[ RadSafe ] Adopting the International System of Units for Radiation Measurements in the United States: Proceedings of a Workshop

Mon Mar 6 14:53:53 CST 2017

Yes - many manufacturers sell instruments that "readout" in dose units - 
Sv - BUT they do not measure DOSE - only exposure.  So they are usually 
wrong - especially for soft x-rays.

In the example cited an Ion Chamber was specified for DOSE measurements 
- but Ion Chambers only measure exposure.

To go from exposure to dose, calculations are necessary knowing the 
spectrum and the body part to which the dose is to be evaluated.

On 3/6/2017 10:15 AM, Konstantin V Povod wrote:
> If we are talking about measurements applicable to the personnel protection, there is no need to use exposure units with following calculations. Instead, Ambient Dose Equivalent  (H*(10)) could (should?) be used. It is measured in Sv, and many monitoring equipment manufacturers now give you an option of scales in exposure or H*(10) units. There are many publications and articles on this toping, probably ICRU 1993 would be a best source, but here's also a couple:
>
> https://hps.org/publicinformation/ate/q8949.html
>
> http://www.nucleonica.net/wiki/index.php?title=Ambient_dose_equivalent_H*(10)
>
> But, of course, until regulations adopt these changes in US, it'd be very difficult to use H*(10) calibrated monitors here.
>
> Konstantin Povod, CHP, RRPT
> RSO, LSO Clemson University
>
>
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Ted de Castro
> Sent: Monday, March 6, 2017 11:54
> To: The International Radiation Protection (Health Physics) Mailing List <radsafe at health.phys.iit.edu>
> Subject: Re: [ RadSafe ] Adopting the International System of Units for Radiation Measurements in the United States: Proceedings of a Workshop
>
> Did the workshop have anything to say about the rampant misuse of units afforded us by SI?
>
> Thanks to an incredibly cumbersome EXPOSURE unit - regulatory exposure limits are now being expressed in DOSE units without specifying - dose to what.
>
> Back in the back old days when we where just too stupid to know any better these things were expressed in exposure units.  When a DOSE unit was expressed - rad - it was expressed as rad in xxxx. And was seldom measured but usually calculated.
>
> So I recently encountered a quasi regulatory document called SEMI 2 which has among other things:
>
> "Direct doserate measurement with an Ion Chamber {or equivalent) calibrated to +/- 10% of true doserate at the surface of the equipment (or at the closest
> approach) in all areas where the operator may have access with the ionizing radiation source active.*"
>
> *Sorry - wrong!  An ion chamber is an exposure instrument NOT dose rate
> - and this is for analytical x-ray for which the spectrum from one end to the other varies considerably and the exposure to dose ratio is spectrum dependent and will vary more than the requisite 10% from one end to the other.  Let along the body part to which their dose limits apply is not specified.  (they give the limits in Sv) I maintain there is in fact no survey instrument that can measure this!
>
> So - with their use of SI and misuse of type of unit we are confronted with a published imperative which is clearly impossible to comply with.
>
> So - what did the workshop have to say about ion chambers with Sv marked on the meter faces?
> *
>
> ***
> On 3/3/2017 5:51 AM, Jason Meade wrote:
>> It was a great workshop and well worth my time, but after it was done,
>> I'm pretty sure it will be done again with almost an identical agenda
>> in 10 years time.
>>
>> Entirely too much "but this is the way we've always done it" and "it
>> would be too hard" type talking among those who've always been doing
>> the work and who are largely in charge for any type of shift in
>> thinking, despite the fact that the majority of the scientific and
>> academic portions of our education system have already made the change.
>>
>> On Thu, Mar 2, 2017 at 11:38 AM, Cary Renquist
>> <cary.renquist at ezag.com>
>> wrote:
>>
>>>   From the National Academies Press.
>>> One can always download the PDF version for free (might require an
>>> account)
>>>
>>> Adopting the International System of Units for Radiation Measurements
>>> in the United States: Proceedings of a Workshop
>>>
>>> Most countries in the world use the SI (Système International, also
>>> known as the metric system) units for radiation measurements in
>>> commercial and technical activities. The United States, in contrast,
>>> uses a mix of SI and conventional units for radiation measurements,
>>> despite 30-year-old national and international recommendations to
>>> exclusively use SI. Radiation professionals in the United States are
>>> faced with the need to understand both systems and make conversions between the two.
>>> Short link
>>> http://bit.ly/2mPP5bQ
>>>
>>> Adopting the International System of Units for Radiation Measurements
>>> in the United States: Proceedings of a Workshop | The National
>>> Academies Press
>>> <https://www.nap.edu/catalog/24645/adopting-the-
>>> international-system-of-units-for-radiation-measurements-in-
>>> the-united-states?utm_source=NASEM+News+and+Publications&
>>> utm_campaign=b2788914c1-Final_Book_2017_03_02_24645&utm_
>>> medium=email&utm_term=0_96101de015-b2788914c1-102196093&goal=0_96101d
>>> e015- b2788914c1-102196093&mc_cid=b2788914c1&mc_eid=3ee8f719d6>
>>>
>>>
>>> ---
>>> Cary Renquist
>>> cary.renquist at ezag.com
>>>
>>> _______________________________________________
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>>
>
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