The ins and outs of radiation shielding

by Lauren Dubinsky, Senior Reporter | October 17, 2022
From the October 2022 issue of HealthCare Business News magazine

“When they put them on the second or third stories, you have to shield the floor,” said Bordeman. “It’s not impossible, but it's very tricky because it raises the floor up. Then it is higher than all the rest of the floors and they have to put in ramps.”

The physicist can also tell you the ideal location of the CT or X-ray unit within the room. Evearitt can look at the floor plan and recommend the best orientation of the equipment to save on shielding costs.

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"Sometimes it makes a big difference where you put the X-ray machine within the room,” he said. “The occupancy on the other side of the wall really matters.”

He explained that the best spot is in the corner of the building so that at least two of the walls are exterior walls. The less occupancy on the other side of the room, the less shielding that’s required.

For shielding guidance, he follows the National Council on Radiation Protection and Measurements (NCRP) 147 for medical X-ray facilities and NCRP 151 for radiation therapy centers. It provides a table that lists the different occupancies for the different types of rooms there are.

If there is an office or a neighboring business on the other side, Evearitt said that he has to assume there will be 100% occupancy. If it’s a hallway, 20% of the time someone may be walking past the wall when a patient is being scanned.

"Board-certified physicists have access to these reports and they're always going to refer back to that,” said Evearitt. “That's your ammunition if somebody sues for radiation exposure. You can point to that document and say you followed this nationally-recognized guidance document."

Know your anticipated workload
You will need to provide the physicist with your anticipated workload so they can accurately determine how much shielding is needed. If you give them an inaccurate number, you’ll be doing yourself a disservice.

A third-party X-ray vendor asked Evearitt to do a shielding report for a machine they sold to a veterinary clinic. When asked about the X-ray’s workload, he noticed they had a tendency to underestimate the amount in order to save the doctor money.

"They want to save the doctor money by not having the expense of all the shielding because they're trying to make the sale,” he said. “They're going to give me a really low workload because they know that's going to result in little or no shielding."

If the workload amount that he’s given seems too low, Evearitt will investigate to determine the accurate amount.

A facility can run into problems with the shield if the workload grows. They might have only done 50 X-rays per week when they first opened, but if they add onto the office and hire more doctors, they may then be doing 100 X-rays per week.

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