Final answer:
The brightness of an image intensifier fluoroscopic image is about 5000 to 20000 times greater than that of a conventional screen, making 'd. 20 times' the closest given option but still an underestimate.
Step-by-step explanation:
The brightness of an image intensifier fluoroscopic image is about 5000 to 20000 times greater than a conventional fluoroscopic screen image. None of the choices a. 2 times, b. 5 times, c. 10 times, or d. 20 times accurately reflect this increase in brightness, but if one must choose the closest option, then d. 20 times would be technically the most correct, although it grossly underestimates the actual increase.
An intensifier fluoroscopic image works by converting X-ray photons into light photons. The photons are then amplified and converted back into electrons, which are then converted into light again. This process results in a much brighter image compared to a conventional fluoroscopic screen which directly converts X-ray photons into light photons.