ACCELERATORS AND MEDICAL PHYSICS 3

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1 ACCELERATORS AND MEDICAL PHYSICS 3 Ugo Amaldi University of Milano Bicocca and TERA Foundation 1

2 People of hadrontherapy Other uses: hadron therapy BUT radiotherapy is a single word particlle therapy BUT also photons are particles 2

3 Neutrontherapy at Berkeley 1935: Ernest and John Lawrence at the control of the 27-inch cyclotron R. Stone at the 60- inch cyclotron 3

4 Harvard Protontherapy Hymer Friendell Bob Wilson Percy Bridgeman 1946 R.R. Wilson proposes the use of protons for teletherapy 1954 First irradiations in Berkeley 1961 New Harvard cyclotron irradiates patients Founder and first director of Fermilab

5 Protontherapy in Europe Bőrje Larsson at Uppsala On the Application of a 185 MeV Proton Beam to Experimental Cancer Therapy and Neurosurgery Doctoral dissertation The modified Uppsala synchrocyclotron ( ) 5

6 SuperHILAC Ion therapy UNILAC Bevatron Cornelius Tobias

7 Tobias and collaborators studied carbon, oxygen, New radiobiology of light ions at Berkeley 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 7

8 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 before the laboratory closes in

9 The Harvard cyclotron and Mas. General Hospital Ray Kjellberg fastens his stereotactic device to a patient. Herman Suit (right) and J. E. Munzenreider visiting the cyclotron when it was closed in EPFL U. Amaldi 9

1992-1994: the turning years 1993 Como, Italy

commercial centre 1993: At GSI the pilot project

10 : the turning years 1993 Como, Italy 1992: Loma Linda treats first patient with protons First International Symposium on Hadrontherapy 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 10

11 Loma Linda Medical Center in California James Slater (left) at the inauguration of the Loma Linda centre. The first hospital based facilitywith rotating gantries EPFL U. Amaldi 11

12 HIMAC in Chiba is the pioner of carbon therapy (Prof H. Tsujii) Yasuo Hirao Hirohiko Tsujii 6000 pts Since the cells do not repair fewer fractions are possible HIMAC: 4-9 fractions! LATER 12

13 The GSI pilot project : patients treated with carbon ions Gerhard Kraft J. Debus 13

14 Summary of the previous lectures 14

15 The beginnings of modern physics and of medical physics 1895 discovery of X rays Wilhelm Conrad Röntgen Henri Becquerel ( ) Marie Curie Pierre Curie ( ) ( ) EPFL U. Amaldi 15

16 The next magnificent three years for experimental physics and medical physics E. Fermi and collaborators Discovery of the effect of slow neutrons Ernest Lawrence with a 0.1 MeV cyclotron Carl D. Anderson discoverer of the positron EPFL U. Amaldi 16

17 Details on accelerators synchrotrons cyclotrons hadrons electrons Loaded structure linacs Phase stability Strong focusing EPFL U. Amaldi 17

18 The icone of radiation therapy Radiation beam in matter Energy imparted to a masse M of matter Delivered dose = D = masse M in J/kg = gray (Gy) Linear Energy Transfer = LET = in kev/µm Δ E Δ x EPFL U. Amaldi 18

19 Energy losses by the semiclassical model Δ E Δ x Exact calculations In water Semiclassical model K / Mc 2 1 EPFL U. Amaldi 19

20 Proton Bragg peak in water The computed quantities R is the residual range i.e. the range measured from the end Electron ranges in water Total range in Al Practical range in Al IMPORTANT RATIO Practical range in water EPFL U. Amaldi 20

21 The losses seen by the water molecules Probability for the incoming particle to loose the energy E c Excitations Excitation due s due to to distant distant coll. coll. Minimal ionization energy Ionizations due to distant coll. Ionizations due to close coll. Absorbed energy E c in kev EPFL U. Amaldi 21

coll. coll. Minimal ionization energy Ionizations due to distant coll.

22 The losses seen by the water molecules Probability for the incoming particle to loose the energy E c Excitations Excitation due s due to to distant distant coll. coll. Minimal ionization energy Ionizations due to distant coll. Ionizations due to close coll. Absorbed energy E c in kev EPFL U. Amaldi 22

23 Interactions with matter in conventional radiotherapy E e max E X 2K e /5 E X dose transition region depth % of max dose KERMA DOSE depth in water EPFL U. Amaldi 23

24 People of hadrontherapy 24

25 Harvard Protontherapy Hymer Friendell Bob Wilson Percy Bridgeman 1946 R.R. Wilson proposes the use of protons for teletherapy 1954 First irradiations in Berkeley 1961 New Harvard cyclotron irradiates patients Founder and first director of Fermilab

26 End of the summary 26

27 X ray therapy 27

28 Different radiations used in radiotherapy Directly ionizing radiations: electrons, positrons effects: ionizations, excitations secondary 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: secondary particles: neutrons (neutral hadrons) effects: secondary particles: photoelectric, Compton, pair creation electrons, positrons, photons nuclear interactions (mainly with protons) protons, nuclear fragments 28

29 Quark composition of hadrons p, n are made of 3 quarks neutron Neutron = ddu = -⅓ -⅓ +⅔ =0 Proton = duu = -⅓ +⅔ + ⅔ =+1 Negative pion = ud = -⅔ -⅓ =- 1 proton Helium = 4 He neutron 29

30 An electron linear accelerator (linac) 10 MeV electrons target gantry X rays Multileaf colimator tumour 30

31 Cell survival and fractionation Repair in few hours 1 gray = 1 Gy = 1 J/kg ionizations per nucleus due to 200 electrons 31

32 Cell survival and fractionation For % of the solid tumours, the tumour tissues are more «radiosensitive» than healthy tissues Repair in few hours 1 gray = 1 Gy = 1 J/kg ionizations per nucleus due to 200 electrons 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 10 8 cells in 1 litre tumour The tumour dose is limited by the nearby healthy tissues which cannot receive more than Gy 32

33 The target volumes GTV: CTV: Gross Target Volume as determined by CT, MRI, SPECT ad PET the Clinical Target Volume takes into account invisible infiltrations PTV: the Planning Treatment Volume takes into account mouvements and misalignments CHALLENGE: Conform the dose to the tumour! 33

34 To delineate the PTV: Computer Tomography => μ Hounsfield numbers H are proportional to electron density 34

35 To delineate the PTV: Computer Tomography => μ Hounsfield numbers H are proportional to electron density from Thomas, Brit. J. Rad., 72 (1999) 35

36 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 head With detectors 0.14 MeV gammas 36

37 To delineate the PTV: PET 37

38 To delineate the PTV: : Magnetic Resonance Imaging = MRI 38

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

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

41 The therapeutic window many biological and clinical phenomena in 30 sessions FAVORABLE TCP TCP UNFAVORABLE NTCP NTCP Dose in Normal Tissue (Gy) Dose in Normal Tissue (Gy) EPFL U. Amaldi 41

42 Quantification of the control without complications 1- NTCP TCP NTCP TPC (1- NTCP) EPFL U. Amaldi 42

43 Tumour conformation to open the window EPFL U. Amaldi 43

44 IMRT = Intensity Modulated Radiation Therapy with photons 9 NON-UNIFORM FIELDS PSI 44

45 THE END 45

Introduction to Medical Physics

Introduction to Medical Physics Ab branch of applied physics concerning the application of physics to medicine or, in other words The application of physics techniques to the human health Marco Silari,