| 摘要 |
<p>1473802 X-ray filters ATOMIC ENERGY OF CANADA Ltd 17 July 1975 [18 Dec 1974] 30031/75 Heading H5R An X-ray beam flattening filter comprises a body, such as a cone, which is axially aligned with a beam of X-rays and provides decreasing attenuation with angular displacement from the central axis of the body which is made of material whose atomic number (or weighted average atomic number for a compound) is less than 25 and whose density is greater than 3 gm./c.c. Suitable materials are Al 2 O 3 , BeO, BeAl 2 O 4 and SiC. The core is arranged with its apex near the source and the base can be covered with 0À06 gm. per sq. cm. of tungsten or gold to harden the X-ray spectrum.</p> |
