| Popis: |
The wide variation in patient exposures for the same examination at different facilities, as shown by the Nationwide Evaluation of X-Ray Trends (NEXT) data, has been previously reported. In order to investigate this variation, an image receptor module (IRM) was designed to be used in conjunction with the NEXT system. It has been used to collect information on the types of films, screens, and grids used for over 900 radiographic exams in 12 States. Numerical relative speed values were experimentally determined for many of the more frequently used film/screen combinations, enabling a speed index to be assigned to these combinations when reported in the IRM. Principal findings to be discussed are the variation in film/screen speeds used for a given examination; the variation in exposures at skin entrance for a given examination, even when film/screen combinations of the same speed range are used; and relationships between the speed of the image receptor system and the exposure at skin entrance. |
