Re: [fluka-discuss]: Scoring Absorbed Dose

From: Francesco Cerutti <Francesco.Cerutti_at_cern.ch>
Date: Fri, 28 Feb 2014 08:11:07 +0100

> FLUKA's quantity scored as DOSE: (Energy density)/(mass density)

which is the

> Standard def. of DOSE: Energy/mass

apart from the special cases where instead of (Energy density) the
code takes Energy since the volume is unknown

**************************************************
Francesco Cerutti
CERN-EN/STI
CH-1211 Geneva 23
Switzerland
tel. ++41 22 7678962
fax ++41 22 7668854

On Fri, 28 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
>
>
> 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