RE: Different colors of dose

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

Dear Donna -



>My issue originates from my going to get a bone scan (27 mCi

Tc-99m-MDP) 

and the rad tech telling me I'm not getting any more dose than if I

stayed 

out in the sun for an hour. How do you even begin to counter that? 



I will tell you that this characterization was nowhere near accurate.

The rating of radiation exposure from medical examinations or other

sources to equivalent exposure to natural background radiation has been

made by many. For a comparison of a number of different medical

examinations on this basis, see

http://www.doseinfo-radar.com/RADARDoseRiskCalc.html   A typical Tc-99m

MDP exam (20 mCi) is comparable to exposure to over 500 days of natural

background, on this basis. Using 27 mCi as the input, we obtain around

700 days of exposure to background.



>the fact that this 27 mCi is completely "safe" for me for medical

purposes, 

but if I were to encounter this same isotope and activity at my

facility, it 

would be regulated and *I* would become a radiation area and visitors 

wouldn't be allowed near it.  But since I got it from a medical

facility, 

it was okay.  I dunno is the 140 keV gamma from safer if it is given to

me 

in a medical facility???  I think not.  There's so much hypocrisy to the



whole thing in my mind.



Peter rightly pointed out the distinction here. In the medical area, the

risk/benefit equation is different; this is not hypocrisy. The issue of

"safe" vs. "not safe" at low levels of dose (the definition of 'low'

includes all diagnostic medical exams) continues to be an issue of some

scientific debate. Except when physicians are reckless in their use of

radiation, or overprescribe it simply for precautionary reasons (which

are both probably rare), the benefits to the patient far outweigh the

small, *theoretical* risks of the radiation exposures.



>I won't even go into the 225 mCi I-131 I'm getting ready to ingest..



This is now a therapeutic, instead of a diagnostic, use of radiation.

Here, the benefits are enormous (this is a well tested, safe, and

effective treatment for thyroid cancer) and the risks will be controlled

by more careful attention by your physician and the medical center

staff. Please note that you can NOT compare the radiation dose from this

procedure to equivalent days of background, they are just not in the

same ballpark. The web link above does allow you to vary the amount of

activity assigned to I-131 studies, but it notes that "Special consent

form language should be developed for situations involving radiation

therapy."



I hope that this information is helpful, and I wish you all the very

best with your medical treatments.



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



 



I won't even go into the 225 mCi I-131 I'm getting ready to ingest..



I think this is a discrepancy that should be pointed out and addressed

with 

folks across the board.  I've certainly incorporated this information

into 

the tours that I give at my facility.



Thoughts anyone?



Donna J. O'Kelly, Ph.D

Laboratory Manager

Reactor Health Physicist

Nuclear Engineering Teaching Laboratory

The University of Texas at Austin

J.J. Pickle Research Campus

10100 Burnet Road, Building 159

Austin, TX  78758



office:  (512) 232-4174

fax:  (512) 471-4589



http://www.me.utexas.edu/~netl  



************************************************************************

You are currently subscribed to the Radsafe mailing list. To

unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu  Put the

text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,

with no subject line. You can view the Radsafe archives at

http://www.vanderbilt.edu/radsafe/



************************************************************************

You are currently subscribed to the Radsafe mailing list. To

unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu  Put the

text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,

with no subject line. You can view the Radsafe archives at

http://www.vanderbilt.edu/radsafe/