[Gate-users] TPS Pencil Beam Source setting

[张晖]

Dear Gate Users:

I previously used Pencil Beam Source to simulate single-energy pencil beam for carbon-ion therapy. The features of the pencil beam source such as spot size, divergence and beam emittance were defined as follows: 3 mm spot size in both x and y directions, 4 mrad divergence and 15 mm·mrad beam emittance. The energy spread was set to 0.1% of the respective energy. Except for dipole scanning magnets,vacuum pipe and window, main and sub-dose monitors, a multi-strip ionization chamber (IC) and a mini ridge filter were modeled in my MC simulations. The source position was located before the vacuum window and a water box was located at isocenter.

#################Pencil Beam Source########################################

# SOURCE PBS
/gate/source/addSource C12 PencilBeam

#particle type
/gate/source/C12/setParticleType GenericIon
/gate/source/C12/setIonProperties 6 12 6 0

#energy spectrum
/gate/source/C12/setEnergy 2687.52 MeV
/gate/source/C12/setSigmaEnergy 2.68752 MeV

#position
/gate/source/C12/setPosition 0 0 -1.4059 m

# spot size
/gate/source/C12/setSigmaX 3 mm
/gate/source/C12/setSigmaY 3 mm

#divergence
/gate/source/C12/setSigmaTheta 4 mrad
/gate/source/C12/setSigmaPhi 4 mrad

#emittance
/gate/source/C12/setEllipseXThetaEmittance 15 mm*mrad
/gate/source/C12/setEllipseYPhiEmittance 15 mm*mrad

#positive-> converging beam; negative diverging beam
/gate/source/C12/setEllipseXThetaRotationNorm positive
/gate/source/C12/setEllipseYPhiRotationNorm positive




Now, I want to use TPS Pencil Beam Source to simulate realistic treatment plan for carbon ion therapy. In Source-properties.txt file, it contains 8 polynomial equations, each equation being a function of the energy at the nozzle entrance.

#################TPS Pencil Beam Source-Source-properties########################################

# Source properties

# Nozzle exit to Isocenter distance
1405.9
# SMX to Isocenter distance
4000
# SMY to Isocenter distance
4000

# ENERGY
# mean energy
# polynomial order
1
# polynomial parameters (highest to lowest)
1
0

# energy spread
# polynomial order
percent
1
# polynomial parameters (highest to lowest)
0.001
0

# SPOT x y theta phi
# x
# polynomial order
1
# polynomial parameters
0
3
# Theta
# polynomial order
1
# polynomial parameters
0
0.004
# y
# polynomial order
1
# polynomial parameters
0
3
# Phi
# polynomial order
1
# polynomial parameters
0
0.004

# SPOT emmittances
# x-theta emmittance
# polynomial order
1
# polynomial parameters
0
0.015
# y-phi emmittance
# polynomial order
1
# polynomial parameters
0
0.015




#################TPS Pencil Beam Source-PlanDescriptionToGate########################################

#TREATMENT-PLAN-DESCRIPTION
#PlanName
IMPT
#NumberOfFractions            ***    CURRENTLY THIS VALUE IS NOT USED    ***
1
##FractionID                ***    CURRENTLY THIS VALUE IS NOT USED    ***
1
##NumberOfFields
1
###FieldsID
1

#TotalMetersetWeightOfAllFields        ***    CURRENTLY THIS VALUE IS NOT USED    ***
662421

#FIELD-DESCRIPTION
###FieldID
1
###FinalCumulativeMeterSetWeight    ***    CURRENTLY THIS VALUE IS NOT USED    ***
336732
###GantryAngle (in degrees)
0
###PatientSupportAngle            ***    CURRENTLY THIS VALUE IS NOT USED    ***
0
###IsocenterPosition            ***    CURRENTLY THIS VALUE IS NOT USED    ***
0 0 0
###NumberOfControlPoints
1

#SPOTS-DESCRIPTION
####ControlPointIndex
0
####SpotTunnedID            ***    CURRENTLY THIS VALUE IS NOT USED    ***
0
####CumulativeMetersetWeight        ***    CURRENTLY THIS VALUE IS NOT USED    ***
0
####Energy (MeV)
2687.52
####NbOfScannedSpots
1
####X Y Weight (spot position at isocenter in mm, with weight in MU (default) or number of ions "setSpotIntensityAsNbIons true")
0 0 100


I simulated the same energy beam in my PlanDescriptionToGate.txt file and the spot position is at isocenter. However, I find that the dose distributions with these two sources in water box were different. I'm puzzled about the parameter settings in TPS Pencil Beam Source if I want to make them consistent with those in Pencil Beam Source settings. How can I do?







Best regards,

Hui Zhang























-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opengatecollaboration.org/pipermail/gate-users/attachments/20200519/ad6d2a66/attachment.html>