Introduction to Optical Coherence Tomography

Alignment of the anatomical part can also affect the image. Shape distortion is when an image appears either longer or shorter based on the way it is positioned in relation to both the central ray and the image receptor; foreshortening is when the object appears shorter than it is in reality, while elongation is when the object appears longer than it truly is. When imaging a part, the long axis is intended to be placed perpendicularly to the central ray and parallel to the image receptor. Distortion happens when either the part or the central ray/image receptor are placed incorrectly. In addition, distortion can also occur due to standard divergence of the beam.

Evers, D. J., B. Hendricks, G. Lucassen, and T. Ruers. "Optical Spectroscopy: Current Advances and Future Applications in Cancer Diagnostics and Therapy." NCBI. National Center for Biotechnology Information, 8 Mar. 2012. Web. 13 Sept. 2015.

PET is the only method that can detect and display metabolic changes in tissue, distinguish normal tissue from those that are diseased, such as in cancer, differentiate viable from dead or dying tissue, show regional blood flow, and determine the distribution and

utilization of an inward reflect close to the subject and a second curved reflect at a remote site. In

Furthermore, X-ray of higher energy than required for imaging is used for radiation therapy. The radiation therapy makes use of ionization radiation (and no images) for the treatment of diseases, such as

I. Ordinary X-rays are used to diagnose many conditions and can be used to see a variety of things in the body,

Another limitation is out of focus light from outside the focal plane reducing image clarity or requiring constant adjusting.  On the other hand, under the right conditions, light microscopy allows for viewing of samples that are still alive.  There are aids such as fluorescent proteins, that can be used to track proteins in real-time in cells though the viewing of where the proteins are may not be very high in resolution, you may see roughly where the protein is in the cell, but will not be able to see the shape of the protein itself. Lastly confocal light microscopy gives moderately higher resolution, and significant enhancements in optical sectioning by limiting out-of-focus light.

An Excimer Laser is an extremely precise laser that uses ultraviolet light to remove minute amounts of corneal tissue. Each pulse of the laser removes mere microns of tissue, far less

We used DRI-OCT1 (Topcon Inc., Tokyo, Japan) based on swept source OCT technology, with a scanning speed of 100000 A-scans/s. The scan protocol was a 3D volumetric macular scan 6x6 mm square containing 512 x 128 A-scans. The center wavelength of the probe beam was 1060 nm. This long-wavelength probe enables deep choroidal penetration. The axial resolution of this system is 8 μ in tissue. Automated built-in software was used to create a choroidal thickness map of 6X6 mm from 128 images of each 3D data set. The consecutive en face images between RPE and chorioscleral interface were constructed using software co-developed with Topcon.21

Such as Imaging – absorbed by material such as bone, enabling images of the bone to be observed

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This type of exposure localizes objects and tumors in the buccolingual dimension, showing the buccal and lingual cortex. The field size is larger on an occlusal film (size 4), which is placed on the occlusal surface of the mandibular teeth and the central ray is coming from underneath the mandible, directed at a right angle. On the film, the depth of the tumor in the bone can be determined. A panoramic projection can also be used for radiographing tumors and cysts. The size of the field allows viewing of the lesion in relation to its surrounding area.

Although brain surgery was the first clinical target for FUS, it provides special challenges due to the higher attenuation of ultrasound of skull bone. Also the lack of accurate targeting and energy deposition control prevented its clinical use in the central nervous system. Bone density also affect the speed of sound. If use conventional focused transducers, It would be difficult to obtain a sharp focal spot through an intact skull. Therefore for earlier clinical trials, there was always removed a part of skull bone to provide an good acoustic access to the brain. The skull problem has been solved by two key developments. And clinical brain treatment is possible now. It was discovered that using low frequency phased arrays with common element sizes can produce a sharp focus through the skull. Or the skull heating problem can be overcome by using phased array applicators with large enough surface areas. It was proved that modern medical instrument can provide enough information to allow precise focusing[31]. InSightec developed a complete system designed for clinical FUS surgery. This technique has been tested in three patients to determine the maximum intensity that could be delivered through the skull bone [29]. Three brain tumor patients in Boston proved that sharp focusing could be

With more replication and standardization, ERG, OCT, and retinal imaging will have significant clinical implications. In addition to the possibility for use as an objective biomarker, results can be translated to monitor disease severity, treatment response, providing personalized therapy, and

The radiograph, one of the most common diagnostic imaging tools utilized in this field, possesses a very important component called contrast. Contrast helps radiologists perceive image detail and glean information from the area of interest. Radiation Technologists, or Rad-Techs, should always ensure that radiographs have the right amount of contrast so that the radiologist can easily read them for faster diagnosis.