Diffusjonstomografi

Diffusjonstomografi, often shortened to diffusion tomography, is an imaging modality that reconstructs images based on the diffusion of particles, typically light or sound waves, through a scattering medium. Unlike conventional imaging techniques that rely on direct transmission or reflection of signals, diffusion tomography exploits the complex scattering and diffusion processes that occur when waves propagate through optically dense or acoustically heterogeneous materials. The principle involves measuring the intensity and phase of diffused waves at multiple points on the boundary of the medium. These measurements are then used in an inverse problem to determine the optical or acoustic properties of the interior of the medium, such as absorption and scattering coefficients or speed of sound.

The mathematical formulation of diffusion tomography often involves solving diffusion equations or radiative transfer equations, which describe the statistical behavior of the diffusing particles. Reconstruction algorithms typically employ iterative methods or model-based approaches to invert the measured data and generate cross-sectional images or 3D reconstructions of the medium's internal structure and properties. Applications of diffusion tomography are found in various fields. In biomedical imaging, it is explored for non-invasive imaging of tissues, particularly for detecting and characterizing tumors or assessing tissue oxygenation, where light diffusion is dominant. In geophysical exploration, it can be used to image subsurface structures using seismic waves. Other potential applications include material science for inspecting opaque materials and industrial process monitoring. Challenges in diffusion tomography include the ill-posed nature of the inverse problem, which can lead to noisy or artifacts-laden reconstructions, and the computational complexity of the reconstruction algorithms.