Re: dental x-rays

[brian whatcott <inet@INTELLISYS.NET>]

I see Steven Ratcliff's 100 mrem and raise him 150 microSievert and
1 microGray: - or to put it another way:

The Health Physics Society provided this potted answer on their web page:

Answer to Question #259 Submitted by Ron Sumner
Category: Medical and Dental Procedures
 The following question was submitted on April 11, 2000,
and was answered by an expert in the appropriate field:

 Question:
My wife recently had a dental exam with xrays,
and we just found out that she was probably about three
weeks pregnant at the time. Where can I find information about
the risks involved? Thanks.
  Answer:
When a pregnant patient undergoes a complete
dental x-ray examination, the radiation dose to the embryo is
about 1 microgray. Compare this to the average dose from
naturally occurring environmental sources of about 3000
microgray per year. Thus, the dose from the dental examination
is less than that from one day of environmental exposure.

 There are no data demonstrating any risk from
such doses. While the absence of data does not provide
conclusive proof of total safety, it does provide assurance that the
risk, if any, is exceedingly small.

 <http://www.hps.org/publicinformation/ate/q259.html>
-----------
By contrast, this Trexler Practice web page takes a different view:

    How often are dental X-ray exams necessary?

     This depends on the patient’s individual health needs. If you are a
new patient, the dentist may recommend X-rays to determine the current
 status of your mouth and to check for hidden problems. The schedule
for needing radiographs at recall visits varies but typically includes
2-4 bitewing X-rays per year. Full- mouth series and/or panoramic films
are typically taken every 3- 5 years. Children may need X-rays more
often than adults because their teeth and jaws are still developing and
they are more prone to tooth decay.

How much radiation is involved in a dental X-ray exam?

Using effective dose equivalents, environmental exposures may be
compared to exposure from dental X-ray exams. Applying this method,
a full mouth X-ray examination of 19 films will deliver an effective
dose equivalent of approximately .15 mSv or 15 days of exposure to
naturally-occurring environmental radiation. The chart below lists

 comparisons of common sources and amounts of radiation:

  Activity / Source
                                            Amount of Radiation
                                                 Received
        Bitewing (4 films)

                                          0.038 milisievert (mSv)

        Full-mouth Series (19 films)

                                          0.150 mSv

        Lower GI series

                                          4.060 mSv

        Average U.S. citizen living in average
        location

                                          3.600 mSv annual dose

<http://www.trexlerdental.com/xrays.htm>


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

At 10:36 12/28/00 -0600, you wrote:
> I brought along a dosimeter to a dental appointment a few years ago.  I
> received several x-rays that day.  Underneath the lead apron, the
> dosimeter did not read any dose.  However, when the x-ray machine was
> aimed right at the dosimeter, it registered about 100 mrem (at least that
> much).  It makes sense that the jaw receives a relatively high dose
> compared to the body as a whole.
>
>
>
>
> Steven T. Ratliff
> Associate Professor of Physics
> Northwestern College
> 3003 Snelling Ave. N.
> St. Paul,  MN     55113-1598
> U. S. A.
>
> Internet:  str@nwc.edu (or stratliff@nwc.edu)
>
>
>
>
>
> Larry Smith <Larry.Smith@SNOW.EDU>
> Sent by: "phys-l@lists.nau.edu: Forum for Physics Educators" <PHYS-L
> 12/27/00 04:49 PM
> Please respond to "phys-l@lists.nau.edu: Forum for Physics Educators"
>
>
>        To:     PHYS-L@lists.nau.edu
>        cc:
>        Subject:        dental x-rays
>
>
> What is the dosage of a typical modern dental x-ray?  My dentist said it
> is
> about the same as a cross-country airplane flight; is he in the ballpark?
> Do the benefits of frequent dental x-rays outweigh the risks?  What would
> be the optimum time interval between dental x-rays for someone with
> healthy
> teeth?
>
> Thanks,
> Larry
brian whatcott <inet@intellisys.net>  Altus OK
                Eureka!