Re: Clarification of DOSE-EQ units in a USRBIN estimator

From: Mina Nozar <nozarm_at_triumf.ca>
Date: Mon, 16 Apr 2012 16:43:56 -0700

Dear Anna and Stefan,

Thank you for your clear explanations.

I have also checked the results of a USRTRACK estimator with the results of a USRBIN estimator (region binning) where I
have scored DOSE-EQ and the region of interest in each estimator is the same.

Integrating the DOSE-EQ over all energy bins in USRTRACK gives me the same result as the USRBIN estimator (once I divide
by the region's volume).

So I understand what is going now.

Thanks again and best wishes,
Mina

On 12-04-15 02:48 PM, Anna Ferrari wrote:
> Dear Mina,
>
> no, the problem must not be seen in this way.
> The units are exactly as written in the manual and as you reported:
>
> 13) The results from USRBIN are normalised per unit volume and per unit
> primary weight,except for (...) and for dose equivalent,
> <==============
> expressed as pSv per unit primary weight.<==============
>
> First: it does not make sense to express the dose equivalent in pSv/cm3!
> You have always to remember how an average dose equivalent in a given volume
> is evaluated: you calculate the average fluence (in part./cm^2 per primary) of
> the components of the radiation field in the volume and then you apply the
> appropriate conversion coefficients (in pSv cm^2) to get the dose equivalent
> due to this average radiation field . To each point of the volume you
> associate then this average dose equivalent, which is expressed in pSv/primary
> (thinking to the meaning of the dose equivalent is helpful).
>
> Let's think then about your examples:
>
> a) USRBIN scoring with space binning
> An average radiation field is calculated in each element of the defined USRBIN
> mesh in the space. The dose equivalent values you get (in pSv/primary) refer
> to these elements. They refer to 1 cm^3 volumes only if you have set this
> granularity.
>
>
> b) USRBIN scoring with region binning
> We have to take care here.
> The manual states that this is the only case where USRBIN results are NOT
> normalized by volume. The delicate point is that at the moment this is not
> dependent on the specification or not of the volume in the geometry section,
> which applies only to the quantities calculated via the SCORE option.
> [ From the FLUKA manual, section: 2.2.6:
> "The only effect of specifying region volumes is to normalise per cm3 the
> quantities calculated via the SCORE option (...): for other estimators
> requiring volume normalisation the volume is input as part of the detector
> definition (USRTRACK, USRCOLL, USRYIELD), or is calculated directly by the
> program (USRBIN)", where the last sentence refers only to the USRBIN scoring
> with space mesh (I admit here it is not too clear).]
>
> This means that with the region binning option you will not get the average
> fluence in the volume (in part/cm^2), but the total tracklength in the
> selected region. To get the fluence and finally the correct average dose
> equivalent (always in pSv/primary) you have to divide offline by the volume.
> I think this is a complication (!) that can be easily avoided by using USRBIN
> with space mesh, a choice that I prefer also under the dosimetric point of
> view (I can choose how well I want to approximate the radiation field -and
> then the dose equivalent calculation- and I can avoid to average on large
> volumes, with probable dangerous underestimations of the dose in critical
> points).
>
> Last: yes, you know already that with the IRRPROF card you pass from pSv/prim
> to pSv/s, because you input the current in prim/s.
>
> I hope this helps to clarify a bit,
> best regards,
> Anna
>
>
> Am Thu, 12 Apr 2012 13:05:43 -0700 schrieb Mina Nozar<nozarm_at_triumf.ca>:
>> Dear FLUKA users, can someone confirm whether the following statements are
>> correct?
>>
>> - USRBIN scoring (spacial binning)
>> pSv/cm^3*prim - with no IRRPROF card
>> pSv/cm^3*sec - with an IRRPROF card
>>
>>
>> - USRBIN scoring (region binning)
>> pSv/prim - with no IRRPROF card and with no volume input for the given in
>> the geometry section)
>> pSv/sec - with an IRRPROF card and with no volume input for the given in
>> the geometry section)
>>
>>
>> pSv/prim - with no IRRPROF card and with the region volume given in the
>> geometry section)
>> pSv/sec - with an IRRPROF card and with the region volume given in the
>> geometry section)
>>
>>
>> So regardless of whether region volumes are given in the geometry section,
>> units are pSv/prim or pSv/sec in the region
>> binning? This is how I interpret the manual under USRBIN:
>>
>>
>> 13) The results from USRBIN are normalised per unit volume and per unit
>> primary weight, except for region binnings and special user-defined
>> binnings, which are normalised per unit primary weight only, for
>> DPA, which are given as number of displacements per atom per unit
>> primary weight, averaged over the bin volume, and for dose
>> <==============
>> equivalent, expressed as pSv per unit primary weight.
>> <==============
>> In case symmetries are requested, proper rescaled volumes are taken
>> into account for normalisation (that is, an extra factor 2 is
>> applied to the volume if symmetry around one plane is required, 8 if
>> the symmetry is around the origin)
>>
>>
>> Thank you for the clarification,
>> Mina
>>
>
Received on Tue Apr 17 2012 - 13:56:10 CEST

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