Advanced Planning for Breast Treatments

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Rick Vaden, CMD, Senior Clinical Applications Specialist
Accuray INCORPORATED

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  • Note that the reason it’s nearly the same beam-on time is the gantry has sped up. So given a specific planning field width, what determines the treatment time is the treatment field length and the fraction dose – not the pitch! (Exceptions at very fast gantry periods, which corresponds to either very small pitches or very low fraction doses.)
  • Note that the reason it’s nearly the same beam-on time is the gantry has sped up. So given a specific planning field width, what determines the treatment time is the treatment field length and the fraction dose – not the pitch! (Exceptions at very fast gantry periods, which corresponds to either very small pitches or very low fraction doses.)
  • Advanced Planning for Breast Treatments

    1. 1. © Accuray Incorporated Company Confidential 1| Advanced Planning for Breast Treatments RICK VADEN, CMD, SENIOR CLINICAL APPLICATIONS SPECIALIST ACCURAY INCORPORATED
    2. 2. © Accuray Incorporated Company Confidential 2| • Factors for creating the best treatment plans • Points to consider for TomoHelical™ breast plans • Points to consider for TomoDirect™ breast plans • Deciding between 3DCRT and IMRT • Evaluating how parameters affect beam-on times Breast Planning Tips and Tricks Topics MKT/TT/0514/0022
    3. 3. © Accuray Incorporated Company Confidential 3| • Pitches in general need to be tighter because of blocking needs for breast planning • TomoHelical™ Breast plans require slightly higher modulation factor (MF) [~2-2.3] • TomoDirect™ breast plans need lower MF [~1.5-2] Breast Planning Tips and Tricks Breast Planning Compared to Other Plans MKT/TT/0514/0022
    4. 4. © Accuray Incorporated Company Confidential 4| Why is Pitch so Important? TomoHelical™ Breast Planning MKT/TT/0514/0022
    5. 5. © Accuray Incorporated Company Confidential 5| Breast Planning Tips and Tricks Pitch Selection – Effect on Dose Homogeneity Homogeneous NOT SO MUCH For illustrative purposes only, diagram uses a limited number of projections and does not account for couch and/or MLC movement Target at isocenter Target not at isocenter MKT/TT/0514/0022
    6. 6. © Accuray Incorporated Company Confidential 6| Breast Planning Tips and Tricks Pitch Selection – Effect on Dose Homogeneity Example of a non-optimal pitch For illustrative purposes only, diagram uses a limited number of projections and does not account for couch and/or MLC movement MKT/TT/0514/0022
    7. 7. © Accuray Incorporated Company Confidential 7| Breast Planning Tips and Tricks Pitch Selection – Effect on Dose Homogeneity NOTE: This example has no blocks! Pitch selection should change when using blocks. For illustrative purposes only, diagram uses a limited number of projections and does not account for couch and/or MLC movement Example of an optimal pitch 0 degrees 180 degrees MKT/TT/0514/0022
    8. 8. © Accuray Incorporated Company Confidential 8| Breast Planning Tips and Tricks Pitch Selection – Effect on Dose Homogeneity BLOCK For illustrative purposes only, diagram uses a limited number of projections and does not account for couch and/or MLC movement The same “optimal” pitch as before… Note how adding a block changes the homogeneity! 0 degrees 180 degrees Tighter pitch should be selected MKT/TT/0514/0022
    9. 9. © Accuray Incorporated Company Confidential 9| Choosing an Optimal Pitch for TomoHelical™ Breast Planning MKT/TT/0514/0022
    10. 10. © Accuray Incorporated Company Confidential 10| What pitches will give the most homogeneous dose? … but the answer actually depends upon the plan. If you have VoLO™, exploring pitches in planning is fast! Breast Planning Tips and Tricks Pitch Selection – How to Choose the Optimal Pitch 0.215 0.225 0.287 0.297 0.430 0.433 Based upon early data, a lot of users think it would be these…?0.86/N MKT/TT/0514/0022
