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Table 1 Sensitivity test cases and modified parameters for introducing errors into prediction model

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

Error Class

Simulated Errors

Plan modification methods

Patient position misalignment

Patient setup errors = 5, 7, 10 mm

Horizontal spatial shift of CT images data set, then recalculate predicted EPID data; only gantry angle at zero is tested.

MU errors

Increasing 5, 7, 10 %

Decrease MU in treatment plan then calculate predicted EPID data; this simulates overdose delivery to patient.

Wrong Patient or Plan

Incorrect patient same treatment site

Apply different patient CT data for predicted EPID data. This simulates wrong patient being treated.

Wrong gantry angle

Correct plan (patient) incorrect field or wrong gantry angle

Re-ordered gantry angle in treatment plan (exchanged gantry angle between treatment fields) then re-calculated predicted EPID data. This simulates wrong gantry angle in IMRT.