ORGANIZING THE MEDICAL IMAGING DEPARTMENT THE MEDICAL IMAGING DEPARTMENT 1

Transcription

1 ORGANIZING THE MEDICAL IMAGING DEPARTMENT THE MEDICAL IMAGING DEPARTMENT 1

2 Modern Medical Imaging methods Modern Medical Imaging includes a lot of methods: Conventional and Digital Radiology. Nuclear Medicine Imaging Methods (SPECT, PET) Sonography. Magnetic Resonance Imaging. There are also other interesting methods, including Endoscopic Imaging, Brain Mapping, Biomagnetic Diagnostics, Impedance Imaging, Thermography etc. that are either closer related to other Departments (Operating Theater, Outpatient Department), or they are not used intensively. THE MEDICAL IMAGING DEPARTMENT 2

3 The birth of X-rays (Roentgen 1895) in the Crookes tube THE MEDICAL IMAGING DEPARTMENT 3

4 X-ray Bremsstrahlung Spectra THE MEDICAL IMAGING DEPARTMENT 4

5 X-ray Anode material characteristic Spectral lines THE MEDICAL IMAGING DEPARTMENT 5

6 Operation principle of the contemporary (Coolidge) X-ray Tubes (V = kv) THE MEDICAL IMAGING DEPARTMENT 6

7 X-ray Tubes in the beginning of the 20 th Century THE MEDICAL IMAGING DEPARTMENT 7

8 Plomb-shielded & Oil-cooled modern X-ray Tubes THE MEDICAL IMAGING DEPARTMENT 8

9 Absorption and Scattering of X-rays THE MEDICAL IMAGING DEPARTMENT 9

10 Intensifying Screens and film Processing Unit THE MEDICAL IMAGING DEPARTMENT 10

11 Various Power Supplies THE MEDICAL IMAGING DEPARTMENT 11

12 Two examination rooms with common Power Supply THE MEDICAL IMAGING DEPARTMENT 12

13 External Power Supply Quality Control (V p, I a ) THE MEDICAL IMAGING DEPARTMENT 13

14 Classification of Radiography Equipment General radiography equipment (bucky systems) for skeletal, chest and head examination. Mammography systems. Dental X-ray equipment (simple and panoramic imaging). Mobile Radiographic Equipment. THE MEDICAL IMAGING DEPARTMENT 14

15 Bucky Systems THE MEDICAL IMAGING DEPARTMENT 15

16 Ceiling suspended X-ray tube THE MEDICAL IMAGING DEPARTMENT 16

17 Typical Bucky System and a usual Cranial Radiography THE MEDICAL IMAGING DEPARTMENT 17

18 Typical Mammography System and corresponding images THE MEDICAL IMAGING DEPARTMENT 18

19 Dental Orthopantograph System (Panoramic Image) THE MEDICAL IMAGING DEPARTMENT 19

20 Dose distribution around a Dental System THE MEDICAL IMAGING DEPARTMENT 20

21 Mobile X-ray System and corresponding image THE MEDICAL IMAGING DEPARTMENT 21

22 Systems equipped with Image Intensifier Remote controlled (mainly over-table X-ray tube) fluoroscopy systems. Mobile C-arm Operating Theater X-ray Equipment. Conventional (mainly under-table X-ray tube) mono or biplane Angiography systems. THE MEDICAL IMAGING DEPARTMENT 22

23 Thorax Fluoroscopic image on Fluorescent Screen and on Image Intensifier THE MEDICAL IMAGING DEPARTMENT 23

24 Operation principle of an Image Intensifier (ZnS:CdS:Ag or CsI) THE MEDICAL IMAGING DEPARTMENT 24

25 Video Camera of an Image Intensifier THE MEDICAL IMAGING DEPARTMENT 25

26 Various size Image Intensifiers and a corresponding Image THE MEDICAL IMAGING DEPARTMENT 26

27 Typical Examination Room THE MEDICAL IMAGING DEPARTMENT 27

28 Over-table and Under-table systems THE MEDICAL IMAGING DEPARTMENT 28

29 Scattered Dose Distribution around an Over-table System THE MEDICAL IMAGING DEPARTMENT 29

30 Scattered Dose Distribution around an Under-table System THE MEDICAL IMAGING DEPARTMENT 30

31 Protection zones according to DIN 6811 THE MEDICAL IMAGING DEPARTMENT 31

32 Ionization chamber THE MEDICAL IMAGING DEPARTMENT 32

33 Geiger-Mueller detector THE MEDICAL IMAGING DEPARTMENT 33

34 Other Detectors THE MEDICAL IMAGING DEPARTMENT 34

35 Radiation Protection Counters THE MEDICAL IMAGING DEPARTMENT 35

36 Dosimetry Phantoms THE MEDICAL IMAGING DEPARTMENT 36

37 Radiological System Maintenance THE MEDICAL IMAGING DEPARTMENT 37

38 One and two level Angiography Systems THE MEDICAL IMAGING DEPARTMENT 38

39 Angiography Systems equipped with synchronized contrast media distributor THE MEDICAL IMAGING DEPARTMENT 39

40 Digital X-ray equipment Computer assisted tomography (CT-scanner). Digital Subtraction Angiography. Digital Fluoroscopy Systems (including remote controlled systems, C-arms etc). THE MEDICAL IMAGING DEPARTMENT 40

