1922904
Descripción
Pregunta 1
Pregunta
Protons and neutrons in a nucleus are termed:
Respuesta
-
Beta-particles
-
Photons
-
Nucleons
Pregunta 2
Pregunta
Linear attenuation coefficient of photoelectric absorption (photoelectric effect interaction probability) τ is:
Respuesta
-
Inversely proportional to the atomic number of the element Ζ
-
Inversely proportional to the mass number A
-
Proportional on the density ρ
Pregunta 3
Pregunta
Linear attenuation coefficient of photoelectric absorption τ depends strongly (approximately to the 4-th power) on:
Respuesta
-
The density of substance
-
The atomic number of element Z
-
The temperature of substance - t
Pregunta 4
Pregunta
Linear attenuation coefficient for Compton effect (Compton scattering interaction probability) δ is proportional to:
Respuesta
-
Atomic mass number A
-
Density of substance
-
The ratio A/Z
Pregunta 5
Pregunta
Linear attenuation coefficient for Compton effect is proportional to:
Respuesta
-
pZ4
-
pZ2
-
pZ/A
Pregunta 6
Pregunta
Linear attenuation coefficient for pair production (electron-positron production probability) X is proportional to:
Respuesta
-
Atomic mass number A
-
The square of the atomic number of the element Z2
-
The ratio of A/Z
Pregunta 7
Pregunta
Predominant mode of interaction between conventional diagnostic x-ray and biological tissues (Figure 11. not included) is:
Respuesta
-
Pair production (electron-positron)
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Photoelectric absorption
-
Compton effect (scattering)
Pregunta 8
Pregunta
Interaction of photonic ionizing radiation with matter will
Respuesta
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Reduce radiation intensity
-
Not change radiation intensity
-
Increase radiation intensity
Pregunta 9
Pregunta
What type of interaction between diagnostic x-rays and matter is improbable:
Respuesta
-
Photoelectric absorption
-
Pair production (electron-positron)
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Compton effect
Pregunta 10
Pregunta
Consider attenuation of photon beam in water/soft tissue (figure 11. not included). Which statement is true:
Respuesta
-
Photons may undergo two successive photoelectric transitions
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Compton scattering has a threshold energy of 1.022 MeV
-
Photoelectric effect increases with photo energies
-
Photoelectric and Compton effects equal at 25 KeV
Pregunta 11
Pregunta
Roentgen Rays are:
Respuesta
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Photons
-
Electrons
-
Positrons
Pregunta 12
Pregunta
Roentgen rays are:
Respuesta
-
Electromagnetic Radiation:
-
Protons
-
Electrons
Pregunta 13
Pregunta
X-rays have
Respuesta
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A wavelength longer than that of the visible light
-
Positive Electric Charge
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Ionizing Capacity
Pregunta 14
Pregunta
The wavelength of the roentgen radiation is within the range of:
Respuesta
-
380 - 760 nm
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0.76 - 1000 µm
-
10 - 380 µm
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Less than 10 nm
Pregunta 15
Pregunta
X-rays have:
Respuesta
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Frequency higher than that of the visible light
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Direct ionizing capacity
-
Negative electric charge
Pregunta 16
Pregunta
Characteristic x-ray radiation:
Respuesta
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Has continuous energy spectrum
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Does not differ from braking radiation spectrum
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Is obtained from K and L shell electron transitions from high atomic shells.
Pregunta 17
Pregunta
Continuous x-ray energy spectrum:
Respuesta
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Contains several photons with different energy
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Does not differ from the characteristic x-ray spectrum
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Is a result of rapid deceleration of electrons near target nuclei
Pregunta 18
Pregunta
Intensity ψ of radiation in x-ray tube is proportional to:
Respuesta
-
The atomic number Z of anode's material
-
The 3-th power of anode U3/a
-
The 2-nd power of anode I2/a
Pregunta 19
Pregunta
Intensity ψ of roentgen radiation (x-ray tube) is proportional to:
Respuesta
-
The 3-th power of anode voltage U3/a
-
The anode current Ia
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The 2-nd power of the atomic number Z2 of anodes material.
