RayStation Planning System (RaySearch) – density uncertainty (2025)

Check Your Product

According to the U.S. Food and Drug Administration (FDA)

Reason for Recall

As stated by FDA

Inconsistency in the use of Density uncertainty in the RayStation functions Robust optimization, Robust evaluation and Compute perturbed dose for proton and light ion treatment plans when a HU-to-mass density CT calibration curve used in RayStation version 4.5 to 2024B including some service packs.

Recommended Action

Per FDA guidance

Raysearch issued Field Safety Notice, Medical Device Correction #148655 RayStation version 4.5 to 2024B including some service packs via email on 1/17/25. Letter states reason for recall, health risk and action to take: For users of HU-to-mass density CT calibration curves If a user wants to evaluate a plan with respect to relative stopping power/WE range error rather than mass density errors, there are two options: Option 1. Use a HU-to-SPR CT calibration curve instead of a HU-to-mass density curve. " For evaluation of an existing case, the evaluation can be done on an anonymized and exported copy of the patient and plan. " Contact RaySearch Service if you need help with the creation of a HU-to-SPR curve from an existing HU-to-mass density curve. Option 2. Evaluate the plan using a higher (effective) mass density uncertainty that gives similar relative stopping power and WE range change as the nominal value. " The following values of Effective mass density errors that give similar result as an intended Stopping power error have been deduced from a limited set of patients: " For other values of intended Stopping power error, interpolate the approximate Effective mass density value from the table above. " The values are estimates based on a few patients and are expected to vary slightly depending on the mass densities along the beam path. " Note that the values are not symmetrical around 0. For users of HU-to-SPR CT calibration curves Be aware that the density uncertainty given in Robust evaluation, Compute perturbed dose and Robust optimization is used directly to scale stopping power and therefore WE range. Starting from RayStation v2025, scheduled for market release in April 2025 (subject to market clearance in some markets), the impact of the mass density uncertainty in Robust evaluation and Compute perturbed dose when using a HU-to-mass density CT calibration curve will be changed to harmonize with the other use cases. This means that as of RayStat