Yves LEMOIGNE, ESI, Archamps, France Medical Physics (a Peacefull activity!) Thanks to Nuclear Physics …. Yves Lemoigne, ESI-Archamps (near Geneva) European

Yves LEMOIGNE, ESI, Archamps, France

Medical Physics (a Peacefull activity!)

Thanks to Nuclear Physics ….

Yves Lemoigne, ESI-Archamps (near Geneva)

European School of Medical Physics (ESMP)

Note for this presentation: - Slides with green background concern mainly ESMP organisation-Slides with yellow background concern mainly Medical Physics taught during the School (within other topics taught in Archamps…)


Yves LEMOIGNE, ESI, Archamps, FranceESMP=6 weeks: 3 Imaging, 3 RT


• - Help to diagnosis (anatomical imaging and functional imaging) : MRI, Echography, X-ray Radiology, SPECT & PET…

• - Radiotherapy: tele- and Brachy-therapy (with X-rays, inserted radioactive products, protons & Ions beams..)

Since More than 50 years Physics is a great help to Medicine and Biomedical research :

Now: (X-rays)

Future: Protons / Ions

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Medical Physics & Nuclear Physics

They have clear links :

-Because techniques used in MP are directly coming from Nuclear Physics :

Ex : Particle accelerators for Radiotherapy (electrons, protons, ions…) or radiotracer production

EX : sealed sources used in Brachytherapy

EX : Radiotracers with PET (SPECT) cameras The case of PET will be developped here


• X-ray imaging is “trans-

mission imaging” and is used mainly for “anatomy”

imaging”

• Nuclear medicine is

“emission imaging”

and is used for “functional

Imaging” (i.e. how this is

Working as function of time) More powerful for oncology

Basic principles for Medical IMAGING

CT-Scan

PET-Scan


• Precise Medical Imaging is now compulsory for Radiotherapy BEFORE and AFTER Radiotherapy

• BEFORE: - Diagnosis- Input for Treatment plannings (accuracy…)

Needed

If available

Future….

• AFTER: - Treatment results

TPS


Estimated absolute yearly

rate (%) of 2nd cancer

Tumor site X-rays IMXT Protons

Oesoph. & stomach 0.15 0.110.00

Colon 0.15 0.070.00

Breast 0.00 0.000.00

Lung 0.07 0.070.01

Thyroid 0.18 0.060.00

Bone & soft tissue 0.03 0.020.01

Leukemia 0.07 0.050.03

All 0.75 0.43 0.05

Compared to X-rays 1 0.60.07

BEFOREAFTER

• AFTER: - Treatment results

3D whole-body PET imaging


• Radio tracers can be used to label the chemical molecule we would like to follow inside the patient body. Positrons emitters more used in PET are : F18

(110mn), C11 (20 mn), (in research :N13 (10 mn), O15

(2mn)….). • They allow to see metabolism, while X-ray scan or

MRI are better to see the anatomy • Nuclear medicine (imaging of metabolism using

molecules labeled with an appropriate radioisotope) is therefore not in competition, but in complement of imaging techniques such as X-ray, X-ray scan or MRI (Magnetic Resonance Imaging).


MRI CT PET

Specification of the GTVComplementarity of imaging devices

Nuclear Magnetic Resonance

X-rays

Positron-electron annihilation

Excellent accuracy but specific only in some cases (could give functional imaging) : detects resonance of atom nucleus

Good accuracy for anatomical imaging

(Only density is measured)

Modest accuracy but good for functionnal imaging (very good sensitivity) : because their abnormal metabolism tumor are avid of glucose which emits photon from e+e-annihilation if radiotracer have been injected previously

Example of brain tumor :

Complementarity :- CT-PET devices are available (Bodygraph-Siemens…)- MRI-PET could be available soon for Small-Animal-PET camera only (Biomedical research only)


Positron Emission Tomography (PET) is one form of radio-pharmaceutical diagnosis. It is a powerful technique whose development owes Nuclear Research. Due to its good sensitivity, PET allows disease-related changes in tissues and organs could be detected long before serious symptoms set in.

PET cameras for IMAGING

Image fusion (CT + PET)

“Standard “is now CT+PET devices


Because its principle :

P

P

N

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PP

P

P

N

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N

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PP

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NF18

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PET CAMERA : a child of Nuclear PhysicsMatter – Antimatter annihilation e+ e- =>

e+ e- =>


PET camera Nuclear Physics (detector @ CERN)

e+ e- => at 1024 KeV

e+ e- => + … because higher energy (100000000 KeV !)