Pregunta 20
Pregunta
Intensity ψ of roentgen radiation (x-ray tube) if proportional to:
Respuesta
-
Density p of the cathode material
-
The 2-nd power of anode voltage U2/a
-
The 2-nd power of anode current I2/a
Pregunta 21
Pregunta
Minimum wavelength λmin (maximum energy) of x-ray tube radiation depends on:
Respuesta
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Anode Voltage Ua
-
Anode current
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The atomic number Z of the element of which anode is made
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Density p of the material of which cathode is made
Pregunta 22
Pregunta
Filters in x-ray apparatus modify:
Respuesta
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The minimum wavelength λmin of x-ray braking spectrum
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The amount of anode Voltage Ua
-
The intensity ψ of roentgen radiation
Pregunta 23
Pregunta
Intensity ψ of the Roentgen rays is proportional to:
Respuesta
-
U2IZ
-
UI2Z
-
UIZ2
Pregunta 24
Pregunta
Hardness of x-ray radiation (harder/softer) is changed by:
Respuesta
-
Anode voltage Ua
-
Beam intensity ψ
-
Anode current Ia
Pregunta 25
Pregunta
The relationship between HVL (Half Value Layer) and linear attenuation coefficient µ is
Respuesta
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HVL = ln(2)/µ
-
HVL = µ/ln(2)
-
HVL = µ*ln(2)
Pregunta 26
Pregunta
Water is said to be soft tissue equivalent with respect to x-ray attenuation. This is because water and soft tissue have approximately the same properties. Which properties are NOT the same? (there are more than one correct answers)
Respuesta
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Effective atomic number Zeff
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Effective molecular weight
-
Physical density p
-
Attenuation Coefficient µ
Pregunta 27
Pregunta
The purpose of the introduction of contrast substances in the roentgen diagnostics is to:
Respuesta
-
Obtain coloring in the roentgenogram and not only black and white images
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Increasing the contrast between soft tissues
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Reduce the radiation dose on patients
Pregunta 28
Pregunta
Contrast substances in diagnostics radiology will:
Respuesta
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Increase contrast between different soft tissues
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Increase contrast between soft tissues and bones
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Obliterate cancer cells
Pregunta 29
Pregunta
Which of the listed chemical elements provides maximum contrast in diagnostic radiology:
Respuesta
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Calcium: Z = 20, p = 1.55 g/cm3
-
Barium: Z = 56, p = 3.5 g/cm3
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Iodine: Z = 53, p = 4.94 g/cm3
Pregunta 30
Pregunta
Roentgen osteo-densitometry (measurement of bone density) is based on which of the following phenomena:
Respuesta
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Diffraction of roentgen rays (x-rays)
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Scattering of roentgen rays (x-rays)
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Attenuation of Roentgen rays (x-rays)
Pregunta 31
Pregunta
Hounsfield Unit (CT number) for bones is equal to:
Respuesta
-
0
-
up to (+3000)
-
(-1000)
Pregunta 32
Pregunta
Hounsfield unit (CT number) for air is equal to:
Respuesta
-
0
-
Up to (+3000)
-
(-1000)
Pregunta 33
Pregunta
Hounsfield unit (CT number) for water is equal to:
Respuesta
-
0
-
up to (+3000)
-
(-1000)
Pregunta 34
Pregunta
Hounsfield unit (CT number) is defined as:
Respuesta
-
(µ-tissue + µ-water) / µ-water
-
(µ-tissue - µ-water) / µ-water
-
(µ-tissue - µ-water) / µ-tissue
Pregunta 35
Pregunta
Predominant x-ray interaction mode in CT scanning is:
Respuesta
-
Photoelectric absorption & compton scattering
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Electron-positron pair production & photoelectric absorption
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Compton scattering & electron-positron pair production
Pregunta 36
Pregunta
CT diagnostic imaging is based on the phenomenon of:
Respuesta
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Reflection of reoentgean rays at the boundary between different structures
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Absorption of roentgen rays by tissues exposed to radiation
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Attenuation of roentgen rays by tissues exposed to radiation
Pregunta 37
Pregunta
What is the meaning of "computed" in name of CT (computed tomography)?
