1. Varian _ Dynamic Targeting TM Image-Guided Radiation Therapy Scott Johnson, PhD Varian Medical Systems Palo Alto, California Varian _

2. VARIAN medical systemsPage 2 Varian IGRT Statistics As of the end of Dec, Varian had booked 80 orders for the On-Board Imager (OBI) As to today, 35 installations have been completed And another dozen installations currently are in progress As of today, cone-beam CT software has been installed at 7 sites Aarau, Switzerland Karolinska, Sweden MSKCC, New York Emory, Atlanta Stanford, Palo Alto Duke, Durham Henry Ford, Detroit With an additional installations scheduled in the very near future MD Anderson, Houston

3. VARIAN medical systemsPage 3 What is IGRT? IGRT means several things … Use of images for online setup correction, before treatment begins Position patient on table. Align the patient to lasers. Acquire images Images usually are kV Images may be an orthogonal pair of radiographs or a volumetric image (e.g., cone-beam CT) Compare the acquire images to reference images Analysis may be automated and/or manual Analysis may rely on radiopaque markers, bony anatomy or soft-tissue anatomy Result of the analysis is data on how to correct the patient position Move the treatment couch remotely to automatically correct the patient position Optional: Acquire and analyze another set of images to verify the correction Begin treatment delivery

4. VARIAN medical systemsPage 4 Movie of the clinical process

5. VARIAN medical systemsPage 5 What is IGRT? Use of images for online setup correction, before treatment begins What’s new here: Use of kV imaging in the treatment room New image analysis tools for the therapist Fast, easy to use, integrated into the existing workflow Remote couch control, to speed the process The result is: Significant improvement in target localization Reduced likelihood of missing the target An opportunity to reduce CTV-to-PTV margins and thus the volume of normal tissue irradiated to high dose May reduce the toxicity of RT

6. VARIAN medical systemsPage 6 What is IGRT? IGRT also may mean adaptive radiation therapy Tumors, hopefully, respond to treatment and shrink over the course of therapy As the surrounding tissues are pulled inward, the result may increase the dose to critical structures With adaptive RT, goal is to use images to Perform online setup correction of patient position Acquire a volumetric image (cone beam CT scan) Automatically detect any changes in the target shape Automatically adapt the treatment plan to reflect the new target shape Provide the therapist with important information on how the plan has changed Deliver the new plan (It’s kind of like a boost plan, but done online with the patient on the table) Above process should occur within 15-20 minutes, or less

7. VARIAN medical systemsPage 7 What is IGRT? With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered Critical structure Target Prescription isodose Original treatment plan and anatomy

8. VARIAN medical systemsPage 8 What is IGRT? With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered Critical structure Target Prescription isodose Original treatment plan and new anatomy with tumor shrinkage due to radiation

9. VARIAN medical systemsPage 9 What is IGRT? With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered Critical structure Target Prescription isodose Adapted treatment plan

10. VARIAN medical systemsPage 10 What is IGRT? With adaptive radiation therapy, images of the tumor size, shape and location are used to adapt the treatment plan before it is delivered No one is doing this yet! Before it can be done, the following are needed Ability to acquire CT scans on the treatment table. DONE! Automated image segmentation tools that automatically contour the patient anatomy New treatment plan analysis tools for the therapist Including tools that clear show what treatment plan adaptations are needed and what the effect of those changes is Fast, easy to use software that is well integrated into the existing treatment delivery process Guidelines on when adapted treatment plans should be reviewed by a physicist or physician Guidelines on how to QA the adaptive radiation therapy process Etc

11. VARIAN medical systemsPage 11 What is IGRT? IGRT also can be considered to include dose guided radiation therapy Acquire a CT scan of the patient on the treatment table in the treatment position Deliver the treatment plan Use an EPID to capture transit dose images or capture linac and MLC log files Use transit dose to back project delivered dose onto CT or use log files to forward project delivered dose onto CT The result is a realistic calculation of the dose delivered that day including the impact of bladder and rectal filling, bowel gas, etc Dose actually emitted by the linac overlayed onto CT scan of patient on treatment table

