After how long of being idle should an x-ray tube undergo a warm-up procedure?

The correct answer regarding the warm-up procedure for an x-ray tube after a period of inactivity is one hour. X-ray tubes are designed to handle high levels of heat, and prolonged idleness can cause condensation of materials within or lead to uneven temperatures.

When the tube remains idle for an hour or more, it's important to follow a warm-up routine to ensure the components are brought back to optimal operating conditions. This warm-up helps to prevent damage to the tube and ensures consistent quality in the x-ray images produced. The procedure typically involves running the tube at lower settings before gradually increasing to higher settings, effectively allowing the anode to stabilize and preventing potential stress fractures.

While shorter intervals may not necessitate a warm-up, as insufficient idle time would not have significant thermal effects, the one-hour mark is a standard practice in radiography to ensure the safety and effectiveness of the x-ray machine. The other options (such as 30 minutes or longer periods) either do not align with industry-standard practices or place unnecessary emphasis on warming up when it's not warranted.