HEAVY-ION TUMOR THERAPY

By- Rashmi Nakate

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Motivation

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Stopping of heavy-ions

Stopping of heavy-ions

Dose deposition Dose deposition

Nuclear Fragmentation

Nuclear Fragmentation

Treatment planning

Treatment planning

Relative biological

effectiveness

Relative biological

effectiveness

INTRODUCTION

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• Radiation Therapy

• Proton Therapy

• Heavy Ion therapy

Bethe-Bloch Formula

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Energy loss is described by Bothe-Bloch formula.Energy loss is described by Bothe-Bloch formula.

‘I’ is Ionization Energy‘I’ is Ionization Energy

‘C/Zt’ is Shell correction term.‘C/Zt’ is Shell correction term.

‘ is density effect correction term.‘ is density effect correction term.

Energy loss is described by Bothe-Bloch formula.Energy loss is described by Bothe-Bloch formula.

‘I’ is Ionization Energy‘I’ is Ionization Energy

‘C/Zt’ is Shell correction term.‘C/Zt’ is Shell correction term.

‘ is density effect correction term.‘ is density effect correction term.

Stopping of heavy-IonsStopping of heavy-Ions

Stopping Power Curve

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Stopping of heavy-IonsStopping of heavy-Ions

Range

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Stopping of heavy-IonsStopping of heavy-Ions

Bragg Peak

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Stopping of heavy-IonsStopping of heavy-Ions

Look at energy loss as function of absorber depthLook at energy loss as function of absorber depth

Expect sharp peak near stopping point due to Expect sharp peak near stopping point due to

Broadening of the peak due to statistical fluctuations of energy loss

Broadening of the peak due to statistical fluctuations of energy loss

Look at energy loss as function of absorber depthLook at energy loss as function of absorber depth

Expect sharp peak near stopping point due to Expect sharp peak near stopping point due to

Broadening of the peak due to statistical fluctuations of energy loss

Broadening of the peak due to statistical fluctuations of energy loss

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Range StragglingRange Straggling

Range Straggling

Calculation of path length

R(E) =

Calculation of path length

R(E) =

Statistical fluctuationStatistical fluctuation

Vivilov Distributions� many Collisions

Gaussian )

Vivilov Distributions� many Collisions

Gaussian )

R(E) =R(E) =

Statistical fluctuationStatistical fluctuation

Vivilov Distributions� many Collisions

Gaussian )

Vivilov Distributions� many Collisions

Gaussian )

Calculation of pathlength

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Dose depositionDose deposition

Energy Loss and Range of ions

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Dose depositionDose deposition

Dose deposition by Iron ion

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Dose depositionDose deposition

Dose deposition by Neon ion

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Lateral Beam SpreadLateral Beam Spread

Lateral Beam Spread

Elastic Coulomb ScatteringElastic Coulomb Scattering

Small Angular Distribution Approximately Gaussian

d = Absorber thickness,

Small Angular Distribution Approximately Gaussian

d = Absorber thickness,

Elastic Coulomb ScatteringElastic Coulomb Scattering

Small Angular Distribution Approximately Gaussian

d = Absorber thickness,

Small Angular Distribution Approximately Gaussian

d = Absorber thickness,

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Nuclear FragmentationNuclear Fragmentation

Nuclear Fragmentation

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Nuclear FragmentationNuclear Fragmentation

� Stopping process is governed by collisions with atomic

electrons.

� What happens if nuclear reaction occurs?

� Use Abrasion-Ablation Model.

� Loss of primary beam particles

� Secondary particles have longer range than primary beam

particles.

� There are other model describing fragmentation: E.g.

Intranuclear cascade model

� Fragmentation leads to dose tail behind the brag peak.

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Importance Of TreatmentImportance Of Treatment

Importance of Treatment

Carbon Ions Photons

Variation of Energy and positionVariation of Energy and position

Spread out Bragg PeakSpread out Bragg Peak

Uniform Exposure of TumorUniform Exposure of Tumor

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Treatment PlanningTreatment Planning

Treatment Planning

� Determine the location of the target

volume(tumor) using modern imaging techniques

e.g. CT, MRI

� Form a 3D model of the treatment geometry

� Use this model to find suitable beam entrance

points avoiding critical structures

� Adapt the dose distribution to the planned target

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Treatment MethodsTreatment Methods

Treatment Methods

Today: Photon beamsToday: Photon beams

Future: Heavy Ion / Proton BeamsFuture: Heavy Ion / Proton Beams

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Relative Biological EffectivenessRelative Biological Effectiveness Relative Biological

Effectiveness (RBE).

RBE = RBE =

Links conventional radiotherapy to the case of heavy ionsLinks conventional radiotherapy to the case of heavy ions

Depends on the dose, particle type, energy, tissue, biological end pointDepends on the dose, particle type, energy, tissue, biological end point

Can vary drastically within the tumor volumeCan vary drastically within the tumor volume

RBE = dose of x rays/dose of ion radiation that results in the same biological effect

RBE = dose of x rays/dose of ion radiation that results in the same biological effect

Links conventional radiotherapy to the case of heavy ionsLinks conventional radiotherapy to the case of heavy ions

Depends on the dose, particle type, energy, tissue, biological end pointDepends on the dose, particle type, energy, tissue, biological end point

Can vary drastically within the tumor volumeCan vary drastically within the tumor volume

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Relative Biological EffectivenessRelative Biological Effectiveness Relative Biological

Effectiveness (RBE).

LET: Linear Energy Transfer

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Relative Biological EffectsRelative Biological Effects

Biological Effects

Radiation Damage ( Photons)

Radiation Damage ( Heavy-Ions)

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Comparison of X-ray , Protons and Heavy ions

Comparison of X-ray , Protons and Heavy ions

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Further researchFurther research Helium Ions and Anti

protons

On-going DebateOn-going Debate

Production ProblematicalProduction Problematical

Good Depth-Dose-ProfileGood Depth-Dose-Profile

Annihilation: imaging possibilityAnnihilation: imaging possibility

Helium Ions Anti Protons

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CONCLUSIONCONCLUSION

� protons and heavy ions have a advantageous depth-dose profile

� range straggling and lateral beam spread ! � beam shaping

� nuclear fragmentation (useful for PET)

� heavy ions: bigger ionization density

Heavy ions in tumor therapy: no outstanding method for everything

but:

important improvement compared to photons

Heavy ions in tumor therapy: no outstanding method for everything

but:

important improvement compared to photons

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ReferencesReferences

�Dieter Schradt, Thilo Elsaesser, Daniela Schulz-Ertner:

Heavy-ion tumor therapy: Physical and radiobiological benefits

Reviews of modern physics, volume 82, 19th February 2010

�Ugo Amaldi, Gerhard Kraft:

Recent applications of Synchrotrons in cancer therapy with Carbon Ions

Europhysics News, volume 32, july 2005

�Ugo Amaldi, Gerhard Kraft:

European Developments in Radiotherapy with Beams of Large Radiobiological

Effectiveness

Journal of radiation research, volume 48 Suppl A, February 2007

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ReferencesReferences

� Kraemer et al.:

A systematic review of antiproton radiotherapy

Frontiers in physics, 16 January 2014

� Bittner et al.:

Helium ions for radiotherapy? Physical and biological verications of a novel

treatment modality

Medical Physics, volume 43, 30 March 2016

� https://www- zeuthen.desy.de/technischesseminar=texte=siliconre=sld015:htm

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THANK YOU