Medical device manufacturer, IBA Dosimetry, has issued a field safety notice concerning COMPASS 3.1 / 3.1a [Catalogue Number: CS10-100. Manufacturing date: May 2014 (for version 3.1) and Nov 2014 (for version 3.1a)].
The manufacturer found that dose reconstruction for DMLC plans from Monaco or Eclipse-11 when the jaws move or MLC leaves reverse during beam on was not scaled correctly.
Normally, during the measurement-based correction process employed by COMPASS, a step called "Delivery error scaling" is carried out in order to correct for an overall absolute dose difference level between measured and predicted responses. A scale factor derived from this difference in absolute output is averaged over all detector pixels. The error occurs as the "Delivery error scaling" is not properly applied. The reconstructed dose becomes erroneous although the predicted response remains correct. The error occurs when COMPASS is used to acquire measurement data and the evaluation is performed using reconstructed dose. If the predicted response is not evaluated together, the erroneously reconstructed dose may not be noticed. This could happen if the measurement shape is correct but the absolute level is wrong.
The manufacturer will provide software update to correct this issue.
According to the local supplier, the affected product is distributed in Hong Kong.
If you are in possession of the affected products, please contact your supplier for necessary actions.
16 February 2015