REDUCING ELECTRON CONTAMINATION OF CO-60 TELETHERAPY BEAMS

In conclusion, the problem of minimizing electron contamination is particularly relevant to modern telecobalt units which can provide large field sizes at relatively short source skin distance. This contamination may easily be estimated using a commonly available robust ionization chamber and a series of thin absorbing filters. If it is necessary to reduce contamination by the use of an electron filter in the beam, careful attention should be paid both to the material used for the filter and to its position.