[ RadSafe ] definition of Rad

Thu Oct 11 13:37:14 CDT 2007

I have found this discussion quite interesting and enlightening.  Rainer, I would suggest that YOU would be an excellent person to write a Wikipedia entry.  While Wikipedia is far from perfect, it is equally far from useless, and knowledgeable and articulate people contributing improves the knowledge base of the world (less those countries that block Wiki) 

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of Rainer.Facius at dlr.de
Sent: Wednesday, October 10, 2007 7:22 AM
To: Colette.Tremblay at ssp.ulaval.ca; eic at shaw.ca; radsafe at radlab.nl
Subject: AW: [ RadSafe ] definition of Rad

Colette:

In his paper

Russ S, A SUGGESTION FOR A NEW X-RAY UNIT IN RADIOTHERAPY.

Archives of Radiology and Electrotherapy 23(1918)226-32 

Russ refers to the inactivation of malignant (mammalian) cells: 

"The unit proposed is that quantity of X rays which when absorbed will cause the destruction of the cells in question, and the name suggested for the unit is the Rad." (p.226) 

For the realization of the unit he proposes:

"THE METHOD OF MEASURING THE UNIT.

The photographic action of the rays which are being administered to the patient is obtained upon a photographic plate; upon the same plate is impressed the photographic effect of a standard source of radiation; for convenience this is a capsule of radium emitting beta and gamma rays. The plate is developed with any developer, and with no restrictions as to time or temperature - any of these variables will affect the X-ray and the radium units to an equal degree; a comparison is then made between the photographic impressions so obtained." (p.230)

In other words, he proposes a "capsule of radium emitting beta and gamma rays" as a "standard source of radiation" against which an unknown X-ray source is to be 'calibrated' by means of comparing their "tint" in photographic plates. Hence his proposal to name this unit "Rad"(ium) which conceptually as well as materially has no relationship whatsoever to the unit "rad" adopted 1953 by the ICRU. 

Apparently, his conceived standard radium source "... when applied to malignant cells, causes complete inhibition of their proliferation after an exposure thereto for one hour;" i.e., it deposited an absorbed of the order of several Gy (1 Gy the order of the D-37 for killing mammalian cells in culture). So, indeed that would approach the LD50(30) for killing of mice although Russ himself does not mention this at all.

Interestingly he mentions already the Dose Rate Effectiveness Factor in noting that " M.M. Regaud and Nogier have repeatedly called attention to the fact that successive doses of X rays have less effect upon a tumour than the first applied dose, but, whatever may be the explanation of such an important fact, ...".

In summary, Jerrard and McNeil (1992). Dictionary of Scientific Units. Chapman and Hall. have not read the original paper by Russ if you properly quoted them. The new Wikipedia entry (as quoted by Kai) is as bad as the previous.

Kind regards, Rainer

________________________________

Von: radsafe-bounces at radlab.nl im Auftrag von Colette Tremblay
Gesendet: Fr 05.10.2007 15:59
An: Facius, Rainer; eic at shaw.ca; radsafe at radlab.nl
Betreff: RE: [ RadSafe ] definition of Rad

Hi Rainer,

I checked the 1986 edition of Jerrard. I quote it:

Historically the rad can be traced back to 1918. In this year Russ suggested that the unit of X-Ray dose should be the dose required to kill a mouse and that the unit should be named the rad (4)
(4) Russ S., Arch Rad and Electrotech 23:226 (1918)

What I understand is that the name proposed by Russ was later adopted but the magnitude of the adopted unit was much smaller than what he had in mind. Maybe this caveat could be added to the Wikipedia entry to remove any confusion?