In principle :

Realisation:

Size and cost are different !

Particlebeam

Particlebeam

Positron Radio-Tracer Emitter inside the body

detectors in circle around Colliding

point of the two beams

Take care of Scale : 1 meter 15 meters !

In Hospitals … In Research centers (CERN, Geneva)

Versus


Inside a PET camera(here CPET from Philips) in 90’s

Medical imaging / Nuclear Physics : Similar techniques

Scintillators + PM’sNuclear Physiscs research (ex: CMS exp @ CERN) have

replaced photomultipliers (PM) by Avalanche Photodiode (APD). Medical imaging begins to do the same (ex: Lab-PET)


Coincidence detection in a PET scanner

Why PET camera are powerful …

From Y. Yongen (IBA)

Great selectivity due to the 3 conditions we are demanding: -1- detect with Energy selection ≈ 511 KeV-2- detect two in sharp timecoincidence (≈ 10 nanosecond)-3- detect two in opposite directions (within a few degres)


Medical Physics &Nuclear Physics

PET Photon detectors are done like several Nuclear Physics detectors.

Typically : Crystals, PM, gantry, electronic chains and controllers, computer interfaces, hard discs or tapes for mass storage, displays devices…


• A PET needs a complex environment… Chemistry, Bio-Chemistry, Physics,

mathema-tics, computing and… medicine.

• A cyclotron to produce radioactive tracers (F18, C11..) is needed not too

far…

• Previously only availablein big centres (USA, UE…).

• With modern transport facilities, a regional centrecould supply hospitals in a 1500 km radius (about)…

• PET camera for biomedical research can use

“generator” Ge68 - Ga68 => e+

(not for human use)


• All these techniques are studied during the three first weeks of ESMP (111 hours) with some of the best experts from Belgium, France, Germany, Italy, Nether-lands, Switzerland, USA….

+ One week of Medical computingSimulation / modelling of Physics and/or Live systems, Networks,Tools for computer simulation (GEANT4, EGS5…), Image reconstruc- tion algoritms, Data compression and processing…

ESMP organisation


Then ESMP students study the sophisticated techniques of tumors killing by use of radiations (External sources for Radiotherapy, internal sources for brachytherapy) = 74 h

Modern Radiotherapy is more and more obliged to use accurate medical imaging of previous ESMP weeks (Role of Treatment Planning Systems)

or teletherapy or curiethérapie


• External radiation therapy refers to radiation applied externally to the body using a beam of high-energy x-rays (or proton / light ion beams) to kill tumor cells (also called Tele-Therapy).

• Internal radiation therapy refers to the use of small radioactive seeds implanted in the tumor tissue. The seeds emit radiation over a period of time to kill tumor cells (Brachytherapy or Curiethérapie).


21

In TeletherapyIn Teletherapy linear linear accelerators dominateaccelerators dominate

To irradiate only the tumour oncologists To irradiate only the tumour oncologists use :use :

• collimator homothetic to tumor shape collimator homothetic to tumor shape ((BlocksBlocks))

• MMulti-ulti-LLeaf eaf CCollimator (static) : Conformal ollimator (static) : Conformal RTRT

• Dynamic MLC (position varyingDynamic MLC (position varying during during the irradiation). Driven by computer, it’s the irradiation). Driven by computer, it’s IMRT IMRT ((IIntensity ntensity MModulated odulated RRadiation adiation TTherapy)herapy)

IMRT is an advanced RT technique to treat tumor and to spare surrounding tissue from doses above tolerances.

In the world radiation oncologists use 10 In the world radiation oncologists use 10 000 electron linacs delivering X-ray 000 electron linacs delivering X-ray beams.beams.The planning of RadioTherapy treatment has been revolutionized by the ability to delineate tumors.

Hight-tailored computing applications are needed to perform optimisation and treatment simulation (treatment planning)

Often limitations due to availibility of experienced medical personnel (time consuming technique)…

High-level education needed…. (ESMP provides it)

Screen Blocks

or


SIMULATORand/or

ELECTRONIC PORTAL IMAGING

ACCELERATOR

BLOCK CUTTING DEVICE

or MLC

MRI or / and PETCT-SCAN

VERIFIY AND RECORD SYSTEM

OPTIMISATION

•Dose distribution •Dose-Volume

Histograms •Biological indices

BEAM DEFINITION

•Treatment parameters•Treatment

time(monitor units)

•Field shapeor

•Position of leaves

•Reconstructed radiographs

(DRR)

