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RADT 334 - Final
radiology physics final exam review
| Question | Answer |
|---|---|
| effect of an increase in kVp on compton scatter | decrease |
| energy range for photodisintegration | 10 MeV |
| energy range for pair production | 1.02 MeV |
| energy range for coherent scatter | < 10 keV |
| interactions with matter occurring in the diagnostic energy range | Compton scatter and photoelectric |
| The x-ray intensity is lower on the anode side of the tube because of the _____. | anode heel effect |
| as the angle of a target gets bigger, the effective focal spot will get ______ | bigger |
| the effective focal spot is ____ than the actual focal spot | smaller |
| what makes a good contrast agent? | high mass density, high atomic number |
| the difference in x-ray interaction by various body tissue | differential absorption |
| differential absorption is dependent upon this | kV, Z number, mass density |
| used to make a uniform density on a radiograph for a non uniform part thickness | compensating filter |
| What happens to the x-ray beam when you increase the kV by 15% | you get the effect of the mAs doubling (increase in density) |
| circuits on the operating console are _____ voltage | low |
| how does AEC work? | exposure ends once a certain radiation level reaches the image receptor |
| Voltage ripple of high-frequency generator | <1% |
| Voltage ripple of single-phase generator | 100% |
| Voltage ripple of three-phase, six-pulse generator | 14% |
| Voltage ripple of three-phase, twelve-pulse generator | 4% |
| If you have greater voltage ripple, you will have a ____ in image quality | decrease |
| If you have greater voltage ripple, you will have a ____ in image quantity | decrease |
| where radiation is made in the x-ray tube | anode |
| where electrons strike the target to make x-rays | focal spot |
| where electrons are boiled off | filament |
| what keeps the electrons together in a cloud near the filament | focusing cup |
| the kinetic energy of electrons is converted into mostly _____ in the x-ray tube | heat |
| _______ of the kinetic energy of electrons is converted into x-rays | <1% |
| two interactions that occur at the anode to produce radiation | characteristic and bremsstrahlung |
| five interactions in matter | coherent scatter, compton scatter, photoelectric absorption, pair production, photodisintegration |
| interaction at the anode where electron interacts with inner shell electron | characteristic |
| interaction at the anode where electron interacts with nuclear field and slows | bremsstrahlung |
| discrete portion of x-ray emission spectrum is from _____ radiation | characteristic |
| continuous x-ray emission spectrum is from _____ radiation | bremsstrahlung |
| to change the discrete x-ray emission spectrum, one would need to change this | atomic number of target material |
| electrical charge of an atom | 0 |
| electrical charge of an electron | negative |
| electrical charge of a proton | positive |
| electrical charge of a neutron | 0 |
| name the orbital shells from innermost to the fourth outer shell | K, L, M, N, O . . . |
| smallest part of an element | atom |
| smallest part of electromagnetic energy | photon |
| as the distance between the source and image increases, x-ray quantity at the image _____ | decreases |
| as the wavelength of a photon increases, the energy of the photon ______ | decreases |
| as the frequency of a photon increases, the energy of the photon _____ | increases |
| like charges | repel |
| unlike charges | attract |
| unit of electric potential | volt |
| unit of electric charge | coloumb |
| unit of power | Watt |
| unit of electric current | amp |
| unit of electric resistance | ohm |
| rate of doing work | power |
| faraday proved what? | a magnetic field in motion could produce an electric current |
| Oersted proved what? | a current produces a magnetic field |
| an electric current is induced in a circuit if some part of that circuit is in a changing magnetic field defines ________ | electromagnetic induction |
| removal of an electron from an atom | ionization |
| electron removed from atom and atom it originated from | ion pair |
| acronym for as low as reasonably achievable | ALARA |
| basic quanities in mechanical physics | mass, length, time |
| mass x distance | force |
| KE of random motion of molecules | heat |
| electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the distance between them | coulomb's law |
| electric charge distribution is ______ in a diffuse nonconductor (electrified object - like a cloud) | uniform |
| electric charge distribution is ______________ in a conductor (like a wire) | concentrated along the sharpest curvature |
| xrays are produced in this part of the atom | orbital shells |
| gamma rays are produced in this part of the atom | nucleus |
| unit for patient dose | rad, Gray |
| unit for occupational dose | rem, Sievert |
