The investigation was completed by conducting a thorough evaluation of the product and the reported information.The issue was found to be a defect in the product.The customer reported an issue when exceeding table target calculated from cbct.The customer used a random patient to capture data to explain the problem so there was no mistreatment.When the couch move assist (cma) feature is used with the pps interface enabled in the mac, the couch angles are first achieved.When the couch is moved out of position, a message "couch targets not achieved" should be displayed and blue indicators should be displayed next to the couch values that are out of tolerance.The investigation found that this does not happen.The message still displays "couch targets achieved" and no blue indicators are displayed.If the user fails to notice that the couch is in the wrong place and proceeds with the treatment, the wrong area of the patient could be treated resulting in a geometric miss.When exiting cma, there will be a warning that "couch targets not achieved", so the error should be caught after one fraction.However, if treatments are hypofractionated, deviations of 1.5 - 2.5 mm from the intended target could go undetected.Elekta performed a risk assessment and assessed the severity as "non-serious" " and probability "incredible which is within the acceptable region.The customer has been informed that the issue has been fixed in mosaiq version 2.83 and higher.
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