Medical device manufacturer, RaySearch Laboratories AB, has issued a medical device safety alert concerning its RayStation 4.0, RayStation 4.5, RayStation 4.7, RayStation 4.9 (RayPlan 1), RayStation 5, RayStation 6 (RayPlan 2), RayStation/RayPlan 7, RayStation/RayPlan 8A, RayStation/RayPlan 8B, RayStation/RayPlan 9A and RayStation/RayPlan 9B.
The Field Safety Notice (FSN) concerns an issue found with the dose calculation for Siemens Virtual Wedge in the affected products. Due to physical limitations of the treatment machine, the maximum field opening for Siemens Virtual Wedge fields recommended by the LINAC vendor will be more restricted in the wedged direction than the maximum field opening without a wedge. Delivering a larger field opening with a virtual wedge will not result in a wedged field shape over the entire field. Instead, a high dose plateau region will be the result at the toe side of the field beyond the recommended field size. The issue has not caused any patient mistreatment or other incidents. However, the users must be aware of the information listed in the FSN to avoid incorrect dose calculations during treatment planning.
According to the manufacturer, affected users should not use Siemens Virtual Wedge fields outside the Siemens recommended specification. If a field outside the recommended specification with a virtual wedge is sent to the LINAC, the treatment machine console (console software versions 8 and higher) will display a warning message, for example "Initial gap > 1 cm! Proceed (y/n)?", or "The distance between the static jaw and the moving jaw is greater than 1 cm. Do you want to continue? (y/n)". If this happens, select 'n' to prevent the treatment machine from delivering the field.
In RayPhysics, it is advised to use the wedge Field size limits parameters to restrict the maximum allowed field size for a wedged field. Affected users should verify through measurement at the LINAC that a wedged shape is delivered for the maximum field opening allowed by the Field size limits parameters for each wedge angle for Siemens Virtual Wedge before clinical use. Planning staff and all users should be educated about this workaround.
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 9 March 2020