Discovery of x-rays and development of modern radiology During the 1870s and 1805 many university physic laboratories were investigating the conduction of cathode rays; through a large partially evacuated glass tube know as Crookes tube. An English man Sir William Crookes discovered the tube. The tube that bears his name was the forerunner of modern lamps and x rays. William Roentgen was experimenting with a type of Crookes tube when he discovered X rays.
On November 8, 1895, Roentgen was working in his physic laboratories at Wurzburg University, Germany. He had darkened his laboratory and completely enclosed his Crookes tube with block photographic paper so that he could better visualized the effect of the cathode rays in the tube. A plate coated with barium Platinocyanide, a fluorescent material, which was lying on a bench top several feet from the Crookes tube. No visible light escaped from the Crookes tube because the block paper enclosing it, Was Roentgen noted that barium platinocyanide glowed regardless of its distance from the Crookes tube.
The intensity of the glow increased as the plate was brought closer to the tube. This glow is called fluorescence. Roentgen called the unknown rays as X- rays. He kept various materials – wood, aluminum, his hand between the Crookes tube and fluorescing plate.
Roentgen was able to report his experimental results to the scientific community before the end of 1895. For his work he receives the Nobel prize in 1901. He produced and published the first medical x-ray image in early 1896. It was an image of his wife’s hand.
Development of modern radiology There are two general types of x ray examination: radiography and fluoroscopy. Radiography uses x ray films and usually an x-ray tube mounted from the ceiling on a track that allows the tube to be moved in any direction. Such examination provides the radiologist with fixed images. Fluoroscopy is usually conducted with an x ray tube located under the examination table, The radiologist is provided with the moving image on a television monitor or flat panel display. There are many variations of these two types of examination, but x ray equipment is similar.
At Roentgen’s time only simple static generator were available. These units could provide current of only a few mill ampere and voltage to 50kvp.Today 1000mA and 150KVP are common. Radiographic procedure using equipment with limitations of electric current and potential often required exposure times of 30 minutes or more for satisfactory examination. Long exposure time results in image blur,development that helped reduce the exposure time was the use of fluorescent intensifying screen in conjunction with the glass photographic plates.
Michal Pupin is said to have demonstrated the use of a radiographic intensifying screen in 1896. Charles L. Leonard found that by exposing two glass x ray plates with the emulsion surface together, exposure time was halved and the image was considerably enhanced. Double emulsion film become commercially available in 1918. During the world war 1 st, radiologist began of to make use of film rather than glass plates. Much of the high quality glass used in radiology came from Belgium and other European countries. Thus supply was interrupted during the 1 st world war. The substitute for glass was cellulose nitrate. It quickly became popular and better than the glass plate.
The fluoroscope was developed in 1898 by American inventor Thomas A. Edison. Edison’s original fluorescent material was barium platinocyanide. He investigated the fluorescent properties of over 1800 other material including zinc cadmium sulphide and calcium tunstate.Two materials in use today. Two devices designed to reduce the exposure of patient to x rays thereby minimize the possibilities of x ray burn were introduce before the turn of the 20 th century by a Boston dentist, William Rollins.Rollins used x rays to image teeth and found that restricting the x ray beam with a sheet of lead having a hole in the centre a diaphragm, and inserting a leather or filter improved the diagnostic quality of his radiograph.
This first application of collimation and filtration was adopted slowly. In 1907 HC snook introduced a substitute high voltage power supply, and interrupter less transformer, for the static machines and induction coils then in use. After considerable clinical testing, William D Coolidge unveiled his hot- cathode x-ray tube to the medical community in 1913.It was immediately recognized as far superior to the Crookes tube. It was vacuum tube and allowed x-ray intensity and energy to be selected separately with great accuracy.
In1921, grid was developed by potter Bucky grid which greatly improved image contrast. In 1946, the light amplifier tube was demonstrated; this device was adapted for fluoroscopy by 1950. Diagnostic Ultrasound appeared on the 1960s as well as the gamma camera. Positron emission tomography (PET) and x-ray computed tomography (CT) were developed in the 1970s. MRI, became an accepted modality in the 1980 and now magnetoenceohalography (MEG) is being investigated.
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