Optical Coherence Tomography
Optical coherence tomography (also optical coherent tomography, OCT) is a modern diagnostic method that enables non-invasive imaging of the structure of tissues in the human body. The principle of OCT is the use of reflections and scattering of light waves to create a detailed image of tissues and organs with high resolution.
Principle of OCT operation[edit | edit source]
OCT works on the basis of interferometry, which is a measurement method that uses the interference of light waves. Interferometry in OCT is carried out using an interferometer, which consists of a light source, lenses and a detector. Radiation with a higher wavelength is used, most commonly in the near-infrared (radiation) range which penetrates deeper into tissue and, at the same time, provides high image resolution due to lower scattering. The light source emits short pulses that are reflected from the tissues. The reflected light meets a reference light beam inside the interferometer. The interference between the reflected and reference light allows accurate measurement of time, which is then converted into information about tissue depth.
A-scanning and B-scanning[edit | edit source]
During the OCT scanning process, two basic types of images are created: A-scan and B-scan images.
A-scanning[edit | edit source]
This type of imaging records the intensity of reflected light depending on tissue depth. Each point on an A-scan image corresponds to a reflected signal from a specific depth within the tissue. In this way, information about the tissue structure in one direction can be obtained. In ophthalmology, an A-scan can provide information about the thickness of ocular structures, for example, the eye lens.
B-scanning[edit | edit source]
This type of image creates a two-dimensional image of tissue structure. The B-scan image is created by combining several A-scans side by side, producing an image that allows visualization of the tissue structure on the surface or in a cross-section. In ophthalmology, a B-scan can provide an image of the retinal structure and detect possible pathologies.
Use in medicine[edit | edit source]
OCT is used not only in ophthalmology, but also in cardiology, dermatology and other fields. In cardiology, it is used to diagnose diseases of the coronary vessels, while in dermatology it can provide detailed images of skin layers. OCT is also used in dentistry, where it can be used to diagnose conditions of the dental pulp and root canals during endodontic treatment. In periodontology, it is further used in assessing the condition of gums affected by periodontal disease.
Advantages and disadvantages of OCT[edit | edit source]
OCT offers several advantages compared with other diagnostic methods. These include high resolution, scanning speed and minimal invasiveness, making it an ideal tool for diagnosis in ophthalmology and in many other medical fields.
However, the acquisition of OCT equipment is financially demanding, which may limit access to this technology in some healthcare facilities. In some cases, OCT, despite its increased penetrative ability through the use of IR radiation, may encounter limitations in the penetration of light into deeper tissues. Last but not least, it is important to mention that correct interpretation of OCT images requires expert knowledge, and therefore trained personnel are needed.
Given these advantages and limitations, optical coherence tomography, with its wide range of applications and non-invasive nature, is a key tool in modern medicine.
