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ACCELERATORS AND MEDICAL PHYSICS

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Ugo Amaldi

University of Milano Bicocca and TERA Foundation

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People of hadrontherapy

EPFL 3- 28.10.10 - U. Amaldi

Other uses:“hadron therapy” BUT radiotherapy is a single word“particlle therapy” BUT also photons are particles

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Neutrontherapy at Berkeley

1935: Ernest and John Lawrence at the control of the 27-inch cyclotron

R. Stone at the 60- inch cyclotron

EPFL 3- 28.10.10 - U. Amaldi

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Protontherapy

Hymer Friendell Bob Wilson Percy Bridgeman

1943 - Harvard

Founder and first director of Fermilab -1990

1946 R.R. Wilson proposes the use of protons for teletherapy

1954 First irradiations in Berkeley

1961 New Harvard cyclotron irradiates patients

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Protontherapy in Europe

The modified Uppsala synchrocyclotron

Bőrje Larsson at Uppsala

“On the Application of a 185 MeV Proton Beam to Experimental

Cancer Therapy and Neurosurgery”

Doctoral dissertation - 1962

(1931-1998)

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Ion therapy – 1974-92

Cornelius Tobias

1918 - 2000

SuperHILAC

Bevatron

UNILAC

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New radiobiology of light ions at Berkeley“Tobias and collaborators studied

carbon,

oxygen,

neon (400 patients)

beams revealing both physical and biological characteristics favourable to eradicating hypoxic, radioresistant tumour cells at deep locations in the body, while sparing radiation damage to overlying normal tissues”

Eleanor Blakeley, Lawrence Radiation Laboratory

Later it was found that the neon ions have a charge

too large a charge and their RBE at the tumour is not optimal.

Around 1992 carbon ions have been chosen as optimal

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30 years of pioneering protontherapy in physics labs

Lawrence Berkeley Laboratory USA 1954

Uppsala Sweden 1957

Harvard Cyclotron Laboratory (*) USA 1961

Dubna Russia 1964

Moscow Russia 1969

St. Petersburg Russia 1975

Chiba Japan 1979

Tsukuba Japan 1983

Paul Scherrer Institute Switzerland 1984

(*) 9,116 patients were treated with protons beforethe laboratory closes in 2002

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The Harvard cyclotron and Mas. General Hospital

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Ray Kjellberg fastens his

stereotactic device to a patient.Herman Suit (right) and

J. E. Munzenreider visiting the cyclotron

when it was closed in 2002.

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1992-1994: the turning years

1993 Como, Italy

First International Symposium on Hadrontherapy

1992: Loma Linda treats first patient with protons

1993: MGH selects IBA for first commercial centre

1993: At GSI the ‘pilot project’ is approuved

1994: HIMAC treats the first patient with C ions

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Loma Linda Medical Center in California

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James Slater (left) at the inauguration of the Loma Linda centre.

The first hospital based facilitywith rotating gantries

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HIMAC in Chiba is the pioner of carbon therapy (Prof H. Tsujii)

Yasuo Hirao

Hirohiko Tsujii

6000 pts 1994-2010

Since the cells do not repair fewer fractions are possible

HIMAC: 4-9 fractions! LATEREPFL 3- 28.10.10 - U. Amaldi

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The GSI pilot project : 1997-2008

Gerhard Kraft

J. Debus

450 patients treated with carbon ions

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Summary of the previous lectures

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The beginnings of modern physics andof medical physics

1895discovery of X raysWilhelm Conrad Röntgen

Henri Becquerel (1852-1908)

Marie Curie Pierre Curie(1867 – 1934) (1859 – 1906)

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The next magnificent three years for experimental physics and medical physics

E. Fermi and collaboratorsDiscovery of the effect of slow neutrons - 1934

Carl D. Andersondiscoverer of the positron

Ernest Lawrencewith a 0.1 MeVcyclotron

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Details on accelerators

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Loaded structure

cyclotrons

linacs

synchrotrons

hadrons

electrons

Phase stabilityStrong focusing

The icone of radiation therapy

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Radiation beam in matter

Delivered dose = D = in J/kg = gray (Gy)Energy imparted to a masse M of mattermasse M

Linear Energy Transfer = LET = in keV/µm Δ EΔ x

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Energy losses by thesemiclassical model

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Semiclassical model

Exact calculations

In water

Δ EΔ x

K / Mc21

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The computed quantitiesR is the residual rangei.e. the range measured from the end

IMPORTANT RATIO

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Electron ranges in water

Practical range in Al

Practical range in water

Total range in Al

Proton Bragg peakin water

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The losses seen by the water molecules

Prob

abili

ty fo

r the

inco

min

g pa

rtic

le to

lo

ose

the

ener

gy E

c

Absorbed energy Ec in keVMinimal ionization energy

Excitations due to distant coll.

