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

Mon Mar 6 15:31:41 CST 2017

It can be simulated as you suggested for a SINGLE SPECTRUM - but on an 
analytical x-ray machine where you COULD have FULL bremstralung primary 
leak, to a heavily filtered leak such as a tubehead leak - to a filtered 
and mirrored highly selected spectrum.

There is no ion chamber instrument no mater what its calibrated to or 
how its filtered that will measure "true dose" to 10% over all those 
spectra - as specified in that SEMI S2 requirement I quoted.

Also - if dose is specified as opposed to exposure - the useful energy 
range for an instrument will get considerably smaller.  Ion Chamber 
survey instruments may have changed the meter face label to Sv - but 
they haven't changed their spec energy range.

It cannot be both.

Remember - I am talking field survey instruments here and field surveys 
- the research dosimetry.

On 3/6/2017 1:06 PM, Konstantin V Povod wrote:
> I agree, it is impossible (at least, as of now, in the future - who knows? Nanobots? :-)  ) to measure dose inside of human body. But it can be simulated using various filters and detectors. And at the same time, calculations of dose from exposure readings are not 100% precise either and use certain assumptions as well.
>
> 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 15:54
> 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
>
> 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_96101
>>>> d
>>>> e015- b2788914c1-102196093&mc_cid=b2788914c1&mc_eid=3ee8f719d6>
>>>>
>>>>
>>>> ---
>>>> Cary Renquist
>>>> cary.renquist at ezag.com
>>>>
>>>> _______________________________________________
>>>> You are currently subscribed to the RadSafe mailing list
>>>>
>>>> Before posting a message to RadSafe be sure to have read and
>>>> understood the RadSafe rules. These can be found at:
>>>> http://health.phys.iit.edu/ radsaferules.html
>>>>
>>>> For information on how to subscribe or unsubscribe and other
>>>> settings
>>>> visit: http://health.phys.iit.edu
>>>>
>> _______________________________________________
>> You are currently subscribed to the RadSafe mailing list
>>
>> Before posting a message to RadSafe be sure to have read and
>> understood the RadSafe rules. These can be found at:
>> http://health.phys.iit.edu/radsaferules.html
>>
>> For information on how to subscribe or unsubscribe and other settings
>> visit: http://health.phys.iit.edu
>> _______________________________________________
>> You are currently subscribed to the RadSafe mailing list
>>
>> Before posting a message to RadSafe be sure to have read and
>> understood the RadSafe rules. These can be found at:
>> http://health.phys.iit.edu/radsaferules.html
>>
>> For information on how to subscribe or unsubscribe and other settings
>> visit: http://health.phys.iit.edu
>
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and understood the RadSafe rules. These can be found at: http://health.phys.iit.edu/radsaferules.html
>
> For information on how to subscribe or unsubscribe and other settings visit: http://health.phys.iit.edu
> _______________________________________________
> You are currently subscribed to the RadSafe mailing list
>
> Before posting a message to RadSafe be sure to have read and understood the RadSafe rules. These can be found at: http://health.phys.iit.edu/radsaferules.html
>
> For information on how to subscribe or unsubscribe and other settings visit: http://health.phys.iit.edu