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10 may sbrt

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10 may sbrt

  1. 1. Stereotactic body radiation therapy (SBRT) Dr Sadia Sadiq PGR 2,INMOL
  2. 2. Historical Perspective We should recognize and acknowledge that Stereotactic Body Radiation Therapy (SBRT) is an extension or evolution of Stereotactic Radiosurgery (SRS)
  3. 3. Why ? If we acknowledge this evolution, we should also provide EXTRA-ORDINARY CARE for SBRT as demanded in Stereotactic Radiosurgery (SRS)
  4. 4. Questions: Why is EXTRA- ORDINARY CARE necessary? Why is EXTRA-ORDINARY CARE needed ?
  5. 5. Stereotactic body radiation therapy (SBRT) Management and delivery of image -guided high-dose radiation therapy with tumor-ablative intent within a course of treatment that does not exceed 5 fractions American Society of Therapeutic Radiology and Oncology (ASTRO) Also called SART
  6. 6. Tumors include lung, liver, spine, pancreas, kidney, and prostate. Prospective trials have demonstrated efficacy and acceptable acute and subacute toxicities Late toxicity requires further careful assessment
  7. 7. Radiation: Fractionation Standard fractionation:  1.8-2.0 Gy a day, 5 days a week for 25-30 treatments Conventional hypofractionation:  3-5 Gy a day, 5 days a week for 10-15 treatments Stereotactic radiotherapy:  15-25 Gy a day, 1-3 days a week for 1-5 treatments
  8. 8. Rationale of SBRT  Conceptual theories of cancer growth and numerous lines of evidence behind use of SBRT for metastatic lesions are (a) The Empiric Or Phenomenological, (B) The Patterns-of-failure Concept, (C) The Theory Of Oligo metastases, (D) A Lethal Burden Variation Of The Norton-simon Hypothesis, Or (E) Immunological Enhancement.
  9. 9. Methods Of Cell Kill in SBRT DNA damage Anti Angiogenesis Endothelial cell Apoptoses
  10. 10.  1. Qualified personnel:  a. Board-certified radiation oncologist b. Qualified medical physicist  c. Licensed radiation therapist d. Other support staff as indicated (dosimetrists, oncology  2. Ongoing machine quality assurance program;  3. Documentation in accordance with the ACR Practice Guideline for Communication: Radiation Oncology;  4. Quality control of treatment accessories;  5. Quality control of planning and treatment images;  6. Quality control of treatment planning system;  7. Simulation and treatment systems based on actual measurement of organ motion and setup uncertainty.
  11. 11. SBRT PHYSICS AND TECHNOLOGY  1. CT simulation: Assess tumor motion  2. Immobilization: Minimize motion, breathing effects  3. Planning: Small field dosimetry considerations  4. Repositioning: High precision patient set-up: Fiducial systems, IR/LED Active and Passive markers, US, Video  5. Relocalization: Identify tumor location in the treatment field: * MV/ KV Xray, Implanted markers and/or set-up fiducials * Motion tracking and gating systems * Real-time tumor tracking systems with implanted markers  6. Treatment delivery techniques  Adapted conventional systems  Specialized SRT: Novalis, Cyberknife, Trilogy
  12. 12. 4D CT Simulator A technique that allow an evaluation of the motion of the target Figure: Christopher Willey, MD, PhD
  13. 13. 4D CT Simulator The trace of the target motion allow the creation of a internal target volume (ITV) for treatment planning
  14. 14. Stereo Imaging Technology: To localized the target on images On-Board Imager on Linac In-Room Localizer
  15. 15. Breathing-related motion control devices and systems fall into three general categories: (a) dampening, (b) gating, and (c) tracking or “chasing.”
  16. 16. Respiratory dampening techniques  Include systems of abdominal compression intended to diminish one of the largest contributors to breathing-related motion, namely diaphragmatic excertion.
  17. 17. ABC:  Also included in this category are the systems employing breath- holding maneuvers to stabilize the tumor in a reproducible stage of the respiratory cycle (e.g., deep inspiration).
  18. 18. Gating systems for SBRT  It follow the respiratory cycle using a surrogate indicator for respiratory motion, for example, chest wall motion, and employ an electronic beam activation trigger allowing irradiation to occur only during a specified range of expected tumor locations.
