AW: [ RadSafe ] New Radiation Protection Unit? The Taylor (Ty)

Tue Nov 22 11:43:21 CST 2005

Sandy (John):

Effective dose (tissue weighted equivalent organ dose) conceptually is quite distinct from equivalent dose (radiation weighted) organ dose. Effective dose e.g. will have to reflect progress being made in cancer therapy. Cancer of a tissue which in future might become more or less 100% curable would get a zero tissue weighting factor. 

It is most unfortunate that this obvious mistake of assigning the same unit to conceptually different quantities has been made at all and in principle I therefore concur with the NCRP proposal. 

Since I am not really working with radiation standards I cannot assess the expenses necessary to implement such a change. However, what I know of, e.g., the German Radiation Protection Ordinance, the majority of paragraphs where numbers are given address effective dose, and for that quantity the unit of Sievert shall be kept according to the NCRP proposal. Only in the few instances where, e.g., tissue doses for the eye lens or the skin are mentioned, the Sievert would have to be replaced by the Taylor. 

Given the anyway regular reprints/updates of most of these texts, one might gradually convert from the Sievert to the Taylor where indeed organ dose is denoted. That reminds me of the change from the CGS- System to the SI System in physics, where for many years the units of both systems were tolerated. Given that that change was much more extensive and yet was executed rather smoothly (e.g. from the rem to the Sievert) I cannot imagine that (gradual) implementation of the Taylor would spell horrendous efforts. After all, the numbers remain the same - until the radiation weighting factors become modified the next time, and then a larger reprinting effort might become necessary.

My EUR0.02.

Best regards, Rainer

________________________________

Von: radsafe-bounces at radlab.nl im Auftrag von Sandy Perle
Gesendet: Di 22.11.2005 16:19
An: sandyfl at earthlink.net; radsafe at radlab.nl; nielseec at nv.doe.gov; John Jacobus
Betreff: Re: [ RadSafe ] New Radiation Protection Unit? The Taylor (Ty)

On 21 Nov 2005 at 17:36, John Jacobus wrote:

> As one who answers patients questions, I always feel
> that I should apologize for the confusion between DE
> and ED. I am not sure if naming a new unit would be
> more confusioning tahn the current situation.

John,

I expect that most, if not all patients, would be confused. Heck,
even most physicists remain confused on how to use the terms as
intended!  MY biggest issue is that any new term would be contrary to
the current definitions used throughout the world, and, are included
in various international standards. The USA should not embark on a
new term that is sued solely in the USA, and would further increase a
a chasm in the standards area where there needs to be more
harmonization, and not a continual splitting.

-------------------------------------
Sandy Perle
Senior Vice President, Technical Operations
Global Dosimetry Solutions, Inc.
2652 McGaw Avenue
Irvine, CA 92614

Tel: (949) 296-2306 / (888) 437-1714  Extension 2306
Fax:(949) 296-1144

E-Mail: sperle at dosimetry.com
E-Mail: sandyfl at earthlink.net

Global Dosimetry Website: http://www.dosimetry.com/
Personal Website: http://sandy-travels.com/

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