•beam data library

REGISTRATION

•anatomical structures

•external contours •densities•anatomical

structures

TREATMENT PLANNING SYSTEM

CENTRAL ROLE OF TPS


MRI CT PET

Specification of the GTV

Impact of the imaging method on the Tumor Volume definitionKneschaurek, 2002

Recall Summary Volumes and Margins[ICRU-50 Supplement of rules definitions]

GTV

CTV

ITV

PTV

Specification of the GTV

Nuclear Magnetic Resonance

X-rays

Positron-electron annihilation


Target Volume

In case of deep tumor, it is better to use “several” beams, all converging to the tumor, to avoid excessive doseirradiation of heathly tissues around

Beam 1

Beam 2Beam 3

“Simplest” way : Rotate the accelerator or the patient

X-ray BeamProton beam@PSI


Inverse Planning

TreatedVolume

OAR

Target Volume

TreatedVolume

OAR

Target Volume

Inverse Planning"Conventional" Planning

OAR = Organ At Risk (for instance Spinal Cord) which is compulsory to protect from high dose.


Clinical Example

Modern RT technique : Intensity Modulated Radio-Therapy (Dose Intensity is driven by computer following the previously treatment planning calculating – only if precise imaging taken before)


Accelerators for Hadrontherapy: developed first in physics labs

They are used routinely in hospitals

Courtesy of IBA

Hadron Therapy

Around 9000 of the 17000 accelerators operating in the World today are used for medicine. Very few ( less than 50) are hadron (P or light Ions) accelerators.(Future ? Next slide : why they are better despite higher cost: the Bragg peak)


Archamps - 17.11.08 – U.Amaldi 2828

Protons and ions spare healthy Protons and ions spare healthy tissuestissues

charged hadron beam

that loses energy in matter

27 cm

tumour

target

200 MeV - 1 nA200 MeV - 1 nAprotonsprotons

4800 MeV – 0.1 nA4800 MeV – 0.1 nAcarbon ionscarbon ions

which can control which can control radioresistantradioresistant

tumourstumours

Photons ProtonsX raysprotons or

carbon ions

tail

cobalt 60

linac

httt://global.mitsubishielectric.com/bu/particlebeam/index_b.htmlhttt://global.mitsubishielectric.com/bu/particlebeam/index_b.html

light ion(carbon)

proton


Photon IMRT Photon

Proton

Conventional Radiotherapy:Important dose outside the tumor

IMRT = Intensity Modulated

Radio Therapy:still non negligable dose

outside the tumor

Particle Therapy: Comparing Proton & photon Conventional RT

Scattering technique :Low dose outside

Y.Yongen (IBA)


Proton Therapy is growing rapidly!

PT center under operation

Courtesy Janet Sisterson & PTCOG

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Yves LEMOIGNE, ESI, Archamps, FranceExample of IBA Proton Therapy System

• Hadron therapy owe very much to Nuclear Research Centres experience for accelerators, beam transport, detectors…

• A Proton therapy system is a complex system, filling a Hospital building.

• The treatment rooms are larger and complex (gantries),• The total investment is around 100 M€, about half for the

equipment,• A Proton facility can treat 1500 patients/year mainly for special

cases (Proximity organ-at-risk tumors, radioresistive tumor, children tumor…)

• Hadron facilities providing protons and carbon ions are more costly….


3232

The accelerators used today The accelerators used today in hadrotherapy are in hadrotherapy are

“circular”“circular”

SYNCHROTRONS

18-25 metres

CYCLOTRONS (Normal or SC)

4-5 metres

OR

SYNCHROTRONS

6-9 metres

Teletherapy with protons (200-250 MeV)

Teletherapy with carbon ions (4800 MeV = 400 MeV/u)

Archamps - 17.11.08 - UA


LET > 20 keV/μm = 200 MeV/cm =40 eV/(2 nm)LET > 20 keV/μm = 200 MeV/cm =40 eV/(2 nm)Production of many unreparable localized double strand

breaks and clustered damages DNA- double strand

Why light Ions (C12) are better than protons (photons):

Effect of Effect of ΔΔE/E/ΔΔx = x = LETLET

2 nmsize


LOMA-LINDA :since 1992 : first Hospital-basedProton therapy centre

2005 : 160 sessions per day

Accelerators for Accelerators for protontherapyprotontherapy


Concepts directly transferred from Nuclear Physics Reasearch centres (CERN, DESY, Fermilab…)

• In the world protontherapy has already treated 55'000 In the world protontherapy has already treated 55'000 patients.patients.