Respuesta
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Calculation of radiation dose
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Control of the scanning process
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Formation of the final image
Pregunta 38
Pregunta
Computed tomography uses higher anode voltage compared to conventional roentgenography because
Respuesta
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Patients are placed further away from x-ray source
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Rotation of x-ray tube exposes more massive parts of patients body radiation
-
CT x-ray detectors are less sensitive
Pregunta 39
Pregunta
CT exposes pateints to higher radiation doses compared to conventional roentgenography (x-ray imaging) because:
Respuesta
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Anode voltage is higher
-
Multiple images are taken
-
Both A and B
Pregunta 40
Pregunta
Radionuclides used in "in vivo" radionuclide diagnostics are:
Respuesta
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Alpha-radionuclides
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Beta-radionuclides
-
Gamma-Radionuclides
Pregunta 41
Pregunta
What type of radioactivity is related to SPECT radionuclide diagnostics:
Respuesta
-
Beta
-
Alpha
-
Gamma
Pregunta 42
Pregunta
Alpha-rays are a beam of:
Respuesta
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Electrons
-
Helium nuclei
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Positrons
Pregunta 43
Pregunta
Radiopharmaceuticals are:
Respuesta
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Contrast substances used in MRI
-
Contact gels used in ultrasound diagnostics
-
Chemical compounds containing radioactive isotopes
Pregunta 44
Pregunta
The following quantity participates in the law of radioactive decay:
Respuesta
-
Huddersfield unit (CT-number)
-
Index of refreaction n
-
Linear attenuation coefficient
-
Decay constant
Pregunta 45
Pregunta
Half-life T1/2 is defined as:
Respuesta
-
Energy of gamma-radiation
-
Probability of radioactive decay
-
The time it takes for radioactivity to be reduced by half.
Pregunta 46
Pregunta
Isomeric transition is a type of decay that changes:
Respuesta
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The atomic number Z of the element
-
The energy of the nucleus
-
The mass number A of the nucleus
Pregunta 47
Pregunta
Radionuclides produced in generators have:
Respuesta
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Long half-life T1/2
-
Short half-life T1/2
-
High energy gamma-radiation
Pregunta 48
Pregunta
Radionuclide generators contain:
Respuesta
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Only gamma-radionuclides
-
A meta-stable mother radionuclide
-
A metastable daughter radionuclide
-
Mother (parents) and daughter radionuclides - metastable radionuclides
Pregunta 49
Pregunta
Radionuclides are:
Respuesta
-
Transformers of radiowaves
-
Radioactive nuclei
-
Ultrasound detectors
Pregunta 50
Pregunta
How does activity of a radio-pharmaceutical change after sterilization for intravenous application (sterilization time ignored):
Respuesta
-
Reduces abruptly due to chemical changes
-
Increases abruptly due to chemical changes
-
Remains unchanged
Pregunta 51
Pregunta
Radio-pharmaceuticals used in nuclear medicine include:
Respuesta
-
Elements with radioactive nuclei
-
Transformers of infared rays
-
Sources of ultrasound
Pregunta 52
Pregunta
Radio-pharmaceuticals used for "in vivo" diagnostics contain radionuclides with the following mode of radioactivity:
Respuesta
-
Isometric Transition
-
Beta minus decay
-
Alpha decay
Pregunta 53
Pregunta
Time required for intial activity A0 for a radioactive source to decay to 10% is between:
Respuesta
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1 and 2 half-lives
-
2 and 3 half-lives
