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Science

Radiation treatment

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X-rays, gamma rays and beta particles are all used in medicine to treat internal organs. X-rays are produced by firing electrons at a metal target and gamma rays are emitted by the nucleus of radioactive atoms.

Gamma rays are used to kill cancer cells, to sterilise medical equipment and in radioactive tracers.

Radiation

X-rays, gamma rays and beta particles are all used in medicine. X-rays and gamma rays are members of the same group of waves called the electromagnetic spectrum.

Electromagnetic spectrum from long wavelength, low frequency, low energy to short wave length, high frequency, high energy. The uses are (top to bottom) Aircraft and shipping bands; AM radio; Shortwave radio; TV and FM radio; Microwave radar; Infrared light; Visible light; Ultraviolet light; X-rays; Gamma rays.

As both X-rays and gamma rays have very short wavelengths they are both very penetrating and can pass into the body to treat internal organs. The main difference between them is the way they're produced. X-rays are produced by firing electrons at a metal target in an X-ray machine. Gamma rays are emitted by the nucleus of an unstable (radioactive) atom.

There are two other radiations emitted by the nucleus of an unstable atom – alpha and beta particles. Due to their relatively large size alpha particles are easily stopped by our skin and are not used in medical diagnosis or therapy. Beta particles can pass through skin so are used in medicine.

alpha radiation cannot pass through humans, beta is stopped by aluminium, gamma by lead

Penetrative properties of different types of radiation

Higher tier only

X-rays are manufactured by an X-ray machine. A hot cathode emits electrons that are attracted to a tungsten anode. When the fast-moving electrons hit the target, most of their kinetic energy is transferred to heat but some is transferred to X-rays.

Shows a cross section of an X ray machine, where fast moving electrons move from a cathode to an anode. The X ray can pass through skin but not bone, onto a film behind the body part.

This machine allows the energy and intensity of the X-rays to be controlled. Gamma rays, on the other hand, are given out by the nucleus of an unstable atom. This process is totally random and so cannot be controlled as easily as X-rays.

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