TPS modeling and Beam commissioning at UIHC Radiation Oncology

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TPS modeling and Beam commissioning at UIHC Radiation Oncology

  1. 1. ROTATION  5:  TPS  MODELING  AND  BEAM   COMMISSIONING  at  UIHC  Radia9on   Oncology   Mentors:  John  Bayouth,  Ph.D.     (04/23/09  –  06/11/09)   By     Vibha  Chaswal  
  2. 2. Goals   •  Model  1  photon  beam    -­‐  Know  parameters  and  their  effects   •  Model  1  electron  beam   -­‐  Know  parameters  and  their  effect   •  Model  Wedges   •  Validate  the  beams  modeled   •  Understand  the  nuances  of  TPS  modeling    
  3. 3. Photon  beams:  data  requirements   •  Pdds   •  Profiles   •  Calibra9on  output  factor   •  Rela9ve  output  factors   Data  For  Valida9on!   -­‐  A  subset  of  above   -­‐  Sc  and  Sp   -­‐  Dosimetric  tests,  match  computed  and  measured   dose  distribu9ons  
  4. 4. Data  collected  for  assumed  clinical   applica9on  
  5. 5. TPS  modeling:  The  Machine  
  6. 6. TPS  Modeling:  The  machine  
  7. 7. TPS  Modeling:  The  Radia9on  Beam   •  Fine  tuning  Profiles    -­‐  Effec9ve  source  size  for   Penumbra  matching   -­‐  Gaussian  width  and   height  of  FF  scacer   source  for  tails     -­‐  Transmission  factors  of   Jaw  and  MLC  for  tails   region    
  8. 8. Energy  Spectrum  
  9. 9. Energy  Spectrum:  Build-­‐up  region  
  10. 10. In-­‐field  Region:  FF  acenua9on  using   cone  model   With  Off-­‐axis   Soeening  factor  
  11. 11. In-­‐field  Region:  FF  acenua9on  using   arbitrary  profile   With  Off-­‐axis  Soeening  factor  
  12. 12. Off-­‐axis  soeening  
  13. 13. Out-­‐of  field  regions:     Penumbra  and  tails  
  14. 14. Out-­‐of  field  modeling  parameters  
  15. 15. Beam  Valida9on:  PDDs   Result:  All  Pdds  pass  within  2%  or  2mm  
  16. 16. Beam  Valida9on:  Profiles   Result:  Within  3%  or  3mm  except  outliers  in  tail  regions  
  17. 17. Beam  Valida9on  tests:  MU  verifica9on  
  18. 18. Beam  valida9on:  R  and  V  import  
  19. 19. Rela9ve  Decision  Maps:  error  Limit  =  3  %,  dta  Limit  =  3  mm  
  20. 20. TPS  Modeling:  The  machine,   Collimator  rota9on  incorrect  
  21. 21. Electron  beams:  Data  required    
  22. 22. Electron  Beam  Parameters  
  23. 23. Two  adjustable  parameters   - Off-axis ratios, and - The scatter correction factor (FMCS), dose spread out in media relative to air.
  24. 24. Electron  Beam  modeling  
  25. 25. Electron  PDD  
  26. 26. Thank  you!!!!!  

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