Enhancing the error detection capability of the DAVID system with the use of adaptive warning and alarm levels

An adaptive warning and alarm level has been developed in order to enhance the error detection capability of the DAVID system. This method takes the intrinsic fluctuation or noise associated with the measured signal into consideration. As an example, the irradiation according to a head and neck IMRT plan was performed repeatedly, and the adaptive warning and alarm levels were derived from the computed relative standard deviation of each measurement channel. For the evaluation, the example IMRT plan was modified by introducing errors into the MLC positions and simulating a sudden change of the energy fluence. The adaptive levels were suitable to detect these artificial errors better than a fixed default level when dealing with clinically irrelevant decviations. This method promises to overcome the limitations of the fixed warning and alarm levels currently implemented in the software.