This tube is usually made out of glass or gold and is inserted into the cancerous tissue.
Radon-220 has a half-life of 55 seconds and is also known as Thoron as it is formed from the decay of an isotope of thorium.
This isotope was discovered by Ernest Rutherford in 1899.
Radon-219 is a product of the decay of an isotope of actinium, with a half-life of 4 seconds.
The physical features of radon are a colourless and odourless gas which melts at -71° C (about -96° F), boils at -62° C (-80° F), and has a density of 9.73 g/litre at 0° C (32° F) and 1 atmosphere pressure.
As background radiation is mostly made up of radon isotopes, it is feared that it is a health hazard, with an estimated 2,500 people in the UK dying from radon-induced lung cancer.
It is formed from the decay of uranium minerals, and by passing air through a solution of radium salt.
This isotope can be used to treat cancers by using the latter process of obtaining radon to collect the gas in a tube, called a "radon seed".
Gamma rays are emitted from various rocks that exist naturally in the environment; such rocks include igneous rocks like granite, uranium and thorium.Granite is found in abundance in Cornwall, and it is known that background radiation is slightly higher inn Cornwall as a result.Radon is a radioactive noble gas, and is the heaviest of the noble gases with atomic number 86 and relative atomic mass 222.Radon can be found with twenty different isotopes, three of the most common being Radon-222, Radon-220 (also known as Thoron) and Radon-219.
Radon can be found in small quantities seeping up from rocks and soils in the Earth.
Radon-222 has a half life of 3.8 days, decaying into Alpha particles (helium nuclei) and a polonium isotope.