X-ray mammography system with dosage control - has dosage controlled to maintain constant film exposure for different object thicknesses

摘要

The dosage applied to a mammograph X-ray process is controlled to maintain a constant exposure level of the film. The system uses two counters (6,7) for dosage control, one of which is controlled by the output of a comparator (8). The comparator has one input (10) that is the measured value and the other is the reference dose multiplied by a factor of 1/n. The tube current value is integrated (12) and converted into a frequency (19). A further input (17) controls the start of the cycle. During the operating cycle the signal generated accesses a memory (17) and a correction is made to the dosage value. ADVANTAGE - Corrects exposure for differences in object thickness.