1. Lectures on Medical Biophysics Department of Biophysics, Medical Faculty, Masaryk University in Brno

2. Nuclear medicine and radiotherapy Lectures on Medical Biophysics Department of Biophysics, Medical Faculty, Masaryk University in Brno

17. E lectron - positron pair production Interaction of ionising radiation with matter

28. The Gamma Camera thin (about 1.5 cm) NaI phosphor crystal photomultiplier tubes (now being replac ed by a flat digital sensor) parallel hole Pb collimator for localisation MCA

31. Principle of SPECT An object with a radiation source Z is surrounded by scintillation detectors F with collimators K. The collimators allow detection only of gamma-rays falling normally onto the detector blocks. It enables us to localise the source of rays. In SPECT, common sources of radiation (iodine-131, technetium-99m) are used . Nuclear medicine

32. SPECT – images http://www.physics.ubc.ca/~mirg/home/tutorial/applications.html#heart Perfusion of heart in different projections. „Hot“ regions are well blood supplied parts of the heart Brain with „hot“ regions Nuclear medicine

34. PET principle E xplan ation of the high spatial resolution of PET : The opposite detectors in a coincidence circuit. A source of radiation Z is detected only when lying on a line connecting the detectors. Detector A but not the detector B can be hit through a collimator from the source Z 2 , because this source is outside the detection angle of B. In SPECT, the signal detected by A from Z 1 would be partially overlapped by the signal coming from source Z 2 . Nuclear medicine

35. Functional PET of brain http://www.crump.ucla.edu/software/lpp/clinpetneuro/lggifs/n_petbrainfunc_2.html resting Music – a non-verbal acoustic stimulus Visual stimulus Nuclear medicine

36. intensive thinking remembering a picture skipping on left leg Nuclear medicine

37. Brain tumour - astrocytoma Nuclear medicine

40. „ The cobalt bomb“ Radiotherapy In 1951, Canadian Harold E. Johns used cobalt-60 for therapy first.

41. „ The cobalt bomb“ http://www.cs.nsw.gov.au/rpa/pet/RadTraining/ Radiotherapy

43. Leksell Gamma Knife Radiotherapy

45. Leksell Gamma Knife Radiotherapy

46. Leksell Gamma Knife Radiotherapy

47. Afterloader Blessing-Cathay works with Ir-192. An instrument for safe intracavitary irradiation main unit applicators phantom Control unit Radiotherapy

49. The linear accelerator CLINAC 2100C in Masaryk memorial institute of oncology in Brno Radiotherapy

50. The linear accelerator http://www.cs.nsw.gov.au/rpa/pet/RadTraining/MedicalLinacs.htm Radiotherapy

51. The cyclotron Z – source of the accelerated particles (protons), D 1 and D 2 – duants or dees, G - generator of high-frequency voltage. Radiotherapy

53. The cyclotron in oncology – proton therapy The Sumitomo cyclotron Radiotherapy

54. Hadron radiotherapy Hadrons (protons and light ions) lose their energy mainly in collisions with nuclei and electron shells. The collisions with electrons are dominant for energies used in radiotherapy. The energy deposited is indirectly proportional to the second power of hadron velocity. It means practically that the hadrons deposit most of their energy shortly before end of their tracks in the tissue. This fact is exploited in hadron therapy because (in contrary to the conventionally used photons) the tissues lying in front of the Bragg peak receive a much smaller dose compared with the target area. The tissues behind the target are not irradiated. The target can be precisely determined and thus damage to the surrounding healthy tissue is minimised. The Bragg peak area is given by energy of the particle. In therapy, the necessary penetration depth is about 2 – 25 cm, which corresponds to an energy of 60 – 250 MeV for protons and 120 – 400 MeV for light ions. Radioterapie

55. Radiotherapy planning for X-ray beams After tumour localisation, the radiotherapist determines the best way of irradiation in co-operation with a medical physicist. The tumour has to receive maximum amount of radiation but the healthy tissues should be irradiated minimally and some should be totally avoided. When irradiating the tumour from only one side, the tissues in front of it would receive higher dose than the tumour and the near side of the tumour more than the far one. That is why irradiation is performed from different directions. The skin area, through which the radiation beam enters the body, is called the irradiation field ; irradiation from different directions (2, 3, 4) is called multi-field treatment. In some cases (tumours of oesophagus and prostate) the multi-field treatment is replaced by moving beam treatment – the source of radiation moves above or around the patient in circle or arc (tumour-centred) during irradiation. The radiotherapeutic plan involves the energy of radiation, daily and total dose of radiation, number of fractions etc. Radioterapie

56. Simulator X-ray simulator is an XRI device having the same geometry as the accelerator. It is used to locate the target tissues which should be irradiated. To ensure always the same patient positioning both in the simulator and the accelerator, there is a system of laser lights in the room. An identical system of laser beams is used in the accelerator room. Radiotherapeutic simulator Acuity Radioterapie

59. Author s : Vojtěch Mornstein , Ivo Hrazdira Content collaboration and language revision: Carmel J. Caruana Presentation design: Lucie Mornsteinová Last revision: May 200 9