X-rays founded by physicist Wilhelm Conrad roentgen(1895).He called it as the new kind of rays or x-ray .by using this ray he taken photograph of his wife and showing the her bones ,wedding rings. Afterwards it’s used to visualize the internal anatomy of humans. Nowadays x-rays are used to diagnostic tool in medical profession and used in simple chest radiography to a digital subtraction angiography, CT (computer tomography) depends on use of x-rays.
Depends on anatomical structures of body have different densities for the x-rays. When x-ray from source penetrate to the body, the internal body absorbs varying amount of radiation. The radiation coming from body has spatial intensity variation that’s image of the internal structure of body. We are using photographic film for the visualization of x-ray intensity distribution.2 properties of x-rays which are used for diagnostics are
NATURE OF X-RAYSx-rays are electromagnetic radiation located at low wavelength in electromagnetic spectrum. For diagnostic purpose, using wavelength of order of 10^-10m and speed of 3*10^10 cm/s which is unaffected by electric and magnetic fields. According to quantum theory ,interaction of matter involves energy exchange and their relationship between the wavelength and the photon
h-Planck’s constant =6.32*10^-34js , c- velocity of propagation of photons (3*10^10 cm/s), v-velocity of radiation .
To characterize x-rays by the voltage ,which is measure of energy of the radiation.
Properties of x-rayIt has short wavelength and extremely high energy so which can penetrate through material which can absorb & reflect visible light. X-ray can produce secondary radiation which is composed of scattered radiation. It can produce ionization in gases and influence the electrical properties of liquids and solids, which can also produce fluorescence in certain material to help them emit light.
Units of x-rayRadiological units adopted Rontgen(R) as a measure of the quality of of x-ray radiation. one R can produce 2.08*10^9 ion pairs per cubic cm of air at standard temperature and pressure. Other units are millirontgen and microrontgen.The units are based on the ionization produced by the rays and which is not effects like the blackening of photographic films. The biological effects of x-rays are due to energy that’s very closely correlated with absorbed dose(D).unit of absorbed dose is rad.(one rad=1.0 *10^-2j/kg in irradiated material).The relationship between roentgen and absorbed dose is D=f R,where f=.86rad/R for air and 1 rad/R for soft tissue.
PRODUCTION OF X-RAYSX-rays produced by electrons collide by high speed with matter and are thus suddenly stopped. The energy produced by electrons are in the form of highly penetrating electromagnetic waves(x-rays) having different wavelength. x-rays are produced in a constructed glass tubes which comprises of 1) source for production of electrons 2) energy source to accelerate an electrons 3)free electrons pathways 4) a mean of electron beam and last one a device to stop the electrons. 2 main types of x-ray are stationary anode tubes and rotating anode tubes.
Stationary anode tube
Electrons are generated from the filament of tube which is vacuum diode. The electron stream is focused on a target on a anode by suitable shaped of cathode cup. The kinetic energy of electrons is converting to x-rays .here , electrons emitted by hot filament become current carriers across tube.so we have adjust filament temperature for tube current and primary voltage for tube voltage. Some of the tubes function as a triode with bias voltage, it can used to control the size and shape of the focal spot by focusing electron beam. The cathode block contains filament made up of nickel or stain less steel. Where filament is closely wound helix of tungsten wire o.2 mm thick and 1.0-1.5 diameter. the target is comprised a small tablet of tungsten about 15 cm wide .20mm long, and 3mm thick soldered into block of copper. Tungsten is used because of high melting point and high atomic number (24).copper is best thermal conductor which can carry heat away from target .The heat flow from anode to outside of the tube. For additionally electrons have high voltage and shielded.the tube will emit electrons in all directions and protection provided.we apply metal container for completely surrounding the tube.thats shield. We are using this tubes in small capacity x-ray machines.