    11. 11. © Accuray Incorporated Company Confidential 11| Breast Planning Tips and Tricks Pitch Selection – How to Choose the Optimal Pitch Theoretical analysis of the thread effect in helical TomoTherapy Mingli Chen, Yu Chen, and Quan Chen, Accuray Inc., Weiguo Lu, 21st Century Oncology (Received 17 May 2011; revised 17 August 2011; accepted for publication 7 September 2011; published 17 October 2011) MKT/TT/0514/0022
    12. 12. © Accuray Incorporated Company Confidential 12| Breast Planning Tips and Tricks Examples of Different Pitches .430 .433 TomoHelical™ 3DCRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning MKT/TT/0514/0022
    13. 13. © Accuray Incorporated Company Confidential 13| Breast Planning Tips and Tricks Examples of Different Pitches .287 .297 TomoHelical™ 3DCRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning MKT/TT/0514/0022
    14. 14. © Accuray Incorporated Company Confidential 14| Breast Planning Tips and Tricks Examples of Different Pitches .215 .225 TomoHelical™ 3DCRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning MKT/TT/0514/0022
    15. 15. © Accuray Incorporated Company Confidential 15| Breast Planning Tips and Tricks Choosing a Pitch Optimal pitches will vary depending on the plan field width and target axial offset from the isocenter. Homogeneous NOT SO MUCH For illustrative purposes only, diagram uses a limited number of projections and does not account for couch and/or MLC movement Target at Isocenter Target not at isocenter MKT/TT/0514/0022
    16. 16. © Accuray Incorporated Company Confidential 16| How to measure target axial offset from the isocenter Breast Planning Tips and Tricks Choosing a Pitch MKT/TT/0514/0022
    17. 17. © Accuray Incorporated Company Confidential 17| Breast Planning Tips and Tricks Choosing a Pitch Theoretical analysis of the thread effect in helical TomoTherapy Mingli Chen,a) Yu Chen, and Quan Chen, Accuray Inc., Weiguo Lu, 21st Century Oncology (Received 17 May 2011; revised 17 August 2011; accepted for publication 7 September 2011; published 17 October 2011) MKT/TT/0514/0022
    18. 18. © Accuray Incorporated Company Confidential 18| Pitch and Beam-On Time MKT/TT/0514/0022
    19. 19. © Accuray Incorporated Company Confidential 19| What pitches will give the shortest beam-on time? Usually it doesn’t matter! Beam-on time is largely independent of pitch, and is more dependent upon field width. Breast Planning Tips and Tricks Pitch and Beam-On Time 0.215 0.225 0.287 0.297 0.430 0.433 MKT/TT/0514/0022
    20. 20. © Accuray Incorporated Company Confidential 20| Breast Planning Tips and Tricks Examples of Different Pitches 0.430 0.433 5.8 minutes total beam-on time 40-second gantry period TomoHelical™ 3DCRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning 5.78 minutes total beam-on time 40-second gantry period MKT/TT/0514/0022
    21. 21. © Accuray Incorporated Company Confidential 21| Breast Planning Tips and Tricks Examples of Different Pitches 0.287 0.297 TomoHelical™ 3DCRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning 5.63 minutes total beam-on time 26-second gantry period 5.65 minutes total beam-on time 27-second gantry period MKT/TT/0514/0022
    22. 22. © Accuray Incorporated Company Confidential 22| Breast Planning Tips and Tricks Examples of Different Pitches 0.215 0.225 TomoHelical™ 3DCRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning 5.74 minutes total beam-on time 20-second gantry period 5.53 minutes total beam-on time 20-second gantry period MKT/TT/0514/0022
