1. Development of a superconducting rotating-gantry for carbon therapy
2017/4/27
HIMAC
NIRS
Development of a superconducting rotating-gantry for carbon therapy
Yoshiyuki Iwata
National Institute of Radiological Sciences (NIRS)
2014/12/1

2. Outline Introduction SC-gantry developments Summary Design
Construction and tests of the SC magnets
Summary

3. Introduction

4. Carbon radiotherapy Heavy Ion Medical Accelerator in Chiba (HIMAC)
Ion species: p ~ Xe
E/A=800 MeV for q/m=1/2
Cancer treatments using energetic carbon ions since 1994
Successful clinical results ~9000 patients
Linacs
(RFQ+Alvarez DTL)
Ion sources
(ECRx2, PIG)
Treatment rooms
(3 rooms)
Synchrotron rings

5. New treatment facility
Construction completed in FY2010
3 treatment rooms
Room E & F
Fixed H&V scanning ports
(in treatment operation)
Room G
Rotating gantry port
(Under construction)

6. Treatment floor (B2F) CT simulation room Gantry room Room E & F
2017/4/27
Treatment floor (B2F)
CT simulation room
Gantry room
HIMAC accelerators
Room E & F

7. Superconducting
rotating-gantry

8. Needs for a rotating gantry
【Advantage of a rotating gantry】
No need to rotate a patient
Accurate dose distributions
Intensity Modulated Particle Therapy (IMPT)
Irradiation with the existing fixed port
Beam can be directed to a target from any of medically desirable angles

9. Rotating gantry for hadron therapy
Proton therapy
Gantries are commonly used
Commercially available
Carbon therapy
Required Br is 3 times higher
Magnets will be very large and heavy
Difficult to
Design and
Construct
PSI: Gantry 2
Mitsubishi
Hitachi

10. Rotating gantry for carbon therapy
Only one gantry in the world
Heidelberg Ion Beam Therapy Center (HIT)
World first carbon-gantry
Clinical use since November 2012

11. Superconducting rotating-gantry
Use of superconducting (SC) magnets
Ion kind　 : 12C
Irradiation method: 3D Scanning
Beam energy : 430 MeV/n
Maximum range : 30 cm in water
Scan size : □200×200 mm2
Beam orbit radius : 5.45 m
Length : 13 m
The size and weight are considerably reduced
Weight: order of 300 tons

12. Layout of the SC gantry Combined function SC magnets （BM01～BM06）
　→No quadrupole magnet required
Scanning magnets on top
　→Large scan size
Combined function SC magnets
　→Square irradiation field
　→Parallel beam

13. Beam optics design Beta and dispersion functions
Beam envelope functions with kicks of scanning magnets

14. Design of superconducting magnets

15. Development of curved SC magnets
SC magnet (BM02-05)
Cross-sectional view
4K Cryocoolers
(SHI RDK-415D)
Liquid He free!
Dipole and quadrupole coils can be independently excited

16. Design of superconducting coils
2D field calculation
Dipole
|DB/B|<6×10-6
Quardupole
|DG/G|<2×10-4

17. 3D field calculation with Opera-3D
SC coils were precisely modelled
Curved SC coil

18. Corrections with the outermost layer
Coil positions of the outermost layer were modified to cancel out the measured multi-pole components
Corrected uniformity
DBL/BL<1×10-4!

19. Design of the quadrupole coil
Before
After
DGL/GL<2×10-4!

20. All the SC magnets were designed by using a 3D magnetic field solver
Design of SC magnets
All the SC magnets were designed by using a 3D magnetic field solver

21. Beam tracking simulations

22. Beam tracking simulations
Beam tracking to the isocenter
Field map data
(from Opera-3d code)
Numerical integration of
equation of motion
(4th order Runge-Kutta method)
Beam profile at isocenter
Kick angle of scanning magnets: varied
81 spots at isocenter

23. Beam tracking simulations
Phase space distribution of
three beam spots
Beam profile at the isocenter
(E=430 MeV/u)
Beam profile after correction with the scanning magnets

24. Construction and tests of the SC magnets

25. Rotation tests Model SC magnet (Toshiba corp.)
Rotation over ±180 degrees
Appling maximum coil-current
No quench observed!

26. Construction of SC magnets
BM04 (26deg)
BM10 (22.5deg)

27. Field measurements Magnetic field measurements were performed
to verify the SC magnet design

28. Fast slewing tests Tests with maximum slew-rate
I=45~136 A (E=56~430 MeV/u)
No quench observed
Average temperature converged below Tc~6.8 K
BM05
Current Pattern

29. Summary Design of the SC rotating-gantry Compact (~proton gantries)
2017/4/27
Summary
Design of the SC rotating-gantry
Compact (~proton gantries)
Construction and tests of the SC magnets
→ The test results agreed with those designed
Future plan
All the construction and installation will be made by the end of FY2014 (March 2015)
Commissioning will be made in FY2015 29

30. Collaborators
K. Noda, T. Shirai, T. Murakami, T. Furukawa, T. Fujita, K. Shouda, S. Sato, K. Mizushima, Y. Hara, and S. Suzuki (NIRS)
T. Fujimoto, H. Arai (AEC)
T. Orikasa, S. Takayama, Y. Nagamoto, T. Yazawa (Toshiba)
T. Ogitsu (KEK)
T. Obana (NIFS)
N. Amemiya (Kyoto Univ.)

31. 2017/4/27 31

32. Specifications of SC magnets
Parameters
Symbol
Unit
BM01
BM02
BM03
BM04
BM05
BM06
BM07
BM08
BM09
BM10
Type －
Superconducting sector magnet
Coil
Dipole+Quard.
Dipole
Bending angle q
deg 18 26
22.5
Bending radius r m
2.3
2.8
Maximum field
Bdipole T
2.88
2.37
Maximum field gradient
Gmax
T/m 10
1.3
Bore size
Dbore mm
f60
□122
□170
□206
Effective radius or area
Df or Af
f40
□120
□160
□200
Uniformity (dipole)
ΔBL/BL
±1×10-4
Uniformity (quadrupole)
ΔGL/GL
±1×10-3
Inductance (dipole) L H
6.2
9.1
5.2
8.9 12
Stored Energy (dipole) P kJ 57 84
133
225
319

33. Cooling of SC magnets 4K GM compact cryocoolers Liquid He free
Rotation
Heat penetration
SC coils
Beam duct
Cryocoolers
Thermal shields &
Current leads
Cooling plates

34. 2D maps of DBL/BL
I=136A
I=50A
Good field region
Aperture

35. Coil design for BM10 (large aperture)
The same corrections were made for BM10
DBL/BL map for I=231.2A
Good field region

36. New correction method DBL/BL map for I=231.2A
Good field region
New correction method was applied for dipole coil to obtain uniform BL over the 2D map

37. Uniformity for different excitation levels
DBL/BL map for I=180 A
DBL/BL map for I=91.34 A
Good field region
Good field region

38. Multiple-flattop operation
Operation pattern having multiple flattops
Each flattop can be extended
Beams having various energies can be extracted!
Extended flattop
Output beam

39. Full energy scanning
Beam energy is varied by 1 or 2 mm step in water range
E=430 – 56 MeV/u
201-flattop pattern
No energy degrader
Scanning magnets
Ridge filter
Energy degrader
Target 39