Carbon ion gantries Marco Pullia Fondazione CNAO M. Pullia Carbon - PowerPoint PPT Presentation

Carbon ion gantries Marco Pullia Fondazione CNAO M. Pullia – Carbon ion gantries – ICTR-PHE 2012 1

What is a gantry A gantry is a rotating beam line that allows directing the beam on the patient from any direction Conventional RT Gantry M. Pullia – Carbon ion gantries – ICTR-PHE 2012 2

Why a gantry Allows better, more robust planning: e.g. minimize fields pointing towards OAR (Organ At Risk) With horizontal line only With gantry O.A.R. M. Pullia – Carbon ion gantries – ICTR-PHE 2012 3

Treatment planned with gantry + + = M. Pullia – Carbon ion gantries – ICTR-PHE 2012 4

Size and magnetic rigidity Carbon Ion Gantry Conventional RT B ρ < 6.4 Tm Proton Gantry B ρ < 2.4 Tm M. Pullia – Carbon ion gantries – ICTR-PHE 2012 5

The CNAO 90° magnet during installation in the vertical line. The size is the same as for a gantry final magnet. M. Pullia – Carbon ion gantries – ICTR-PHE 2012 6

Present Many proton gantries (tens) Only one C gantry worldwide: L = 25 m x φ = 13 m, 600 t Very large, very heavy, very expensive Fixed Isocenter 360° rotation Parallel scanning 200 mm x 200 mm 140 t magnets 120 t shielding-counterweight (Udo Weinrich, GSI) 600 t total rotating mass M. Pullia – Carbon ion gantries – ICTR-PHE 2012 7

Can we make it better? — As usual we want everything and its opposite at the same time… ◦ Small aperture final magnet to lower power consumption, but scanning upstream ◦ Small radius, but space around isocenter ◦ Light magnets, but possibly non superconducting ◦ Maximum performance, but cheap ◦ … M. Pullia – Carbon ion gantries – ICTR-PHE 2012 8

Aspects and ideas to be considered — Scanning or scattering Not really a choice M. Pullia – Carbon ion gantries – ICTR-PHE 2012 9

Aspects and ideas to be considered — Scanning — SAD and scanning magnets position M. Pullia – Carbon ion gantries – ICTR-PHE 2012 10

Scanning magnets position — Large aperture dipole: weight and power consumption — Large gantry radius and large room size M. Pullia – Carbon ion gantries – ICTR-PHE 2012 11

Aspects and ideas to be considered — Scanning — SAD and scanning magnets position — 360° vs 180° M. Pullia – Carbon ion gantries – ICTR-PHE 2012 12

360° vs 180° — By rotating the couch by 180°, all the beam directions are possible also with only 180° of rotation of the gantry 180° M. Pullia – Carbon ion gantries – ICTR-PHE 2012 13

Aspects and ideas to be considered — Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching M. Pullia – Carbon ion gantries – ICTR-PHE 2012 14

Field patching Scan in one go Scan and move (~PSI gantry 1) Move Move Move couch couch couch Reduces magnet aperture, but slower procedure and difficulties somehow similar to simultaneous optimisation of multiple fields with IMPT M. Pullia – Carbon ion gantries – ICTR-PHE 2012 15

Aspects and ideas to be considered — Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching — Fixed or mobile isocenter M. Pullia – Carbon ion gantries – ICTR-PHE 2012 16

Fixed or mobile isocenter — Most of the existing gantries have a fixed isocenter on the rotation axis of the gantry. This implies large masses rotating at large radius. M. Pullia – Carbon ion gantries – ICTR-PHE 2012 17

Mobile isocenter PSI gantry 1 ( E. Pedroni ) An isocenter, through which all the directions pass, exists but its position depends on gantry orientation. M. Pullia – Carbon ion gantries – ICTR-PHE 2012 18

PSI Gantry 1 M. Pullia – Carbon ion gantries – ICTR-PHE 2012 19

Mobile isocenter - 2 Side access, PIMMS Patient positioned in a small room “somewhere” 15 m 10 m 5.6 m Gantry is longer, than just the last magnet but at small r Front access M. Pullia – Carbon ion gantries – ICTR-PHE 2012 20

Aspects and ideas to be considered — Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching — Fixed or mobile isocenter — Multi-room system M. Pullia – Carbon ion gantries – ICTR-PHE 2012 21

Multi-room system — Proposed by A.Brahme 1 -90<f<-30 1 -90<f<-30 2 -30<f<30 3 30<f<90 3 30<f<90 15m 0 5m 15m 10m 0 5m 10m ( M. Kats ) M. Pullia – Carbon ion gantries – ICTR-PHE 2012 22

Aspects and ideas to be considered — Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching — Fixed or mobile isocenter — Multi-room system — Divergent scanning M. Pullia – Carbon ion gantries – ICTR-PHE 2012 23