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Ionizations due to close coll.

Ionizations due to distant coll.

Excitations due to distant coll.

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The losses seen by the water molecules

Prob

abili

ty fo

r the

inco

min

g pa

rtic

le to

lo

ose

the

ener

gy E

c

Absorbed energy Ec in keVMinimal ionization energy

Excitations due to distant coll.

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Ionizations due to close coll.

Ionizations due to distant coll.

Excitations due to distant coll.

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Interactions with matter in conventional radiotherapy

EX

Ee max ≈ EX≈ 2Ke/5

KERMA

DOSE

depth in water

% o

f max

dos

e

transition region depth

dose

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People of hadrontherapy

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Protontherapy

Hymer Friendell Bob Wilson Percy Bridgeman

1943 - Harvard

Founder and first director of Fermilab - 1990

1946 R.R. Wilson proposes the use of protons for teletherapy

1954 First irradiations in Berkeley

1961 New Harvard cyclotron irradiates patients

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End of the summary

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X ray therapy

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Different radiations used in radiotherapyDirectly ionizing radiations:

electrons, positronseffects: ionizations, excitationssecondary particles: electrons (delta rays), photons, positrons

protons, carbon ions, other fully stripped ions (charged hadrons)……effects: ionizations, excitations secondary particles: electrons, nuclear fragments , photons

Indirectly ionizing radiations photons

effects: photoelectric, Compton, pair creationsecondary particles: electrons, positrons, photons

neutrons (neutral hadrons)effects: nuclear interactions (mainly with protons) secondary particles: protons, nuclear fragments

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Quark composition of hadrons

Neutron = ddu = -⅓ -⅓ +⅔ =0

Proton = duu = -⅓ +⅔ + ⅔ =+1

Negative pion = ud = -⅔ -⅓ =- 1

protonneutron

proton

neutronp , n are made of 3

quarks

Helium = 4He

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An electron linear accelerator (linac)

10 MeV electrons

gantry

target

X rays

Multileaf colimator

tumour

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Cell survival and fractionation

1 gray = 1 Gy = 1 J/kg

30 000 ionizations per nucleus

due to 200 electrons

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Repair in few hours

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Cell survival and fractionation

1 gray = 1 Gy = 1 J/kg

30 000 ionizations per nucleus

due to 200 electrons

60-75 Gy are typically given in 30 fractions over 6 weeks so that healthy tissues have the time to repair. Argument:

(1/2)30 = 10-9 and there are 108 cells in 1 litre tumour

The tumour dose is limited by the nearby healthy tissues which cannot receive more than 30-40 Gy

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For 80-90 % of the solid tumours, the tumour tissues are more « radiosensitive » than healthy tissues

Repair in few hours

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The target volumes

GTV: Gross Target Volume as determined by CT, MRI, SPECT ad PET

CTV: the Clinical Target Volume takes into account invisible infiltrations

PTV: the Planning Treatment Volume takes into account mouvementsand misalignments

CHALLENGE: Conform the dose to the tumour !EPFL 3- 28.10.10 - U. Amaldi

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To delineate the PTV:Computer Tomography

=> μ

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“Hounsfield numbers” H are proportional to electron density

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To delineate the PTV:Computer Tomography

=> μ

“Hounsfield numbers” H are proportional to electron density

EPFL 3- 28.10.10 - U. Amaldi from Thomas, Brit. J. Rad., 72 (1999)

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To delineate the PTV:: SPECT scanner

85% of all nuclear medicine

examinations use molibdenum/technetium

Generators for diagnostics of

… liver

lungs

bones ……

Lead collimators to channel the gammas of 0.14 MeV

Rotating headWith detectors

0.14 MeVgammas

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To delineate the PTV: PET

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To delineate the PTV:: Magnetic Resonance Imaging = MRI

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80 3050

BUT: Two opposite photon beams are not enough to deliver a conformal dose

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110 110100100

BUT: Two opposite photon beams are not enough to deliver a conformal dose

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The therapeutic window

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Dose in Normal Tissue (Gy) Dose in Normal Tissue (Gy)

many biological and clinical phenomena in 30 sessions

NTCP

TCP

NTCP

TCP

UNFAVORABLE

FAVORABLE

Quantification of the control without complications

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TCP

NTCP

1- NTCP

TPC (1- NTCP)

Tumour conformation to open the window

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IMRT = Intensity Modulated Radiation Therapy with photons

9 NON-UNIFORM FIELDS

PSI

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THE END

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