[Gate-users] How to convert Dose per Particle to Gy in Phantom Voxels

[Nicollas Goncalves Cavedini]

Dear Merry,

The dose matrix from DoseActor is in Gy according to the manual. The
relative statistical uncertainty file is by each voxel, that is, you must
multiply the voxel dose by the relative statistical uncertainty (of the
file) thus obtaining the statistical uncertainty of your simulation.
Best regards,



*Nícollas Gonçalves Cavedini*
Undergraduate Student -  Medical Physics (PUCRS)
Lattes: http://lattes.cnpq.br/7248406497106855
Contact: +55 (51) 99922-9957
Porto Alegre, Brazil.



2018-09-11 14:24 GMT-03:00 Mery MB <mery.mb.mph at gmail.com>:

> *Hi Dear Gate User*
>
>
> *I simulated a medical linac and calculated dose in a voxelized phantom
> (h33,i33 format of Rando Phantom) with the dose actor which I written below*
>
> /gate/actor/addActor
> DoseActor meshdose
> /gate/actor/meshdose/save
> output1/Randodose.hdr
> /gate/actor/meshdose/attachTo                              phantom
> /gate/actor/meshdose/stepHitType                         random
> /gate/actor/meshdose/setSize                                652 362 872 mm
> #/gate/actor/meshdose/setResolution                   326 181 436
> /gate/actor/meshdose/setVoxelSize                      2 2 2 mm
> /gate/actor/meshdose/enableEdep                        true
> /gate/actor/meshdose/enableUncertaintyEdep     true
> /gate/actor/meshdose/enableSquaredEdep         true
> /gate/actor/meshdose/enableDose                       true
> /gate/actor/meshdose/enableUncertaintyDose     true
> /gate/actor/meshdose/enableSquaredDose         true
> /gate/actor/meshdose/saveEveryNSeconds         60
>
>
> *I want to convert dose in each voxel to Gy. *
> *As I read in Gate Manual the dose in voxel should be in Gy.*
> ""The output file is a binary file (number format is 4 bytes float)
> containing the absorbed dose in cGy. It has the same dimensions as the
> phantom. The output module optionally writes a second binary file
> containing the uncertainty on absorbed dose expressed as a fraction between
> 0 and 1.""
>
> *but the numbers which I obtained for each voxel inside fields and outside
> fields are in orders of 10 to power of -5 and 10 to power of -7,
> respectively. based on the number it should not be in Gy!!! So I want to
> convert them to Gy and compare them with the TPS result for inside fields
> voxels..*
>
> *My first question is: what is that number? Dose per incident Particle?!!!
> If yes, Why they increased with increase in the number of primary particle!
> even after reduce the dose uncertainty to near zero*
>
> *           If the number of hit effect the number for each voxel, how I
> should calculate them and how I should effect them in my conversion to
> Gy???*
>
> *Then: How I can convert them to Gy? *
>
> *I found the below article and thesis for this conversion but both of them
> works with EGSnrc. the number in each voxel in this code are dose per
> incident voxel.*
> Francescon P, Cavedon C, Reccanello S and Cora S 2000 Medical Physics
> 27(7), 1579–1587.
> Monte Carlo Treatment Planning for Advanced Radiotherapy. Chapter 5,
> Cronholm, Rickard; F. Behrens, Claus; Helt-Hansen, Jakob; E. Andersen, Claus
> *I will be thankful if someone have experience in this issue and help me.*
>
> *Best regards*
>
> *Mery*
>
>
>
>
>
>
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>
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