Diffuse Optical Tomography (DOT) and Fluorescence Diffuse Optical Tomography (FDOT) are non-invasive tools to detect and reconstruct the optical properties inside highly scattering media. This can be interesting when one is trying to detect, for example, a cancer tumor, which will turn up as an anomaly in the reconstructed model. A special case of DOT and FDOT is the Imaging case, where information in only two dimensions are extracted, neglecting the depth information, much like a photograph. This has the advantage of simpler systems and algorithms compared to to tomographic cases.
For the case of DOT, the intrinsic optical properties, namely the effective scattering and the absorption coefficients, are sought. This is a highly non-linear problem which usually is solved through numerical iterative algorithms. FDOT uses a contrast agent (fluorophore) which marks the interesting regions with a fluorescent signal. The sought parameter is the fluorophore concentration (which usually is linear with respect to the fluorophore absorption). Under some assumptions, this also has the advantage that the problem becomes linear in the fluorophore concentration.
Our research currently is more focused on FDOT, where we are developing new systems and algorithms to enhance the 3D reconstruction of the collected data. The research also involves Fluorescence Diffuse Optical Imaging (FDOI), since this is the natural starting point when testing new systems and/or new fluorophores for reasons mentioned above.
Fluorescence diffuse optical tomography using upconverting nanoparticles
C. T. Xu, J. Axelsson, and S. Andersson-Engels
Appl. Phys. Lett. 94, 251107 (2009)
A matrix-free algorithm for multiple wavelength fluorescence tomography
Athanasios D. Zacharopoulos, Pontus Svenmarker, Johan Axelsson, Martin Schweiger, Simon R. Arridge, and Stefan Andersson-Engels
Optics Express 17, 3042-3051 (2009)
In vivo photosensitizer tomography inside the human prostate
J. Axelsson, J. Swartling and S. Andersson-Engels
Optics Letters 34, 232-234 (2009)
Autofluorescence insensitive imaging using upconverting nanocrystals in scattering media
C. T. Xu, N. Svensson, J. Axelsson, P. Svenmarker, G. Somesfalean, G. Chen, H. Liang, H. Liu, Z. Zhang, and S. Andersson-Engels
Appl. Phys. Lett. 93, 171103 (2008)