RE: Risk from dental x ray

["Weiner, Ruth" <rfweine@sandia.gov>]

Dr. Gibbs' comment really should apply to all diagnostic x-ray.  21 years
ago, when I had my first hip replacement, seven pelvic x-rays were taken
even while I was hospitalized.  Ten years later, with the second
replacement, three sufficed.  Now this is down to two.  As a risk analyst, I
could discuss the relative risks with my physician (and incidentally this
applies to any diagnostic procedure, not just x-ray) and I would urge all
physicians to discuss the relative risks of diagnostic procedures (vs. not
having the procedure) with all patients.

Clearly only my own opinion.

Ruth F. Weiner, Ph. D.
Sandia National Laboratories 
MS 0718, POB 5800
Albuquerque, NM 87185-0718
505-844-4791; fax 505-844-0244
rfweine@sandia.gov


-----Original Message-----
From: Gibbs, S Julian [mailto:s.julian.gibbs@vanderbilt.edu]
Sent: Wednesday, March 10, 1999 8:05 AM
To: Multiple recipients of list
Subject: Re: Risk from dental x ray


All comments on this issue are appropriate.  Over the past 
20 years or so I have devoted most of my time to study of 
patient exposure from diagnostic x ray, especially dental.  
We have developed a Monte Carlo radiation transport code 
that provides specific organ doses to the entire body.  The 
results as effective doses in microsievert:
Procedure		Typical technique State of the art
Full mouth intraoral, 21 film	350		45
Bitewing, 4 film		70		8
Panoramic, 1 film				20
(Gibbs et al, Dentomaxillofacial Radiology 17:15, 1988)

I too have used time of environmental exposure that gives 
the same effective dose as the diagnostic exposure.
However, the more compelling issue is simply: Is the 
exposure justified on clinical grounds?  Dentists have been 
trained to perform repeat radiography on asymptomatic 
patients at regular intervals.  In many offices this is 
done by the dental hygienist before the dentist sees the 
patient.  Now there are high-yield criteria for deciding on 
the diagnostic need for radiographs, based on history and 
physical exam. I would therefore advise the patient to ask 
the dentist to justify the exposure on clinical grounds.  
Clinically indicated and justified radiographs should be 
obtained on grounds that the expected health benefit should 
outweigh any radiation risk.  On the other hand, exposure 
that is not justified is by definition wasted.
Hope this helps.
***********************************************************
S. Julian Gibbs, DDS, PhD               Voice: 615-322-3190
Professor of Radiology                    FAX: 615-322-3764 
Dept. of Radiology & Radiological Sciences
Vanderbilt University Medical Center
Nashville TN 37232-2670 Email:s.julian.gibbs@vanderbilt.edu
***********************************************************
"Where there's a will there's a family!"  -Anonymous

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