Comment from michael steckner
AnonymousOpposeIndividual
Summary: The commenter argues that the petition is scientifically flawed and fails to address the primary safety concern, which is the electric field induced in the patient rather than the magnetic field of an empty bore. They suggest that existing standards already provide adequate protection and that the petition's proposed requirements would hinder medical providers' ability to treat larger patients.
The petition is flawed on multiple scientific points. Regarding the intense fields from the transmit coil in the immediate vicinity, IEC 60601-2-33 ed 4.0 (2022) requires the MR vendors to provide details on the length of the transmit coil. Thus, the bore wall can be marked to identify the range needing padding. This addresses the fields in the immediate vicinity of the bore wall. This is a simple and effective measure to provide protection.
To reduce the aperture size to increase the spacing from the transmit coil then reduces, or prohibits, the ability for medical providers to serve larger patients. The physician can choose to forgo the padding as necessary to serve the patient, knowing the risks.
Now consider the region beyond the immediate vicinity of the bore wall and the solution noted above. It is the electrical field induced in the patient that is the pertinent safety concern. Those are created/induced by the transmit coil. The distribution of electric field within the patient away from the bore wall is very sensitive to the unique patient habitus, composition. The petitioner requests empty bore magnetic field maps and those hold nearly ZERO correlation to the electric fields within the patient. Therefore it is of no exploitable clinical benefit.
The petitioner does not offer any peer reviewed literature that demonstrates any meaningful correlation between an empty coil magnetic field map vs the electric fields induced across the population with regards to the space some distance away from the bore wall. The cited MSc thesis relates to the close bore wall contact condition, and that has already been adequately considered in IEC 60601-2-33 ed 4.0 (2022)