X-ray

X-radiation is a kind ofelectromagnetic radiation.X-raysarewavesof X-radiation. They have a shorterwavelength,and therefore moreenergy,thanultravioletradiation. X-rays have a much shorter wavelength thanvisible light(the light that we can see). Radiation with shorter wavelengths (more energy) than the X-ray is calledGamma radiation(γ-rays). These are all parts of theelectromagnetic spectrum.

The wavelength of X-rays covers a widerange.Most X-rays have a wavelength in the range of 0.01 to 10nanometres.This corresponds withfrequenciesin the range 30petahertzto 30exahertz(3×10¹⁶Hz to 3×10¹⁹Hz) and energies in the range 100eVto 100 keV.

X-rays can go through manysolid materials.For this reason, takingphotogramswith X-rays is used inmedicinein order to seebonesand other things inside the body. Sometimes the term "X-ray" means these pictures instead of the radiation that makes them.

What these images show will depend on three things:Rayleigh scattering,Compton scatteringandphotoabsorption.^[1]^[2]^[3]The images show bone because it isdenseenough that X-rays are not able to pass through it. Instead, the X-rays are either absorbed orscattered.The images do not showskinandmuscle,however, because thesetissuesare transparent enough for the X-rays to pass through them without being absorbed too much. To detecttumors,other imaging devices are used; such asmagnetic resonance imaging.Acomputed tomography scannercombines an X-ray machine and computer to construct a three dimensional (3D) picture. This has some ability to see other things besides bone.

X-rays are made by hittingmetalwith fast-movingelectrons.They arephotons,tiny packets of energy that can moveatomsand change chemicals in the body. They areionizing radiationbut the things they do depend on the wavelength of the X-rays (or how much energy they have). X-rays with smaller energies ( "soft" x-rays) cause thephotoelectric effect.Mid-level energies causeCompton scattering.High-level energies ( "hard" X-rays) causepair production.X-rays used for making pictures of people have low to medium energy.Radiation therapythat treatscanceruses Compton scattering and sometimes Pair production.

There are small amounts of X-rays in the air. Like otherenergy in the air,X-rays can change living cells. Exposing the human body to high doses of X-rays for a long time is dangerous. It can causecancer.However, cancer cells are hurt more easily, so X-rays are sometimes used tokill them.

Related pages

References

↑"RTAB: the Rayleigh scattering database".Lynn Kissel. 2000-09-02. Archived fromthe originalon 2011-12-12.Retrieved2012-11-08.
↑David Attwood (1999). "3".Soft X-rays and extreme ultraviolet radiation.Cambridge University Press.ISBN 978-0-521-65214-8.Archived fromthe originalon 2011-04-12.Retrieved2013-10-30.
↑Jerrold T. Bushberg, J. Anthony Seibert, Edwin M. Leidholdt, and John M. Boone (2002).The essential physics of medical imaging.Lippincott Williams & Wilkins. p.38,42.ISBN 978-0-683-30118-2.{{cite book}}:CS1 maint: multiple names: authors list (link)

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[1] "RTAB: the Rayleigh scattering database".Lynn Kissel. 2000-09-02. Archived fromthe originalon 2011-12-12.Retrieved2012-11-08.

[2] David Attwood (1999). "3".Soft X-rays and extreme ultraviolet radiation.Cambridge University Press.ISBN 978-0-521-65214-8.Archived fromthe originalon 2011-04-12.Retrieved2013-10-30.

[3] Jerrold T. Bushberg, J. Anthony Seibert, Edwin M. Leidholdt, and John M. Boone (2002).The essential physics of medical imaging.Lippincott Williams & Wilkins. p.38,42.ISBN 978-0-683-30118-2.{{cite book}}:CS1 maint: multiple names: authors list (link)

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