NPL’s activities dosimetry for proton and ion therapy

Hugo Palmans

Radiation Dosimetry Team, National Physical Laboratory, Middlesex, UK

hugo.palmans@npl.co.uk

Why proton dosimetry at NPL?

• Only one low-energy centre in the UK for tumours of the eye (Clatterbridge Centre of Oncology: CCO)

• Since then: fail bids for high-energy proton facilities from CCO, Oxford, Daresbury, etc and now BASROC and LIBRA + NRAG documents

• In the mean time in USA (6+5), Japan (8), Germany (6), Italy (3), France (3), China (2) + new technologies (superconducting cyclotrons, dielectric wall accelerators, laser induced protons)

• Recent proton dosimetry projects with the aim of getting it to the level of photon and electron beam dosimetry: SR project 2002-2003, 2 NMS projects 2004-2007, 1 NMS project 2007-2010, LIBRA (Laser induced proton and ion beams) 2008-2011, EMRP JRP7 WP3 2008-2010

• Microbolometry with the aim of extending the scope of the quantiy of absorbed dose: SR project 2008, PhD UoS/NPL 2008-2011

Overview: 8 experiments or simulations, 1 slide each

• Graphite calorimetry• Total absorption calorimetry• Water equivalence of graphite and other materials I: DD

measurements• Water equivalence of graphite and other materials II:

Faraday cup attenuation measurements• Alanine dosimetry• Ionization chamber dosimetry• Near future: Microbolometry• Distant future: Biosensors

Calorimetry: Graphite calorimetry for protons (Palmans et al 2004, Phys Med Biol 49:3737-49)

T.khcD .

0.96

0.97

0.98

0.99

1.00

1.01

1.02

Dca

l/Dio

n

0.98

0.99

1.00

1.01

1.02

1.03

1.04

NE2561 (Co-60)

NACP02 (Co-60)

Markus (Co-60)

NACP02 (e-19)

Markus (e-19)

modulated beam

Jun-03

Jun-03

Jun-03

Jun-03

Jun-03

Jun-03

Jun-03

non-modulated beam

0.96

0.97

0.98

0.99

1.00

1.01

1.02

Dca

l/Dio

n

0.98

0.99

1.00

1.01

1.02

1.03

1.04

NE2561 (Co-60)

NACP02 (Co-60)

Markus (Co-60)

NACP02 (e-19)

Markus (e-19)

modulated beam

Jun-03

Jun-03

Jun-03

Jun-03

Jun-03

Jun-03

Jun-03

non-modulated beam

33,0

34,0

35,0

36,0

37,0

0 100 200 300 400

E (MeV)

wair

(J/C

) ECHED

AAPM-16

ICRU 59

IAEA TRS398

33,0

34,0

35,0

36,0

37,0

0 100 200 300 400

E (MeV)

wair

(J/C

) ECHED

AAPM-16

ICRU 59

IAEA TRS398

33,0

34,0

35,0

36,0

37,0

0 100 200 300 400

E (MeV)

wair

(J/C

)

33,0

34,0

35,0

36,0

37,0

0 100 200 300 400

E (MeV)

wair

(J/C

) ECHED

AAPM-16

ICRU 59

IAEA TRS398

ECHED

AAPM-16

ICRU 59

IAEA TRS398

ICRU 59ICRU 59

IAEA TRS398IAEA TRS398

Total absorption calorimetry (Palmans et al 2007 NPL report IR 4)

pin

p

n

pin

p

n

• Proton beam energy determination using total absorption calorimetry requires knowledge of the escaping energy fraction

• Simulations using PTRAN, MCNPX and Geant4

PlatesMarkus

Roos

Protonbeam

Markus

Roos

Protonbeam

0.98

0.99

1.00

1.01

1.02

1.03

1.04

0.0 0.5 1.0 1.5 2.0 2.5 3.0

depth (g cm-2)

flu

en

ce

co

rre

cti

on

fa

cto

r

r0 @ 50% distal

r0 @ 80% distal

r0 from ICRU49

Geant4 simulations:

