geant4 for microdosimetry

Maria Grazia Pia, INFN Genova

Geant4 for MicrodosimetryGeant4 for Microdosimetry

MICROS 2005Venezia, 13-18 November 2005

DNADNA

R. Capra, S. Chauvie, Z. Francis, S. Guatelli, S. Incerti, B. Mascialino, Ph. Moretto, G. Montarou, P. Nieminen, Maria Grazia Pia


Object Oriented Toolkit for Object Oriented Toolkit for the simulation of particle the simulation of particle interactions with matterinteractions with matter

An experiment of distributed software production distributed software production

and managementand management

An experiment of application of rigorous software engineering methodologiessoftware engineering methodologies

and Object Oriented technology Object Oriented technology to particle physics environment

also…

Born from the requirements of large scale HEP experiments

Widely used not only in HEP

• Space science and astrophysics• Medical physics, medical imaging• Radiation protection• Accelerator physics• Pest control, food irradiation• Landmining, security• etc.

• Technology transfer

R&D phase: RD44, 1994 - 1998

1st release: December 1998

2 new releases/year since then


Domain decomposition

hierarchical structure of sub-

domains

Geant4 architecture

Uni-directional flow of

dependencies

Interface to external products w/o dependencies

in a in a nutshellnutshellRigorous software engineering

– spiral software process– object oriented methods– quality assurance– use of standards

Geometry– multiple solid representations handled through the

same abstract interface (CSG, STEP compliant solids, BREPs)

– Simple placements, parameterised volumes, replicas, assembly-volumes etc.

– Boolean operations on solids

Physics independent from tracking

Subject to rigorous, quantitative validation

Electromagnetic physics– Standard, Low-Energy, Muon, Optical etc.

Hadronic physics– Parameterised, data-driven, theory-driven models

Interactive capabilities– visualisation, UI/GUI– multiple drivers to external systems w/o

introducing dependencies


Geant4 CollaborationGeant4 Collaboration

Major physics laboratories:CERN, KEK, SLAC, TRIUMF, TJNL

European Space Agency:ESA

National Institutes:INFN, IN2P3, PPARC

Universities:Budker Inst., Frankfurt, Karolinska Inst., Helsinki, Lebedev Inst., LIP, Lund, Northeastern etc.

MoU basedDevelopment, Distribution and User Support of Geant4

~80 members


Dosimetry with Geant4Dosimetry with Geant4

Radfet #2 Radfet #4

Radfet #1#3

S300/50G300/50D300/50D690/15

DG300/50

G690/15

S690/15

DG690/15

Bulk

BulkDiode

Space science

Radiotherapy Effects on components

Multi-disciplinary application environment

Wide spectrum of physics coverage, variety of modelsPrecise, quantitatively validated physics

Accurate description of geometry and materials


Dosimetry Dosimetry in Medicalin Medical ApplicationsApplications

Courtesy of L. Beaulieu et al., Laval

Radiotherapy with external beams, IMRT

Brachytherapy

Hadrontherapy

Radiation Protection

Courtesy of J. Perl, SLAC

Courtesy of P. Cirrone et al., INFN LNS

Courtesy of S. Guatelli et al,. INFN Genova

Courtesy of F. Foppiano et al., IST Genova


Precise dose calculationPrecise dose calculation

Distance (mm)

Per

cent

dos

e

Lateral profile6MV – 10x10 field – 50mm depth

IMRT Treatment Headrange D p-valuep-value

-84 -60 mm 0.39 0.23

-59 -48 mm 0.27 0.90

-47 47 mm 0.43 0.19

48 59 mm 0.30 0.82

60 84 mm 0.40 0.10

Kolmogorov-Smirnov Test

Geant4 Low Energy Electromagnetic Physics packageElectrons and photons (250/100 eV < E < 100 GeV)

– Models based on the Livermore libraries (EEDL, EPDL, EADL)– Penelope models

Hadrons and ions– Free electron gas + Parameterisations (ICRU49, Ziegler) + Bethe-Bloch– Nuclear stopping power, Barkas effect, chemical formulae effective charge etc.

