Proton Beam Therapy at Mayo Clinic

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1 Proton Beam Therapy at Mayo Clinic Jon J. Kruse, Ph.D. Mayo Clinic Dept. of Radiation Oncology Rochester, MN

2 History of Proton Therapy at Mayo 2002: Decided to consider particle therapy analysis and education 2006: Initial meetings with manufacturers 2007: Initial RFP Protons + Carbon Scattered + Scanned beams 2008: Decision that the future was scanning particle beams 2/2010: Permission to Plan RST + AZ

3 History of Proton Therapy at Mayo 3/2010: Final RFP, protons only 11/2010: Board of Trustees approval 12/2010: Selected Hitachi as vendor 5/2011: Mayo/Hitachi contract signed 9/2011: RST groundbreaking 6/2013: Equipment installation began 3/2015: First RST Tx rooms accepted 6/2015: First Tx in RST

4 Mayo Clinic Proton Beam Therapy Centers Two identical treatment facilities Rochester, MN 2015 Phoenix, AZ 2016 Synchrotron-based Four gantries (180 degrees) One fixed beam room All five nozzles in each facility are identical optimized for scanning beam only

5 Mayo Clinic Proton Beam Therapy Centers Design goals Highest quality treatment available High efficiency ~1200 patients per year, per facility Infrastructure for efficient treatment of complex disease sites Radiographic imaging suites outside treatment room Remote anesthesia Scanning beam nozzles

6 Both Centers Adjacent to Photon Clinics

7 Facility Layout

8 Facility Layout

9 Half Gantry Treatment Room

11 10/15/2011

12 Richard O. Jacobson Building 03/09/2012 5/8/2012

13 Richard O. Jacobson Building 05/03/2012 5/8/2012

14 05/22/2012 Richard O. Jacobson Building 5/8/2012

15 08/30/ /08/2012

16 11/12/2012

18 Rochester Install

19 Rochester G

21 Treating Cancer with Scattered Protons Patient 250 MeV Proton Beam Tumor

22 Treating Cancer with Scattered Protons Patient 250 MeV Proton Beam Tumor

23 Treating Cancer with Scattered Protons Patient Reduced Energy Proton Beam Tumor

24 Treating Cancer with Scattered Protons Patient Add Double Scatterer Tradeoff between field size and range Tumor

25 Treating Cancer with Scattered Protons Patient Add Field Aperture Tumor

26 Treating Cancer with Scattered Protons Patient Custom And Nozzle brass machined must is expensive, be very brass part and close a must potential to be patient changed source between of neutrons fields Tumor

27 Treating Cancer with Scattered Protons Spread out peak with modulator wheel Patient Must accept maximum modulation width over entire tumor Tumor

28 Treating Cancer with Scattered Protons Match Distal Proton Range with Compensator Patient Compensator must be machined for each field, and changed by hand Tumor

29 Raster-scanned Proton Beam Patient 250 MeV Proton Beam Tumor

30 Treating Cancer with Scanned Protons Patient Y-Scanning Magnets Variable Energy Proton Beam X-Scanning Magnets Tumor

31 Active Scanning Proton Beams Passive Scattering Active Scanning

32 Proton Developments at Mayo Hitachi has installed a scanning proton treatment room at M.D. Anderson Mayo s facility is scanning beam only Redesign of many components Synchrotron Gantry Nozzle Console/HMI IGRT Efficient treatment of complex cases

33 MDA -> Mayo Synchrotron Smaller Footprint 24ft 18.5ft dia. Fewer Components Lower Cost Less Power Simpler Maintenance Fast Room Switch Smaller Beam Spot

34 Mayo Gantry ~5M smaller ~60 tons lighter Better patient access MDA Gantry ~5M smaller ~60 tons lighter Better patient access

35 New Nozzle: Smaller Spot Old Spot New Spot Tumor Normal Organ 10/08/2012 Richard O. Jacobson Building

36 MD Anderson Nozzle Scanning Nozzle Redesign Mayo Nozzle Gillin et al., Med Phys 37 (2010) p. 154

37 New Console

38 New HMI

39 New HMI

40 HMI Design w/ RTT in Omika

41 ~Monthly Design Meetings in Hitachi

42 Mayo-Hitachi Omika Teams at Omika Works Mayo-Hitachi Design Teams at Hitachi Works

43 Facility Infrastructure for Complex Cases Anesthesia Suite Imaging Rooms Beam Matched Tx Rooms

44 Why Do Active Scanning? Dosimetric advantages No tradeoff between field size/depth Variable modulation width Higher resolution distal range compensation No hardware in the beam Easier planning IMPT Adaptive planning without new hardware Efficiency Cycle through Tx fields from control room

