III. Proton-therapytherapy. Rome SB - 3/5 1

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1 Outline Introduction: an historical review I Applications in medical diagnostics Particle accelerators for medicine Applications in conventional radiation therapy II III IV Hadrontherapy, the frontier of cancer radiation therapy Proton-therapytherapy Carbon ion therapy Neutrons in cancer therapy V Rome SB - 3/5 1

2 Electron linacs for radiation therapy Rome SB - 3/5 2

3 An electron linac mounted on a rotating gantry Rome SB - 3/5 3

4 Characteristics 3 GHz cavities Traveling wave principle p (electrons are already relativistic at 500 kev) Gradient about 10 MeV / m Rome SB - 3/5 4

5 Klystrons Klystrons (sometimes magnetrons) are used to produce the 3 GHz radiofrequency power that t is brought to the cavities by a wave guide. The electron gun In a klystron: produces a flow of electrons. The bunching cavities regulate the speed of the electrons so that they arrive in bunches at the output cavity. The bunches of electrons excite microwaves in the output cavity of the klystron. The microwaves flow into the waveguide transports them to the accelerator. The electrons are absorbed in the beam stop., which Rome SB - 3/5 5

6 Proton and ion accelerators Rome SB - 3/5 6

7 Main uses and types Production of isotopes Hadrontherapy Cyclotrons Cyclotrons (linacs) Synchrotrons (linacs?) Rome SB - 3/5 7

8 Main components Components: Ion sources Injection devices Vacuum chamber and vacuum pumps Radio-frequency acceleration cavities and radio-frequency generators Magnets Bending dipoles Focusing quadrupoles (sextupoles) Extraction devices Beam transport lines Rome SB - 3/5 8

9 Magnets Rome SB - 3/5 9

10 Bending dipoles Rome SB - 3/5 10

11 C and H bending dipoles Rome SB - 3/5 11

12 Quadruploles Rome SB - 3/5 12

13 Quadrupoles Used for focusing the beams The quadrupole poles are hyperbolic constant t magnetic field gradient focusing lens in x and defocusing in y,, or vice versa. Focusing Defocusing Rome SB - 3/5 13

14 Strong focusing Quadrupoles are used in multiplets the global effect is focusing! Example : in a doublet lenses alternate in sign, and x and y are opposite. Focusing and defocusing alternate in the two planes. x, x Emittance plane (x plane only!) The key point is that the beam is smaller in the defocusing lenses than in the focusing lenses. Rome SB - 3/5 14

15 Cyclotrons for the production of radio-isotopesisotopes Rome SB - 3/5 15

16 The cyclotron Cyclotron frequency ν = qb /2πm Independent from the speed! For protons: ν = B[T]x1528MHz/T Rome SB - 3/5 16

17 Main requirements for the production of radioisotopes High currents : 10 μa to 2 ma Energies: MeV protons for PET isotopes (18-F) 30 MeV for industrial production of isotopes for SPECT 70 MeV or more and multi-particle (deuterons, alphas, ions) mainly for research Rome SB - 3/5 17

18 Example: the TR30 cyclotron 30 MeV, up to 1.5 ma proton beams Magnetic field (average) 1.2 T Cyclotron frequency : MHz CYCLOTRON CONCEPT Courtesy ACSI Vancouver, Canada Rome SB - 3/5 18

19 Extraction Inside the cyclotron H - ions are accelerated (not protons) Extraction through stripping foil (efficiency about 100%) Two 45 degrees dees RF frequency 73 MHz (4 th harmonic) RF field 50 kv Magnetic field Not constant! 4 accelerations per turn: 50 kev x4= 200 kev/turn 150 turns to reach 30 MeV Hills : 1.9 T Valleys : 0.5 T Trajectories are not circular! Rome SB - 3/5 19

20 The world s largest cyclotron Non relativistic relativistic i Rome SB - 3/5 TRIUMF laboratory, Vancouver Canada 500 MeV protons (they start to be relativistic see the shape of the dees ) up to 50 μa (25 kw power only on the beam!) 18 m diameter, 4000 tons 20

