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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
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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
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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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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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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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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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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)
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IMRT = Intensity Modulated Radiation Therapy with photons
9 NON-UNIFORM FIELDS
PSI
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