2.2:
Computed Tomography
Computed tomography, or CT, is a diagnostic imaging technique that uses traditional X-ray imaging with computer processing to create a detailed view of regions within the body.
Here, the X-ray source rotates around the body, emitting rays that pass through very thin cross-sections, often just a few millimeters in thickness.
The detector opposite the X-ray source receives the signals and helps build a 2d slice or CT scan image.
Then the X-ray source moves further along the circumference to take slices one after the other. Several such 2D slices are put together to form the 3D image of the CT scans.
The intensity of the X-rays absorbed by the tissues is measured in Hounsfield units, a relative quantitative measurement of radiodensity, used to interpret the CT scans.
Unlike traditional X-ray imaging, CT can clearly distinguish structures with similar densities. It can also help analyze bone defects, clots, or tumors.
2.2:
Computed Tomography
Tomography refers to imaging by sections. Computed tomography (CT) is a non-invasive imaging technique that uses computers to analyze several cross-sectional X-rays to reveal minute details about structures in the body.
The technique was invented in the 1970s and is based on the principle that as X-rays pass through the body, they are absorbed or reflected at different levels. In the technique, a patient lies on a motorized platform while a computerized axial tomography (CAT) scanner rotates 360 degrees around the patient, taking X-ray images. A computer combines these images into a two-dimensional view of the scanned area, or a "slice."
Recently, the development of more powerful computers and more sophisticated software has made CT scanning routine for many diagnostic evaluations. It is especially useful for soft tissue scanning in areas like the brain, thoracic, and abdominal viscera. Its level of detailing is so precise that it can allow physicians to measure the size of a tumor mass or tissue down to a millimeter. Furthermore, different anatomical planes, in addition to the axial, like sagittal and coronal, can be viewed using software that processes or reformats the image slices obtained. This reduces unnecessary exposure to more X-rays for studying different planes.
CT scanning exposes patients to a dose of radiation many times higher than X-rays. In fact, children who undergo CT scans are at increased risk of developing cancer, as are adults who have multiple CT scans.
This content is derived from Openstax, Anatomy and Physiology, Section 1.7: Medical Imaging