Re: [fluka-discuss]: Scoring Absorbed Dose

From: Mina Nozar <nozarm_at_triumf.ca>
Date: Fri, 28 Feb 2014 09:53:14 -0800

Dear Alfredo,

Thank you for your explanation.

You say 'as clearly explained in the manual'. But it is not explained
in the manual at all. As such, a clear explanation should be added to
remove all confusion.

Best wishes,
Mina

On 14-02-27 10:46 PM, Alfredo Ferrari wrote:
> Dear Mina
>
> I am afraid it is not (yet) clear at all. Obviously for FLUKA DOSE is
> dose
> that is energy/mass and it would be crazy to claim otherwise! Only for
> a region scoring where the volume normalizations are generally unknown
> to the code, FLUKA gives you energy/density/ASSUMED VOLUME=1 cm^3
> which is a nice way to say this is energy/density, I don't know the
> volume,
> please apply it yourself.
>
> It is to you as clearly explained in the manual and by Francesco to do
> the final step, that is to divide by the region volume. There is no
> mistake
> in the manual, no need for corrections, and contrary to your claim
> dose for FLUKA is what it is for everybody as Francesco made already
> crystal clear in his answer (which evidently was not clear enough).
>
> Ciao
> Alfredo
>
> +----------------------------------------------------------------------+
> | Alfredo Ferrari || Tel.: +41.22.76.76119 |
> | CERN-EN/STI || Fax.: +41.22.76.69474 |
> | 1211 Geneva 23 || e-mail: Alfredo.Ferrari_at_cern.ch |
> | Switzerland || |
> +----------------------------------------------------------------------+
>
> On Thu, 27 Feb 2014, Mina Nozar wrote:
>
>> 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 - 20:11:04 CET

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