What is the annual output factors for electron applicators tolerance?

• A. ±1% from baseline
• B. ±2% from baseline
• C. ±3%
• D. ±5%

Answer: (B)

The main idea is maintaining long-term consistency of the electron beam’s output factors. Over a year, small changes in machine calibration, monitor chamber response, energy, and scatter can occur, so a realistic tolerance is set to catch meaningful drift without overreacting to normal measurement noise. For electron applicators, the accepted annual tolerance is ±2% from the baseline. This means if a baseline output factor is 1.000 at commissioning, the annual measurement should fall between 0.980 and 1.020. Tighter limits like ±1% are often too strict given typical dosimetry variability, while looser limits such as ±3% or ±5% could allow clinically significant drift.