Transcript Document
ميحرلا نمحرلا الله مسب
Simulation of Photon Beam Interaction with the ZUBAL Head Phantom
Presented by:
Mostafa Hossni El-Soubki
Plan-UNC-Image plotter
Outline 1. Preparing the phantom and Converting to MCNP using the MATLAB software 2. Commissioning the geometry 3. Dealing with MATLAB GI to view the output data.
4. Transfer the phantom to plan-UNC, and compare the same plan with MCNP 5. Conclusion 6. References.
Preparing the Phantom
• • Maximum number of cells allowed is 99999
(#cells x-axis * #cells y-axis* #cells z-axis)<99999
Preparing the Phantom
• The voxels outside the head have been excluded Fig-4 (By image-j)
Preparing the Phantom
• The slice matrix has to be resized Slice 23 after resizing from 59*40 to 50*37
Preparing the Phantom
• Material indexing has to be adjusted for MCNP.
Fig-5
Preparing the Phantom
Material # 1 2 3 4 5 6 71 72 10 75 76 77 78 79 16 17 Organ outside phantom skin brain spinal cord skull spine dens of axis jaw bone skeletal muscle lachrymal glands spinal canal hard palate cerebellum tongue pharynx esophagus Material # 86 23 24 27 92 30 31 100 105 107 114 120 122 123 126 Organ medulla oblongata fat blood pool bone marrow pons trachea cartilage uncus (ear bones) sinuses/mouth cavity optic nerve cerebral falx eye lens cerebral aqueduct teeth
Preparing the Phantom
•
Converting all slices to MCNP
Converting From material excel sheets to MCNP.
Validating the Geometry
Applied Beam:
• • •
SSD =100cm Field size = 5x5 cm2.
Photon Beam energy = 6 MV
Validation in a Water Phantom
Primary collimator
Voxel volume = 0.5*0.5*0.5 cm3 Phantom volume= 30* 30 * 30 cm3
Ion chambers Light mirror X-y jaws Fig-11 Blue is air.
Blue sky is water Light field reticle (MYLER)
Percent Depth Dose Comparison PDD% for 6mv LINAK 5x5 cm2 at 100cm SSD
100.000
90.000
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70.000
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30.000
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10.000
0.000
0
dmax=1.5 cm
5 10 15
Fig-21
20 25 30 35 MCNP 5x5 cm2 6MV PDD% ion chamber 6mv 5x5 Diference
Percent Depth Dose Comparison
100.000
90.000
80.000
70.000
60.000
50.000
40.000
30.000
20.000
10.000
0.000
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6mv PDD 5x5 cm2 100cm SSD dmax=1.5cm
5 10
Depth cm
15 Fig-24 20 25 MCNP 6MV 5x5 PDD % planUNC PDD Differnce
PDD Comparison
beam energy field size cm2 6MV depth cm PDD% dmax=1.5 cm ±ΔPDD 5*5 5*5 1.5
5 100 85 0.70
0.60
5*5 10*10 10*10 10*10 10 1.5
5 10 63.8
100 86.9
67.5
0.48
1.018
0.92
0.77
Beam Profile Comparison
-20 -15
6MV beam Profile for 5x5 cm2 at differnt depths
1.00
-10 -5 0.90
0.80
0.70
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0.50
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0.10
0.00
0
off axis cm
5 10 15 20 Profile at dmax 1.5cm
profile at 5cm depth profile at 10cm depth
Measured and Simulated Profile at 1.5cm Depth (Field Size 5x5 cm 2 )
-5 -4 -3 -2 100 90 80 70 60 50 40 30 20 10 -1 0 0
off axis
1 2 3 4 5 6MV measured profile% at dmax MCNP 6MV profile at dmax depth Difference %
Measured and Simulated Profile at 5 cm Depth (Field Size 5x5 cm 2 )
100.00
90.00
80.00
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6MV measured profile% at 5cm depth MCNP 6MV profile 5 cm depth Diifernce % -5 -4 -3 -2 -1 0.00
0
off axis cm
1 2 3 4 5
Measured and Simulated Profile at 10 cm Depth (Field Size 5x5 cm 2 )
100.00
-5 -4 -3 -2 90.00
80.00
70.00
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of axis cm
1 2 3 4 5 6MV measured profile% at 10cm depth 6MV MCNP profile% at 10 cm depth Difference %
6 MV Beam Interaction with Head Phantom Applied Beam:
• • •
SSD =100 cm Field size =5x5 cm 2 Photon Beam energy = 6 Mev
Transverse Cross Section
Fig-25 slice-8 (MCNP MATLAB GUI)
Coronal Cross Section
Transfer the Phantom to Plan-UNC MCNP
converting to excel sheets
Plan-UNC
converting to dicom
Beam Setup of Head Phantom in Plan-UNC SSD = 100 cm at slice number 8.
Field size = 5 x 5 cm2.
Photon Beam energy = 6 Mev
Central PDD
PDD% for 6mv LINAK 5x5 cm2 at 100cm SSD for slice-8
100.000
90.000
80.000
70.000
60.000
50.000
40.000
30.000
20.000
10.000
0.000
0
Inhomogeneous region
2 4 6 8 10 12 14 16 18 MCNP slice-8 6MV 5x5 PDD % plan-UNC slice8 PDD Differnce
Fig-28 the inhomogeneous region in slice 8
Fig-27 Central PDD of slice-8 Skull bones at 2cm depth
Isodose Lines ISO-Dose levels: [ 0.98 0.95 0.9
0.7 0.5
]
Plan-UNC MCNP
Plan-UNC-Image plotter
MCNP surface dose distribution
Fig-30
Conclusions
• Validation of geometry – Good agreement in PDD in decay region – Need better agreement in dose profiles in penumbra region • There is disagreement between MCNP and Plan UNC in the inhomogeneous regions (transition from bone to soft tissue • Need for better quantitative methods to compare dose distribution in the phantom
References
• • •
Visual Basic 6 MSDN library.
Matlab7 Help.
http://noodle.med.yale.edu/phantom/get data.htm
(ZUBAL phantom).