Re: [fluka-discuss]: Scoring Absorbed Dose

From: Mina Nozar <nozarm_at_triumf.ca>
Date: Thu, 27 Feb 2014 17:15:55 -0800

Dear Francesco,

Yes, this makes it clear and I appreciate your explanation, THANK YOU.
The key point is that the FLUKA quantity scored as DOSE is not the
standard definition of DOSE.

FLUKA's quantity scored as DOSE: Energy/density
Standard def. of DOSE: Energy/mass

Can your explanation please be added to the manual for the future release?

Cheers,
Mina


On 14-02-27 02:20 PM, Francesco Cerutti wrote:
>
> Dear Mina,
>
> deposited energy and absorbed dose are evidently related, one could
> even dare to say that basically they are the same thing, just
> differently normalized. But I think you are overlooking a basic
> aspect: actually the strict relationship is between deposited energy
> *density* and dose. Let's consider that with a regular USRBIN mesh you
> get a local value and with a USRBIN per region you get a global value.
> In case of ENERGY, this will yield local energy density [GeV/cm3] and
> total (or integrated) energy [GeV], respectively. Note that these are
> two different quantities, as their units demonstrate, and both are
> well defined and meaningful, because energy is an extensive quantity,
> increasing with volume (or with mass=volume*density). Instead in case
> of DOSE, calculated by FLUKA as ENERGY/density, you will have local
> dose [GeV/g] and average dose times volume [GeV/(g/cm3)],
> respectively. The second quantity is not a dose, since a total (or
> integrated) dose does not make sense! And you have to divide it -
> divide, not multiply - by the region volume in order to get back the
> dose averaged over the region.
> So you can happily compare the SCOREd ENERGY ([GeV], with no input
> volume) divided by the region mass (volume*density) - this way getting
> the average dose - to the USRBIN (per region) DOSE divided by the
> region volume. But you cannot call "dose" the value produced by the
> USRBIN per region, being the latter an odd quantity unless you divide
> it by the region volume.
>
> As you will score, e.g., PROTON, regular USRBIN on one side and USRBIN
> per region and SCORE on the other will yield you fluence [cm-2] and
> tracklength [cm], respectively. Here again two different and
> meaningful quantities.
>
> Hope this helps
>
> Francesco
>
> **************************************************
> Francesco Cerutti
> CERN-EN/STI
> CH-1211 Geneva 23
> Switzerland
> tel. ++41 22 7678962
> fax ++41 22 7668854
>
> On Thu, 27 Feb 2014, Mina Nozar wrote:
>
>> Hello Francesco,
>>
>>
>> I completely understand the difference B/N 'binning' and 'region'
>> definition in USRBIN (or at least I think I do). In the 'binning'
>> case, quantities scored are given as /cm3*primary but for 'region'
>> case, the quantities are given over the volume of the region (so
>> integrated/total values).
>>
>> The manual, under USRBIN, note 5 says:
>>
>> 5. Energy deposition will be expressed in GeV per cm3 per unit
>> primary weight.
>> Doses will be expressed in GeV/g per unit primary weight. To obtain
>> dose in Gy, multiply GeV/g by 1:602176462  10E7.
>>
>> Why is the unit for the the Dose scored as the quantity, not
>> GeV/g/cm3 here??? This is inconsistent with note 13:
>> "The results from USRBIN are normalised per unit volume and per unit
>> primary weight, except for region binnings and special user-dened
>> binnings, which are normalised per unit primary weight only"
>>
>> ----------------------------------------------------------------
>>
>> The forum links you have sent, say in USRBIN region binning, the
>> units are GeV/[g/cm3] when one scores Dose and has to multiply to
>> results by the volume to get the actual dose [GeV/g]. Fine, but this
>> should be added to the manual.
>>
>> We used SCORING through score as a cross-check of the USRBIN Region
>> binning results.
>> Can we compare (non-normalized values) from SCORE for deposited
>> energy to Dose from USRBIN region binning, scoring Dose, by dividing
>> the dep. energy values in through SCORE by the mass of the region???
>> I guess the question is whether deposited energy and absorbed dose
>> are related.
>>
>> Thank you in advance,
>> Mina
>>
>> On 14-02-27 02:02 AM, Francesco Cerutti wrote:
>>>
>>> Hallo Mina & Martin,
>>>
