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Using TomoTherapy’s MVCT images for dose re-computations Katja Langen

MD Anderson Cancer Center Orlando. Using TomoTherapy’s MVCT images for dose re-computations Katja Langen. Dose Re-calculation. Use pre-treatment MVCT. Recalculate plan based on planned MLC pattern. Recalculate Dose on MVCT image. Need MVCT to electron density calibration. kVCT. MVCT.

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Using TomoTherapy’s MVCT images for dose re-computations Katja Langen

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  1. MD Anderson Cancer Center Orlando Using TomoTherapy’s MVCT images for dose re-computations Katja Langen

  2. Dose Re-calculation Use pre-treatment MVCT Recalculate plan based on planned MLC pattern Recalculate Dose on MVCT image

  3. NeedMVCT to electron density calibration kVCT MVCT RMI, Model 467, CT to electron density phantom

  4. MVCT to electron density calibration curves kVCT MVCT

  5. MVCT Integrity ? Does the calibration change with time ? Does calibration change with phantom arrangement ? Does the calibration change with MVCT pitch ? Does the calibration change with phantom material ?

  6. MVCT Integrity ? Does the calibration change with time ?

  7. MVCT Integrity ? Does the calibration change with phantom arrangement ?

  8. MVCT Integrity ? Does the calibration change with MVCT pitch ratio ?

  9. MVCT Integrity ? Does the calibration change with phantom material ? Side view of phantom

  10. MVCT Integrity ? Does the calibration change with phantom material ?

  11. Dosimetric effect ? -Convert to e-density using in-phantom calibration recalculate dosimetry -Convert to e-density using in-air calibration recalculate dosimetry -Compare dose distributions

  12. Dosimetric effect ?

  13. Dosimetric effect ?

  14. Dosimetric effect ?

  15. MVCT Integrity ? Which curve should we use ?

  16. MVCT Integrity ? Use average

  17. Dose re-computation end-to-end tests Rigid phantom kVCT scan Fictitious target Generate treatment plan MVCT scan phantom Re-calculate dose in MVCT Compare plan DVH with recalculated DVH Expect agreement !!!

  18. Dose re-computation end-to-end tests

  19. Dose re-computation end-to-end tests all target D95 are within 0.5 %

  20. - MVCT numbers are reproducible MVCT to electron density calibration is reliable Conclusions - Phantom end-to-end test results are typically within 1 % of plan results MVCT images can be used for reliable dose computations

  21. Prostate Case Doserecalculation Obtain MVCT MVCT contours

  22. Prostate Case Plan DVH39 “true” DVHs

  23. MD Anderson:TomoTherapy: Sanford Meeks Gustavo Olivera Tom Wagner Jason Haimerl Twyla Willoughby Ken Ruchala Darrell Poole Patrick Kupelian Daniel Buchholz Alan Forbes Wayne Jenkins Thanks !

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