1. 4D Radiotherapy Paul Keall Virginia Commonwealth University

3. Medical rationale What is the purpose of your research?

6. Why 4D? Chemo-response GI motion Inter-observer differences Tumor growth Tumor shrinkage Tumor spread Reoxygenation Repair Repopulation Redistribution Vascular growth Weight loss Cardiac motion Hormone response Diet Bladder filling Rectal filling Intra-observer differences Skeletal motion Respiratory motion Weight gain Respiratory motion

8. Problems of respiratory motion in radiotherapy

9. The tumor moves with time

10. Distorted images, incorrect anatomical positions, volumes or shapes Conventional With gated imaging Keall et al Aust Phys Eng Sci Med 2002 Tumor

12. IMRT Delivery: Interplay between anatomy and MLC leaf motion leads to motion artifacts Dose Position Planned dose Delivered dose

13. Basic science and technology What is the underlying scientific/technological basis of your research?

15. The 4D radiotherapy process 4D Radiotherapy 4D CT Imaging 4D Treatment Planning 4D Treatment Delivery Acquisition of a sequence of CT image sets over consecutive phases of a breathing cycle The explicit inclusion of the temporal changes in anatomy during the imaging, planning and delivery of radiotherapy Designing treatment plans on CT image sets obtained for each phase of the breathing cycle Continuous delivery of the 4D treatment plans throughout the breathing cycle

16. 4D Radiotherapy I: 4D CT Imaging

17. 4D CT imaging

18. 4D CT images Vedam et al PMB 2003 48:45-62 8 respiratory phases Peak inhale Early inhale Mid inhale End inhale Peak exhale Early exhale Mid exhale Late exhale

20. 4D Radiotherapy II: 4D Planning

21. 4D Planning Flow Chart Acquire 4D CT Define anatomy Create/adjust treatment plan Evaluate dose distribution 1 4 3 2 Proceed to treatment 6 … Plan acceptable? No Yes Deformable registration … Automated planning … Deformable registration 5

22. 4D PTVs

23. BEVs 3D BEV 4D BEV

24. 3D (solid) vs 4D (dashed) DVHs

25. 4D Radiotherapy III: 4D Delivery

26. 4D radiotherapy delivery

27. MLC leaf motion 3D 4D Keall et al PMB 2001 46:1-10

28. MLC leaf motion 3D IMRT 4D IMRT

29. Tracking motion perpendicular and parallel to the MLC

30. Finite response time- need motion prediction

32. State-of-the-art How does your research fit into the overall scheme of medical research?

34. Future needs, directions and opportunities What is currently limiting your research or what change in direction do you anticipate in the future?

39. Advice

44. Another great team!