45 Why Not Do Active Scanning? Lateral penumbra Scattered beams can achieve a very sharp lateral penumbra, via brass aperture very close to the patient With scanning beams, in some cases the lateral penumbra is dominated by spot size in air not as sharp as a collimated scattered beam Interplay Time dependent dose delivery of a scanning beam is problematic for moving tumors

46 Interplay Scattered beams irradiate entire target volume with almost no time dependence Traditional photon ITV approach to moving targets works fairly well Scanning beams scan through the target volume ~msec time scale for a single spot ~100s to 1000s spots per layer ~Several to dozens of layers per field ~Seconds to change energy 1 field may take tens of seconds to ~ 1 min Some portions of target may be double painted, others missed

47 Interplay Effects Bert et al., PMB 53 (2008) p. 2253

48 Solutions for Moving Targets Optimized Planning Parameters Gating Breath hold Repainting Tracking

49 Optimized Planning: Spot Spacing Bert et al., IJROBP 73 (2009) p. 1270

50 Optimized Planning: Scanning Direction Static 1 cm parallel 1 cm orthogonal Johnson et al., in preparation

51 Delivery Options: Breath Hold Careful patient selection a must Feedback tools, coaching Reduced treatment time Faster energy changes Reduced number of energy levels

52 Reducing Number of Energy Levels Gillin et al., Med Phys 37 (2010) p. 154

53 Reducing Number of Energy Levels Cournyea et al., AAPM 2013 Tues AM Mini ridge filter introduces modest spatial dependence of beam energy Spatial component disappears quickly with phantom scatter Shallower dose falloff allows for fewer energy levels Decreased treatment time Higher dose/spot

54 Treatment Times with Ridge Filter Standard plans: 67 s (no MRF) <30 s (w/ MRF) Stereotactic plans: 95.4 s (no MRF) 47.7 s (min) Diminishing gains as MRF thickness increased. Average Time/Field (s) σ SR σ SR 4 σ SR 2 σ 3 σ 4 σ MRF Thickness (cm) Cournyea et al., AAPM 2013 Tues AM

55 Delivery Options: Repainting Only a portion of the prescribed dose delivered in a single pass Repeat the delivery multiple times per fraction Individual hot/cold spots averaged out as number of repaints increases

56 Delivery Options: Repainting 1 Scan 10 Scans Furukawa et al., Med Phys 37 (2010) p. 4874

57 IGRT in Mayo Clinic Half Gantry Fast Intra-Tx imaging at any gantry/couch position Fluoroscopy capable Large FOV No moving parts stable imaging isocenter 6 DOF matching software

58 IGRT in Mayo Clinic Half Gantry Limited to two imaging angles FOV is 30 cm x 30 cm at isocenter may not see center of tumor volume for non-isocentric plans Not CBCT capable

59 Utility of CBCT for Protons Bony anatomy is often a poor surrogate for target/critical anatomy Fiducials or CT localization required in cases where we expect movement of soft tissues relative to radiographically evident bony anatomy Photons: Place target tissue at isocenter, don t worry about upstream bony anatomy Protons:??

60 CT Localization for Protons: Pelvis Change in position of bony anatomy alters dose distribution CT localization may be of limited use

61 CT Localization for Protons: Lung Change in position of rib causes minimal disturbance of dose distribution CT localization of lung tumors desirable for proton therapy

62 CBCT for Lung? Mayo proton facilities will be scanning beam only Treatments of mobile tumors will probably require gating/breath hold Free-Breathing CBCT imaging a poor reference for gated/breath held treatment Gated/breath held CBCT not impossible, but not easy

63 CBCT for Adaptive Protocols Proton dose calculation is extremely sensitive to CT number accuracy CT number accuracy / consistency not generally a priority in CBCT Increased scatter relative to helical CT degrades imaging performance

64 Helical/CBCT Phantom Images CBCT Helical CT Images Courtesy of T.J. Whitaker

65 CT on Rails

66 CT on Rails Robot moves patient to imaging isocenter CT translates over patient for imaging Robot moves patient back to treatment isocenter while CT registration is performed Helical CT image quality Images for adaptive imaging Fast image acquisition 4D imaging capability

Learning Objectives. Clinically operating proton therapy facilities. Overview of Quality Assurance in Proton Therapy. Omar Zeidan

Learning Objectives. Clinically operating proton therapy facilities. Overview of Quality Assurance in Proton Therapy. Omar Zeidan Overview of Quality Assurance in Proton Therapy Omar Zeidan AAPM 2012 Charlotte, NC July 30 st, 2012 Learning Objectives Understand proton beam dosimetry characteristics and compare them to photon beams