0.980

0.990

1.000

1.010

1.020

1.030

1.040

0.0 0.5 1.0 1.5 2.0 2.5 3.0

water equivalent depth (g cm-2)

flu

en

ce

co

rre

cti

on

fa

cto

r

QGSP

QGSP BERT

QGSP BIC

precompund

Water equivalence of graphite I: PDD and TPR measurements

Water equivalence of graphite II: Faraday cup attenuation measurements

To elec-trometer

Plates

Faraday cup

Monitorchamber

Protonbeam

Guard

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

0.0 1.0 2.0 3.0 4.0

Graphite thickness (cm)

Ch

arg

e (

nC

)

Measured data points

Attenuation fit

Tangent at 50% range

Distal edge fit

•Factor 2 to 3 higher than expected from ICRU 63 tables: not as yet understood. •Hypothesis: wide angle secondary protons:

Plates

Faraday cup

Guard

Alanine dosimetry: CCO experiment I

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0

depth (cm)

do

se p

er m

.u. (

Gy)

diodealanine pelletsresponse 1response 2

response 3

0.00

0.10

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0.50

0.60

0.70

0.0 0.5 1.0 1.5 2.0 2.5 3.0

depth (cm)

do

se p

er m

.u. (

Gy)

ion chamberalanine pelletsresponse 1response 2response 3

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10

0.00 0.50 1.00 1.50 2.00

log(Eeff)

rela

tive

eff

ecti

ven

ess

Bradshaw et al. (1962)Ebert et al. (1965)Hansen and Olsen (1985)Onori et al. (1997)Cuttone et al. (1999)Bartolotta et al. (1999)Fattibene et al. (2002)

NPL1 (range scaled)

Alanine dosimetry: CCO experiment II

0.60

0.70

0.80

0.90

1.00

0.01 0.1 1 10Rres (g cm-2)

Re

lati

ve

Eff

ec

tiv

en

es

s

Thin pellets per two

Stack of thin pellets

Thick pellets one by one

Full energy

0.60

0.70

0.80

0.90

1.00

0.01 0.1 1 10Rres (g cm-2)

Re

lati

ve

Eff

ec

tiv

en

es

s

Thin pellets per two

Stack of thin pellets

Thick pellets one by one

Stack of thick pellets

Full modulated

PlatesProtonbeam

MarkusPlatesProtonbeam

MarkusPlatesProtonbeam

Markus Plates

OR

Ionization chamber dosimetry

Ion recombination (Palmans et al 2006, Phys Med Biol 51:903-17)

BEAM

PHANTOM

IC AIR CAVITIES

IC1 IC2BEAM

PHANTOM

IC AIR CAVITIES

IC1 IC2

Ion chamber perturbations (Palmans 2006, Phys Med Biol 51:3483-501 + ongoing work)

1

2

3

Geometry interrogation region

Protonbeam

E

d /dE

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

0.0 10.0 20.0 30.0

Depth (mm)

D air p

er p

roto

n p

er c

m2

(Gy)

-5.0

0.0

5.0

Differen

ce pd

d an

d

recon

structio

n

Mobit et al. 2000 Med. Phys. 27:2780-2787

78 MeV protons

Jäkel et al. 2000 Phys. Med. Biol. 45:599-607

3 GeV 12C

0.0

0.5

1.0

1.5

2.0

2.5

0.0 20.0 40.0 60.0

depth (mm)

no

rmal

ised

do

se (

a.u

.)

AttixCapintec PR06Reconstructed

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

115.0 120.0 125.0 130.0

depth (mm)

rela

tive

do

se

ReferencePTW-30006Markus

Reconstructed 0.995

1.000

1.005

1.010

1.015

1.020

0 5 10 15

Chamber #

Dw

,NE

2571

/Dw

,Ch

C-C&PTW30002

A150-Al&NE2581

PMMA-Al&PTW30001

Nylon66-Al

IC18

ExrT2

Microbolometry

•Absorbed dose to water OK for conventional photon and electron beams•Not sufficient for protons and carbon ions ->absorbed dose * biological quality factor•Need for physical quantity that is relevant for biological effect expressed by CCRI/BIPM

Microbolometer

Energy absorption

Absorber

Squid Superconductor

•NPL SRER project in collaboration with quantum detection group

•UoS/NPL PhD project

Biosensor

• A biochemical system with a relevant biological response to ionising radiation that can be determined physically in a reproducible (and preferably reversible) way.

• Questions to explore:Where is the need?

Level of complexity of response?

How good are biological effects understood?

Engineering of such a system?