41 Digital Angiography Systems THE MEDICAL IMAGING DEPARTMENT 41

42 Two differently processed Digital Subtraction Angiography Images THE MEDICAL IMAGING DEPARTMENT 42

43 Digital Radiology Systems and Digital C-arm System for the Operation Room THE MEDICAL IMAGING DEPARTMENT 43

44 Conventional Tomography: Principle THE MEDICAL IMAGING DEPARTMENT 44

45 Conventional Tomography: Implementation THE MEDICAL IMAGING DEPARTMENT 45

46 2 - D Object Reconstruction based on its multiple projections (Algorithm: J. Radon, Austria, 1917) THE MEDICAL IMAGING DEPARTMENT 46

47 The Invention (Sir Godfrey Hounsfield, EMI, London, and Alan Cormack, Tufts University, Medford, MA) and the Evolution of CT THE MEDICAL IMAGING DEPARTMENT 47

48 Modern CT THE MEDICAL IMAGING DEPARTMENT 48

49 CT Gantry and Patient Table Movements THE MEDICAL IMAGING DEPARTMENT 49

50 CT Detectors Scintillators (NaI, CaF2, CdWO4, CsI) connected to Photomultiplier or Photodiodes. High Pressure Ionization Chambers (Xe or Xe-Kr). THE MEDICAL IMAGING DEPARTMENT 50

51 Typical CT Examination Room THE MEDICAL IMAGING DEPARTMENT 51

52 CT Slices and 3-D Image Reconstruction THE MEDICAL IMAGING DEPARTMENT 52

53 CT Service and Maintenance Contracts THE MEDICAL IMAGING DEPARTMENT 53

54 Bone Densitometry Systems THE MEDICAL IMAGING DEPARTMENT 54

55 80 kv filtered X-ray spectrum and NaI(Tl) detector THE MEDICAL IMAGING DEPARTMENT 55

56 40 kv and 70 kv X-ray spectra and 80 kv 400 mg/cm 2 Ce filtered X-ray spectrum THE MEDICAL IMAGING DEPARTMENT 56

57 Typical Layout of a Bone Densitometry Examination Room THE MEDICAL IMAGING DEPARTMENT 57

58 Typical Bone Densitometry Examination Room THE MEDICAL IMAGING DEPARTMENT 58

59 Typical Bone Densitometry Examination Print-outs THE MEDICAL IMAGING DEPARTMENT 59

60 Management of X-ray Diagnostic Equipment Workflow planning to optimize existing architectural design. Selection of appropriate system, fitting to the Hospital needs. Selection and sharing of X-ray equipment power supply (generator). Film processing method and associated quality control. Conditions of X-ray equipment maintenance contract. Conditions of X-ray tube guarantee. Archiving and Digital Image handling. Radiation Protection. Quality Assurance in everyday Operation. THE MEDICAL IMAGING DEPARTMENT 60

61 Marie and Pierre Curie / Ernest Rutherford THE MEDICAL IMAGING DEPARTMENT 61

62 Nuclear Medicine ƒ - Decay Nuclear Medicine is the specialty that uses radioactive tracers to medical situations, mainly for imaging purposes, but also for therapeutic ones. A complete nuclear medical service includes several sections and rooms. THE MEDICAL IMAGING DEPARTMENT 62

63 Nuclear Medical Service Sections and Rooms. Radio-pharmaceutical preparation: hot-lab, application room and in some major University Hospitals also a Cyclotron Facility for the production of positron emitting isotopes for Positron Emmission Tomography (PET). Examination area: -Camera examination rooms, also for planar, SPECT, etc., image-processing room, physical examination room, dark room. Physics area: Radiation shielded store for isotopes, laboratory, electronic shop. Patient area: Waiting rooms for ambulant and for non-ambulant patients, lavatories. Therapy: Preparation and treatment rooms, treatment planning room, radiation protected isotope store, nuclear medicine ward. THE MEDICAL IMAGING DEPARTMENT 63

64 Planar Bone scanning gamma- Camera I THE MEDICAL IMAGING DEPARTMENT 64

65 Modern Bone scanning gamma - Camera II THE MEDICAL IMAGING DEPARTMENT 65

66 -Camera Tl 204 examination combined to stress test THE MEDICAL IMAGING DEPARTMENT 66

