Using Standard Land Survey Technology to Generate 3-D Radiological Characterization Data

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Preface: ORAU has developed a method for using a robotic total station to capture the geospatial data necessary for mapping radiological contamination indoors.

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Using Standard Land Survey Technology to Generate 3-D Radiological Characterization Data

Ben Estes:

Outdoors we use GPS to capture our position and our scans, but indoors the GPS signals blocked, so we needed something to do the same thing inside. So we came up with using the Robotic Total Station to capture our X,Y, and Z coordinates with the rate meter and be able to match that and map it out.

James Viars:

The equipment is strictly off the shelf. We use a Trimble Robotic Total Station that you can just buy at a survey store and the Ludlum2221 is just the standard run-of-the-mill 2221 that most health physicists use in this industry. The key was actually getting the two to communicate together. The software for a GPS you can just purchase from the dealer. This software we had developed in-house.

Ben Estes:

The two components of the Total Station, the head unit and the prism, and the head unit sends a pulse to the prism which reflects it back, and as you move the prism it’s able to track its position. So whatever you attach the prism to whether it s a floor monitor, radiation detector that you’re just using by hand, it’ll capture that position information, then the head of the unit will then connect to the laptop for data logging.

James Viars:

We take the captured X, Y, Z data, the coordinates, and then we take the captured count rate and then we combine the two, and we output that on a paper map, or a computerized map, and therefore, you can see exactly where the contamination is inside of a building or outside.

Ben Estes:

Since we capture 3-D coordinate for the position, if you’re scanning a floor that’s fairly 2-D, that’s straight forward, but when you move into the walls, it’s hard to represent a 3-dimensional box in report and print it on paper, so what we chose to do was fold the walls down and splay the room out so it all becomes represented as a 2-D image.

James Viars:

The main advantage for our customers of being able to see captured inside data is when you’re reading a report and it says, let’s say, 25 percents of the room is contaminated, and 75 percent of it s clean, that doesn’t really give you a good picture because that contamination could be spread throughout the room, or it could be confined to one area. The customer, whoever reviews this paperwork can now see the map of the room and look at it and say, “Okay, well, now I know exactly where these areas of contamination are, provided a high-density scan.”