Radioactive source

Radionuclides are chosen according to the type and character of the radiation they emit, intensity of emission, and the half-life of their decay.

Many radioactive sources are sealed, meaning they are permanently either completely contained in a capsule or firmly bonded solid to a surface.

Note that sources with sufficiently low radioactive output (such as those used in Smoke detectors) as to not cause harm to humans are not categorised.

Capsule sources, where the radiation effectively emits from a point, are used for beta, gamma and X-ray instrument calibration.

This has a known amount of radioactive material fixed to its surface, such as an alpha and/or beta emitter, to allow the calibration of large area radiation detectors used for contamination surveys and personnel monitoring.

Unsealed sources are also used in industry in a similar manner for leak detection as a Radioactive tracer.

[5] A notorious incident of neglect in disposing of a high level source was the Goiânia accident, which resulted in several fatalities.

A metal cylinder with a ruler next to it, 3.1cm high
A new sealed cesium-137 radiation source as it appears in its final state
A cutaway diagram of a teletherapy capsule
A cutaway diagram of a radioactive source used for teletherapy ( external beam radiotherapy ): A key to the lettering can be found on the file page
2007 ISO radioactivity danger symbol intended for IAEA Category 1, 2 and 3 sources defined as dangerous sources capable of causing death or serious injury. [ 9 ]
Hand-held large area alpha scintillation probe under calibration using a plate source