Acta Materialia Turcica
Yazarlar: Huseyin Ozgur KAZANCİ
Konular:Mühendislik, Ortak Disiplinler
Anahtar Kelimeler:Biomedical Imaging,Diffuse optic tomography (DOT) technique,Transmission through,Back-reflected,Cylindrical ring,Continuous Wave (CW),Frequency Domain (FD),Time Resolved (TR)
Özet: The philosophy of laser imaging first thought by the idea of visualizing the photon trajectories which are even seen by naked eyes when anybody looks inside to the photon diffusing object. If white light beams onto the imaging tissue, blood vessels can be seen by the naked eye from the tissue surface, roughly. One of the important biomedical molecular macroscopic imaging technique is the laser imaging. Most of the works cover research infrastructures, laboratories, and hospitals for diffuse optic laser imaging. Naturally, in most of the clinical applications, near infrared (NIR) laser is being used, since the main motivation trial is the cancer case, obviously. NIR laser helps to figure out hemoglobin content which uses the blood absorption maxima wavelength, hence in most of diffuse optic tomography (DOT) research, NIR laser is used. Most of the diffuse optic laser imaging technique are using low energy incident collimated isotropic un-polarized gaussian beam which is generated by semiconductor laser diode. Applied power is usually less than 10 mW/cm2. At the beginning of the laser diffuse optic imaging (DOI) research era, most of the researchers have jumped into the research without reading and understanding the limitations of the modality. Low energy light has some restrictions, the most important is the scattering nature of the light depend on the tissue type. However, some tissue types such as cerebrospinal fluid has low optic scattering coefficients. Another important factor besides the scattering, caused by low energy, hence photons are penetrating only superficially. Photons are scattering much and penetrating only superficially. On the other hand, if x-ray bremsstrahlung photons were used, it would go deeper tissue layers, nevertheless it becomes ionized radiative light. The philosophy of laser diffuse macroscopic molecular imaging modality is covering scattering of light, therefore device concept should be thought according to this phenomenon, source and detector placement should be arranged based on this truth. In this review paper, the philosophical concept will be evaluated for laser imaging.