Medical device manufacturer, Varian Medical Systems, has issued an urgent field safety notice concerning TrueBeam and TrueBeam STx Versions 1.0 through 1.5
The manufacturer reported that an anomaly that has been identified with the respiratory gating software of TrueBeam. When importing breath-hold gating protocols, the gating thresholds can be reset to default values; rather than retaining the thresholds established during planning
When using the respiratory gating functionality of TrueBeam and TrueBeam STx, it is necessary to import the gating protocol during the first treatment session. An anomaly has been observed when importing gating protocols that have been designated as "breath-hold" during CT simulation. The anomaly causes the "breath-hold" setting to be ignored upon import of the gating protocol. This by itself does not lead to changes in the gating thresholds, but the respiratory gating software has been designed to discard the imported gating thresholds when the gating technique (i.e., breath-hold, amplitude, or phase) is changed from one setting to another. Thus, the gating thresholds for "breath-hold" gating are discarded when the operator realizes that the parameters of the imported gating protocol are not correct and they select the "breath-hold" option.
It is also possible for the default gating thresholds to replace the planned thresholds if operators navigate forward and backward through the steps in the gating import wizard. At one step in the process, the default gating thresholds will be selected if the gating technique has been changed. There is no indication that the default settings are being selected by the selection during the gating import process. Once the replacement has occurred, the only way to recover the plan gating thresholds is to cancel the import process and start again.
According to the local supplier, the affected devices were distributed in Hong Kong. If you are in possession of the product, please contact your supplier for necessary actions.
Posted on 18 May 2012