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

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Presentation on theme: "TREATMENT PLANNING PHOTONS & ELECTRONS Karen P. Doppke 3/20/2007."— Presentation transcript:

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 Correction Based Methods % Depth Dose Calculations Tissue Maximum/Phantom Ratios Tissue-Air Ratios Model Based Methods Pencil Beam Methods Convolution Superposition Monte Carlo Calculations

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

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8 10 Mv X-ray Beam

9 Isodose Curves High Energy

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11 Variation in Dose for Various Energy Beams

12 COMPARE MONTE CARLO DOSES IN LUNG

13 Comparison Dose Distribution 6 MV X-Rays

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15 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

16 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.

17 ICRU 62

18 EXAMPLE OF TREATMENT VOLUMES

19 TREATMENT VOLUMES GTVCTVITVPTV

20 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)

21 AP/PA OPPOSED FIELDS

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

23 FOUR FIELD PLAN AP/PA/RLAT/LLAT

24 DVH 4 FIELD PLAN CTV PTV Liver Heart Kidney RT Lung RT

25 5 FIELD PLANE AP/RA/RP/LP/LA

26 DVH 5 FIELD PLAN CTV PTV Liver Lung RT Heart Kidney RT

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31 CTV Lung RT Kidney RT

32 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

33 Stereotactic Radiosurgery 1982: Modified Linear Accelerator

34 Stereotactic Radiosurgery SRS Frame Placement

35 STEROTACTIC RADIATION THERAPY SRT

36 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

37 STEROTACTIC RADIATION SURGERY SRS

38 Fractionated Stereotactic Radiation Therapy

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