Final answer:
With a fluoroscopic system using ABC, decreasing the SID distance does not change the patient's output dose rate because the system adjusts to maintain constant image brightness.
Step-by-step explanation:
When using a fluoroscopic system with Automatic Brightness Control (ABC) activated, if the target-to-image intensifier (SID) distance is decreased, the output dose rate will not change. This is because the ABC system automatically adjusts the radiation output to maintain a constant image brightness on the monitor, despite changes in distance or other factors that could affect image quality.
Therefore, by reducing the SID, the system will lower the dose rate to maintain the same image brightness, keeping the patient dose consistent with before the distance change. This concept relates to the inverse square law, in physics, where intensity of radiation is inversely proportional to the square of the distance from the source, but the ABC compensates for this change.