The actual kilovoltage peak (kVp) of an exposure must correspond to the selected kVp within what percentage?

The actual kilovoltage peak (kVp) of an exposure must correspond to the selected kVp within what percentage?

• A. +/- 5%
• B. +/- 1%
• C. +/- 2%
• D. +/- 10%

Answer: (A)

The key idea here is kVp accuracy tolerance in radiographic QA. The actual kilovoltage delivered by the x-ray tube should stay within a small, defined margin of the kVp you dial in. In practice, that margin is plus or minus 5 percent. This keeps image contrast and exposure predictable because even small drift in the generator or measurement can affect beam quality and patient dose. For example, if you set 90 kVp, the ring of acceptable results would be about 85.5 to 94.5 kVp. Choices tighter than 5% (like ±1% or ±2%) would be very hard to maintain in routine practice, while a wider tolerance (such as ±10%) could allow clinically noticeable changes in image quality and dose. So, ±5% best balances practicality with consistent imaging.

The key idea here is kVp accuracy tolerance in radiographic QA. The actual kilovoltage delivered by the x-ray tube should stay within a small, defined margin of the kVp you dial in. In practice, that margin is plus or minus 5 percent. This keeps image contrast and exposure predictable because even small drift in the generator or measurement can affect beam quality and patient dose.

For example, if you set 90 kVp, the ring of acceptable results would be about 85.5 to 94.5 kVp. Choices tighter than 5% (like ±1% or ±2%) would be very hard to maintain in routine practice, while a wider tolerance (such as ±10%) could allow clinically noticeable changes in image quality and dose. So, ±5% best balances practicality with consistent imaging.