Answer to Question #7565 Submitted to "Ask the Experts"
The following question was answered by an expert in the appropriate field:
I am wondering if there are any studies on using a CT (computerized tomography) scanner, rather than fluoroscopy, for inspection of lead aprons. We have tried this and believe that the results were good. We used a Siemens Emotion 6 scanner at 80 kVp and 50 mA and performed a topogram scan (scout). We did not do an actual spiral scan of the apron. We used an apron that had failed previously with fluoroscopy and had known holes in it. We believe that the CT scanner was able to detect the holes as well as the fluoroscopy.
We would like to implement a new protocol that uses the CT scanner for apron inspections. It would eliminate the need for someone to actually fluoroscope an apron, thereby reducing personal dose exposure. We are wondering your thoughts on this and if you know of anyone else who is doing this or has studied this.
You raise an interesting question. I have not seen anything on this, so I conducted an informal poll of some colleagues who are medical physicists. They agreed that this should work and be an acceptable approach to testing the integrity of lead aprons. From a physics standpoint, you are using a similar kVp with a different type of detector, but the end results should be the same. Advantages include having no one in the x-ray room during exposure (which you mentioned), speed of scans, having a permanent digital record of each apron, and the possibility of performing multiple aprons with a single scan (you should be able to place two aprons end to end on a typical CT table). The biggest disadvantage appears to be the availability of a scanner to perform testing. Most facilities that we deal with have very busy schedules on their CT scanners, and it may be difficult to find time to do the testing. Also, you are tied to using a CT technologist to perform the testing, so you may be at the mercy of unscheduled and scheduled patients to perform your testing. You will also want to make sure that when you spread an apron on the table you are able to scan all of the apron and not lose the edges if they reach down over the sides of the table.
Ken "Duke" Lovins, CHP