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 - 00:17:42 CET