67 Mobile gamma - Camera THE MEDICAL IMAGING DEPARTMENT 67

68 Typical gamma - Camera Images THE MEDICAL IMAGING DEPARTMENT 68

69 Gamma - Camera round NaI(Tl) crystal and the associated Photomultipliers THE MEDICAL IMAGING DEPARTMENT 69

70 Photomultiplier Amplifier THE MEDICAL IMAGING DEPARTMENT 70

71 Gamma - Camera Gantry THE MEDICAL IMAGING DEPARTMENT 71

72 Tomographic gamma - Camera with round crystal THE MEDICAL IMAGING DEPARTMENT 72

73 Tomographic gamma - Camera with rectangular crystal THE MEDICAL IMAGING DEPARTMENT 73

74 Tomographic gamma - Camera with double round and rectangular crystals THE MEDICAL IMAGING DEPARTMENT 74

75 Positron Emission Tomography (PET) Positron Emission Tomography (PET) has proven to be a unique tool in analyzing biomedical metabolic function or dysfunction, qualitatively and quantitatively. It finds application in cardiology for tissue viability and perfusion studies, in neurology for studying epilepsy, dementia, and other investigative brain studies, and in oncology for early tumor diagnosis, tumor grading, and extent of metastasis. THE MEDICAL IMAGING DEPARTMENT 75

76 PET Implementation Positron emission tomography begins with isotopes such as Rubidium 82, Oxygen 15, and Fluorine 18. The typical isotopes used in PET scanning have a half-life that ranges from 75 seconds to 110 minutes. Cyclotron is a cost effective, easy to operate, shelfshielded radioisotope delivery system. A commercially available modern machine, produces substantial quantities of the major positron emitting isotopes and compounds in a variety of chemical forms under full automation. THE MEDICAL IMAGING DEPARTMENT 76

77 A typical commercially available Cyclotron THE MEDICAL IMAGING DEPARTMENT 77

78 PET System Console THE MEDICAL IMAGING DEPARTMENT 78

79 PET scan of a heart following acute myocardial infarction and thrombolytic therapy The Rubidium areas show that the tissue, although mechanically abnormal, is metabolically alive. THE MEDICAL IMAGING DEPARTMENT 79

80 PET 3-D Brain Image Reconstruction THE MEDICAL IMAGING DEPARTMENT 80

81 Magnetic Resonance Imaging (MRI) THE MEDICAL IMAGING DEPARTMENT 81

82 Magnetic Resonance Imaging In common with all other imaging processes in medical diagnostics, magnetic resonance tomography makes use of the interaction of anatomical structures within the human body with a radiation field. With the aid of a radio-frequency field in the Mhz range and a locally variable magnetic field, the sharp resonance absorption of magnetic nuclei in biological tissue is used in order to obtain the spatial distribution of the nuclear magnetization. THE MEDICAL IMAGING DEPARTMENT 82

83 MRI Principle In particular, Hydrogen atoms, which occur naturally in large numbers, allow medically meaningful images to be formed, with a spatial resolution comparable to that of X- ray computed tomography, and which show previously unseen contrasts between tissues. In addition, it is even possible to detect magnetic nuclei, such as 13 C, 19 F, 23 Na, 31 P, in spite of their low concentration in biological tissue; nevertheless, the value of the information thus gained does not approach that obtained through proton resonance. THE MEDICAL IMAGING DEPARTMENT 83

84 Magnetic Moment alignment of a probe with Nuclear Spins In the case of thermal equilibrium, the magnetic moment of a probe with nuclear spins, aligns itself parallel to the external magnetic field. If this equilibrium is disturbed, for example by suddenly changing the direction of the external magnetic field, then a torque acts on the magnetic moment of the sample, causing a change in time, of the angular momentum of the probe. THE MEDICAL IMAGING DEPARTMENT 84

85 The magnetic moment of a probe with nuclear spins aligns itself parallel to the external magnetic field THE MEDICAL IMAGING DEPARTMENT 85

86 Precession of the nuclear magnetization This results in, the precession of the nuclear magnetization, around the direction of the magnetic field, with the Larmor frequency. This precession (Nuclear Magnetic Resonance) can be detected easily, by measuring the induced alternating voltage, in a coil surrounding the sample. After a finite period of time the thermal equilibrium which had previously been disturbed is reestablished. THE MEDICAL IMAGING DEPARTMENT 86

87 Changing the direction of the magnetic field a torque acts on the magnetic moment of the sample THE MEDICAL IMAGING DEPARTMENT 87

88 The precession (NMR) can be measured as induced alternating voltage in a coil surrounding the sample THE MEDICAL IMAGING DEPARTMENT 88

