has many applications to neuroscience, sports medicine, wound monitoring, and cancer detection. Typically DOI techniques monitor changes in concentrations of oxygenated and deoxygenated

hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyt ...

and may additionally measure redox states of

cytochrome Cytochromes are redox-active proteins containing a heme, with a central Fe atom at its core, as a cofactor. They are involved in electron transport chain and redox catalysis. They are classified according to the type of heme and its mode of bi ...

s. The technique may also be referred to as diffuse

optical tomography Optical tomography is a form of computed tomography that creates a digital data, digital volumetric model of an object by reconstructing images made from light transmitted and scattered through an object. Optical tomography is used mostly in medi ...

(DOT), near infrared optical tomography (NIROT) or fluorescence diffuse optical tomography (FDOT), depending on the usage. In neuroscience, functional measurements made using NIR wavelengths, DOI techniques may classify as functional near infrared spectroscopy fNIRS.

Physical mechanism

Biological tissues can be considered strongly diffusive media, since during light propagation the scattering phenomenon is dominant over absorption in the so-called "therapeutic window" spectral range. Photon migration in diffusive media is described by the heuristic model of the diffusion equation, which offers analytical solutions for some specific geometries. Starting from the measured absorption and scattering coefficients, it is possible to derive the concentrations of tissues' main

chromophores A chromophore is the part of a molecule responsible for its color. The color that is seen by our eyes is the one not absorbed by the reflecting object within a certain wavelength spectrum of visible light. The chromophore is a region in the mo ...

. Diffuse optical imaging can be implemented in

time domain Time domain refers to the analysis of mathematical functions, physical signals or time series of economic or environmental data, with respect to time. In the time domain, the signal or function's value is known for all real numbers, for the c ...

, frequency domain or continuous wave, in reflectance or transmittance configuration.

References

{{reflist Medical imaging Optical imaging

Physical mechanism

See also

References