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Re: Subject: RE: Bq soon



Perhaps some units don't need converting. The corresponding physical quantity may just become irrelevant.
 
Why would anyone need to know the number of charges floating around in the air? (Unless you worry about electrical discharges and then you probably want to know it in C/m3, rather than in Roentgen.) Your meter might accurately read roentgen, but you need to convert that number to rad, rem, Gy or Sv to make any practical use out of it.
 
Maybe WL will eventually become irrelevant as well, if someone comes up with a better proxy measurement for lung dose. (One that takes into account the difference between attached and unattached radon progeny, for example.)
 
How many of you who express your "weight" in pounds say at what altitude that "weight" is measured?
 
Kai
----- Original Message -----
Sent: Tuesday, April 08, 2003 9:31 PM
Subject: RE: Subject: RE: Bq soon

A question for the pro-SI crowd.  How do you reconcile using a standard ion chamber type radiation detector that reads out in microSv / hr, and recording that reading as the exposure level?  (I hope your answer doesn’t include a discussion of quality factors.  Regardless of what you may know about beta & gamma radiation, the meter ain’t displaying microSv / hr)

 

I think this is my main discomfort with using SI units in that there is no useful conversion for Roentgens.  If you are TRULY a proponent of SI, you should have a meter that reads out in Coulombs / kg-hr (or metric subunits thereof), and then try to work with that unwieldy number.  Or else only use tissue equivalent meters.

 

-Brent Rogers

 

P.S.  How many of you express your weight in Newtons?   

 

-----Original Message-----
From: Ivor Surveyor [mailto:isurveyor@vianet.net.au]
Sent: Tuesday, 8 April 2003 6:38 PM
To: radsafe@list.vanderbilt.edu
Subject: Subject: RE: Bq soon

 

To a person living outside of the USA it is a matter of amazement to find the bizarre combination of units used in American texts.  For instance on a single page of a recently published text on Radiation Protection [ J. Shapiro 4th Edition] I found the student had to contend with a plethora of units.

On page 361:   Ft; Ft^2; Ft/min; Ft^3/min;  cm^3/day;  pCi/cc;   microCi/cc;   mCi; MBq

Or on page 372:  1 acre = 4,047 m^2; 1km^2 = 247 Acres; pCi/m^2-s
and a reminder to multiple mCi by 37 to obtain MBq, and pCi by 0.037 to convert to Bq; or Ci by 37 to obtain GBq.

Though out the book there is a continuous need to convert  Sv to rem(s); Gy to rad(s); length in cm, ft or m and so on.  

By the way in strict SI there is no place for the cm, cc, or cm^3.  or use of "pleural forms for units.


I just wonder how this irrational jumble of old and new units is tolerated.   Surely more then one "Mars probe" must have gone  astray, because of this confusing jumble?   I suspect that more then one author has developed a severe "headache" from proof reading of texts.  The high quality of  many American texts and publications are such as to have a great appeal to international readers     What a waste of intellectual effort is expanded in converting backwards and forwards from one system to the other, as one reads and studies papers, text books, or regulations.  

I am not aware of any real problem in Australia or UK when we adopted the SI system, except perhaps a feeling of joyous relief.

Ivor Surveyor  [isurveyor@vianet.net.au]



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