Innovative developments for proton therapy at PSI beam
Innovative developments for proton therapy at PSI: beam delivery with SC magnets Marco Schippers, Alex Gerbershagen, David Meer Paul Scherrer Institut Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 1
Contents • Dose spreading in proton therapy • Gantries • PSI’s Gantry-2 with SC magnets • Conclusions & WHAT DO WE NEED ? Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 2
Dose delivery techniques: Width transversal spread: scattering Scatter syst. scanning Collimator Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 3
scanning Down-stream scanning: + small aperture, - large radius because of SAD - small spots difficult X Y Rgantry SAD = 1. 5 m X Y Up-stream scanning: + parallel Rgantry + small gantry radius + small spots possible - wide aperture SC magnet Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 4
3 D Pencil beam scanning: DEPTH V e E=155 M e. V M 0 5 1 = E V e M 5 4 E=1 ts e n n ing n ca S g a M il c n m a be pe Developments at PSI: beam delivery with SC magnets. > = y ) g r e lane n e p n n o t a o c Pr h (s t p de Marco Schippers, PSI 5
3 D Pencil beam scanning: DEPTH After each layer: Energy change in 100 ms (~1% d. B/B) Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 6
Using large momentum acceptance: Static Delivery of Spr. Out Bragg Peak p 0 -δ p 0 Developments at PSI: beam delivery with SC magnets. p 0+δ • SOBP can be delivered without magnetic field changes Marco Schippers, PSI 7
Gantry design Some typical gantries…. . Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 8
R≈6 m IBA & Optivus Gantry for protons ~90 t Loma Linda (Optivus) Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 9
PSI Gantry-2: fast 3 D scanning magnets (x & y) for 2 D // scanning R=3. 5 m 90 degr. magnet: 1. 5 T 15 cm gap, 45 Tons, d. B/B 1% in 80 -100 ms PSI-”Gantry-2” Eros Pedroni Field: 20 x 12 cm 2 Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI David Meer 10
PSI-Optics for 350 Me. V originaly from: 235 Me. V y-plane 5 cm 350 Me. V x-plane 14 m SCAN 5 cm δ = 0% δ = 3% IN-Beam (2 ): x = y = 3. 0 mm , x’ = y’ = 7. 0 mr PSI optics: • Point-to-point imaging • Positive pole face rotations Large emittance and momentum acceptance: ε = 21π mm. mrad and δ = ± 3% Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 11
Gantry 2 Layout Three dipoles with -60°, 60° and 90° bending Scanning magnets upstream from the 90° bending section: parallel scanning Radius = 3. 2 m Length = 8. 9 m Weight = 200 t Gantry 2 Scanning field: 12 x 20 cm 2 Radius = 4. 5 m (can be reduced for upstream scanning version) Length = 8. 4 m Superconducting gantry Developments at PSI: beam delivery with SC magnets. Weight < 50 t Scanning field: 20 x 25 cm 2 Marco Schippers, PSI 12
Beam Optic Gantry-2 & SC version Q M L 1 Q M L 2 A M L 1 Q M L 3 Q M L 4 A M L 2 Q M L 5 Q M L 6 Q M L 7 W M L T W M L U A M L 3 Gantry 2 optics: Momentum acceptance: Δp/p = 0. 7 % M M M K M M B D B B M 2 H H B C C B 3 3 4 2 1 2 2 M L P 1 Q M L C H M L 1 M L P 3 M L P 5 H M L 2 I E S N O D 3 Disp D=0 ersio S M L 1 K K M M B B 1 1 S M L 2 n (1% dp) S M L 3 U P G 3 SC Bending sections: dipole +combined Q+D : dispersion suppression => Very large momentum acceptance: S M D 5 M M D DM B 1 7 2 3 H K U M P B 1 G 3 Q D 1 4 A M L A A M L B A M L C Q M L 1 Q M L 2 Q M L 3 Q M L 4 Δp/p > 10 % A M L D A M L E A Q M 3 L F 3 3 x 20° bending magnets Developments at PSI: beam delivery with SC magnets. Q 3 4 Q M L 5 A M L 4 Q M L 6 A Q M M L 6 L 7 2 x 45° S bending W M magnets +3 quadrupoles Marco Schippers, PSI 13
Required magnet properties Types of used magnets BField (T) Maximal gradient (T/m) Aperture radius (mm) Normal conducting quadrupoles 0 31. 7 30 Superconducting combined function magnets for the first two bending sections 3 23 30 Superconducting combined function magnet for the last bending secton 4 14 125 Superconducting quadrupoles 0 9. 8 125 Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 14
Magnets in consideration Canted Coil Solenoid Cosine Theta Race rack with much less iron Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 15
Conclusions on SC-Gantry SC GANTRY: Not much smaller in diameter. Much less weight New beam optics possible large energy acceptance Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 16
What do we need ? Faster: d. B/dt > 10%/s (≈ 0. 8 T/s) Lighter: 20 tons Stronger fields: 4 T + 30 T/m But „no“ stray fields: <0. 5 T but at patient < 0. 5 m. T SC: no LHe AND no quenching Radiation resistant Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 17
The End Developments at PSI: beam delivery with SC magnets. Marco Schippers, PSI 18
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