>>> you do not need to send your inputs, your expectations concerning
>>> USRBIN
>>> per region are wrong, not complying with what is written in the manual
>>> (USRBIN, Note 13) and with what has been already explained in this
>>> forum
>>> (http://www.fluka.org/web_archive/earchive/new-fluka-discuss/4288.html,
>>>
>>> http://www.fluka.org/web_archive/earchive/new-fluka-discuss/3458.html).
>>>
>>>
>>> Once more: FLUKA does not know region volumes, so values per region
>>> cannot
>>> be normalized per region volume. If you ask for ENERGY, you will
>>> get GeV
>>> (per primary) and not GeV/cm3, if you ask for DOSE you will get the
>>> same
>>> as before divided by the material density (i.e. GeV/(g/cm3) and not
>>> GeV/g).
>>>
>>> (Only) SCORE values can be normalized by region volumes provided
>>> that one
>>> inputs them (though the practical benefit of that is quite
>>> questionable -
>>> I'm not aware of anybody using it -, since one can always renormalize
>>> SCORE values at postprocessing level; all this still assuming that
>>> people
>>> actually use values from SCORE, which is an historical scoring
>>> option not
>>> supporting automatic statistical analysis). If not, a default value of
>>> 1cm3 is used for normalization purposes as you noticed, meaning
>>> that the
>>> SCORE value for ENERGY should be intended as GeV, contrary to your
>>> conclusions and according to what is in the manual (SCORE, Note 4).
>>>
>>> Coming now to your case 2b, if you follow the manual and set IVLFLG
>>> = 3 in
>>> the geometry title card and write the volumes (in fixed format: 10
>>> fields
>>> per region, 7 regions per row) before the GEOEND card (after the
>>> region
>>> END card), everything works as expected: the SCORE values will get
>>> normalized by your volumes and the latter ones will appear in the
>>> volume
>>> column. You still got default volume values of 1cm3 due to a Flair
>>> bug,
>>> not translating correctly what was input in the region metacard
>>> under the
>>> Volume label. This is going to be fixed in the next Flair version
>>> (by the
>>> way, Flair 2 is coming!), but it gives me the nasty opportunity to
>>> remind
>>> people that in case of problems and unexpected behaviors one should
>>> look
>>> at the input file as actually fed to FLUKA, leaving for a little
>>> while the
>>> wonderful Flair world and using a trivial text editor to inspect
>>> what is
>>> underneath.
>>>
>>> Best wishes
>>>
>>> Francesco
>>>
>>> **************************************************
>>> Francesco Cerutti
>>> CERN-EN/STI
>>> CH-1211 Geneva 23
>>> Switzerland
>>> tel. ++41 22 7678962
>>> fax ++41 22 7668854
>>>
>>> On Thu, 27 Feb 2014, Mina Nozar wrote:
>>>
>>> > Hello everyone,
>>> > > We are trying to score Absorbed Dose in a given region. We
>>> have tried > two scoring methods:
>>> > 1) via a USRBIN card with REGION binning and DOSE as the quantity
>>> scored
>>> > and
>>> > 2) via a SCORE card and Energy as the quantity scored, with no
>>> volume > input (case 2a) and with volume input (case 2b).
>>> > > According to the manual, we should get
>>> > - GeV/g per primary for option 1
>>> > - GeV per primary for option 2a
>>> > - GeV/cm3 per primary for option 2b
>>> > > > As for the volume setting for the SCORE card, we set IVFLG to
>>> 3 in the > GEOBIN title card and inputted the region volume in the
>>> geometry region > card for the region.
>>> > > > We are seeing some discrepancies. The value we get from
>>> SCORE (with no > volume setting, case 2a) agrees with the value
>>> from the USRBIN, if we > divide the SCORE value by the density.
>>> This implies that the SCORE > value is GeV/cm3 per primary which
>>> doesn't agree with what is in the > manual.
>>> > > Furthermore, when we do set the volume, following the
>>> instructions > above, we still see a value of 1.000000000D+00 for
>>> the region's volume > and the same deposited energy value as in
>>> case 2a.
>>> > > This is a source of confusion for us and we are eager to find
>>> whether we > are missing something. Can someone shed some light on
>>> this please?
>>> > Is there another way to score absorbed dose in a region?
>>> > > Thank you very much,
>>> > Mina & Martin
>>> > >
>>
>>
>>
>
Received on Fri Feb 28 2014 - 05:38:16 CET

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