01 suh brain anatomy, planning and delivery hyderabad 2013 (cancer ci 2013) john h. suh

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01 suh brain anatomy, planning and delivery hyderabad 2013 (cancer ci 2013) john h. suh

  1. 1. Basics of Anatomy, Planning and Treatment Delivery for Brain Tumors John H. Suh, M.D. Professor and Chairman, Dept. of Radiation Oncology Associate Director of the Gamma Knife Center Rose Ella Burkhardt Brain Tumor and Neuro-oncology Center Taussig Cancer Institute
  2. 2. Conflict of interest• Abbott Oncology Consultant• Varian Travel funds
  3. 3. Objectives• Provide overview of brain anatomy• Review advances in treatment planning and delivery oncology that have allowed optimization of radiation therapy of brain tumors.• Discuss methods to direct dose to the tumor while minimizing dose to the normal neural tissues.• Review advances in stereotactic radiosurgery.
  4. 4. Brain anatomy
  5. 5. Structures that are contoured• Lenses• Eyes (retina)• Optic nerves and chiasm• Brain stem• Spinal cord• Cochlea• Temporal lobes and hippocampus• T2/FLAIR and T1 changes for gliomas
  6. 6. Cranial Anatomy• Brainstem = midbrain + pons + medulla Cerebral Aqueduct Chiasm Midbrain Pons Medulla C1 Foramen Magnum
  7. 7. Cranial Anatomy Motor Strip “Omega” Sign Motor Strip
  8. 8. Cochlea
  9. 9. Optic Chiasm• Chiasm is always above the sella Chiasm Pituitary
  10. 10. Visual CortexVariability of visual cortex fMRI Visually Evoked Potentia
  11. 11. RTOG AtlasRed: Hippocampus Green: Hippocampal Avoidance Zone Hippocampal 1)Hippocampal Tail 1) Tail 2) Body 3)2) Body Head 3) Head The hippocampus has three anatomic subdivisions: the head, body, and tail; note that the head is inferior or caudad, the body is superoposterior and the tail is most cephalad (superior) and posterior, and an overall “banana” shape emerges on sagittal images, located in the plane of the lateral ventricle. MR Images courtesy of: Holmes CJ, Hoge R, Collins L, et al. "Enhancement of MR Images Using Registration for Signal Averaging" Journal of Computer Assisted Tomography 22, 324-333 (1998)
  12. 12. Radiation Therapy in 1990s
  13. 13. Dose distribution for WBRT
  14. 14. Linear accelerator
  15. 15. Conventional Radiotherapy Conventional Beam Shaper Desired Actual Dose Dose Distribution Distribution
  16. 16. CT simulator use in radiation oncologyProvides cross sectional anatomical information1) Target volume delineation2) Relative geometry of critical structures3) Beam placement and field shaping4) Dose distribution calculation and analysis
  17. 17. Beam’s Eye View (BEV)
  18. 18. What are the Best Beam Directions?
  19. 19. Fusion of MRI to CT
  20. 20. Intensity Modulated Radiotherapy (IMRT) IntensityTransmitted ModulatorBeamlets Desired Dose Actual Dose Distribution Distribution
  21. 21. IMRT using Rotational Arc (Peacock)- 1996
  22. 22. 3D Multileaf Collimator Photo courtesy of Siemens Medical Solutions
  23. 23. TransitionRADIATION Guided Radiation to Image ONCOLOGY TherapyElekta Synergy
  24. 24. Therapeutic Index 100 Tumor control (%) Control 5 0 Complications 0 Dose (Gy) 95002052-01
  25. 25. On Board Imager (OBI)– KV/MV-Cone Beam CTElekta KV-OBI Varian KV-OBI Siemens MV-OBI
  26. 26. Daily CT Prior to Treatment Tomotherapy UnitsSiemens CTvision
  27. 27. Image guided radiation therapy (IGRT) Novalis Shaped Beam Therapy
  28. 28. Cranial Patient PositioningExacTrac CBCT
  29. 29. Glioblastoma of right temporal region
