Simulation of Photon Beam Interaction with the ZUBAL Head Phantom

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Simulation of Photon Beam Interaction with the
ZUBAL Head Phantom
Presented by Mostafa Hossni El-Soubki
Plan-UNC-Image plotter
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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.

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Preparing the Phantom

• Maximum number of cells allowed is 99999
• (cells x-axis cells y-axis cells
  z-axis)lt99999

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Preparing the Phantom

• The voxels outside the head have been excluded

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Preparing the Phantom

• The slice matrix has to be resized

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Preparing the Phantom

• Material indexing has to be adjusted for MCNP.

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Preparing the Phantom
Material Organ Material Organ
1 outside phantom 86 medulla oblongata
2 skin 23 fat
3 brain 24 blood pool
4 spinal cord 27 bone marrow
5 skull 92 pons
6 spine 30 trachea
71 dens of axis 31 cartilage
72 jaw bone 100 uncus (ear bones)
10 skeletal muscle 105 sinuses/mouth cavity
75 lachrymal glands 107 optic nerve
76 spinal canal 114 cerebral falx
77 hard palate 120 eye
78 cerebellum 122 lens
79 tongue 123 cerebral aqueduct
16 pharynx 126 teeth
17 esophagus    
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Preparing the Phantom

• Converting all slices to MCNP

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Validating the Geometry

• Applied Beam
• SSD 100cm
• Field size 5x5 cm2.
• Photon Beam energy 6 MV

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Validation in a Water Phantom
Voxel volume 0.50.50.5 cm3 Phantom volume
30 30 30 cm3
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Percent Depth Dose Comparison
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Percent Depth Dose Comparison
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PDD Comparison
beam energy 6MV   dmax1.5 cm
field size cm2 depth cm PDD ?PDD
55 1.5 100 0.70
55 5 85 0.60
55 10 63.8 0.48
1010 1.5 100 1.018
1010 5 86.9 0.92
1010 10 67.5 0.77
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Beam Profile Comparison
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Measured and Simulated Profile at 1.5cm Depth
(Field Size 5x5 cm2)
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Measured and Simulated Profile at 5 cm Depth
(Field Size 5x5 cm2)
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Measured and Simulated Profile at 10 cm Depth
(Field Size 5x5 cm2)
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6 MV Beam Interaction with Head Phantom

• Applied Beam
• SSD 100 cm
• Field size 5x5 cm2
• Photon Beam energy 6 Mev

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Transverse Cross Section
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Coronal Cross Section
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Transfer the Phantom to Plan-UNC
converting to excel sheets
converting to dicom
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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
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Central PDD
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Isodose Lines
ISO-Dose levels 0.98 0.95 0.9 0.7 0.5
MCNP
Plan-UNC
Plan-UNC-Image plotter
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MCNP surface dose distribution
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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

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References

• Visual Basic 6 MSDN library.
• Matlab7 Help.
• http//noodle.med.yale.edu/phantom/getdata.htm
  (ZUBAL phantom).

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• Thank you