    23. 23. © Accuray Incorporated Company Confidential 23| • Same great treatment plans, but beamlet calculations require the user to choose the pitch first – choosing a new pitch means calculations must start over. • However, it is still possible to experiment, without spending a lot of time on extra beamlet calculations: › Select a pitch and calculate a few iterations in either Scatter or Terma mode. › Then, once the optimal pitch is selected, calculate the plan in Beamlet mode. Breast Planning Tips and Tricks What If I Don’t Have VoLO™? • Terma does not consider scatter during optimization – Fast but less accurate. • Scatter calculates with all scatter – Slower but more accurate. • Beamlet Optimization considers scatter but with some approximations– Accurate, requires longer initial calculation, but optimization is fast. MKT/TT/0514/0022
    24. 24. © Accuray Incorporated Company Confidential 24| TomoDirect™ Breast Planning MKT/TT/0514/0022
    25. 25. © Accuray Incorporated Company Confidential 25| • Choosing the best beam angles is critical • Pitch is per projection and not per rotation • More beams doesn’t necessarily mean longer treatment time • Although IMRT is often better, 3DCRT is good too • Target MUST be within 40cm of isocenter Breast Planning Tips and Tricks Considerations for Planning TomoDirect™ Breast Treatments MKT/TT/0514/0022
    26. 26. © Accuray Incorporated Company Confidential 26| Breast Planning Tips and Tricks Setting Beam Angles for TomoDirect™ Breast Treatments Set medial beam angle so that the medial field edge is as close to the target as possible on entrance and exit. Add flash if desired. Set lateral beam angle so the medial field edge divergence matches the other field. MKT/TT/0514/0022
    27. 27. © Accuray Incorporated Company Confidential 27| Breast Planning Tips and Tricks Calculate Dose: Two-Beam 3DCRT Plan High Dose 2.2 minutes total beam-on time Two-beam 3DCRT plan TomoDirect™ 3DCRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning Consider planning with 4 fields MKT/TT/0514/0022
    28. 28. © Accuray Incorporated Company Confidential 28| Breast Planning Tips and Tricks Try Adding Beam Angles MKT/TT/0514/0022
    29. 29. © Accuray Incorporated Company Confidential 29| Breast Planning Tips and Tricks Calculate Dose: 4-Beam 3DCRT Plan Consider IMRT if still unsatisfactory 2.5 minutes total beam-on time 4-beam 3DCRT plan TomoDirect™ 3DCRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning High Dose is better MKT/TT/0514/0022
    30. 30. © Accuray Incorporated Company Confidential 30| Breast Planning Tips and Tricks IMRT Plan: Slightly Faster, More Conformal 2.4 minutes total beam-on time 4-beam IMRT plan TomoDirect™ IMRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning MKT/TT/0514/0022
    31. 31. © Accuray Incorporated Company Confidential 31| Normal Tissue Dose Uniformity MKT/TT/0514/0022
    32. 32. © Accuray Incorporated Company Confidential 32| • An automated way to improve uniformity of dose Outside of the target, user-selectable on the Planning Station. • This option may be selected for either TomoHelical™ 3DCRT or TomoDirect™ 3DCRT plans. Breast Planning Tips and Tricks What is “Normal Tissue Dose Uniformity”? MKT/TT/0514/0022
    33. 33. © Accuray Incorporated Company Confidential 33| • During calculation beamlet compensation is calculated to avoid hotspots outside of target • Implementation of this option has improved with the 5.X release of the treatment planning software. Breast Planning Tips and Tricks What is “Normal Tissue Dose Uniformity”? MKT/TT/0514/0022
    34. 34. © Accuray Incorporated Company Confidential 34| Breast Planning Tips and Tricks Without Normal Tissue Dose Uniformity TomoDirect™ IMRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning High Dose MKT/TT/0514/0022
    35. 35. © Accuray Incorporated Company Confidential 35| Breast Planning Tips and Tricks With Normal Tissue Dose Uniformity TomoDirect™ IMRT TomoEDGE™ 5cm Dynamic Jaws VoLO™ Treatment Planning No High Dose MKT/TT/0514/0022
    36. 36. © Accuray Incorporated Company Confidential 36| DISCUSSION TomoTherapy® for Breast Cancer: Realities and Results MKT/TT/0514/0022

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