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

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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

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Carbon ion gantries

Marco Pullia Fondazione CNAO

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  • M. Pullia – Carbon ion gantries – ICTR-PHE 2012
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What is a gantry

  • M. Pullia – Carbon ion gantries – ICTR-PHE 2012

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A gantry is a rotating beam line that allows directing the beam on the patient from any direction

Conventional RT Gantry

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Why a gantry

  • M. Pullia – Carbon ion gantries – ICTR-PHE 2012

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Allows better, more robust planning: e.g. minimize fields pointing towards OAR (Organ At Risk)

O.A.R. With gantry With horizontal line only

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Treatment planned with gantry

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+ + =

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Size and magnetic rigidity

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Conventional RT Proton Gantry Bρ < 2.4 Tm Carbon Ion Gantry Bρ < 6.4 Tm

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The CNAO 90° magnet during installation in the vertical line. The size is the same as for a gantry final magnet.

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Present

Many proton gantries (tens) Only one C gantry worldwide: L = 25 m x φ = 13 m, 600 t

(Udo Weinrich, GSI)

Fixed Isocenter 360° rotation Parallel scanning 200 mm x 200 mm 140 t magnets 120 t shielding-counterweight 600 t total rotating mass

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  • M. Pullia – Carbon ion gantries – ICTR-PHE 2012

Very large, very heavy, very expensive

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Can we make it better?

— As usual we want everything and its

  • pposite 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

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Aspects and ideas to be considered

— Scanning or scattering

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Not really a choice

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Aspects and ideas to be considered

— Scanning — SAD and scanning magnets position

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Scanning magnets position

— Large aperture

dipole: weight and power consumption

— Large gantry

radius and large room size

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Aspects and ideas to be considered

— Scanning — SAD and scanning magnets position — 360° vs 180°

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360° vs 180°

— By rotating the couch by 180°, all the

beam directions are possible also with

  • nly 180° of rotation of the gantry
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180°

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Aspects and ideas to be considered

— Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching

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Field patching

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Move couch Move couch Move couch

Scan in one go Scan and move (~PSI gantry 1) Reduces magnet aperture, but slower procedure and difficulties somehow similar to simultaneous

  • ptimisation of multiple fields with IMPT
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Aspects and ideas to be considered

— Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching — Fixed or mobile isocenter

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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.

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Mobile isocenter

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PSI gantry 1

(E. Pedroni)

An isocenter, through which all the directions pass, exists but its position depends on gantry

  • rientation.
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PSI Gantry 1

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Mobile isocenter - 2

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  • M. Pullia – Carbon ion gantries – ICTR-PHE 2012

5.6 m 15 m

Side access, PIMMS Front access

Gantry is longer, than just the last magnet but at small r 10 m Patient positioned in a small room “somewhere”

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Aspects and ideas to be considered

— Scanning — SAD and scanning magnets position — 360° vs 180° — Field patching — Fixed or mobile isocenter — Multi-room system

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Multi-room system

— Proposed by A.Brahme

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5m 10m 15m 5m 10m 15m

1 -90<f<-30 2 -30<f<30 1 -90<f<-30 3 30<f<90 3 30<f<90

(M. Kats)

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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

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Divergent scanning

— Last drift 2m — Quad g = 8 T/m

Scan ¡V Scan ¡H Quad

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  • M. Pullia – Carbon ion gantries – ICTR-PHE 2012

— SAD 5.5 m (1 plane only!) — Gap reduced by 30%

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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

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Superconducting magnets

Fabbricatore et al, 2001

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  • M. Pullia – Carbon ion gantries – ICTR-PHE 2012

If possible no He, use cryo-coolers

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  • M. Pullia – Carbon ion gantries – ICTR-PHE 2012

Straight coil heads Difficult to wind GFR 200 mm x 60 mm (field patching)

Fabbricatore et al, 2001

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Ulice meeting 23/11//2010 28

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
  • Prolongation of the study under discussion

(Courtesy of F. Kircher)

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Double helix

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Courtesy of Caspi, Robin, Arbelaez, Sessler, Sun, Hafalia, Yoon, Wan

5 T, Large good field region (26 cm diameter)

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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

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FFAG Gantry

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150-400 MeV/u 1500 kg of magnets Very large

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FFAG Gantry

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(D. Trbojevic)

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Other ideas

— Active alignment — Active compensation of magnetic defects

(scanning quadrupoles and sextupoles)

— Scanning by moving magnets — …

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Gantry in european projects

— Gantry studies have been proposed in the

framework of european projects: ULICE and PARTNER

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Functional specifications survey

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https://espace.cern.ch/project-ULICE-WP6-Hadrontherapy-Survey/Lists/ULICE%20WP6%20Questionnaire/AllItems.aspx

Involve users (doctors) since the beginning of the study

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Specs from questionnaire analysis

38 Gantry functional specifications ¡ Field size ¡ 15 x 15 cm2 or 10/15 x 20 cm2 ¡ 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 mm3 ¡ 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

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GFR 20 x 20 cm GFR 20 x 15 cm 1.89 m 1.78 m

The 90° conventional dipole

20cm 20cm 20cm 15cm

Min 2.57x10-9(T)

Max 3.208 (T)

Min 2.57x10-9

Max 3.208 (T)

3 2.5 2.0 1.5 1.0 0.5 3.0 2.5 2.0 1.5 1.0

m m

20 ton gain

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March 2011: choice of typology

  • Cheaper and simplified mechanical structure
  • Less magnets in the gantry line
  • Total weight reduced as well as deformations
  • Design conceived for conventional magnets
  • Well known magnet technology
  • Layout adaptable to SC magnets

Rationale for our choice

The ULICE WP6 collaboration decided to realize the conceptual design of a 180°, normal conducting, mobile isocenter gantry, 20 x 20 cm2 field, revisiting the layout of the Riesenrad gantry investigated by the PIMMS

LOWER COST ESTIMATE by mechanical firms with experience in the field

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Access

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Mechanical structure: preliminary study

Gaddi: Physics Dep. CERN

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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

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That’s all,folks

— Thank you for your attention

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