Medical device manufacturer, RaySearch Laboratories AB, has issued a medical device safety alert concerning its RayStation 6, RayStation 6 SP1, RayStation 6 SP2, RayStation 7, RayPlan 2, RayPlan 7 [Build Number: 6.0.0.24, 6.1.0.26, 6.1.1.2, 6.2.0.7, or 7.0.0.19].
The manufacturer has found an issue with the photon Collapsed Cone dose calculation. For machines with fixed jaws (Elekta BM and Vero) or machines with the MLC closer to the source than both x- and y-jaws (Elekta Synergy with MLCi/MLCi2), the dose calculation accuracy may in some situations be less than expected. The error is that leaf pairs that are closed inside the field with a non-zero minimum tip gap are considered open when computing the field measure (equivalent square) for output factor correction (OFC).
The error can manifest in BC for Elekta Synergy MLCi/MLCi2 when using "mlc only" dose curves, potentially leading to a beam model with incorrect OFC (scenario A). The error may also manifest in RayStation main dose calculation for Elekta Synergy MLCi/MLCi2, Elekta BM and Vero, where the bug would lead to using OFC for an incorrect field size (scenario B). For both scenarios, dose deviation will for most cases be marginal. The likelihood that it will occur in such a way that the dose deviation would be significant is very low
According to the manufacturer, the issue relates to an error that is triggered only for certain conditions in a well-defined use case. There is an acceptable workaround that can be easily understood by users and adhered to in order to avoid harm:
The issue has been corrected by means of updated labeling. The long term solution is to release a new version of the RayStation system eliminating the problem.
According to the manufacturer, the affected products are distributed in Hong Kong.
If you are in possession of the affected products, please contact your supplier for necessary actions.
Posted on 23 April 2018