RE: question concerning stress tests

["Stabin, Michael" <michael.g.stabin@vanderbilt.edu>]

>I asked an operating room assisting cardiologist, following an

angioplasty involving 30 minutes of real time x-radiography, how much

exposure I had received.  He didn't have a clue.  He tried to read the

information from the computer that controled the X-ray system, and told

me an exposure that would have left me "smoking" had it been true.



It is truly amazing the laxity that we (as a society) accept in the

knowledge and control of medical doses (10's of mSv) range while we

demand rigorous analysis and scramble dozens of emergency workers to

deal with situations involving nSv doses. We have reasonable dosimetry

for standard nuclear medicine and radiography exams. Individual

variations exist - kVp/mAs setting, individual patient parameters, etc.

- but are not huge. Few if any physicians, however, track how much dose

subjects may be getting from multiple and repeat examinations, however,

and these doses can add up. One subject may get multiple static film

x-rays, one or two CTs and a number of nuclear medicine exams, with 10's

of mSv doses to individual organs in many of the individual cases.



In the fluoro world we really don't know the doses well, and they are

very, very important. We all know the stories of serious acute injuries

occurring because of overexposures, and if this does not occur, the

doses to skin and some organs are pretty high. My understanding is that

there is no good live time measuring system for fluoro, because they are

fairly difficult to design and make (motion of the source and other

variables make it more difficult to quantify than standard radiology),

and when systems were made that gave good estimates of dose, no one

bought them, so the manufacture was discontinued. There are

film-dosimetry based methods, but they are of course retrospective. 



No one in the HP community wants to interfere with the practice of

medicine, but I feel that we should be a LOT more cognizant of (1) how

much dose patients are getting with multiple and repeat nuclear medicine

and/or radiology exams and (2) the real dose that we are giving to

patients' skin and organs in fluoroscopy exams. (Operative word

"cognizant")

 



Mike



Michael G. Stabin, PhD, CHP

Assistant Professor of Radiology and Radiological Sciences

Department of Radiology and Radiological Sciences

Vanderbilt University

1161 21st Avenue South

Nashville, TN 37232-2675

Phone (615) 343-0068

Fax   (615) 322-3764

Pager (615) 835-5153

e-mail     michael.g.stabin@vanderbilt.edu

internet   www.doseinfo-radar.com



  

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