IGRT Robotica G.Beltramo Centro Diagnostico Italiano

1. IGRT Robotica G.Beltramo Centro Diagnostico Italiano Varese 13 Giugno 2009

2. Image-GuidedRadiationTherapy “Any use of imaging within the radiation treatment room, to improve the precision ofradiation-therapy delivery” “Use of any planar imaging, volumetric imaging, or volumetric ciné imaging, marker localization, marker tracking, patient surface imaging, patient surface tracking to improve the precision of radiation therapy delivery.” “IGRT is the process of in-room imaging that guides the radiation delivery.”

3. Focus: Imageguided RT Intervention Three essentialsteps: Acquireanimage • Acquire the positional information of the target, targetsurrogates, or avoidance structures Obtain “target” registrationerror • Imageregistration • Deviations from the original plan Performanintervention • Correctionstrategies – Inter fraction/intra fraction, online/offline etc.

5. Advances in radiationtechnology

7. StereotacticRadiosurgery System CyberKnife® In 1991 Jonh Adler, an american neurosurgeon, develop a deliveringstereotacticradiosurgery system without the needforrigidimmobilization

8. CyberKnife® Robotic Radiosurgery • Non-coplanar treatment delivery • Total of more than 1500 different beams • Delivery of 150 to 200 uniquely angled beams per fraction Image courtesy of Georgetown University Hospital

9. Need X ray vision! • The target volume is located on X rays (orthogonal or stereoscopic) with fiducial markers or without them (if the target volume can be seen on X rays) • The images are to be fused and registered with the pretreatment DRR’s • The required shifts are calculated using customized software. • Shifts are made

10. Stereotactic Radiosurgery System CyberKnife® Cyberknife (CK) therapy. CK (Accuray, Inc., Sunnyvale, California) is an image guided, frameless, radiotherapy device with a compact linear accelerator installed on an industrial-derived robotic arm, The intelligent arm has the capability of rotating around 6 axes with millimetric accuracy allowing a stereotactic radiosurgery (SRS) with high radiation doses to relatively small lesions. The treatment unit can verify target position with a real-time tracking during radiation delivery using two kV X-ray sources mounted on the ceiling and two amorphous-silicon image detectors mounted on the floor on either side of the patient in an orthogonal geometry to detect bony landmarks or fiducial markers within or near the target. The targeting system continuously acquires radiographs that are compared with the digitally reconstructed radiographs (DRR) derived from the treatment planning CT scans to update the changes in target position which are compensated by adjusting the aim of the robotic arm [ ]. Dx X-Ray Sources Amorphous Silicon Detectors

11. Cyberknife data acquisition Image guidance • Stereographic X-ray images are compared with DRRs or fiducial positions • Robot corrects after each stereographic X-ray image acquisition • Robot can correct: • ± 10 mm all components • ± 1º roll • ± 1º pitch • ± 3º yaw Flowchartof the patient set up and delivery process in Cyberknife treatment

12. X-ray source A X-ray source B Y Pitch Camera A Camera B Image B Image A Planar X Rays (2D+) Advantages – Fast image acquisition (single or fluoroscopic modes) – High temporalresolution – Tracking – Beambybeamcorrection – Motion management Disadvantages – Use of target surrogates (in most situations) – Obstructions in imageviewingangles (anatomies or couch support in the beam path) – Not easy to reconstruct 3D dose distributions “On-line Correction” Analysis of images and/or related data for potential corrections of the delivery of the current fraction (i.e. analysis performed while the patient is still on the treatment couch).

13. Verification of treatment accuracy Skull may be good surrogate for brain

14. Verification of treatment accuracy • Bone or marker??? spine bone poor surrogate for extracranial cancer

15. Verificationof treatment accuracy Accuracyofradiotherapy delivery depends on the visualisationofimplantedgoldfiducials at the timeof treatment and comparisonwithreferencesimagesobteinedduring treatment planning, . The advantageofCyberknifetrackingsistemistoverify in everystepof treatment the real position ofneoplstic target and the possibilitytoadjust the aimofroboticarmif the target position changeduringradiotherapy treatment

16. Accuracyoffiducialtargetting • Total error in patient pose is dependent on the number of fiducials being tracked • 3 fiducials significant improvement in targeting accuracy • > 6 fiducials adds little more improvement • Error in translations unaffected by spacing • Error in rotation is  50% by doubling the distance between fiducials

17. Rigid body constraint Distances between like fiducials compared

18. Histogramof prostate volume as a functionoftimeduration and shift

19. Accuracyoffiducialtargetting Percentageof data set ofhaving a movementas a functionoftime Rigid body error curve ofthreefiducialsforfour rappresentative patients

20. Inter-fractionalmotionof the prostate duringhypofractionatedradiotherapy CDI Cyberknifeexperience

21. RealTimeImaging Imaging with a temporal resolution that’s sufficient to capture the trajectory of a moving or changing subject. Real time IGRT correction refers to frequent imaging while the treatment is being delivered, with repositioning based on thatimaging. real-time monitoring of any parameter must be fast enough to modify the treatment in order to account for the impact of that parameter on treatment.