carbon ion therapy has already treated 4500 patients (Japan, carbon ion therapy has already treated 4500 patients (Japan, RFA)RFA)

• Close Future : CNAO in ItalyClose Future : CNAO in ItalyThe synchrotron (proton and CThe synchrotron (proton and C1212 ions ): beams ready in summer 2009 ions ): beams ready in summer 2009

25 m synchrotron and 3 treatment rooms

Other centres in progress:Germany (Heidelberg, Marburg)France (Lyon, Caen, Orsay),USA, China, India…


A new concept: A new concept: CyclinacCyclinac=Cyclotron+ Linac for Image Guided =Cyclotron+ Linac for Image Guided HadronTherapyHadronTherapy

2 Modules tested at LNS, Catania, Italy

now in Microcosm at CERNnow in Microcosm at CERN

This project would allow radio-tracer production cyclotrons to be transformed at raisonable cost in hadrontherapy facility : A real breakthrough !


Brachytherapy

A few words about Brachytherapy :Local Eradication of a Tumor by Radioactive Implants

Example of Prostate cancer

Real advantage in case of tumor on moving organs (ab-domen)… Note the spectacu-lar progress when seeds are implanted under Magnetic Resonance Imaging (Geneva)


Last Part of ESMP : RADIOPROTECTION in Medical Physics

Public (and media) are very concerned by this topic !


Origin of participants involved in EUROPEAN SCHOOL OF MEDICAL PHYSICS

.*

*

ESMP is known by all European countries (and farer…)

MORE THAN 1000 STUDENTS WENT IN ARCHAMPS-GENEVA SINCE THE SETTING UP OF THE SCHOOL

IN EUROPE….

… And IN The WORLD

EGYPT (as 6 other neighbouring countries) is eligible to a subsidy from

NATO Scientific Department in the frame of the “South Mediterranean Dialogue

group of countries”

Medical Physicists (or students in MP) can contact

the secretariat : [email protected]


Please, Visit our website :

www.cur-archamps.fr/esi

Or the EFOMP website :

www.efomp.org

For further information and application form for ESMP 2009 (deadline : June 2009)

School activities are on bothsides of the border : - French side : Archamps- Swiss side : Genevabut as Switzerland recently joined the “schengen System”, only one visa is needed !!


Physics Medicine application in

Statics (mechanics) Orthopaedics

Dynamics (mechanics) Heart motion

Elasticity and strength of materials Orthopaedics

Fluid statics Blood pressure

Fluid dynamics Blood flow in vascular system

Sound and acoustics Stethoscope, ultrasound, acoustic microscope

Electricity All life processes, ion transfer at membranes

Magnetism Nuclear magnetic resonance imaging

Atomic physics and spectroscopy "Chemical shift" in NMR imaging, lasers in medicine

Molecular physics Genetics, antibodies, protein structure, electron microscope

Ultraviolet and infrared energy Skin treatment and imaging

X-rays Radiology, CT imaging

Quantum mechanics Electron diffraction microscope

Crystallography Structure of proteins

Solid-state physics & semiconductors Computers in medicine, scintigraphy, Fast electronics

Nuclear physics Radioisotope labelling, nuclear medicine, radiation therapy

Radioactivity Positron emission tomography (PET), Radiotracers

Elementary particle physics Proton & ion therapy, Huge & complex devices

Accelerators, cyclotrons, etc Tumour therapy,

etc…. etc…

Correlations between Physics & Medicine (from Nobel Prize Robert Hofstadter, Stanford University in 1983)still true As a Conclusion-1 :


18.11.2006 ESMP 2006Key Areas for Biomedicine

In conclusion, there is no doubt that the contribution of Medical Physics (and thus Nuclear Physics) is not negligible in the better efficiency of Medicine during the past decades. This is why a high level education in Medical Physics, done by first class experts deeply involved in this science branch, is absolutely compulsory .

Fundamental breakthroughs in physics are continuing to yield new medical technologies for identifying and treating a range of diseases.

The 50-year tenure of Nuclear Physics in Medicine and Biology has coincided with some of the most important developments in oncology and radiological science, including the introduction of artificial radioactivity, computers and 3D imaging into medicine. These events have profoundly influenced the development of Medicine

CONCLUSION-2


Further information : www.cur-archamps.fr/esior www.efomp.org


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Yves LEMOIGNE, ESI, Archamps, France Medical Physics (a Peacefull activity!) Thanks to Nuclear Physics …. Yves Lemoigne, ESI-Archamps (near Geneva) European