What is the annual enhanced dynamic or gated delivery dose tolerance expressed as?

• A. 100 MU or expected delivery
• B. 200 MU or expected delivery
• C. 50 MU or expected delivery
• D. 10 MU or expected delivery

Answer: (A)

In dynamic or gated delivery QA, the dose tolerance is expressed in monitor units (MU) because MU directly corresponds to the delivered dose and can account for changes in dose rate during motion management. The annual tolerance is 100 MU, meaning the measured MU for the dynamic or gated delivery should match the planned (expected) MU within ±100 MU. This fixed MU threshold provides a straightforward check that isn’t tied to percent values, which can be misleading when the amount of MU varies widely across fields or during gating. For example, if a gated segment is planned for 300 MU, the delivered MU should fall roughly within 200–400 MU. The 100 MU figure is a practical margin that covers typical variations in dynamic/gated delivery without being overly permissive. The other options would either be too tight or too loose for standard annual checks.