Final answer:
In fluoroscopic systems with automatic brightness control and an under the table x-ray tube, as the intensifier is moved away from the patient, the patient dose decreases and fewer x-rays are intercepted at the image intensifier before ABC activates.
Step-by-step explanation:
In fluoroscopic systems equipped with automatic brightness control (ABC) and under the table x-ray tube, as the intensifier is moved away from the patient, patient dose decreases. This is because the intensity of the x-rays decreases with distance, reducing the dose received by the patient. Additionally, as the intensifier moves away, fewer x-rays are intercepted at the image intensifier (before ABC activates). The automatic brightness control (ABC) system adjusts the brightness of the image by regulating the amount of x-rays that reach the intensifier, so as the distance increases, fewer x-rays are intercepted before ABC activates.
3. More x-rays are intercepted at the image intensifier (before ABC activates).
When the image intensifier is moved away from the patient, fewer x-rays reach it, and this can result in a decrease in image brightness. To maintain a constant image brightness, the ABC system will respond by increasing the exposure factors, which leads to more x-rays being generated to compensate for the increased distance. This adjustment helps to maintain a consistent image quality despite changes in the distance between the intensifier and the patient.