Stereotactic Body Radiation Therapy

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  • Stereotactic Body Radiation Therapy

    1. 1. Stereotactic Body Radiation Therapy: Is It Ready For Primetime? Joseph Herman MD, MSc Department of Radiation Oncology
    2. 2. SBRT Overview <ul><li>Stereotactic body radiation therapy (SBRT) uses sophisticated technology to deliver a focused ablative dose to tumors. </li></ul><ul><li>Tumors include lung, liver, spine, pancreas, kidney, and prostate. </li></ul><ul><li>Prospective trials have demonstrated efficacy and acceptable acute and subacute toxicities </li></ul><ul><li>Late toxicity requires further careful assessment </li></ul>
    3. 3. Radiation Delivery <ul><li>Conventional (3-5 beams) </li></ul><ul><ul><li>3-D conformal radiation therapy </li></ul></ul><ul><ul><li>Intensity modulated radiation therapy (IMRT) </li></ul></ul><ul><ul><ul><li>Linac based radiation </li></ul></ul></ul><ul><ul><ul><li>Tomotherapy </li></ul></ul></ul><ul><li>Stereotactic Radiation Therapy (10-12 beams) </li></ul><ul><ul><li>Gamma Knife </li></ul></ul><ul><ul><li>Linac based (isocenter) </li></ul></ul><ul><ul><li>Cyberknife (non-isocenter) </li></ul></ul><ul><li>Proton Therapy (one beam repeated) </li></ul>
    4. 4. Radiation: Fractionation <ul><li>Standard fractionation: </li></ul><ul><ul><li>1.8-2.0 Gy a day, 5 days a week for 25-30 treatments </li></ul></ul><ul><li>Conventional hypofractionation: </li></ul><ul><ul><li>3-5 Gy a day, 5 days a week for 10-15 treatments </li></ul></ul><ul><li>Stereotactic radiotherapy: </li></ul><ul><ul><li>15-25 Gy a day, 1-3 days a week for 1-5 treatments </li></ul></ul>
    5. 5. Treatment Planning Liver Planning Target Volume Target Volumes
    6. 6. Target Volumes Gross Tumor Volume Planning Target Volume
    7. 7. Pre-radiation 6 months post-radiation Radiographic Response
    8. 8. Survival as a Function of Dose Dawson et. al., J Clin. Onc . 18:2210, 2000 ; Ben-Josef et al 2006 Time (years)
    9. 9. IMRT Plan to Deliver High Dose to Potential Resection Margin Vineberg and Ten Haken, 2004
    10. 11. Eliminating Organ Motion and Set-up Error <ul><li>In the past we expanded the region of treatment to include breathing motion </li></ul><ul><li>This increases the volume of normal structures treated and limits total dose to the tumor </li></ul><ul><li>Set-up error </li></ul><ul><ul><li>Daily or 4-D CT scan or radiographs </li></ul></ul><ul><ul><li>Lasers </li></ul></ul><ul><li>Monitoring and controlling breathing </li></ul><ul><ul><li>Limit breathing (body cast or compression device) </li></ul></ul><ul><ul><li>Radio-opaque markers implanted in liver (margin) </li></ul></ul><ul><ul><li>Active breathing control device to stop breathing in fixed phase of respiratory cycle </li></ul></ul><ul><ul><li>Follow breathing motion (vest and fiducials) </li></ul></ul>
    11. 12. Image Alignment: AP Radiographs Reference Image Treatment Image Hepatic microcoil
    12. 13. Body Frame
    13. 14. Active Breathing Control Mouthpiece and filter Flow sensor Valve (air bladder) <ul><ul><li>Dawson et al Int . J. Radiat. Oncol. Biol. Phys. , 51:1410, 2001 </li></ul></ul>
    14. 15. Breath Hold at Normal Exhale Pressure Volume Flow Valve closed, Breath held Valve open
    15. 17. Synchrony ™ camera Treatment couch Linear accelerator Manipulator Image detectors X-ray sources Targeting System Robotic Delivery System Cyberknife
    16. 18. Patient Setup <ul><li>No rigid fixation required </li></ul><ul><li>Intracranial cases: Thermoplastic mask </li></ul><ul><li>Extracranial cases </li></ul><ul><ul><li>Spine: no fiducials or markers needed </li></ul></ul><ul><ul><li>Soft-tissue lesions: Gold seed markers </li></ul></ul><ul><ul><li>Moving lesions: Synchrony vest </li></ul></ul>Photo courtesy of Naples Community Hospital
    17. 19. CyberKnife ® Conformality <ul><li>Non-Coplanar Beam Delivery </li></ul><ul><ul><li>Automatically minimizes entrance/exit beam interactions </li></ul></ul><ul><ul><li>No patient or linac re-positioning required </li></ul></ul>
    18. 20. SRS Axial View GTV 60% 50% Koong et al. Stanford; IJROBP 2004
    19. 21. SRS Coronal View GTV 60% 50% Koong et al. Stanford; IJROBP 2004
    20. 22. SRS Toxicity <ul><li>Radiobiology: </li></ul><ul><ul><li>Tumor vs. Normal Tissue </li></ul></ul><ul><li>Normal Tissue Toxicity </li></ul><ul><ul><li>Lung: pneumonitis and fibrosis </li></ul></ul><ul><ul><li>Pancreas: duodenum and stomach </li></ul></ul><ul><ul><li>Spine lesions: cord </li></ul></ul><ul><ul><li>Prostate: rectum and bladder </li></ul></ul><ul><ul><li>Liver: normal liver (radiation induced liver disease-RILD) </li></ul></ul>
    21. 23. Results of a phase I dose-escalation study using single-fraction stereotactic radiotherapy for lung tumors. Le et al. 2006 (Stanford) <ul><li>32 patients with metastatic or unresectable lung cancer </li></ul><ul><li>Dose escalation using Cyberknife </li></ul><ul><li>1-year freedom from local progression was 91% for dose >20 Gy </li></ul><ul><li>RT-related complications were noted for doses greater than 25 Gy </li></ul><ul><ul><li>4 cases of pneumonitis, one pleural effusion, and three possible treatment-related deaths </li></ul></ul><ul><li>Lower doses in patients previously irradiated or tumor volumes >50 cc </li></ul>
    22. 24. SRS: Questions <ul><li>Long term toxicity to normal structures </li></ul><ul><ul><li>Depend on prognosis </li></ul></ul><ul><li>Movement between imaging and delivery of radiation </li></ul><ul><li>Overall Efficacy: Response and QOL </li></ul><ul><li>Cost and efficiency </li></ul><ul><li>Patient selection </li></ul><ul><li>Prospective clinical trials (RTOG) </li></ul><ul><li>Radiobiology of large fraction sizes </li></ul>
    23. 25. Small Animal Irradiation
    24. 27. Thank You <ul><li>Jeff Geschwind </li></ul><ul><li>John Wong </li></ul><ul><li>Laura Dawson </li></ul><ul><li>Bob Timmerman </li></ul><ul><li>Ted Lawrence </li></ul><ul><li>Ted DeWeese </li></ul>

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