Radiology

Radiology is the branch or speciality of medicine that deals with the study and application of imaging technology like x-ray and radiation to diagnosing and treating disease.Radiologists direct an array of imaging technologies (such as ultrasound, computed tomography (CT) Computed Axial Tomography, nuclear medicine, Positron Emission Tomography (PET) and magnetic resonance imaging (MRI)) to diagnose or treat disease. Interventional radiology is the performance of (usually minimally invasive) medical procedures with the guidance of imaging technologies. The acquisition of medical imaging is usually carried out by the radiographer or radiologic technologist. Outside of the medical field, radiology also encompasses the examination of the inner structure of objects using X-rays or other penetrating radiation.

History
Originally radiology was the aspect of medical science dealing with the use of electromagnetic energy emitted by X-ray machines or other such radiation devices for the purpose of obtaining visual information as part of medical imaging. Radiology that involves use of x-ray is called roentgenology. The modern day radiological imaging is no longer limited to the use of x-rays, and now includes technology-intensive imaging with high frequency sound waves, magnetic fields, and radioactivity. Wilhelm Conrad Röntgen (English spelling Roentgen) discovered x-radiation on 8 November 1895 at the Physical Institute of Würzburg University. He named the radiation he had discovered "X-radiation". This term is still in use today in the Anglo-American region. His work was first published in a meeting protocol of the Würzburg Physical-Medical Society in the 1895 volume; the article was submitted by W.C. Röntgen on 28 December 1895. Roentgen received the first Nobel Prize for Physics for the discovery of X-rays in 1901.

Fluoroscopy
Fluoroscopy and angiography are special applications of X-ray imaging, in which a fluorescent screen or image intensifier tube is connected to a closed-circuit television system.[2]:26 This allows real-time imaging of structures in motion or augmented with a radiocontrast agent. Radiocontrast agents are administered, often swallowed or injected into the body of the patient, to delineate anatomy and functioning of the blood vessels, the genitourinary system or the gastrointestinal tract. Two radiocontrasts are presently in use. Barium (as BaSO4) may be given orally or rectally for evaluation of the GI tract. Iodine, in multiple proprietary forms, may be given by oral, rectal, intraarterial or intravenous routes. These radiocontrast agents strongly absorb or scatter X-ray radiation, and in conjunction with the real-time imaging allows demonstration of dynamic processes, such as peristalsis in the digestive tract or blood flow in arteries and veins. Iodine contrast may also be concentrated in abnormal areas more or less than in normal tissues and make abnormalities (tumors, cysts, inflammation) more conspicuous. Additionally, in specific circumstances air can be used as a contrast agent for the gastrointestinal system and carbon dioxide can be used as a contrast agent in the venous system; in these cases, the contrast agent attenuates the X-ray radiation less than the surrounding tissues.

CT scanning
CT imaging uses X-rays in conjunction with computing algorithms to image the body. In CT, an X-ray generating tube opposite an X-ray detector (or detectors) in a ring shaped apparatus rotate around a patient producing a computer generated cross-sectional image (tomogram). CT is acquired in the axial plane, while coronal and sagittal images can be rendered by computer reconstruction. Radiocontrast agents are often used with CT for enhanced delineation of anatomy. Intravenous contrast can allow 3D reconstructions of arteries and veins. Although radiographs provide higher spatial resolution, CT can detect more subtle variations in attenuation of X-rays. CT exposes the patient to more ionizing radiation than a radiograph. Spiral Multi-detector CT utilizes 8,16 or 64 detectors during continuous motion of the patient through the radiation beam to obtain much finer detail images in a shorter exam time. With computer manipulation these images can be reconstructed into 3D images of carotid, cerebral and coronary arteries. CT scanning has become the test of choice in diagnosing some urgent and emergent conditions such as cerebral hemorrhage, pulmonary embolism (clots in the arteries of the lungs), aortic dissection (tearing of the aortic wall), appendicitis, diverticulitis, and obstructing kidney stones. Continuing improvements in CT technology including faster scanning times and improved resolution have dramatically increased the accuracy and usefulness of CT scanning and consequently increased utilization in medical diagnosis. The first commercially viable CT scanner was invented by Sir Godfrey Hounsfield at EMI Central Research Labs, Great Britain in 1972. EMI owned the distribution rights to The Beatles music and it was their profits which funded the research. Sir Hounsfield and Alan McLeod McCormick shared the Nobel Prize for Medicine in 1979 for the invention of CT scanning. The first CT scanner in North America was installed at the Mayo Clinic in Rochester, MN in 1972.