HISTORY OF X-RAYS
X-rays were discovered accidentally on the 8th of November 1895, by Wilhelm Conrad Roentgen.
Roentgen was a German physicist from the University Wurzburg. He was engaged in studying the behavior of an electron beam as it passed through a vacuumized tube to strike a tungsten plate. To his surprise, he observed that, in addition to electrons certain unknown rays were also produced, which could penetrate the glass envelope of his apparatus and produce a glow on a distant fluorescent screen. He was able to photograph the bones of the hand of his wife by placing it over a photographic plate and then shining the rays on it.
Since no name had been given to this kind of radiation, the name X-ray was given by him. For his unique discovery, Roentgen was awarded the Nobel Prize in Physics in the year, 1901,
- Penetrating Power X-rays closely resemble visible light rays in having a similar photographic effect. But they differ from the light rays in being invisible and in having a shorter wavelength. The wavelength of X-rays is 0.01 to 10 nanometers. It is this property of short wave length which gives them the power of penetration through different materials.
Properties of X-ray:
When X-rays pass through matter, they are absorbed to carving extent. The degree of absorption depend on the density (atomic weight) of the matter. Radiography is based on the differential absorption of the X-rays. Dense tissues such as bones, metals and materials having high atomic numbers absorb X-rays far more easily than do the soft tissues of the body. These cast a white shadow on the image plate as no X-rays can reach the imaging plate. Structures which are easily penetrated by X-rays such as air and fat allow the X-rays to reach the image plate, thereby casting a black to grey impression, identical to the physical appearance of the intervening structure. These are described as radiolucent shadows and the structures which are penetrated with difficulty or are not penetrated at all are described as radiopaque,
Different density structures, therefore, can be arranged in a scale of increasing radiopacity.
How it works:
Production of X-rays- X- rays are produced in the x-rays tube. which is vaccum created by glass bulb, having a cathode and anode. There is tungsten wire filament towards cathode side which emit electron, when heated. This electron strike over a rectangular tungsten plate, which is lying at 20 angle towards anode side, consequently more amount of heat energy amd less amount of X Rays are produced at tungsten plate. The x rays produced and passed through a lead shielded tube. The heat energy produced in the target is dissipated through a copper bar attached to the target. The copper bar is cooled by three method-ar cool method, oil cool method, oil and water cooled method. The number of X-rays are controlled by regulating the temperature of filament. Filament is given 4-8 ampere of current from a low voltage step down transformer.
Analyzing x-ray film
- Air, in the respiratory passages, stomach and intestines is black
- Fat is greyish black and relatively less dark than air.
- Soft tissue, l.e.g. muscles, vessels, nerves, and viscera cast an impression by virtue of the adjoining fator air outlining them or else they would not be visible on X-rays.
- Bones, due to their calcium content appear grayish white.
- Enamel of teeth, and metallic foreign bodies, eg, metallic filling of the teeth, and radiopaque contrast media also appear white the brightness being much more than the bone.
Benifits:-
- Mammography- Mammograms are specialized x-rays that create detailed images of the breasts. They are used to screen for and diagnose breast cancer and other breast conditions, such as cysts. The American Cancer Society recommends that women have annual mammograms starting at age 40
- Intravenous pyelography (IVP)- These x-rays of the urinary tract use a contrast medium to help detect conditions such as kidney stones, bladder cancer and prostate enlargement (benign prostatic hyperplasia).
- CAT scan (computed axial tomography). This noninvasive or minimally inva sieve test uses multiple x-ray images, taken from different angles, to create three-dimensional images of body structures.
- Arthrography- This minimally invasive test involves injection of a contrast medium into a joint, followed by a standard x-ray, CAT scan or MRI (magnetic resonance imaging). Its uses include identification of tendon and ligament injuries.
- Discography. This test is often performed on patients who are considering back surgery or who have not responded well to conventional treatments for back pain caused by conditions such as degenerative disc disease or a herniated disc.
- Fluoroscopy – This type of test uses x-rays to image internal body organs while they are in motion. A continuous X-ray beam is focused on the part of the patient.
Fluoroscopy can be used in pain management-for example, to guide corticosteroid injection inside a joint.
- DEXA scan (dual-energy x-ray absorptiometry). Also known as a bone density scan, DEXA is the standard method of measuring bone mineral density DEXA scans are often used to screen for the bone-thinning disease osteoporosis, especially in women.