- Definition
X-ray is an electromagnetic wave which has a wavelength ranges from of 10 to 0.01 nm.
X-rays can be produced by two different atomic processes; Bremsstrahlung or braking radiation and K-shell emission.
X-ray is produced whenever when the velocity of the electron decreases. When the electron is shot to the metal target, typically tungsten, the electron goes approaching the tungsten nucleus. This electron slows down or even stopped whenever approaching the nucleus of a tungsten atom due to the electron rejection. The loose energy caused by deceleration then being converted by radiating x-rays. After emitting the x-ray, the original electron is slowed down or stopped.
Each atom has shells which contain electrons arranged at different energies. The K-shell is the lowest energy state of an atom. An incoming energy from the electron affect the K-shell has sufficient energy to move across to other lower energy state and make it “empty. A tungsten electron of higher energy can replace into the K-shell. Then, the tungsten electron lost its energy.Such loose energy is converted in an x-ray photon.
K-shell emission produces higher-intensity x-rays than the Bremsstrahlung, and the x-ray photon comes out at a single wavelength.
1895 Wilhelm Röntgen discovered X-rays.
1895 Thomas Edison discovered calcium tungstate as the most effective substance to produce x-rays.
1896 The fluoroscope became the standard for medical X-ray examinations
1898’s X-rays were produced in cold cathode tubes.
1904 Sir John Ambrose Fleming invented the thermionic diode valve which was applied as the X-ray tube.
1906 Charles Barkla discovered that X-rays could be scattered by gases
1950’s The X-ray microscope was invented
1999 The Chandra X-ray Observatory – the universe X-rays was launched
X-rays are categorized as a medical imaging device, which is used for diagnostic radiography such as:
Chest X-ray
- To identify lung diseases.
- To identify pneumonia, lung cancer, fluid collection (Pulmonary Edema) in the lungs
Abdominal X-ray
- To detect obstructions of the intestine (Ileus)
- To observe the presence of air in the abdominal organs, fluid collection in the abdominal cavity (Ascites)
- To detect of stones in the urinary system and the gallbladder
Real-time imaging
- Angiography: a procedure conducted to display blood vessels with the radio-opaque dye is injected within.
- Angioplasty : a procedure used to widen narrowed blood vessels
- To observe the organ; the blood vessels, urinary system, skeletal system
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