| unit for radiation in air | roentgen, Coulomb per kilogram |
| unit for radioactivity | curie, Becquerel |
| 1 R = | 1 rad or 1 rem |
| SI unit of occupational dose | Sievert |
| SI unit of patient dose | Gray |
| Si unit of radiation in air | gray in air, Air kerma, or Coulomb per kilogram |
| SI unit of radioactivity | bequerel |
| what type of transformer has a single winding | autotransformer |
| the kV meter is on the ____ side of the x-ray circuit | primary |
| the mA meter is on the ____ side of the x-ray circuit | secondary |
| as voltage is _____, amperage decreases | increased |
| the focal spot selector is located in this portion of the x-ray circuit | filament circuit |
| a step up transformer is used in what part of the circuit? | between low and high voltage/between primary and secondary sides |
| a step down transformer is used in what part of the circuit? | filament circuit |
| the step up transformer changes _____ into _____ | volts; kilovolts |
| emission spectrum: increasing mAs | increase amplitude |
| emission spectrum: increasing kV | increase amplitude and shift to right |
| emission specturm: increase filtration | decrease amplitude and shift to right |
| emission spectrum: increase atomic number of target material | increase amplitude and shift to right |
| When distance is doubled, intensity of x-ray beam is ______ by _______. | reduced; factor of four |
| controlling factors of beam quality | kV, filtration |
| controlling factors of beam quantity | mAs, kv, filtration - mAs being the main controlling factor |
| beam quantity is directly proportional to | mAs |
| HVL is a measurement of | beam quality |
| no ionization takes place in which of the radiation interactions with matter | coherent |
| No more electrons can be boiled off of the filament because of this phenomenon | space charge |
| What is a radiographic rating chart used for? | maximum exposure times |
| ways to increase efficiency of x-ray production | increase kV, increase atomic number of target material, use equipment with least voltage ripple |
| as the peak of the x-ray emission spectrum moves to the left, what is affected? How? | beam quality, decreases |
| electrons boiled off of the filament and being attracted to tungsten plating the inside of the x-ray tube | tube arcing |
| which way do electrons flow in the x-ray tube? | cathode to anode |
| which side of the beam is "hotter" or more intense? | cathode |
| varying power supplies to the x-ray circuit will be corrected by what component of the circuit? | line voltage compensator |
| transformers only operate on this type of current | AC |
| primary side- 200 turns; secondary side - 400 turns; primary voltage 110V; secondary voltage = ______ | 220V |
| what would provide a DC? | battery |
| V=IR is the formula for this law | Ohm's law |
| if there are more windings on the primary side versus the secondary side of a transformer, you have a ________ transformer | step down |
| types of induction | self, mutual |
| prupose of a transformer | change electric potential intensities |
| how does something become electrified? | gains excess electrons |
| frequency is _______ proportional to wavelength | inversely |
| What is constant with all electromagnetic energies? | velocity |
| most damaging form of ionizing radiation | alpha particle |
| type of ionizing radiation that travels the least distance | alpha particle |
| sources of manmade ionizing radiation? | atomic fallout, smoke detectors, nuclear power plants, medical x-rays |
| how does an x-ray tube cool primarily (what method is used)? | radiation |
| The Z number determines this about the atom | chemical element |
| how do you calculate atomic mass | add protons and neutrons |
| unit of measurement for electricity | joules or electron volts |
| any quantity of one type of molecule of at least 2 different elements chemically bonded together | compound |
| combination of one or more types of atoms of various elements bonded together | molecules |
| base quantities in mechanical physics | mass, length, time |
| derived quantities in mechanical physics | velocity, acceleration, momentum, work, volume |
| each electron shell is representative of this within the atom | binding energies of electrons |
| person noted as describing elements being composed of identical atoms | Dalton |
| person noted as describing atoms as being made of four different elements in varying quantities (earth, water, air, and fire) | greeks |
| model of atom with hooks and eyes to account for chemical combination | Dalton's |
| model of atom described similar to plum pudding | Thomson's |
| person noted for introduction of a nuclear model where the atom had a small dense positively charged center surrounded by negative charged cloud of electrons | Rutherford |
| model of atom with a central nucleus and well defined electron orbital paths | Bohr's |
| SI unit for velocity | m/s |
