Near miss associated with a software defect.Therapist discovered issue prior to commencing treatment.Reported as mdr to risk of mistreatment in case of recurrence.Customer reported a near miss that occurred during patient positioning setup for treatment.During setup, the radiation therapist noted that one of the couch correction elements (couch pitch) was not communicated and corrected.The customer detected the failure to correct couch position and did not execute treatment.The missing correction was caused by a software defect: using verity with a single planar image will deselect degrees of freedom (dof) which are not determinable by the acquired image, or a user may manually deselect any of the dof by unchecking the boxes next to the axis.If a 3d ct or cbct scan is then acquired and used for 6 dof alignment there is a small probability that the couch correction widget will retain the unchecked axis state from the previous image registration.If the user fails to notice the verity widget has unchecked boxes, ignores the dialog on verity that indicates which moves are being sent to the couch, and also fails to notice that the in room monitor is only showing some of the intended corrections, then it is possible that the couch will not execute all the intended movements and the patient will be misaligned.The customer believes that has occurred a few times and likely has resulted in a geometric error of up to 1.5 cm (for a single fraction only).This is of negligible medical severity, but could potentially recur and result in an offset of up to 2 cm.
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