ACCELERATORS AND MEDICAL PHYSICS 4 - physique.cuso.ch · EPFL 4- 4.11.10 - U. Amaldi 1 ACCELERATORS...

EPFL 4- 4.11.10 - U. Amaldi 1

ACCELERATORS AND MEDICAL PHYSICS

4

Ugo Amaldi

University of Milano Bicocca and TERA Foundation

2

The distribution of the dose in hadrontherapy

EPFL 4- 4.11.10 - U. Amaldi

The narrow peak has to

be enlarged longitudinally

3

Spread Out Bragg Peak

SOBP

General laws:

R = Ro (E/Eo)1.82

ΔR/R = 1.8 ΔE/ E

For Δd<1.5 mm at d=150 mm

ΔE/ E < 0.5%

tail

cobalt 60

linac

light ion

(carbon)

proton

Longitudinally and transversally

the carbon peak is 3 times

narrower than the proton peak.

The widths are prop. to 1/√M

3

Distal

fall-off

Δd/d=1%


4

Carbon ions have less multiple scattering than

protons : higher lateral precision

carbon beam

proton beam

Depth in tissue

12 cm


EPFL 4- 4.11.10 - U. Amaldi 5

Protons and ions spare healthy tissues

charged hadron beam

that loses energy in matter

27 cm

tumour

target200 MeV - 1 nA

protons

4800 MeV – 0.1 nAcarbon ions

VERY LOW

CURRENTS !

Photons ProtonsPhotons ProtonsX raysprotons or

carbon ions

Two methods for imparting the dose:

“passive” system

EPFL 4- 4.11.10 - U. Amaldi 6

7

Respiratory gating with a synchrotron

Cyclotrons are better because the beam is always present


1A. Standard procedure: Passive beam spreading

with respiratory gating

EPFL 4- 4.11.10 - U. Amaldi 8

Collimator

Double scatterer

Bolus: has to be

machined for each case.

PSI

1A. Standard procedure: Passive beam spreading


EPFL 4- 4.11.10 - U. Amaldi 9

Collimator

Double scatterer

Bolus: has to be

machined for each case.

PSI

1B. Advanced procedure: layer stacking


EPFL 4- 4.11.10 - U. Amaldi 10

2A. Active “spot scanning” technique by PSI

(Villigen)

EPFL 4- 4.11.10 - U. Amaldi 11

1

2

3

1

2

3

‘spot’ position

During the displacement

the cyclotron beam is

switched off for 5 ms

Distance between the centers

is 75% of the FWHM

12

Gantry 2

Gantry 1

ACCEL

SC cyclotron

250 MeV protons

ExperimentOPTIS

PROSCAN

TERA


with respiratory gating (Villigen)


PROSCAN at PSI (Villigen):

with Gantry 1 and Gantry 2

13


with respiratory gating (Villigen)

PROTONS


1414

Next: Spot scanning compensated by correcting the

spot position and multipainting

PROTONS


Feedback from a

device which detects

the position of the

tumour

EPFL 4- 4.11.10 - U. Amaldi 15

2B. Active “raster scanning” technique by GSI

with respiratory gating (Darmstadt)

Distance between the centers of the

mini-voxels is 30% of the FWHM.

The beam is always on.

16

The GSI pilot project : 1997-2008

Gerhard Kraft

J. Debus

450 patients treated

with carbon ions


GSI: procedure to cover uniformly a spherical target

EPFL 4- 4.11.10 - U. Amaldi 17

More dose at the periphery

Conformity of the irradiation with protons and ions

EPFL 4- 4.11.10 - U. Amaldi 18

1919

IMPT = Intensity Modulated Particle Therapy with protons

4 NON-UNIFORM FIELDS

PSI


20

To be compared with IMRT with photons

9 NON-UNIFORM FIELDS

PSI


21

Protons are quantitatively different from X-rays


22

Carbon ions are qualitatively different from X-rays

Carbon ions deposit in a cell 22 times more energy than a proton

producing not reparable multiple close-by double strand breaks

Carbon ions can control radio-resistant tumours


Biological effects of protons and carbon ions

EPFL 4- 4.11.10 - U. Amaldi 23

Electrons put in motion by X rays: “sparsely ionizing”

24

d=200 nm

X beam

30 cm


25

d=200 nm

30 cm

Beam of 200 MeV proton


d=50 nm

d= 15 nm

d=90 nm

Protons1: more favorable dose- 2. same „indirect effects‟

X ray beam

26

d=200 nm

30 cm


d=50 nm

d= 15 nm

d=90 nm

Protons1: more favorable dose- 2. same „indirect effects‟

Also protons are „sparsely ionizing

Beam of 200 MeV proton

X ray beam

Microscopic distribution of the X ray dose

7

μm

e- range = 15

mm

X ray = 3 MeV γ

EPFL 4- 4.11.10 - U. Amaldi 27

150 ionizations/cell


7

μm

e- range = 15

mm

X ray = 4 MeV γ

EPFL 4- 4.11.10 - U. Amaldi 28

X ray = 4 MeV γ

150 ionizations/cell


7

μm

e- range = 15

mm

EPFL 4- 4.11.10 - U. Amaldi 29

Microscopic distribution of the proton dose

EPFL 4- 4.11.10 - U. Amaldi 30


EPFL 4- 4.11.10 - U. Amaldi 31


EPFL 4- 4.11.10 - U. Amaldi 32


Protons are “sparsely ionizing”

as photons/electrons

SAME CLINICAL EFFECTS BUT

MUCH BETTER “CONFORMITY”

