[fluka-discuss]: dose scoring in a thin volume

From: Giuseppe Prestopino <giuseppe.prestopino_at_uniroma2.it>
Date: Fri, 10 Oct 2014 09:24:52 +0200

Dear FLUKA experts,

I need to simulate dosimetric properties of a solid state detector in high
energy carbon and proton beams (energies typical of hadrontherapy
application). Since the scoring volume is very thin, of the order of 1 - 3
microns (cylindrical shape, radius 1.1 mm), my first test was to check the
constancy of scored dose by evaluating DOSE calculated by USRBIN per Region
in a volume placed at the plateau of the depth dose curve and decreasing the
volume thickness from 5 mm to 1 micron (radius 1.1 mm).

What I see is that the scored dose (calculated as dose by USRBIN per region
divided by scoring volume) varies with scoring volume thickness, and that it
is more pronounced for a beam that is not defined as a pencil beam (I
considered a square beam). Relative deviation of the thin volumes (1-3 um) I
am interested to, with respect dose value for thicker volumes, is too high.
I have attached my input file (executable "test" is compiled linking to
"ldpmqmd") and my simulation results (10000 primaries x 3 cycles for the
square field, and 3000 primaries x 3 cycles for the pencil beam).

Please, give me some idea for reducing such effect..


Best regards,


(image/jpeg attachment: dose_vs_scoring_volume.jpeg)

Received on Fri Oct 10 2014 - 11:15:55 CEST

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