Safety Alerts

Medical device manufacturer, RaySearch Laboratories AB (publ), issued a medical device safety alert concerning RayStation 4-11B, and RayPlan 1, 2, 7-11B including some service packs. [Build Numbers: ‘4.0.0.14’, ‘4.0.3.4’, ‘4.5.1.14’, ‘4.7.2.5’, ‘4.7.3.13’, ‘4.7.4.4’, ‘4.7.5.4’, ‘4.7.6.7’, ‘4.9.0.42’, ‘5.0.1.11’, ‘5.0.2.35’, ‘5.0.3.17’, ‘6.0.0.24’, ‘6.1.1.2’, ‘6.2.0.7’, ‘6.3.0.6’, ‘7.0.0.19’, ‘8.0.0.61’, ‘8.0.1.10’, ‘8.1.0.47’, ‘8.1.1.8’, ‘8.1.2.5’, ‘9.0.0.113’, ‘9.1.0.933’, ‘9.2.0.483’, ’10.0.0.1154’, ’10.0.1.52’, ‘10.1.0.613’, ‘10.1.1.54’, ‘11.0.0.951’, ‘11.0.1.29’, ‘11.0.3.116’ or ‘12.0.0.932’] [HKMD No.: 180268].

The manufacturer concerns an issue found with the SSD calculation in RayStation 4-11B, and RayPlan 1, 2, 7-11B including some service packs. The SSD displayed and exported may in very rare cases be too high.

According to the manufacturer, in very rare cases, the SSD calculation algorithm will miss the entry point of the ROI and instead calculate the distance to the exit point, resulting in an incorrect SSD. If this occurs, the SSD will be incorrect in the GUI, in the plan report, in DICOM export and when accessed via scripting. Both treatment beams and setup beams are affected. It is unlikely that all beams in a beam set are affected, since the issue will only be triggered under special circumstances of ROI geometry and beam angles. The SSD saved to a beam commissioning field to be used with arbitrary photon fields in RayPhysics can also be affected.

The issue may be triggered both when SSD is calculated by RayStation, and when SSD is entered by the user.

If the issue is triggered when an intended SSD is entered in RayStation, the intended SSD will be displayed and exported but the actual SSD of the plan will be shorter than intended.

Dose calculation will not use the displayed SSD, so the calculated dose is correct with respect to the plan.

However, if the displayed and exported SSD is used for setting up the patient, the calculated dose will not match the delivered dose. The delivered dose will be overall lower than intended, but the irradiated volume will be larger.

The magnitude of the error depends on the intended SSD and the distance between the beam’s entry and exit point.

The manufacturer is instructing affected users to take the following actions:

• If SSD is to be used for patient setup or other critical tasks, use the Measure tool to measure the distance in the patient view to make sure that the SSD value is correct.
• If the SSD value is found to be incorrect, small changes to isocenter, beam angles or the affected ROI’s geometry can be made until the correct value is achieved.
• Educate planning staff and all users about this workaround.
• Inspect the product and identify all installed units with the above software version number(s).

This issue will be resolved in the next version of RayStation/RayPlan, scheduled for market release in June 2022.

According to the local supplier, the affected devices are distributed in Hong Kong.

If you are in possession of the affected products, please contact your supplier for necessary actions.

Posted on 28 Feb 2022