[fluka-discuss]: RE:Dose from Activity Units

From: Ricardo Manuel Dos Santos Augusto <r.s.augusto_at_cern.ch>
Date: Sat, 30 May 2020 08:07:12 +0000

Dear Dirk,

The approach is correct*, but are you sure about the 0.5 u? in some cases U is used to indicate the source strength.

*Note that your conversion to dose, in your particular case, is valid because you have a single isotope in the chain. Since semi-analogue mode you get all the decay products if you had additional isotopes in the decay chain (e.g. a very short lived and a long lived for instance) the dose rate calculation would be meaningless. In such cases, it is often preferrable to employ a TIME-CUT to restrict the scoring to the parent isotope (age=0) by discarding the daughters' contribution (age according to their respective half-life).

Kind regards,
Ricardo

//Ricardo dos Santos Augusto
TRIUMF-EH&S
Office: +1 604 222 10 47 (6375)
4004 Wesbrook Mall,
Vancouver, BC V6T 2A3, Canada//
________________________________
De : owner-fluka-discuss_at_mi.infn.it [owner-fluka-discuss_at_mi.infn.it] de la part de Bartkoski,Dirk Alan [DABartkoski_at_mdanderson.org]
Envoyé : mercredi 27 mai 2020 16:53
À : 'fluka-discuss_at_fluka.org'
Objet : [fluka-discuss]: Dose from Activity Units

I just want to verify that I am properly converting the units of my results.

I have a 0.5 u radioactive Iodine 125 source that is defined as an ISOTOPE in the BEAM card.
I am using Semi-Analogue in the RADDECAY card and have applied Semi-Analogue to my USRBINs with DCYSCORE.

I want to measure dose to volume from my radioactive source. I have defined the desired volume using USRBIN for DOSE.

From what I understand, my USRBIN with be in GeV/g/decay since I am scoring DOSE from a radioactive isotope.

I want dose rate.

GeV/g/decay*1.602176462E-7 = Gy/decay

Iodine 125 specific activity = 642E12 Bq/g => 642E12 decay/s/g

To get dose rate in Gy/s => (USRBIN value in GeV/g/decay)* 1.602176462E-7*642E12 decay/s/g*0.5*(flair atomic mass unit to gram conversion constant amugr)

My conversion constant is = 1.602176462E-7*642E12*0.5*amugr => Gy/s

Is my approach correct?


_______________________________________________________________________________
Dirk A. Bartkoski, Ph.D.
Research Scientist | Division of Radiation Oncology
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Received on Sat May 30 2020 - 10:07:12 CEST

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