  19. 19. Clinical Experience with Stereotactic Body Radiation Therapy in Selected Sites 1)Lung 2)Liver 3)Spine 4)Prostate 5)Pancreas
  20. 20. SBRT:LUNG Indications: Stage I NSCLC Pulmonary metastases
  21. 21.  One important observation from the Indiana University studies was that although the treatment was generally well tolerated,  tumor location near large airways in the vicinity of the pulmonary hilum (called the zone of the proximal bronchial tree) was associated with a markedly higher risk of toxicity.
  22. 22. RTOG 0236: •59 patients • Median age 72 • All pts inoperable •T1 – 80%; T2- 20% •Dose: 60Gy in 3 fxs (BED 180) Median FU 3 yrs: •Local control = 97.6% •Distant mets = 22.1% •Overall survival @3yrs = 55.8% •Median survival = 48 months
  23. 23. Pulmonary metastases
  24. 24. SBRT: LIVER  Underlying severe liver disease often renders patients medically inoperable  Other nonsurgical therapies have generally achieved at best rather modest success in that setting.
  25. 25. Challenges in Targeting Liver Tumors Limited visualization of the target Liver deformation with respiration Changes in GI organ luminal filling  Critical structures (stomach) may change in shape and position between planning and treatment Interfraction target displacement with respect to bony anatomy
  26. 26. Abdominal Compression Abdominal belt with inflatable bladder Inflation: 15-40 mmHg
  27. 27. First Liver SBRT Experience  50 patients treated to 75 lesions with SBRT for primary and metastatic liver tumors  15 to 45 Gy, 1-5 fractions  Mean follow-up of 12 months  30% of tumors demonstrated growth arrest, 40% were reduced in size, and 32% disappeared by imaging studies  4 local failures (5.3%)  Mean survival time was 13.4 months Blomgren, et. al., J Radiosurgery, 1998
  28. 28. SBRT:SPINE SBRT is an emerging technology used for the treatment of spinal tumors.  Effective dose escalation  For patients who are not candidates for conventional radiotherapy  To improve the quality of life for patients who may be spared a prolonged treatment course.  Acute Radiation toxicity is reduced.
  29. 29. Indications for Spinal SBRT Pain control in vertebral metastases Malignant Epidural Spinal Cord compression Benign Spinal Cord Tumors
  30. 30. Dose volume constraints  In a Randomized trail of 260 patients investigators have not observed a single case of Myelopathy at 1 year with dose of 8Gy *1fr.  Partial volume tolerance of the human spinal cord to Radiosurgery was analyzed in 177 patients with 230 metastatic lesions. The authors concluded that an acceptable estimate of partial cord tolerance is 10 Gy to the 10% volume. 1.Rades D, Stalpers LJ, Veninga T et al. J Clin Oncol 23:3366–3375 2.Ryu S, Jin JY, Jin R et al 2007Cancer 109:628–636
  31. 31.  The a/b ratio of Prostrate Cancer is lower than for most other tumors. Values between 1.2 and 3 Gy are suggested.  It is lower than surrounding normal tissues like rectum (a/b of 4 Gy for late rectal sequelae).  It is hypothesized that hypofractionation if accurately delivered increases the tumor control by sparing surrounding late responding normal tissues. SBRT:PROSTRATE
  32. 32. Indications Primary treatment for organ confined low risk prostrate cancer Dose escalation for intermediate and high risk prostrate cancer
  33. 33. prostate
  34. 34. SBRT: PANCREAS Stereotactic body radiation therapy (SBRT) In Pancreas is indicated for 1.Boderline resectable tumors to improve resectability in Neo Adjuvuvant setting. 2.In Unresectable due to their lower life expectancy to reduce 5 -6 weeks treatment to less than 5 days 3.In resectecd Ca Pancreas with positive margins.
  35. 35. Challenges of SBRT in Pancreas  The head of the pancreas, where majority of tumors reside, is in close proximity to the C-loop of the duodenum  Delivery of conventionally fractionated radiation (1.8–2 Gy/day) to more than 50 Gy results in damage to the small bowel such as ulcerations, stenosis, bleeding, and perforation.  The pancreas move with respiration, as well as with peristalsis that is not easily predictable.
  36. 36. SIDE EFFECTS Radiobiology:  Tumor vs. Normal Tissue Normal Tissue Toxicity  Lung: pneumonitis and fibrosis  Pancreas: duodenum and stomach  Spine lesions: cord  Prostate: rectum and bladder  Liver: normal liver (radiation induced liver disease-RILD)
  37. 37. The dose constraints of SBRT
  38. 38. Stereotactic Body Radiation Therapy: The Report of AAPM Task Group 101
  39. 39. The SBRT:Ultimate “Targeted Therapy”
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