Atomic relaxation– Fluorescence, Auger electron emission, PIXE


Dosimetry: protons and Dosimetry: protons and ionsionsagreement with data

better than 3%WHOLE PEAK

(N1=149 N2=66)

Cramer –

von Mises test

Anderson – Darling test

Test statistics 0.06 0.499375

p-value 0.79 0.747452

0.52 0.443831Electromagnetic only

Inventory of Geant4 hadronic models


Radiation protection for Radiation protection for interplanetary manned interplanetary manned missionsmissions


2.15 cm Al

10 cm water

5 cm water

4 cm Al

rigid/inflatablerigid/inflatablehabitats are equivalenthabitats are equivalent

10 cm water5 cm water

Doubling the shielding Doubling the shielding thickness decreases the thickness decreases the energy deposit by ~10% energy deposit by ~10%

10 cm water10 cm polyethylene

e.m. physics + Bertini set

e.m. physics

only

shielding shielding materialsmaterials


AnthropomorphiAnthropomorphic Phantomsc Phantoms

A major concern in radiation protection is the

dose accumulated in organs at riskdose accumulated in organs at risk

Development of anthropomorphic phantom models for Geant4

– evaluate dose deposited in critical organs

Original approachOriginal approach

– analytical and voxel phantomsanalytical and voxel phantoms in the same simulation environment

Analytical phantomsAnalytical phantomsGeant4 CSG, BREPS solids

Voxel phantomsVoxel phantomsGeant4 parameterised volumes

GDMLGDML for geometry description storage


Radiation exposure Radiation exposure of astronautsof astronauts

5 cm water shielding

Sku

llU

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er

spin

e

Lo

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Arm

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10 cm water shielding

Sku

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Dose calculation in critical organs

Effects of external shieldingexternal shieldingSelf-body shieldingSelf-body shielding


Object Oriented technology+

Geant4 architecture

Processes are handled transparently by Geant4 kernel

through an

abstract interfaceabstract interface

Geometry objects (solids, logical volumes, physical volumes)

are handled transparently by Geant4 kernel through

abstract interfacesabstract interfaces

So why not describing DNA?

So what about mutagenesis as a

process?

DNADNA


Biological models in Geant4 Biological models in Geant4

Relevance for space: Relevance for space: astronaut and aircrew radiation hazardsastronaut and aircrew radiation hazards


“Sister” activity to Geant4 Low-Energy Electromagnetic Physics– Follows the same rigorous software standards

International (open) collaboration– ESA, INFN (Genova, Torino), IN2P3 (CENBG, Univ. Clermont-Ferrand), Univ. of Lund

Simulation of nano-scale effects of radiation at the DNA level– Various scientific domains involved

medical, biology, genetics, physics, software engineering– Multiple approaches can be implemented with Geant4

RBE parameterisation, detailed biochemical processes, etc.

First phase: 2000-2001– Collection of user requirements & first prototypes

Second phase: started in 2004– Software development & public, open source release

The concept of “dose” fails at cellular The concept of “dose” fails at cellular and DNA scalesand DNA scales

It is desirable to gain an understanding to the processes at all levels

(macroscopic vs. microscopic)DNADNA


Multiple domains in the Multiple domains in the same software same software environmentenvironment

Macroscopic level– calculation of dose– already feasible with Geant4– develop useful associated tools

Cellular level– cell modelling– processes for cell survival, damage etc.

DNA level– DNA modelling– physics processes at the eV scale– bio-chemical processes– processes for DNA damage, repair etc.

Complexity of

software, physics and biologysoftware, physics and biology

addressed with an iterative and incremental software process

Parallel development at all the three levels

(domain decomposition)


http://www.ge.infn.it/geant4/dnahttp://www.ge.infn.it/geant4/dna


Cou

rtes

y A

. Bra

hme

(KI)

Courtesy A. Brahme (Karolinska Institute)

Biological processesBiological processes

PhysicalPhysicalprocessesprocesses

BiologicalBiologicalprocessesprocesses

ChemicalChemicalprocessesprocesses

Known, available

Unknown, not available

E.g. E.g. generation of generation of free radfree rad icals icals in the cellin the cell


RequirementsProblem domain analysis

Theories and models for cell survivalTheories and models for cell survival

TARGET THEORY MODELSTARGET THEORY MODELS Single-hit model Multi-target single-hit model Single-target multi-hit model

MOLECULAR THEORY MODELSMOLECULAR THEORY MODELS Theory of radiation action Theory of dual radiation action Repair-Misrepair model Lethal-Potentially lethal model

Analysis & DesignImplementationTest

Experimental validation of Geant4 simulation models

Critical evaluation of the models

in progress

Cellular level Cellular level Cellular level Cellular level

Geant4 approach: variety of models all handled through the same abstract interface


Target theory modelsTarget theory models

Single-hitmodel

Multi-targetsingle-hit

model

Single-targetmulti-hitmodel

Joiner & Johns model

No hits: cell survivesOne or more hits: cell dies

S(ρ,Δ) = PSURV (ρ0, h=0, Δ) = (1- ρ0)Δ = exp[Δ ln (1- ρ0)]

PSURV(q,b,n,D) = B(b) (e-qD)(n-b) (1- e-qD)b n!

b! (n -b)!