| SI unit for acceleration | m/s(squared) |
| SI unit for work | joule |
| SI unit for force | Newton |
| atom with same atomic number but different atomic mass numbers | isotope |
| protons in an atom determine the atom's _____. | atomic number |
| sum of proton's and neutrons in an atom determine the atom's ______. | atomic mass |
| symbol for atomic number | Z |
| symbol for atomic mass number | A |
| smallest particle of an element | atom |
| smallest particle of a compound | molecule |
| SI unit for mass | kg |
| SI unit for time | second |
| SI unit for length | meter |
| one-half the range from crest to valley over which the sine wave varies | amplitude |
| number of wavelengths that pass a point of observation per second | frequency |
| rate of rise and fall of a sine wave | frequency |
| velocity of electromagnetic radiation | c |
| wavelength is represented by this greek letter | lambda |
| distance from one crest to another | wavelength |
| electromagnetic wave equation | c=frequency x wavelength |
| E=mc(squared) can be used in radiology for what purpose | calculating mass equivalence of x-ray photons |
| study of stationary electric charges | electrostatics |
| study of moving electric charges | electrodynamics |
| rotation of electrons on their axis | electron spin |
| magnet created by a coil of wire with a current passing through it | solenoid |
| ability of a material to attract the lines of magnetic field intensity | magnetic permeability |
| degree to which material can be magnetized | magnetic susceptibility |
| device that uses mechanical motion to create electrical energy | generator |
| device that uses electrical energy to create mechanical motion | motor |
| transformer uses self induction or mutual induction to _____ | transform electrical energy into higher or lower intensities |
| Which type of circuit do the following laws apply: total R=R1+R2+R3; total I= I1=I2=I3; total V=V1+V2+V3 | series |
| Which type of circuit do the following laws apply: total R=1/R1+1/R2+1/R3; total I= I1+I2+I3; total V=V1=V2=V3 | parallel |
| kVp meter is located in this part of the x-ray circuit | low-voltage |
| mA meter is located in this part of the x-ray circuit | high-voltage |
| this circuit provides electrons for tube current | filament |
| where would a step up transformer be located in an x-ray circuit | between the primary and secondary sides |
| where would a step down transformer be located in an x-ray circuit? | filament circuit |
| a full wave rectified single phase generator would have how many x-ray beam pulses per second? | 120 |
| a half wave rectified single phase generator would have how many x-ray beam pulses per second? | 60 |
| a full wave rectified three phase generator would have how many x-ray beam pulses per second? | 360 |
| what changes about the voltage waveform from primary to secondary side of the x-ray circuit | amplitude |
| process of converting AC to DC | rectification |
| a single excessive exposure will damage the x-ray tube in this way | cracking of the anode |
| tungsten vaporization can cause this tube failure issue | arcing |
| cooling charts for x-ray tubes demonstrate this | thermal capacities and heat dissipation characteristics |
| induction motors use this to operate | magnetic field |
| the x-ray tube is an example of this type of motor | induction |
| mA setting on the operator console controls this in the x-ray beam | quantity of electrons emitted through thermionic emission |
| kV settings on the operator console controls this in the x-ray beam | penetrability/energy of the beam |
| to figure HU for a _________phase generator, multiply kVp x mA x s | single |
| to figure HU for a ______ phase gnerator, multiply 1.4 x kvp x ma x s | three |
| the maximum energy for an exposure taken at 90 kVp would be ____ | 90 keV |
| increases in mass density of the absorber _____ (increases/decreases/do not affect) Compton and Photoelectric interactions | increases |
| increases in atomic number of the absorber _____ (increases/decreases/do not affect) photoelectric interactions | increases |
| increases in atomic number of the absorber ______ (increases/decreases/do not affect) Compton interactions | do not affect |
| major benefit of using high kVp | decrease patient dose |
| Of Compton and photoelectric, even though both decrease as kV increases, which is more prevalent at higher kV? | Compton |
| backscatter is caused by this interaction | compton |
| interaction responsible for occupational dose | compton |
| interaction responsible for patient dose | photoelectric |
| interaction where no ionization takes place and results in an atom releasing an energy photon of equal energy in a different direction | coherent |
| type of ionizing radiation most similar to an ejected electron | beta emission |
| true/false: Physics is Phun! | True!! |
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hschmuck1
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