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Table 4 Sensitivity test of four test cases

From: Investigation of a real-time EPID-based patient dose monitoring safety system using site-specific control limits

Sensitivity test cases Error parameters # test fields # error detection aDetection delay ± 1SD
(seconds)
Wrong dose delivery (MU error) +5 % 14 14 4.6 ± 1.5
+7 % 14 14 3.3 ± 0.9
+10 % 14 14 2.5 ± 0.6
Patient setup errors Shift 5 mm 6 0 N/A
Shift 7 mm 6 0 N/A
Shift 10 mm 6 1 8.7 ± 0.0
Wrong patient treatment Incorrect plan, same treatment site 10 10 Immediately detected after 2 s
Wrong gantry angle Correct plan, incorrect field/gantry angle 10 10 Immediately detected after 2 s
  1. aDetection delay is the period from the start of treatment to the time that the system is able to detect the simulated errors. The system was designed not to take the first 2s into account; therefore, the detection delay must greater than 2s