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US 4,286,167 AGranted
Multi-element X-ray equalizing filter
AssigneeVarian Associates, Inc.
InventorPhilip D. La Riviere
Life of this patent
Estimating the term…
Abstract
A filter for megavolt X rays has an absorbing member shaped to provide greater thickness for rays in the direction of higher intensity, e.g., the axis of the electron beam. A second absorbing member of a material of different atomic number is shaped to provide greater thickness for rays in the direction of higher photon energy, e.g., said axis. By selecting the combined shapes, both the intensity and the effective photon energy can be equalized over the field of radiation. Thin removable shims may be added for further adjustment. A neutron filter may also be added.
Claims14
A filter for a high-voltage X-ray beam comprising:
- a first filter element made of a material having a relatively low effective atomic number and
- a second filter element made of a material having a relatively high atomic number,
- said elements being so shaped and positioned with respect to said beam that said filter elements absorb energy in a direction-dependent manner so as to make both the intensity and the photon energy distribution substantially uniform over a useful irradiated field.
Dependencies are inferred from the claim text.