21 Accelerators for hadrontherapy Rome SB - 3/5 21

22 The accelerators used today in hadrontherapy Teletherapy with protons (~ 200 MeV) CYCLOTRONS (Normal or SC) SYNCHROTRONS OR 6-9 metres 4-5 metres Teletherapy with carbon ions (~ 4800 MeV) SYNCHROTRONS metres Rome SB - 3/5 22

23 Why? Beam rigidity : is the product of the magnetic field B and the radius of curvature ρ for a charged particle in that magnetic field With some kinematics B ρ = 2 2mc E q e c For 200 MeV protons : 2.1 T m For 4800 MeV carbon ions : 5.8 T m For the same B the radius of curvature is three times larger for carbon ions! Rome SB - 3/5 23

24 The time structures of the beams are very different CYCLOTRONS (*) (Normal or SC) SYNCHROTRONS Current 15 1 sns BEAM ON Energy BEAM ON 1-4s OFF 1.5 s BEAM ON time A pulsed beam of fixed energy is always present time A cycling beam of variable energy has ~1 second gaps (*) () A synchrocyclotrons y cycles at hundreds Hertz Rome SB - 3/5 24

25 Cyclotron solution for protons by IBA - Belgium Beam transport lines Energy Selection System (ESS) IBA 230 MeV Cyclotron Gantry Rome SB - 3/5 Courtesy, IBA, Belgium 25

26 A cyclotron needs a long ESS Courtesy, IBA, Belgium 230 MeV Cyclotron ESS = Energy Selection System MGH, Boston, USA Beam energy <230 MeV According to the treatment panning Rome SB - 3/5 26

27 Proton synchrotron solution by Mitsubishi Synchrotron 4 Bending Magnets Gantry Rome SB - 3/5 Horizontal beam room 27

28 Hitachi synchrotron: M.D. Anderson center in Houston 6 Bending Magnets Rome SB - 3/5 28

29 Synchrotron solution for protons and carbon ions Ion- Source s Synchrotron LINAC High Energy Beam Transport Line Quality Assurance Gantry Treatment halls 29 HIT project in Heidelberg (Germany) 24 m diameter synchrotron Carbon ion gantry : 600 tons, 24 m diameter Rome SB - 3/5

30 The synchrotron of the CNAO under construction in Pavia, Italy 25 m Centro Nazionale di Adroterapia Oncologica 25 m diameter synchrotron based on the PIMMS study (CERN, TERA, et al.) Protons and carbon ions 4 fixed beams, 3 treatment rooms Rome SB - 3/5 30

31 Two projects for the future of hadrontherapy Rome SB - 3/5 31

32 IBA: the new 400 MeV/u SC cyclotron Axial injection 65m m Field map Still in a R&D phase 600 tons Proton and carbon ion therapy Other ions can be accelerated (Li, Be) Rome SB - 3/5 32

33 The CYCLINAC: a project of the TERA Foundation, Italy Linear accelerator Cyclotron Hadron therapy CYCLINAC = CYClotron + LINAC Commercial cyclotron for the production of radioisotopes Linac to boost the beam energy for hadron-therapy Two main functions DIAGNOSTICS + THERAPY Rome SB - 3/5 33

34 Prototype of LIBO (3 GHz LInac BOoster) 73 MeV Collaboration INFN-CERN CERN-TERA Module tested at LNS of INFN, Catania NIM A 521 (2004) 512 Accelerated beam from the 60 MeV cyclotron clotron of LNS Rome SB - 3/5 34

35 Bragg curves obtained by switching off klystrons 1 20 Klystrons on 15 Klystrons on Klystrons on tits] Dose [scaled u Klystrons on 0Kl Klystrons stronson Variation by dephasing last klystron Depth [cm] Rome SB - 3/5 35

36 End of part III Rome SB - 3/5 36