Divergent scanning — Last drift 2m — SAD 5.5 m (1 plane only!) — Quad g = 8 T/m — Gap reduced by 30% Scan ¡V Scan ¡H Quad M. Pullia – Carbon ion gantries – ICTR-PHE 2012 24

Aspects and ideas to be considered — Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching — Fixed or mobile isocenter — Multi-room system — Divergent scanning — Superconducting magnets M. Pullia – Carbon ion gantries – ICTR-PHE 2012 25

Superconducting magnets If possible no He, use cryo-coolers Fabbricatore et al, 2001 M. Pullia – Carbon ion gantries – ICTR-PHE 2012 26

Straight coil heads Difficult to wind GFR 200 mm x 60 mm (field patching) Fabbricatore et al, 2001 M. Pullia – Carbon ion gantries – ICTR-PHE 2012 27

Preliminary studies done at Saclay ▪ Preliminary study for IBA (2008 - … ) - Irfu (SACM, SIS) - Focused on the SC 90 d° dipole - End of the first part: mid 2010 (Courtesy of F. Kircher) - Prolongation of the study under discussion Ulice meeting 23/11//2010 28

Double helix 5 T, Large good field region (26 cm diameter) Courtesy of Caspi, Robin, Arbelaez, Sessler, Sun, Hafalia, Yoon, Wan M. Pullia – Carbon ion gantries – ICTR-PHE 2012 29

Aspects and ideas to be considered — Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching — Fixed or mobile isocenter — Multi-room system — Divergent scanning — Superconducting magnets — FFAG gantry M. Pullia – Carbon ion gantries – ICTR-PHE 2012 30

FFAG Gantry 150-400 MeV/u 1500 kg of magnets Very large M. Pullia – Carbon ion gantries – ICTR-PHE 2012 31

FFAG Gantry (D. Trbojevic) M. Pullia – Carbon ion gantries – ICTR-PHE 2012 32

Other ideas — Active alignment — Active compensation of magnetic defects (scanning quadrupoles and sextupoles) — Scanning by moving magnets — … M. Pullia – Carbon ion gantries – ICTR-PHE 2012 33

Gantry in european projects — Gantry studies have been proposed in the framework of european projects: ULICE and PARTNER M. Pullia – Carbon ion gantries – ICTR-PHE 2012 34

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Functional specifications survey Involve users (doctors) since the beginning of the study 37 https://espace.cern.ch/project-ULICE-WP6-Hadrontherapy-Survey/Lists/ULICE%20WP6%20Questionnaire/AllItems.aspx

Specs from questionnaire analysis Gantry functional specifications ¡ Field size ¡ 15 x 15 cm 2 or 10/15 x 20 cm 2 ¡ Number of fields per session ¡ 4 ¡ Penetration depth (range) ¡ 3 – 30 cm (corresponding energy: p = 60 - 220MeV; ¡ C ion = 120 – 430 MeV/u) ¡ Voxel dose accuracy ¡ ±1% ¡ Dose uniformity ¡ ±2.5% ¡ Voxels characterization ¡ 3 x 3 x 3 mm 3 ¡ Voxels out of range ¡ 1% ¡ Field position accuracy ¡ ±0.5 mm ¡ SAD ¡ 4 m ¡ Maximum treatment time ¡ 30 min ¡ Required space around isocentre ¡ 60 cm ¡ Achieved beam directions ¡ ALL ¡ “Deliverable Report JRA6.1 – Functional specifications”, June 2010 38

The 90° conventional dipole GFR 20 x 20 cm GFR 20 x 15 cm Max 3.208 (T) Max m 3.208 (T) 3 3.0 2.5 2.5 2.0 2.0 m 20cm 15cm 1.5 1.5 20cm 20cm 1.0 1.0 0.5 Min 2.57x10 -9 (T) 1.89 m Min 2.57x10 -9 1.78 m 20 ton gain 39

March 2011: choice of typology The ULICE WP6 collaboration decided to realize the conceptual design of a 180°, normal conducting, mobile isocenter gantry, 20 x 20 cm 2 field , revisiting the layout of the Riesenrad gantry investigated by the PIMMS Rationale for our choice Cheaper and simplified mechanical structure Design conceived for conventional magnets • • Less magnets in the gantry line Well known magnet technology • • Total weight reduced as well as deformations Layout adaptable to SC magnets • • LOWER COST ESTIMATE by mechanical firms with experience in the field

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Access M. Pullia – Carbon ion gantries – ICTR-PHE 2012 42

Mechanical structure: preliminary study Gaddi: Physics Dep. CERN 43

Conclusions — Carbon ion gantries are needed — There are margins for optimisation — There are studies ongoing — It looks likely that new carbon ion gantries will be built in the next future M. Pullia – Carbon ion gantries – ICTR-PHE 2012 44

That’s all,folks — Thank you for your attention M. Pullia – Carbon ion gantries – ICTR-PHE 2012 45