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TREATMENT PLANNING PHOTONS & ELECTRONS

TREATMENT PLANNING PHOTONS & ELECTRONS. Karen P. Doppke 3/20/2007. Regions of Radiation Field Considered in Dose Calculations. DOSE TO A POINT IN TISSUE. Major Processes that Effect Dose in Tissue from Photon Beams Inverse Square Law Photon Attenuation Photon Scatter.

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TREATMENT PLANNING PHOTONS & ELECTRONS

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  1. TREATMENT PLANNING PHOTONS & ELECTRONS Karen P. Doppke 3/20/2007

  2. Regions of Radiation Field Considered in Dose Calculations

  3. DOSE TO A POINT IN TISSUE Major Processes that Effect Dose in Tissue from Photon Beams Inverse Square Law Photon Attenuation Photon Scatter

  4. Dose Calculation Methods Used to Determine Dose at a Point in a Patient Model Based Methods Pencil Beam Methods Convolution Superposition Monte Carlo Calculations Correction Based Methods % Depth Dose Calculations Tissue Maximum/Phantom Ratios Tissue-Air Ratios

  5. The General Form of Equation Used to Calculate Dose at Depth in the Patient TPR (d, r, h) = Dose at Depth / Dose at Reference/Max

  6. 10 Mv X-ray Beam

  7. Isodose Curves High Energy

  8. Variation in Dose for Various Energy Beams

  9. COMPARE MONTE CARLO DOSES IN LUNG

  10. Comparison Dose Distribution 6 MV X-Rays

  11. Conformal Planning Process PATIENT DATA SET/S CT, MRI, PET DEFINATION OF TARGET AND NORMAL TISSUES PRESCRIPTION DOSE and FRACTIONATION TOTAL DOSE TO VOLUMES DOSE TO NORMAL TISSUES

  12. EXAMPLE OF A CONFORMAL PLAN The prescription should include the total dose to the target volumes, the fractionation, a statement of the expansion of the GTV to the CTV and PTV. The dose limits to the normal tissues that are near the site of treatment need to be defined.

  13. ICRU 62

  14. EXAMPLE OF TREATMENT VOLUMES

  15. TREATMENT VOLUMES GTV CTV ITV PTV

  16. NORMAN TISSUES NEAR TREATMENT SITE SPINAL CORD < ~45 Gy LIVER <~25Gy/100%, 30Gy/35%, 35Gy/25% KIDNEYS <~23Gy/66% LUNG <~30Gy/40%, 60Gy/20% HEART <~30Gy/100% LV, 45Gy/100% (atrium)

  17. AP/PA OPPOSED FIELDS

  18. DVH FOR TISSUES AP/PA CTV PTV Liver Lung RT Kidney RT Heart

  19. FOUR FIELD PLAN AP/PA/RLAT/LLAT

  20. DVH 4 FIELD PLAN CTV PTV Liver Heart Kidney RT Lung RT

  21. 5 FIELD PLANE AP/RA/RP/LP/LA

  22. DVH 5 FIELD PLAN CTV PTV Liver Lung RT Heart Kidney RT

  23. CTV Lung RT Kidney RT

  24. Stereotactic Radiosurgery • 1905: Introduction of stereotactic equipment • 1908: Mapping of brain in 3 planes • 1918: First stereotactic frame for humans in London • 1940: Greatest strides in intracranial applications began

  25. Stereotactic Radiosurgery 1982: Modified Linear Accelerator

  26. Stereotactic Radiosurgery SRS Frame Placement

  27. STEROTACTIC RADIATION THERAPY SRT

  28. Fractionated Stereotactic Radiation Therapy Fractionated Stereotactic Radiation Therapy(SRT) combines the target and dose localization characteristics of SRS with the biologic advantages of dose fractionization

  29. STEROTACTIC RADIATION SURGERY SRS

  30. Fractionated Stereotactic Radiation Therapy

  31. Fractionated Stereotactic Radiation Therapy

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