Thoraeus filter

Thoraeus filter

[′thȯr·ē·əs ′fil·tər]
(nucleonics)
A primary radiological filter of tin, combined with a secondary filter of copper to absorb the characteristic radiation of the tin and a third filter of aluminum to absorb the characteristic radiation of the copper; in the range of 200 to 400 kilovolts, such a filter hardens x-rays more efficiently than the usual combination of copper and aluminum.