Extension of single-hit model

S = e-αR [1 + ( αS / αR -1) e ] D – ß D - D/DC

Cell survival equationsCell survival equations based on

model-dependent assumptions

S= e-ßD 2

two hits

No assumption on: • TimeTime• Enzymatic repair of DNAEnzymatic repair of DNA


Molecular theory of radiation action

(linear-quadratic model)

Theory of dualradiation action

Repair or misrepair of cell survival

Lethal-potentiallylethal model

Chadwick and Leenhouts (1981)

Tobias et al. (1980)

Kellerer and Rossi (1971)

Curtis (1986)

Molecular models for cell Molecular models for cell deathdeath

More sophisticated modelsMore sophisticated models


TARGET

THEORY

SINGLE-HIT

TARGET

THEORY

MULTI-TARGET

SINGLE-HIT

MOLECULAR

THEORY

RADIATION ACTION

MOLECULAR

THEORY

DUAL RADIATION ACTION

MOLECULAR

THEORY

REPAIR-MISREPAIR

LIN REP / QUADMIS

MOLECULAR

THEORY

REPAIR-MISREPAIR

LIN REP / MIS

MOLECULAR

THEORY

LETHAL-POTENTIALLY LETHAL

MOLECULAR

THEORY

LETHAL-POTENTIALLY LETHAL – LOW DOSE

MOLECULAR

THEORY

LETHAL-POTENTIALLY LETHAL – HIGH DOSE

MOLECULAR

THEORY

LETHAL-POTENTIALLY LETHAL – LQ APPROX

S= e-D / D0

S = 1- (1- e-qD)n

S = e –p ( αD + ßD )2

S = S0 e - k (ξ D + D ) 2

S = e-αD[1 + (αD / ε)]εΦ

S = e-αD[1 + (αDT / ε)]ε

S = exp[ - NTOT[1 + ]ε ] ε (1 – e- εBAtr)NPL

S = e-ηAC D

- ln[ S(t)] = (ηAC + ηAB) D – ε ln[1 + (ηABD/ε)(1 – e-εBA tr)]

- ln[ S(t)] = (ηAC + ηAB e-εBAtr ) D + (η2AB/2ε)(1 – e-εBA tr)2 D2]

S = e-q1D [ 1- (1- e-qn D)n ]

REVISED MODEL

In progress: evaluation of

model parameters from clinical

data


Low Energy Physics extensionsLow Energy Physics extensions

Specialised processes down to the eV scale– at this scale physics processes depend on material, phase etc.– In progress: Geant4 processes in water at the eV scale, release winter 2006

Details: see poster presentation

Processes for other material than water to follow

DNA levelDNA levelDNA levelDNA level

Electrons Protons (H+) Hydrogen (H) Alpha (He++) He+ He

ElasticBrenner (7.5 - 200 eV)

Negligible effect Negligible effect Negligible effect Negligible effect Negligible effectEmfietzoglou (> 200 ev)

ExcitationEmfietzoglou Miller and Green

Negligible effectMiller and Green Miller and Green Miller and Green

Born (7 ev – 10 keV) Born (100 eV – 10 MeV) (1 keV – 15 MeV) (1 keV – 15 MeV) (1 keV – 15 MeV)

Charge decreaseDingfelder

In progress In progress(100 eV – 2 MeV)

Charge increaseMiller and Green

In progress In progressDingfelder (0.1 Kev – 100 MeV)

Ionization In progressRudd (0.1 - 500 keV)

Rudd (0.1 – 100 MeV) In progress In progress In progressIn progress (> 500 keV)

Not pertinent to this particle







Scenario Scenario for Mars (and Earth…)for Mars (and Earth…)

Geant4 simulationspace environment

+spacecraft, shielding etc.

+anthropomorphic phantom

Dose in organs at risk

Geant4 simulation with biological

processes at cellular level (cell survival,

cell damage…)

Phase-space input to nano-simulation

Geant4 simulation with physics at eV scale

+DNA processes

Oncological risk to Oncological risk to astronauts/patientsastronauts/patients

Risk of nervous Risk of nervous system damagesystem damage

Geant4 simulationtreatment source

+geometry from CT image

oranthropomorphic phantom


ConclusionsConclusionsGeant4 offers powerful geometry and physics modelling in an advanced computing environmentWide spectrum of complementary and alternative physics models

Multi-disciplinary applications of dosimetry simulationPrecision of physics, validation against experimental data

Geant4-DNA: extensions for microdosimetry– physics processes at the eV scale– biological models

Multiple levels addressed in the same simulation environment– conventional dosimetry– processes at the cellular level – processes at DNA level

OO technology in support of physics versatility: openness to extension, without affecting Geant4 kernel

geant4 for microdosimetry

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