http://www.ptcri.ox.ac.uk Ken.Peach@ptcri.ox.ac.uk

A Laser Afternoon:Introduction

Ken PeachParticle Therapy Cancer Research Institute (Oxford Martin School)

&John Adams Institute for Accelerator Science, University of Oxford

Imperial CollegeDecember 13th 2012

The tax mans taken all my dough,And left me in my stately home,Lazing on a sunny afternoon.

Ray Davis (The Kinks) “Sunny Afternoon”

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Outline

• What is needed?• Where could we help?• What should we do?

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WHAT IS NEEDED?

TherapyRadiobiology

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100

80

60

40

20

50 100 150

SOBP

Pristine peak

Depth (mm)

Dos

e (%

)

tumour

Depth Dose curves – photon and proton

MV x-rays

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Relative Biological Effectiveness (RBE) & Linear Energy Transfer (LET)

• LET is related to dE/dx (Bethe Bloch)

but is the energy transferred to the medium,

not the energy lost by the particle

test

rayx

DOSEDOSE

RBE

dxdE

LET dtransferre

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RBE

• The recommended value of RBE for protons is 1.1

photon & proton irradiation

Averaged survival fractions over 3 repeated experiments.

23/Jan/2012 PTCRi Meeting 7

After AI Nagano (PTCRi, private communication)

Dose (Gy)

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Therapy Parameters: Energy30 cm

thickness of human bodyRadiography

300 MeV (p)550 MeV/u (C)

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Summary of Therapy Requirements

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Summary of Radiobiology Desiderata

• Energy reach – Protons, helium, lithium, carbon, oxygen

• to at least 10-100 mm• 20-120 MeV (p)• 60-220 MeV/u (C)

– Study mouse models in and away from the Bragg peak• Cell studies

– Probably down to a few MeV/u

• Flux– From single particle to >2 Gy/min

• Field– Micro- or Nano-beam to 100 x 100 mm2

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Requirements for both

• Desired energy – energy within 1% of specification

• Small distribution of energy– s ~1%

• Desired flux– High flux – 1%– Single particle

• Precise transverse position– <0.5mm– ~microns (single particle)

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c.f. characteristics of a LEIR Radiobiology facility

• Energy reach – Fully stripped 12C or 16O up to 240 MeV/u– 430 MeV/u (magnet limit) with new PS

• Possible beam lines– Horizontal (full energy)– Vertical (limited energy ~100 MeV/u)

• Large Hall – Currently used for storage– Space for radio biology laboratories

• Status: under consideration– Feasability study in progress– Funding?

• EU? Funding Agencies? Special budget?

Species C N O NeIntensity 1.4 109 0.4 109 1.1 109 0.25 109

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WHERE COULD WE HELP?

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A Compact Laser-Plasma Ion Source

• For radiobiology (see above)– Rapid change of ion species

• “Small” footprint– (shielding!)

• (few square metres)• Low(ish) cost

– Not defined, but “less than millions”• For therapy

– Use and an injector to a post-accelerator• FFAG-like (accelerate a spectrum)

• Later (20-30) years?– Full therapy system

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SUMMARY AND CONCLUSION

Develop a simple plasma-driven ion source?reliable, reproducible, flexible, “cheap”

Radiobiologyeasier than therapy as a first phase

Therapy injectoruseful as a second phase

Therapyeventually aim for a compact CPT facility

Is there a possible funding source?