Duty factors for imaging systems must always be ______.

Duty factors for imaging systems must always be ______.

• A. Less than 100%
• B. Equal to 100%
• C. Greater than 100%
• D. Cannot be determined

Answer: (A)

Duty factor is the percentage of time the X-ray beam is on during one cycle of operation. Imaging systems are designed to deliver radiation in pulses to limit patient dose and heat load on the tube, so the beam is on only part of each cycle. That means the on-time divided by the total cycle time is less than 1, i.e., less than 100%. For example, if the beam is on for 10 ms in a 60 ms cycle, the duty factor is 10/60 = 16.7%. Therefore, the best answer is less than 100%.

Duty factor is the percentage of time the X-ray beam is on during one cycle of operation. Imaging systems are designed to deliver radiation in pulses to limit patient dose and heat load on the tube, so the beam is on only part of each cycle. That means the on-time divided by the total cycle time is less than 1, i.e., less than 100%. For example, if the beam is on for 10 ms in a 60 ms cycle, the duty factor is 10/60 = 16.7%. Therefore, the best answer is less than 100%.