Final answer:
The cumulative timer intervenes when fluoroscopic time exceeds 5 minutes, serving as a radiation safety measure.
Step-by-step explanation:
The cumulative timer that produces an audible signal or temporarily interrupts the x-ray beam when the fluoroscopic time has exceeded a given limit is an important safety feature in fluoroscopy to protect both the patient and the operator from excessive radiation exposure. The specific time after which this occurs is often set at 5 minutes. This safety measure ensures that the amount of radiation exposure is kept as low as reasonably achievable (ALARA), especially during prolonged fluoroscopic procedures.