- #1

- 10

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I ask for help for ideas or suggestions.

thanks.

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- Thread starter Alexander Camargo
- Start date

- #1

- 10

- 1

I ask for help for ideas or suggestions.

thanks.

- #2

Astronuc

Staff Emeritus

Science Advisor

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What is the type of radiation source, and what is its distribution?

- #3

- 125

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Hi,

Can you put your file (in ascii) ?

Can you put your file (in ascii) ?

- #4

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mcnpx 2.7

Code:

```
C Alexander Camargo - 23/10/2018
C *******************Celulas********************************
10 2 -1.090 (-1 2 -3 4) #20 imp:p=1 VOL=149.2256511 $ espessura / thickness
20 1 -0.9850 (-5 6 -7 8) imp:p=1 VOL=353.4291735 $ mama / breast
30 3 -0.001205 (-10 -11 12 13) #10 #20 imp:p=1 VOL=10.3059947 $ ar / air
C ----- Acompanhamento -----
80 3 -0.001205 (-80) #10 #20 #30 imp:p=1 $ Mundo-Interno / universe
90 0 (80) imp:p=0 $ Fim do Acompanhamento
C -------------Geometrias / geometries ----------------
C ------------ espessura / thickness ----------
1 cz 8
2 pz -2.5
3 pz 2.5
4 px 0
C ------------ mama / breast -------------
5 cz 7.5
6 pz -2
7 pz 2
8 px 0.5
C ------------ AR / air -------------
10 cz 8.1
11 pz 2.6
12 pz 2.5
13 px 0
C --- Fim de Acompanhamento / universe ---
80 SO 225 $ Mundo
C area 0 0 0 0 0 0 0 0 0 0 100.5312 0 0 0
mode P $ fotons / photons
C -------------- fonte e energia (monoenergetico) ----------------
sc1 raio x monoenergetico para mamografia
SDEF X=d1 Y=d2 Z=60 PAR=2 ERG=0.018 VEC=0 0 1 DIR=-1
SI1 -1 9 $ sampling range Xmin to Xmax
SP1 0 1 $ weighting for x sampling: here constant
SI2 -10 10 $ sampling range Ymin to Ymax
SP2 0 1 $ weighting for y sampling: here constant
C
C **************************** Materiais *********************************
C ***************************** mama padrao 50/50 **********************************
m1 1000 -0.1140 $ H
6000 -0.5250 $ C
7000 -0.0060 $ N
8000 -0.3535 $ O
11000 -0.0005 $ Na
16000 -0.0005 $ S
17000 -0.0005 $ Cl
C
C ------------------------ Pele -------------------------------
m2 1000 -0.100 $ H
6000 -0.199 $ C
7000 -0.042 $ N
8000 -0.650 $ O
11000 -0.002 $ Na
15000 -0.001 $ P
16000 -0.002 $ S
17000 -0.003 $ Cl
19000 -0.001 $ K
C
C ****************************** AR ***************************************
m3 6000 -0.000124 $ C
7000 -0.755268 $ N
8000 -0.231781 $ O
18000 -0.012827 $ Ar
C
C ************************** Tungstenio *********************************
C m4 74000 -1.000
C
C *************************************************************************
C
C
C ***************************** Tallies ***********************************
f4:p 30
f6:p 30
c
C
C
C
C *************************** tempo de Input **********************************
NPS 16000000 $ Stop after XX source particles have been run.
C CTME 120 $ Stop run after XX minutes.
```

Last edited by a moderator:

- #5

- 125

- 36

I suppose you have multiplied F6 by 1.602e-10 to convert in Gy. Remember that to compare results, you have to normalize to the fluence (K/phi) to obtain Gy.cm

Note that for me the "SDEF" is Strange. If you want a rectangular parallel beam you must write something like that "SDEF X=d1 Y=d2 Z=0 pos 0 0 60 …" but in fact I dont know what you want to simulate ...

- #6

- 10

- 1

i need to kerma in air, but, i found very low results. I need multiplicate my results per 16000000 to found the valor?

I want simulate a mamography machine with focal point the 60cm the breast. My card "SDEF" is configured for a one-dimensional collimated beam in direction the -z axis.

sorry for my lack of knowledge, I'm new to the mcnpx area and I'm in the third year of graduation.

- #7

- 125

- 36

Hi,

No ! A F6 result is in MeV/g for one photon emitted

If you want in Gy you have (F6)*1E6 (eV/g)*1E3 (eV/kg)*1.602E-19 (J/kg=Gy)=F6*1.602e-10 in Gy

But you must remember that MCNP normalizes the results to one photon. So you must multiplied by the photon flux (photon/s) to have a result in Gy/s.

For geometry I am not sure to understand. Do you want to simulate a beam like this :

and

Furthermore a mamography device not emitted a monocinetic energy of photon. For example :

In first approximation a photon of 18 keV like in your simulation could be ok.

Hope it's help

No ! A F6 result is in MeV/g for one photon emitted

If you want in Gy you have (F6)*1E6 (eV/g)*1E3 (eV/kg)*1.602E-19 (J/kg=Gy)=F6*1.602e-10 in Gy

But you must remember that MCNP normalizes the results to one photon. So you must multiplied by the photon flux (photon/s) to have a result in Gy/s.

For geometry I am not sure to understand. Do you want to simulate a beam like this :

and

Furthermore a mamography device not emitted a monocinetic energy of photon. For example :

In first approximation a photon of 18 keV like in your simulation could be ok.

Hope it's help

- #8

- 10

- 1

I understood everything your said, but, when I multiply my results in mev / g by 1.602E-10, I get very low results for what I want.

In cell 30 (semi-circular cylinder of air. to obtain kerma in air) i obtained = 6.01751E-05 (mev/g per history). multiplyed by 1,602E-10 i obtain 9,64E-15 (Gy por history).

my fluence obtained in cell 30 is 4.41740E-03 (1/cm**2)

I simulate one million histories. 4.867E+06 histories/minute.

please, help me in this question.

- #9

- 125

- 36

You must known the flux of your device in Xrays/s and multiplied the flux by your results and you have Gy/s

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