Physics

X-ray Definition:

X rays are a type of radiation used in imaging and therapy that uses short wavelengthenergy beams capable of penetrating most substances except heavy metals.

X-rays are produced when fast-moving electrons with sufficient energy strike a target. Most of the electron energy is converted to heat, but a very minute amount —less than 1 per cent —is converted to x-rays


Spectrum of Electromagnetic Radiations. X-rays resemble visible light rays very closely but have the distinguishing feature that their wave lengths are very short

x-ray:electromagnetic radiation 

No mass No charge Travel at the speed of light Short wave length High energy Source of x-ray from the electron shells

X-ray production:

X-rays are generated by an x-ray tube, a vacuum tube that uses a high voltage to accelerate electrons released by a hot cathode to a high velocity. The high velocity electrons collide with a metal target, the anode, creating the x-rays. In medical x-ray tubes the target is usually tungsten

X-ray tube :

the insert is evacuated from air because : Prevent oxidation of the cathode filament Decrease resistance against electron movement Advantage of oil in x-ray tube : Shock absorber Heat absorber

X-ray Tube Components

X-ray
X-Rays are produced either when electrons change orbits within an atom, or electrons from an external source are deflected around the nucleus of an atom. Both are forms of high energy electromagnetic radiation which interact lightly with matter. X-rays and gamma rays are best shielded by thick layers of lead or other dense material and are hazardous to people when they are external to the body.


Radiation is energy traveling in the form of particles or waves in bundles of energy called photons. Some everyday examples are microwaves used to cook food, radio waves for radio and television, light, and x-rays used in medicine.

Ionization is a particular characteristic of the radiation produced when radioactive elements decay. These radiations are of such high energy that when they interact with materials, they can remove electrons from the atoms in the material. This effect is the reason why ionizing radiation is hazardous to health, and provides the means by which radiation can be detected.

The gray (Gy) which has units of (J/kg), is the SI unit of absorbed dose which is the amount of radiation required to deposit 1 joule of energy in 1 kilogram of any kind of matter. The rad is the (obsolete) corresponding traditional unit, equal to 0.01 J deposited per kg. 100 rad = 1 Gy. The equivalent dose is the measure of the biological effect of radiation on human tissue. For X-rays it is equal to the absorbed dose.The sievert (Sv) is the SI unit of equivalent dose, which for X-rays is equal to the gray (Gy). The rem is the traditional unit of equivalent dose. For X-rays it is equal to the rad or 0.01 J of energy deposited per kg. 1 sievert = 100 rem

Glass envelope

CT scan Definition Computed tomography (CT) an imaging method that uses x-rays to create cross-sectional pictures of the body. Alternative Names CAT scan; Computed axial tomography (CAT) scan


In conventional x-rays, a beam of energy is aimed at the body part being studied. A plate behind the body part captures the variations of the energy beam after it passes through skin, bone, muscle, and other tissue. While much information can be obtained from a regular x-ray, specific detail about internal organs and other structures is not available.



With computed tomography scan (also called CT or CAT scan), the x-ray beam moves in a circle around the body. This allows for many different views of the same organ or structure, and provides much greater detail. The x-ray information is sent to a computer which interprets the x-ray data and displays it in two-dimensional form on a monitor.


Examination : Component of x-ray tube Feature of x-ray How the x-ray produced Enumerate radiation unit of x-ray tube