Abstract: An unwanted effect of secondary radiation enhancement from backscatter of incident ionizing radiation on a relatively extensive metallic portion of an instrument to be inserted into a human body under x-ray fluoroscopy is minimized by coating the metallic surface thereof with a biocompatible material having the characteristic of shielding the secondary radiation enhancement effect from reaching body tissue. The depth of penetration of the secondary radiation enhancement is dependent on the atomic number of the metallic portion in conjunction with the expected radiation characteristics and energy level of the radiation incident on the metallic surface.

Abstract: A method for treating a site in a human body to inhibit abnormal proliferation of tissue at the site includes introducing into the body at the site a metal surface which generally conforms in shape to the shape of tissue to be treated at the site. Tissue at the site is then irradiated with ionizing radiation directed onto the metal surface from a point external to the surface so as to obtain locally enhanced radiation therapy by an amplification of the radiation dosage delivered to tissue adjacent to the metal surface as a result of backscattered radiation from the metal surface. Irradiating the tissue is performed by directing a beam of radiation with an energy content selected to have a value in a range from about 10 KeV to about 400 KeV, preferably about 40 KeV, from a point external to the body toward the metal surface and onto the tissue to be treated.