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[IP] CT Scanning May Cause Malfunction of Electronic Medical Devices


FDA is alerting healthcare professionals that the x-rays emitted during CT
exams may cause some electronic medical devices to malfunction. These
malfunctions are different from those related to MRI scanning, which are
caused by strong electrical and magnetic fields.

Most patients with electronic medical devices do not experience problems
with CT scans, but FDA has received a small number of reports in which the
scans may have caused unintended shocks from neurostimulators, malfunctions
of insulin pumps, and transient changes in pacemaker output. Theoretically,
defibrillators, cochlear implants and retinal implants could also be

Here is what FDA recommends to help reduce any possible risk:

 Before beginning a CT scan, use scout views to check whether the patient
has an electronic medical device and where it is. If the device is in or
very near the area to be scanned, there are several steps to take.

 Determine the device type. If it is an externally worn device, try to move
it out of the scan range, if possible. If it is a neurostimulator, ask the
patient to temporarily shut it off.

 During the scan, minimize x-ray exposure to the device by using the lowest
x-ray tube current that will allow you to get the required image, and by
making sure that the x-ray beam does not dwell over the device for more than
a few seconds. If the procedure requires continuous scanning over the device
for longer than that, as with CT perfusion or interventional exams, be ready
to take emergency measures to treat adverse reactions if they occur.

 After the scan, remind the patient to turn the device back on if it was
turned off beforehand. Even if the device was turned off during the scan,
ask the patient to be sure that it is working properly. If not, tell the
patient to contact their healthcare provider as soon as possible.

Additional Information:

FDA MedWatch Safety Alert. Electronic Medical Devices. July 14, 2008.

John S Wilkinson
Rome, NY
"A hospital bed is a parked taxi with the meter running."
-- Groucho Marx
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