Karolinska University Hospital reactivated four retired mobile X-ray systems during the pandemic.
Good teamwork and high system quality enabled Karolinska University Hospital and Siemens Healthineers to bring four decades-old mobile X-ray systems back into operation to provide lung imaging during the COVID-19 pandemic.
At the beginning of the pandemic, experts at Karolinska University Hospital in Sweden concluded that their mobile X-ray equipment would be far from sufficient as a long-term solution during the challenging times ahead. After contacting the hospital physicists and the Karolinska Institutet (KI) university, they gained access to three retired Mobilett Plus systems originating from the mid-1990s that hadn’t been in use for many years.
The experts contacted Siemens Healthineers to work out how to test and commission the systems. Service engineer Laszlo Wohlgang from Siemens Healthineers provided a service manual for the old systems so that the team could carry out a review.
The systems were checked, and it was quite easy to get two of them up and running. The third system caused more trouble: An error message occurred every time the team attempted a high-kilovolt exposure, which is needed for lung imaging. The manual and troubleshooting led to the need for conditioning of the X-ray tube, as the kV value measured by the system deviated too much from what was expected. The technicians tested and ran through calibration and conditioning but could not get the X-ray tube to work with high kV. After running through the conditioning program five or six times over several days, it was eventually possible to generate sufficiently high kV for lung images.
System from 1984 put into operation
In a storage room at Karolinska, the team also found a Mobilett system from 1984 that hadn’t been in use since 1993. The technicians opened it up and quickly discovered that what they had learned about the old Mobilett Plus could not be applied here. There were no notes on which DIP switch would put the machine into service mode. Without service mode they could not start the machine, as this would fully charge the capacitors, which had not been charged for more than 20 years. This, in turn, could put the capacitors at risk of breaking. The team needed a way to slowly charge them.
Mobilett advertising video from around 1983
The technicians from Karolinska called some service engineers who had worked with the system in the 80s and were still with Siemens Healthineers, but no one could remember how to enter the system’s service mode. From a user manual that was attached to the machine, they found out that the information was contained on a microfilm that could be ordered from the manufacturer. Assuming that it was no longer possible to order the microfilm (and even if it was, they no longer had a microfilm reader at Karolinska), they had to find the instructions elsewhere.
“Impressive that such an old machine worked without any error messages.”
After some research, key account manager and former service technician Magnus Kokk managed to get hold of a page from a manual of a former colleague at Siemens Healthineers. He took a photo and sent it via his smartphone to the technicians, who could now put the Mobilett into service mode and slowly charge the capacitor package. After conditioning the system and taking exposures with gradually increasing mAs and kV, they were able to reach the 125 kV needed for lung images.