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3 and 4 half-lives
-
4 and 5 half-lives
Pregunta 54
Pregunta
The decay constant for 182TA is 0.006 day-1. Which is its half life:
Respuesta
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0.006 days
-
83 days
-
115 days
-
167 days
Pregunta 55
Pregunta
The phenomenon of radioactivity is associated with:
Respuesta
-
Decay of atoms
-
Decay of nucleus
-
Fusion of nuclei
-
Emission of valence Orbital electrons
Pregunta 56
Pregunta
Electron capture involves:
Respuesta
-
An electron combining with a neutron
-
A neutron being ejected from the nucleus
-
An electron combining with a proton
-
An electron being ejected from the nucleus
Pregunta 57
Pregunta
In alpha decay:
Respuesta
-
Z and A are unchanged
-
Z decreases by 4 and A decreases by 2
-
Z decreases by 2 and A decreases by 4
-
Z decreases by 4 and A decreases
Pregunta 58
Pregunta
Isomeric transition involves:
Respuesta
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The emission of a gamma-ray
-
The conversion of a neutron to a proton
-
The conversion of a proton to a neutron
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Electron Capture
Pregunta 59
Pregunta
An alpha-particle consists of:
Respuesta
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One proton and two neutron
-
Two proton and one neutron
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Two proton and two neutron
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One proton and One neutron
Pregunta 60
Pregunta
For pair production interactions it is true that:
Respuesta
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Have no energy threshold
-
Occur near the electric field of the nucleus
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Produce 1.022 MeV annihilation radiation
-
Are important in diagnostic radiology
-
All of the above
Pregunta 61
Pregunta
99Tc-m has a half-life t1/2 = 6h. What is the approximate value of 99tc-m decay constant:
Respuesta
-
0.12 sec-1
-
0.12 min-1
-
0.12 hr-1
Pregunta 62
Pregunta
After 40 half-lives have elapsed, the activity A of radionuclide is equal to:
Respuesta
-
A0/40
-
A0/(2*40)
-
A0/(2 40)
Pregunta 63
Pregunta
Polonium-210 has a half-life of 4.5 months, and decays into the stable daughter isotope of lead-206. By measuring the proportion of polonium to lead in a sample, one can establiosh the production date of polonium. If the proportion is 1:15 (Po:Pb), how many months have elapsed since production date?
Respuesta
-
3
-
15
-
18
Pregunta 64
Pregunta
What type of radiation can NOT be detected with scintillation detector?
Respuesta
-
Alpha particles
-
Beta Particles
-
Gamma Rays
Pregunta 65
Pregunta
Ionizing radiation used for "In vivo" radionuclide diagnostics:
Respuesta
-
Alpha and gamma radiation
-
Beta minus radiation
-
Gamma and annihilation radiation
Pregunta 66
Pregunta
Which quantity is NOT a parameter of radionuclides:
Respuesta
-
Activity A
-
Half-Life T1/2
-
Radiation yield
-
Decay constant
Pregunta 67
Pregunta
Activity A is a parameter of:
Respuesta
-
Laser radiation
-
Radionuclides
-
Radioactive sources
Pregunta 68
Pregunta
Why is technetium-99m (99mTC) preferred over iodine-131 (131-I) for thyroid gland diagnostics?
Respuesta
-
99mTC is more cost-effective
-
99mTC has fewer side effects
-
99mTC is a "pure" gamma source and the radiation is orders of magnitude less
-
Natural deposits of 99mTC exists in some tissues
Pregunta 69
Pregunta
1987 an old radiotherapy source of cesium-137 (T1/2 = 30 years) was stolen from an abandoned hospital in the brazilian city of goiania. It was subsequently handled by many people, resulting in four deaths and 249 cases of high radiation exposure. If the activity of the source was 74TBq (Terebecquerels) in 1971, what was the activity in the time of the accident?
Respuesta
-
51 TBq
-
37 TBq
-
30 TBq
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