Effects of Cosmic Radiation on Active Implanted Medical Devices

Abstract

In an ageing society, the number of people with active implanted medical devices such as pacemakers, cardioverter defibrillators and neurostimulators is constantly growing. At the same time, these people are exposed to cosmic radiation in the atmosphere at aviation altitudes or during severe solar particle events. In radiation therapy, it is already known that irregularities in the function of these devices can occur in the form of a reset to a suboptimal back-up mode. These are triggered in particular by neutrons, which are also a significant component of cosmic radiation. However, the effects of particle radiation on active implanted medical devices have not yet been sufficiently quantified. Using a model system consisting of several simple SRAM chips, a method for predicting malfunctions in different radiation environments was developed. The effects of neutrons and protons of different energies on SRAMs as well as pacemakers and defibrillators were investigated and probabilities for single event upsets were determined. Using weighting functions, the results were consequently applied to the neutron spectra of cosmic radiation on the Earth's surface, at aviation altitudes, during severe solar radiation events, and proton radiation therapy to determine an effect rate. In the various scenarios on the ground and at aviation altitudes, the rate of irregularities in the devices was determined to be low for the individual person but not negligible for the entirety of the devices in use worldwide. However, the rates are distinctly higher for radiation therapy and for severe solar radiation events at aviation altitudes. Based on this, a discussion on risk assessment and possible radiation protection measures is possible.