  30. 30. Sequential Planning Six static IMRT beams were used with 3 non-planar beams. The beam was on for 11 minutes.
  31. 31. Dose Constraints for RTOG 0825• Lenses 7 Gy• Retina 50 Gy• Optic nerves 55 Gy• Optic chiasm 56 Gy• Brainstem 60 Gy
  32. 32. Conventional Dose Painting 63.0 59.4 50.4 45.0 30.0
  33. 33. Simultaneous Integrated Boost Delivery Four partial arcs are used for the plan. Estimated beam time was about 4 minutes
  34. 34. Beam arrangement for meningioma
  35. 35. Coronal isodose distribution
  36. 36. RTOG 0933Phase II Trial of Hippocampal Avoidance During WholeBrain Radiotherapy for brain metastases • Fused planning MRI CT image set • Hippocampal avoidance regions will 3D expansion of hippocampal contours by 5 mm.
  37. 37. Hippocampal sparing
  38. 38. Importance of optimizing image performance toachieve fundamental objectives of radiation therapy Dawson LA et al. The Oncologist 15:338-349, 2010
  39. 39. Stereotactic Radiosurgery“Replace the needle by narrowbeams of radiation energy andthereby produce a localdestruction of the tissue”Lars LeksellThe stereotaxic method andradiosurgery of the brainActa Chirurgica Scandinavia Vol 102,Fasc 4, 1952
  40. 40. Early days of Stereotactic Radiosurgery
  41. 41. Therapeutic Index 100 Tumor control (%) Control 5 0 Complications 0 Dose (Gy) 95002052-01
  42. 42. Stereotactic radiosurgery• Small, well-defined target < 4 cm diameter• Single fraction• Steep dose gradient• Intersection of multiple beams of radiation at isocenter
  43. 43. Clinical uses of stereotactic radiosurgery • Vascular malformations • Benign brain tumors • Malignant brain tumors • Functional disorders
  44. 44. Model B unit
  45. 45. Plugging helmets to shape dose
  46. 46. Perfexion Gamma Knife
  47. 47. Leksell Gamma Knife®Treatable volumeLeksell Gamma Knife C Leksell Gamma Knife PERFEXION
  48. 48. Collimator system 8-16-8-16- Collimator system 8-16-8-16-16-16-16 16-8-16-8-16
  49. 49. Treatment plan with composite shots
  50. 50. Discordance caused by loose frame
  51. 51. Artifact caused by dental work
  52. 52. Different radiosurgery units
  53. 53. Novalis Radiosurgery System
  54. 54. Micro Multileaf Collimators (mMLC)
  55. 55. Different linac approaches for brain SRS Dynamic Conformal Arc Conformal Beam Circular Arc IMRT HybridArc
  56. 56. Frameless Cranial Stereotaxy• Upper palate based immobilization – Good dentition helpful – Must be able to tolerate the mouthpiece• Mask based – More uncertainty• Relocatable – Hypofractionation – Larger lesions – Near dose sensitive structures – Post op cavity – Prior RT – Image guided – Skull is an excellent fiducial marker – Reusable• Not restricted by physical limitations
  57. 57. Radiation oncology team• Therapists• Nurses and nurse practitioners• Dosimetrists• Medical physicists• Clinical engineers• Schedulers• Secretaries• Radiation oncologistsStrong teamwork and q/a program helps ensure proper and safe radiation delivery
  58. 58. Conclusions• Understanding brain anatomy and dose constraints are essential.• Technical advances in radiation oncology have allowed optimization of radiation delivery for brain tumors.• Dose painting, dose sculpting, and conformal avoidance for brain tumors can be achieved given the advances in technology, imaging and treatment planning.
  59. 59. Title of Presentation Arial Regular 22ptSingle line spacingUp to 3 lines longDate 20ptsAuthor Name 20ptsAuthor Title 20pts

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