X-Rays
Xray Machines are quite simple machines that emit electromagnetic waves of wavelength 0.01 and 10 nm, giving a cooresponding frequency of 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 120 eV to 120 keV
X-rays produced when high-energy electrons collide with target.
Well they are made in 2 ways k-shell ejection and brehemstralung !
but both are due to close interaction with a body
Principles of the hot-cathode X-ray tube.
X-ray production as inverse of photoelectric effect.
Mention of properties of X-rays:
• electromagnetic waves
• ionisation
Ionisation is the adding or removing of electrons to make a molecule charged. Charged particles are more likely to react/ interact with other particles. X-Rays have this power of ionisation. Particles must be of sufficiently high energy in order to have this Ionisation ability (usually > 10 eV). Ionisation can affect living cells, and has the potential to cause cancers and can also affect the D.N.A.. In
• penetration.
Penetration is how far an X-Ray can travel, the more dense the medium (like bone) the less likely a individual X-ray will travel through it. Skin and muscle tissue is much less dense than bones and so most X-Ray photons will travel through these tissues.
Xrays by scoilnet
X-ray "shadowgraph" of a hand taken at the conclusion of Röntgen's first public lecture on x-rays. (Note the ring on the third finger.)
"If one holds the hand between the discharge apparatus and the screen, one see the darker shadow of the bones within the much fainter shadow picture of the hand itself, " Röntgen
Uses of X-rays in medicine and industry.
We all know the main use of X-rays is to identify broken bones. Identifying the skeletal system in effect. While X-rays can be used to identify 'hard' targets in soft tissue, gallstones, kidney stones, tumors on the lung, they are not designed to work on soft tissue. CAT or MRI scans are needed for these jobs.
Xrays are actually used to help repair people in radiography, where more energetic xrays, than used for scanning, are directed at tumors within the body. Radiography is the field of medicine that carry's out this work. Radiographers are usually physicists first then physicians!
X-Rays are used in manufacturing to check the satisfactory completion of work, especially in welds.
We have all probably put our luggage through an X-Ray machine in the Airport. These are used to reduce the threat of Airline hijackings, by ensuring no weapons are allowed on board. At land border controls it is becoming common to see truck sized xray machines that can check inside the truck without need for opening the container.
Scientists use X-Rays,
- in Crystallography, which allow physists and chemists deduce shape of crystals.
- in XRay Fluroescence, tells scientist the various materials within a compound/
- Astronomy, with 50% of the total xrays on earth coming from space, there must be a whole lot to see out there through an X-Ray telescope.
possibly the most strange and curious Shoe-fitting fluoroscope ........ http://en.wikipedia.org/wiki/Shoe-fitting_fluoroscope
In 1913 Moseley was doing his post grad, and compared the k shell radiation from vaious metals from Al to Au. He derived a relation ship between the wavelength of an x-ray and its atomic number.
Moseley was able to predict the existence of elements not yet observed, such as technetium, promethium and rhenium. And even today, because of the uniqueness of the fingerprints of each element, x-rays are used for chemical analysis as it is very sensitive to impurities.
Hazards.
The W.H.O. world health organization classifies X-Rays as carcinogenic, in 2007 it had caused 2% of all the cancer in the USA.
X-Rays can damage some cells if they ionize them. Usually the worst thing that can happen is that these cells die, millions of cells die every week.
Dental X-Rays are about 1/3 the strength of normal X-Rays