89 Relaxation times Two time constants are of interest: The longitudinal relaxation time T 1 is the time constant with which is restored the magnetization along the direction of the basic field, and it is associated with the emission of energy to the crystal lattice in which the atomic nuclei are embedded (spin-lattice relaxation). The transverse relaxation time T 2 is the time constant with which the transverse component decays, due to the mutual interactions of the nuclear spins (spin-spin relaxation). THE MEDICAL IMAGING DEPARTMENT 89

90 The physical significance of the Relaxation times The relaxation times express the mobility of the molecules in which the nuclei under consideration are located. Each nucleus is surrounded by other magnetic moments which are in constant thermal Brownian molecular motion, and produce a continuously changing magnetic perturbation field. Spectral components which correspond to the precession frequency of the nuclear magnetization, induce the longitudinal relaxation. Transverse relaxation is determined by the frequency of collisions between the molecules as a whole. THE MEDICAL IMAGING DEPARTMENT 90

91 The signal depends on the electron density of the chemical groups to which belong the protons THE MEDICAL IMAGING DEPARTMENT 91

92 MRI signal of characteristic groups THE MEDICAL IMAGING DEPARTMENT 92

93 Typical MRI System THE MEDICAL IMAGING DEPARTMENT 93

94 Typical MRI Suite in the beginning of the 80s THE MEDICAL IMAGING DEPARTMENT 94

95 A modern MRI examination unit THE MEDICAL IMAGING DEPARTMENT 95

96 Patient positioning THE MEDICAL IMAGING DEPARTMENT 96

97 A typical pass-through MRI system THE MEDICAL IMAGING DEPARTMENT 97

98 Cranial examination coil THE MEDICAL IMAGING DEPARTMENT 98

99 Head fixing accessories and a Cranial examination coil THE MEDICAL IMAGING DEPARTMENT 99

100 An open MRI system THE MEDICAL IMAGING DEPARTMENT 100

101 MRI Console THE MEDICAL IMAGING DEPARTMENT 101

102 Some typical MRI images (a) THE MEDICAL IMAGING DEPARTMENT 102

103 Some typical MRI images (b) THE MEDICAL IMAGING DEPARTMENT 103

104 Super-conductive MRI Magnet THE MEDICAL IMAGING DEPARTMENT 104

105 MRI advantages MRI has various attractive attributes: Non-ionizing radiation. Excellent soft tissue contrast. Visualization of any desired plane, without special patient positioning. No bone artifacts. Non invasive character of the examination. Potential for flow measurements. Potential for dynamic studies. THE MEDICAL IMAGING DEPARTMENT 105

106 Sonography The development of Ultra-sound equipment started in the fifties with equipment for examining the skull and the heart. Stimulated by sonar and radar technology, these developments culminated in two-dimensional ultrasound examination of: The abdominal organs. The thyroid glands. Obstetric examinations. Sectional displays of the heart. THE MEDICAL IMAGING DEPARTMENT 106

107 Combination units Today, combination units using several scanning methods and satisfying all diagnostic requirements are widespread. Almost all ultrasound methods used today in medical diagnostics are based on the echo pulse technique. Amplitude modulation (A mode) Time motion mode (M mode) Brightness modulation (B mode) have been used, that evaluate the amplitude of the echo signals received by the transducer. THE MEDICAL IMAGING DEPARTMENT 107

108 Scanning procedures There are two major scanning procedures: Mechanical sector scanning with good price-performance ratio, based on the rotor principle or the wobbler principle. Electronic scanning, i.e. the required scanning width (image width) is covered by a large number of identical individual transducers, formed as a linear or curved array. Scanning may be performed in rectilinear coordinates (linear array) or in polar coordinates (sector, mechanical systems, curved or phased array systems). THE MEDICAL IMAGING DEPARTMENT 108

109 Doppler frequency shift A source for extra information is the frequency content of the ultrasound oscillations and especially the Doppler frequency shift of the moving signal source (e.g. blood). A continuous wave (CW) or a pulse wave (PW) Doppler method can be applied. Duplex and triplex scanners combine independent transducer arrangements allowing for Imaging and Doppler examination. THE MEDICAL IMAGING DEPARTMENT 109

110 A typical ultrasound system THE MEDICAL IMAGING DEPARTMENT 110

111 Various Ultra-sound transducers THE MEDICAL IMAGING DEPARTMENT 111

112 Josephson Effect and the Super-conducting QUantum Interference Devices (SQUID) THE MEDICAL IMAGING DEPARTMENT 112

113 The Current of the Interference Circuit versus Magnetic Field Intensity V = 0, û = c. ( / 0) THE MEDICAL IMAGING DEPARTMENT 113

114 Block Diagram of SQUID applied in Medicine THE MEDICAL IMAGING DEPARTMENT 114

115 SQUID based Magneto-cardiogram (MCG) THE MEDICAL IMAGING DEPARTMENT 115