EPFL 4- 4.11.10 - U. Amaldi 33

34

30 cm

d= 4 nm

d= 2 nm

4 cm

Carbon ions: 1. more favorable dose- 2. „direct effects”

d= 0.3 nm

d=200 nm


Beam of 200 MeV protons

X ray beam

Beam of 4800 MeV carbon ions

35

30 cm

d= 4 nm

d= 2 nm

4 cm

Ioni carbonio: 1. dose più favorevole - 2. effetti „diretti‟ sulle

cellule tumorali

d= 0.3 nm

d=200 nm


Carbon ins are „densely ionizing

Beam of 200 MeV protons

X ray beam

Beam of 4800 MeV carbon ions

36

Effect of ΔE/Δx = LET

Mauro Belli et al

ISS

Sparsely ionizing radiation

with respect to the dimensions

of the double helix (2 nm)

Densely ionizing radiation


37

Two qualitatively different microscopic dose distributions

densely ionizing radiation sparsely ionizing radiation

Visualization

of repair

proteins


38

Definition of Radio-Biological Effectiveness

RBE is defined with respect

to standard X rays:

RBE = = = 5

For a given effect on a given cell

the RBE value is a function of LET

Dγ 5

D 1

C+6

no repair

X rayswith repair


39

Response of different cells to high-LET radiations

Survival of V79 aerated and anoxic cells versus LET of carbon-12 ions

with oxygen without oxygen


40

Response of different cells to high-LET radiations

Survival of V79 aerated and anoxic cells versus LET of carbon-12 ions

with oxygen without oxygen


41

Effect of LET on RBEs of many cells for many „end-points‟„

LET > 20 keV/μm and RBE > 1.5 in the last 40 mm

so that carbon can control radioresistant tumours

i.e. tumours which need 2-3 times larger doses to be controlled with either X rays or protons

4800 MeV stop

RB

E

200 MeV stopp

C

LET (keV/μm)1 MeV/cm

X rays


42

The “effective dose” in Gye is defined as Gy x RBE „

At GSI the values of RBE are computed with X-ray cell survival data

by using the Local Effect Model (LEM) by G. Kraft el al.

To obtain a „flat‟ dose in Gye the “physical dose” is not „flat‟

GSI

Spread Out Bragg Peak


The GSI Local Effect Model (LEM)

EPFL 4- 4.11.10 - U. Amaldi 43

Survival =

Different for

tumour and

healthy tissues

RBE computed from Survivals

M. Scholz, GSI

Elective indications of carbon ions

calculated with LEM

EPFL 4- 4.11.10 - U. Amaldi 44

NO

YES

YES

YES

M. Scholz, GSI

Elective indications of carbon ions

calculated with LEM

EPFL 4- 4.11.10 - U. Amaldi 45

NO

YES

YES

YES

M. Scholz, GSI About 80% of all solid tumours

46

Numbers of potential patients (*)

X-ray therapy

every 10 million inhabitants: 20'000 pts/year

Protontherapy

12% of X-ray patients 2'400 pts/year

Therapy with Carbon ions for radio-resistant tumour

3% of X-ray patients 600 pts/year

TOTAL every 10 M about 3'000 pts/year

______

(*) Combining studies made in Austria, Germany, France and Italy in the framework

of ENLIGHT - Coordinator: Manjit Dosanjh –

Projects in FP7: ULICE, PARTNER, ENVISION , ENTERVISION for a total of 22 MEuro


47

52 -83 %31 – 75 %5 year

survival

Soft-tissue

carcinoma

77 %61 %24-28 %local control

rate

Salivary gland

tumours

100 %23 %5 year

survival

Liver tumours

7.8 months6.5 monthsav. survival

time

Pancreatic

carcinoma

63 %21 %local control

rate

Paranasal sinuses

tumours

96 % (*)95 %local control

rate

Choroid

melanoma

16 months12 monthsav. survival

time

Glioblastoma

63 %40 -50 %5 year

survival

Nasopharynx

carcinoma

89 %88 %33 %local control

rate

Chondrosarcoma

70 %65 %30 – 50 %local control

rate

Chordoma

Results carbon

GSI

Results carbon

HIMAC-NIRSResults photonsEnd pointIndication

Table by G. Kraft

2007

Results of

carbon ions

Similar to protons

THE END

EPFL 4- 4.11.10 - U. Amaldi 48

ACCELERATORS AND MEDICAL PHYSICS 4 - physique.cuso.ch · EPFL 4- 4.11.10 - U. Amaldi 1 ACCELERATORS...

Documents

Transcript of ACCELERATORS AND MEDICAL PHYSICS 4 - physique.cuso.ch · EPFL 4- 4.11.10 - U. Amaldi 1 ACCELERATORS...