| 摘要 |
The method consists of subjecting the organ to pre-exposure with a low dose of rays, creating in the field of the pre-exposure image a multi-cellular image in which each cell represents the mean signal level of a predetermined number of pixels of the detector, selecting from the columns the cell of minimum signal level most distant from a reference point, establishing about this cell a band parallel to the reference point and selecting from the band the cell having the absolute minimum signal level. The parameters of exposure may then be set from this absolute minimum
|