12. VARIAN medical systemsPage 12 What is IGRT? IGRT also can be considered to include dose guided radiation therapy Now, imagine repeating the above process at each treatment session and having the ability to morph the results onto each other Summing the results allows you to visualize the dose actually delivered to the target and critical structures over a series of treatment sessions With advanced treatment planning tools, you then may choose to adapt the treatment plan mid-stream so that the final, cumulative dose satisfies the physician’s prescription

13. VARIAN medical systemsPage 13 What is IGRT? IGRT also can be considered to include dose guided radiation therapy Again, no one is doing this yet, but we are getting close… Before it can be done, the following are needed Ability to acquire CT scans on the treatment table. DONE! Ability to capture linac and MLC log files or transit dose. DONE! Ability to project beams recorded in log files into CT scans. DONE! Image and dose morphing tools that allow you to sum the dose to a volume over several sessions, given that the volume is changing size, shape and location Fast, easy to use software that is well integrated into the existing treatment delivery process Guidelines on when to adapt a plan and when that adapted plan should be reviewed by a physicist or physician Guidelines on how to QA the dose guided radiation therapy process Etc

14. VARIAN medical systemsPage 14 Will IGRT replace IMRT? No, the two are complementary. IMRT allows the dose to conform tightly to the PTV. IGRT allows the PTV to shrink to the CTV. IG-IMRT then allows simultaneously margin- reduction and dose conformation. Conventional RT IMRT IG-IMRT CTV PTV Organ at risk High dose isodose

15. VARIAN medical systemsPage 15 Varian IGRT Technology On-Board Imager accessory Available as an upgrade to any Clinac installed in 1997 and after

16. VARIAN medical systemsPage 16 On-Board Imager Hardware Two robotic arms kV Xray source Amorphous silicon imaging panel OBI workstation Three modes of operation Radiographic Online setup correction Bony anatomy or markers CBCT Online setup correction Bony or soft tissue anatomy Visualization of delivered dose Adaptive radiation therapy Fluoroscopic Verification of gated radiation therapy Fluoro-based tumor tracking (*Future option) Trilogy and the On-Board Imager

17. VARIAN medical systemsPage 17 Command Center Clinac console, 4D Console, OBI workstation, RPM Gating workstation

18. VARIAN medical systemsPage 18 Robotic arm motion

19. VARIAN medical systemsPage 19 Robotic arm motion

20. VARIAN medical systemsPage 20 Robotic arm motion

21. VARIAN medical systemsPage 21 Robotic arm motion

22. VARIAN medical systemsPage 22 Varian IGRT Technology Orthogonal radiographs for online patient setup correction

23. VARIAN medical systemsPage 23 Acquisition of a lateral radiograph

24. VARIAN medical systemsPage 24 Acquisition of an AP radiograph

25. VARIAN medical systemsPage 25 Sample radiographs Images courtesy of Karolinska Medial Center

26. VARIAN medical systemsPage 26 Sample radiographs Images courtesy of Karolinska Medial Center

27. VARIAN medical systemsPage 27 On-Board Imager workstation

28. VARIAN medical systemsPage 28 On-Board Imager workstation

29. VARIAN medical systemsPage 29 Marker matching using the On-Board Imager

30. VARIAN medical systemsPage 30 Marker matching using the On-Board Imager

31. VARIAN medical systemsPage 31 Varian IGRT Technology Cone beam CT for online patient setup correction (and adaptive radiation therapy and dose guided radiation therapy)