22. State of the art in roomtechniquesforrespiratorymotion management Technologies available • Optical • MV/EPI • kV X ray • kV/MV/Optical • 4D CBCT/CT • Electromagnetic • Ultrasound • MRI

23. RespiratoryGuidedRadiationTherapy Infrared LED-camera system records the respiration cycle Real time moving the treatment beam as the targetmoves

24. Motion management methods

25. CyberKnife® Robotic Radiosurgery • Accuracy • Total targeting accuracy • Targets not affected by respiration: 0.5 millimeter** • Targets that move with respiration: 0.7 millimeter*** • Targeting accuracy sustained throughout the treatment * Kuka KR240-2 Specification 04.2004.05 ** Muacevic, A., Staehler, M., Drexler, C., Wowra, B., Reiser, M. and Tonn, J. Technical description, phantom accuracy and clinical feasibility for fiducial-free frameless real-time image-guided spinal radiosurgery. J Neurosurgery Spine. Xsight accuracy specification of .95 mm. *** Dieterich S, Taylor D, Chuang C, Wong K, Tang J, Kilby W, Main W. The CyberKnife Synchrony Respiratory Tracking System: Evaluation of Systematic Targeting Uncertainty. Synchrony clinical accuracy specification of 1.5 mm for moving targets

26. Patientfixation - StereotacticElekta® Body Frame • Individually fitted vacuum pillow • Laser system for tattoos • Device for diaphragm compression • (breathing tumor movements >10 mm at fluoroscopy)

27. Methods to avoid geographic miss - ITV (abd compression), breath hold (ABC), gating, and tracking

28. CyberknifeRadiosurgery : clinicalrationale

29. Take Home Messages • (Target Delineation) • With robotic IGRT, treatment precision may be improved: • More accurate contours are REQUIRED • Inaccurate contourscould introduce unexpected target miss or increased toxicities

30. Use For Tracking • Cannot be extracted • Migration • Obscured Day 0: fiducialinsertion Day 7: treatment planning TC. fiducialmigration Day 10: missing

31. Inaccurate target delineation

32. IMAGE FUSION TC-RM Use CT forgeometricaccuracy Use RM for target delineation Clinicaluseofthistecniquefor treatment planning hasresulted in improvements in localizationof treatment volumes and criticalstructures in the brain Kessler M.L.1991 LattanziJ.P.1997

33. Imageguidancefacilitatestargetting TC-MRI imageFusion

34. MRI for Target Delineation Advantages • Superior soft tissue image quality • For some tumors - greater sensitivity • Greater accuracy - delineation of some normal tissues • Functional information – normaltissues • Biological information – TME, blood flow, hypoxia • No radiation dose Disadvantages • Lack of specificity for tumor vs. other pathological states • Multiple effects that can lead to image distortion • Does not provide relative radiation attenuation • Requires fusion of grayscale images with CT dataset • Motionartifact • Cost

35. 3D CRT and IMRT aimtoachievebetterlocoregionalcontrol and improvesurvivalbyradiation dose escalation, butsuch techniquesdemand more accurate localizationoftumor and surroundingnormaltissues

36. Imaging in Target Delineation PET in Target Definition Use of PET imaging to reduce interobserver variations in contouring STEENBAKKERS et al., IJROBP, Vol64, pp435, 2006 Do SUVsmeananything?

37. Uncertainties in Manual Volume Alignment • Differences in ImageInterpretation • Inter-observervariation • Contours may not be drawn perfectly • One person’s alignment may not agree with another person’s judgment • Impact of organ deformation • Imperfectalignment

38. SBRT theoreticalbasis

39. Operablelungcancerpatients • Extent of resection impacts local control • (e.g., wedge vs. lobectomy – LCSG trial) • Localcontrolimpactssurvival Goal with SBRT in inoperable patients should be very high local control until proven otherwise After 3 months After 12 months At treatment

40. SBRT forearly stage lung carcinoma Large Japanese Study (Onishi, 2007) Indiana phase I trial

42. SBRT toxicity

43. RespectNormalTissueConstraints

44. RespectNormalTissueConstraints

45. Organ at risk dose coinstrain

47. RespectNormalTissueConstraints GRADE II GRADE III GRADE IV 3 months post SBRT 6 months post SBRT 12 months post SBRT

49. LocalTherapy and Image-Guidance • Radiation therapy is a proven local therapy. • Increased precision in therapy offers: – Reduce severity and risk of therapy-induced complications. – Increase both quality and probability of success. • Furtherpotential: – Broaden application of proven therapies. – Permit new therapies that are intolerant to geometric imprecision. • Addressing geometric uncertainties may expose other factorsdeterminingoutcome.

50. Not a single IGRT solution can correct allsourcesofuncertainties Systematic Random Inter-fractional Intra-fraction ShapeVariations TimeTrends