Regards,

Colette

---
Colette Tremblay
Spécialiste en radioprotection
Service de sécurité et prévention
Université Laval

Pavillon Ernest-Lemieux, bureau 2527
2325, Rue de la Vie-Étudiante
Québec QC Canada  G1V 0B1

(418) 656-2131 poste 2893
Télécopie: (418) 656-5617

Colette.Tremblay at ssp.ulaval.ca
www.ssp.ulaval.ca/sgc/radioprotection
--

Message relatif à la confidentialité:
http://www.rec.ulaval.ca/lce/securite/confidentialite.htm

-----Message d'origine-----
De : Rainer.Facius at dlr.de [mailto:Rainer.Facius at dlr.de] Envoyé : 5 octobre 2007 09:36 À : Colette Tremblay; eic at shaw.ca; radsafe at radlab.nl Objet : AW: [ RadSafe ] definition of Rad

Collette:

The lethal doses for mice as quoted in the PNAS paper are given in the 'old' unit R (Röntgen) which for practical purposes - depending on the material - is nearly equivalent to the rad as defined by the ICRU in 1953 (what appears to be part of the rationale for this choice).

With this unit of dose it takes MANY hundreds instead of ONE rad to kill mice. If indeed your source (Jerrard and McNeil, 1992 ) says otherwise, it either speaks of yet another "unit" or it speaks nonsense.

Kind regards, Rainer

________________________________

Von: radsafe-bounces at radlab.nl im Auftrag von Colette Tremblay
Gesendet: Do 04.10.2007 21:40
An: Facius, Rainer; eic at shaw.ca; radsafe at radlab.nl
Betreff: RE: [ RadSafe ] definition of Rad

Hi:

The Wikipedia entry states:

"The rad was first defined in 1918 as the unit of X-ray dose required to kill a mouse.[1]"

And the reference given is:

[1] Russ S, Arch Rad and Electrotech 23, 226, 1918 according to Jerrard and McNeil (1992). Dictionary of Scientific Units. Chapman and Hall.

Our library has the 1986 edition of Jerrard and McNeil. I'm going to check it.

Colette
---
Colette Tremblay
Spécialiste en radioprotection
Service de sécurité et prévention
Université Laval

Pavillon Ernest-Lemieux, bureau 2527
2325, Rue de la Vie-Étudiante
Québec QC Canada  G1V 0B1

(418) 656-2131 poste 2893
Télécopie: (418) 656-5617

Colette.Tremblay at ssp.ulaval.ca
www.ssp.ulaval.ca/sgc/radioprotection
--

Message relatif à la confidentialité:
http://www.rec.ulaval.ca/lce/securite/confidentialite.htm

-----Message d'origine-----
De : radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] De la part de Rainer.Facius at dlr.de Envoyé : 4 octobre 2007 05:44 À : eic at shaw.ca; radsafe at radlab.nl Objet : AW: [ RadSafe ] definition of Rad

Kai,

you may need up to thousand rads (up to 10 Gy)  of acute sparsely ionizing radiation to kill an adult healthy mouse.

Rainer

Morton  J I, Siegel B V, Radiation Sensitivity of New Zealand Black Mice and the Development of Autoimmune Disease and Neoplasia. Proc Natl Acad Sci U S A. 68#1(1971)124-126.

"Young New Zealand Black (NZB) mice manifested extremely high resistance to the lethal effects of acute exposures to ionizing radiation, with a dose necessary to kill 50% of the animals within 30 days, LD50(30), of 964 roentgens (R) at 30 days of age and of 856 R for 90-day-old mice. In contrast, Coombs' positive 9-month-old NZB mice (with low primary immune response) were highly susceptible (LD50(30) = 543 R), possibly because of anemia-stimulated erythropoiesis leading to a depletion of stem cells."

Dr. Rainer Facius
German Aerospace Center
Institute of Aerospace Medicine
Linder Hoehe
51147 Koeln
GERMANY
Voice: +49 2203 601 3147 or 3150
FAX:   +49 2203 61970

________________________________

Von: radsafe-bounces at radlab.nl im Auftrag von Kai Kaletsch
Gesendet: Di 02.10.2007 18:10
An: radsafe at radlab.nl
Betreff: [ RadSafe ] definition of Rad

Friends,

According to the Wikipedia entry for 'Rad', it was defined from 1918 to 1953 as the unit of X-ray dose required to kill a mouse. 1) I never heard this definition before and 2) This seems like a very low dose for killing anything.

This is somewhat before my time and I normally use SI units. Is the Wikipedia statement correct?

Kai

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