Medical imaging applications include all those technologies used to allow medical professionals to "see" inside the human body. The oldest of these, x-ray images or radiographs, have been around since the late 19th century. X-rays are still used in many situations, and have been joined by other applications, including nuclear medical imaging, computed axial tomography, and magnetic resonance imaging.
In most medical facilities, medical imaging applications are usually grouped in radiology departments or biological imaging departments. These departments have medical professionals called radiologists or radiologic technicians, who perform imaging tests using various technologies, taking internal "photographs" of the anatomical structures of the human body. Doctors may use these images to diagnose, treat, and/or do surgical preparations for treatments. Some medical imaging applications involve more radiation exposures than others; however, with two-dimension (2D) images, doctors can assemble many of the images through software and get three dimension (3D) images. Viewable from every angle, these 3D images allow doctors noninvasively to arrive at detailed diagnoses.
The oldest and still widely used medical imaging application is the radiographic x-ray. The name "projectional radiograph" is the medical term for an x-ray, which is frequently used to find fractures or to examine lung changes. The barium-contrast x-ray or fluoroscopy can examine the entire internal gastrointestinal system for problems such as ulcers or colon polyps, while the patient is maneuvered on a tilting table. Another special type of x-ray is the bone densitometry imaging device, which takes measurements of bone mineral-content densities throughout the body; this involves relaxing on a table while the densitometry robotic arm moves over regions of the body, taking images for approximately 20 minutes.
Nuclear medical image applications make use of more than one imaging device for nuclear or molecular imaging. Tests involve introducing radioisotopes into the region of the body being tested, usually orally or intravenously, to look for tumors, infections, or biologic malfunctions in those regions. A gamma ray camera then absorbs images from every angle along the patient's body as it processes the radioisotopes to produce 2D images, checking the functions of the body during that time. For instance, a renal nuclear imaging test may involve the introduction of positron emission tomography (PET) or computed tomography (CT) scans to examine biologic activity near suspected disease in one or both kidneys.
CT medical image applications include several different types of tests. The most commonly used is the orthopantomography exam of the jaw's mandible area in a series of programmed movement angles, producing images as if the mandible were a flattened bone. The CT or computed axial tomography (CAT) exam uses higher dosages of x-rays than simple radiographs, and the patient travels through a donut-shaped ring of image-making detectors. This exam produces images of the body in slices so that medical professionals can look for diseased tissues, blood vessels, or organs.
Medical imaging applications are also found in the radiology departments performing magnetic resonance imaging (MRI) tests. Large magnets polarize hydrogen proton nuclei in the body of the patient, producing a spatially-coded signal that triggers images. The MRI machine excites the hydrogen nuclei by emitting a radio frequency in pulses according to the organ being examined, to spin them in desired directions, thus resonating them. This test also produces slices for diagnostic examinations by a radiologist and other medical professionals.