32. VARIAN medical systemsPage 32 Acquisition of a cone beam CT scan

33. VARIAN medical systemsPage 33 Acquisition of a cone beam CT scan

34. VARIAN medical systemsPage 34 Acquisition of a cone beam CT scan

35. VARIAN medical systemsPage 35 Acquisition of a cone beam CT scan

36. VARIAN medical systemsPage 36 Acquisition of a cone beam CT scan

37. VARIAN medical systemsPage 37 Acquisition of a cone beam CT scan

38. VARIAN medical systemsPage 38 Acquisition of a cone beam CT scan

39. VARIAN medical systemsPage 39 CBCT: field of view and slice thickness With a single 360 degree rotation of the gantry, CBCT scans can be reconstructed with the following specifications OR Field of view 27cm Scan length 17cm Slice thickness, down to 0.5mm Field of view 48cm Scan length 15cm Slice thickness, down to 0.5mm

40. VARIAN medical systemsPage 40 Sample CBCT image Images courtesy of Duke University Hospital

41. VARIAN medical systemsPage 41 Varian IGRT Technology Controlling for respiratory motion

42. VARIAN medical systemsPage 42 Respiratory gating RPM Gating System Infrared camera External marker block Gating workstation Process Place block on patient’s abdomen Camera monitors block motion Respiratory waveform shows how the block moves up and down in time User sets upper and lower thresholds on block motion Whenever the block comes between the thresholds, the beam is on Whenever the block moves outside the thresholds, the beam is off Free-breathing and breath hold protocols are supported, as are gating at inhalation or exhalation or at any other point in the respiratory cycle

43. VARIAN medical systemsPage 43 Fluoro-based verification of gating With the On-Board Imager, gated kV radiographs are used to verify patient setup and kV fluoroscopy is used to verify the gated treatment port.

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48. VARIAN medical systemsPage 48 Varian IGRT Technology What’s next?

49. VARIAN medical systemsPage 49 Where we are headed New software tools for online adaptive radiation therapy and dose guided radiation therapy Automated segmentation of acquired CBCT scans Treatment planning and plan review tools at the Command Center Fast, automated plan modification tools New software tools for fluoro-based gating, in which the gating signal is based on the motion of internal anatomy (rather than an external marker block)

50. VARIAN medical systemsPage 50 Where we are headed New MLC control system to enable real-time tumor tracking

51. VARIAN medical systemsPage 51 Varian IGRT Technology Why we think it is superior

52. VARIAN medical systemsPage 52 Varian’s IGRT technology Compared to Tomotherapy We use kV photons rather than MV for superior image quality We use cone-beam CT rather than helical slice-based CT because cone-beam CT images are superior and CBCT is the future Radiology, in general, is moving toward CBCT 1 slice scanner > 2 slice > 4 slice > 8 slice > 16 slice > … Because of the exquisite detail, CBCT already has been adopted by Cardiology We can develop fluoro-based tools to monitor and control for respiratory motion Tomotherapy will have a difficult time dealing effectively with respiratory motion

53. VARIAN medical systemsPage 53 Varian’s IGRT technology Compared to Novalis and CyberKnife We use a gantry-based system, rather than a room-based system, to have the option of acquiring CBCT scans Volumetic imaging is not possible with Novalis or CyberKnife

54. VARIAN medical systemsPage 54 Varian’s IGRT technology Compared to Synergy We use robotic arms to position the kV source and kV imager to allow remote control and superior flexibility in imaging geometry We use high-quality Varian imagers, which have a much higher image acquisition rate Up to 30 frames per second, compared to 3-5 frames per second for Elekta Most clinicians feel that a frame rate of at least 12-15 images/second is required for fluoro-based gating

55. VARIAN medical systemsPage 55 Conclusion Varian offers the most integrated and comprehensive solution available kV radiographs kV/MV radiographs Gated radiographs Marker-based setup corrections, 2D-2D and 2D-3D CBCT acquisition and analysis Pretreatment verification of gated treatment ports Robotic couch motion IGRT software integrated with the VARiS Vision Eclipse database Varian is well-positioned to quickly deliver the next generation of IGRT technology

56. VARIAN medical systemsPage 56 Thank you