| 摘要 |
1,184,947. Improving contrast in radiographs. COMPAGNIE GENERALE DE RADIOLOGIE. 28 June, 1967 [28 June, 1966], No. 29753/67. Heading H5R. A radiograph of improved contrast is obtained by submitting an object to a beam of X-rays having a prescribed energy spectrum obtained by utilizing an X-ray tube having a target consisting predominantly of an element selected to have a characteristic X-ray spectrum comprising said prescribed spectrum, the electron beam energizing voltage of the X-ray tube being higher than the value required to excite a selected characteristic radiation of said element, passing the X-ray beam through a filter consisting predominantly of the same chemical element as the target and using the beam emitted from the filter to produce the desired radiograph. The energizing voltage may be 1À1 to 2À5 times the critical value and is preferably 1À2-1À7 times said value. The selected characteristic radiation is preferably the K series lines of the target element. The preferred target and filter material is molybdenum, the energizing voltage being 25 to 40 KV. The filter may be 20-40 microns thick. The predominant component of the target and filter preferably has an atomic number exceeding by at least one unit and most preferably not more than two units the atomic number of the predominant element in the sample under examination. The X-ray tube used may have a beryllium window. A preferred sample material is mammary tissue. |
