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Rad Physics Final
| Question | Answer |
|---|---|
| Intensity increase with altitude and latitude in what? | cosmic rays |
| Potassium-40 | internally deposited radionuclides |
| Represented by large deposits of uranium, thorium, and other radionuclides | terrestrial radiation |
| largest source of natural environmental radiation | radon |
| the quantity of matter contained in any physical object and is measured in kg | mass |
| energy of motrion | kinetic energy |
| e=mc2 | mass energy equivalence |
| no mass, no charge and travels at the speed of light | electromagnetic energy |
| anything that occupies space | matter |
| the binding energy of an electron to a nucleus would? | be higher for an L shell than for an M shell of an atom |
| Tungsten (184/74 W) has how many neutrons | 110 |
| The horizontal rows in the periodic table are called? | periods |
| the octet rules state that no outer shell of an atom can contain more than? | 8 electrons |
| What is an isotope? | atoms having the same atomic number but a different mass number |
| what is the theoreticl max number of electrons permitted in the N shell? | 32 |
| radioactive half life is? | the time required for the radioactivity to reach on half its original value |
| how ar ethe elements on the periodic table arranged? | increasing proton number |
| how is atomic number defined? | the number of protons |
| what do 12/6 C and 14/6 C have in common? | same number of protons |
| how many electrons could occupy the M shell of a germanium atom? | 18 |
| upon decay the results in the atomic number increasing by 1 | beta emission |
| similar to xray, but different in origin | gamma ray |
| upon decay results in the atomic mass number decreasing by 4 | alpha emission |
| protons & neutrons | nucleons |
| T/F diagnostic xrays are produced in the shells of atoms, vs gamma rays which are the result of radioactive decay from the nucleus | True |
| t/f the energy of a photon is directly proportional to its frequency | true |
| t/f the energy of a diagnostic xray is less than visible light | false |
| diagnostic ultrasound is part of the electromagnetic spectrum t/f? | false |
| diagnostic xrays have a longer wavelength than ultraviolet light t/f? | false |
| structures that are radiopaque do not absorb xrays? t/f? | false |
| the reduction in the intensity of the beam as it passes through matter is defined as attenuation t/f? | true |
| at a given velocity, wavelength and frequency are directly proportional? t/f? | false |
| according to wave particle duality, diagnostic xrays behave more like | particles |
| characteristics of xray photons | have no mass, and are electrically neutral have a veolcity of 3 x 10*8 m/s |
| the number of wavelengths passing a point per second | frequency |
| the velocity of an xray photon | 3 x 10^8 m/s |
| einstein's theory of relativity | e=mc2 |
| one half the range from crest to valley over which the isne wave varies | amplitude |
| the distance from crest to crest or valley to valley | wavelength |
| electromagnetic induction refers to the production of? | an electric current |
| when a charged particle moves in a straight line, a magnetic field is induced how? | perpendicular to the direction of travel |
| how are the resistance of a wire and the diameter of the wire related? | decreased resistance as the diameter of the wire increases |
| if two magenets were brought together north to north poles will what? and the south poles will what? | repel/attract |
| what is the unit for electric power? | watts (w) |
| an electrical insulator would? | inhibit the movement of electrons |
| the output current in a step up transformer would be? | higher than the input current |
| according to electrostatic laws: | an electron will repel an electron |
| the unit of electrical potential? | Volt |
| coulomb's law states that electrostatic force is? | inversely proportional to the square of the distance between charges |
| what is the best electric conductor? | copper |
| what is the SI unit for magnetic field strength? | tesla |
| the principle difference between self induction and mutual induction is | mutual induction require 2 coils and self only requires one. |
| the xray tube requires Dc not AC to operate. t/f? | true |
| the autotransformer operates off of the principle of self indution t/f? | true |
| increased voltage ripple results in higher radiation quality and quantity? t/f? | false |
| a high frequency generator uses an inverter to square off voltage pulses, resulting in less voltage ripple t/f? | true |
| A RT used the AEC for a lateral C spine and did not position the vertebrae over the center cell this would result in the image looking underexposed? t/f? | true |
| the filament transformer is a step down transformer? t/f? | true |
| the prereading voltmeter reads kVp? t/f? | false |
| the rectifiers are located in the xray tube? t/f? | false |
| a step up transformer has a turns ration of >1? t/f? | true |
| what are the 3 principal parts of an xray unit? | xray tube, control console and high voltage generator |
| what is the preferred choice of material for a radiogrpahic table? | carbon fiber |
| a spinning top is used to check the exposure time on which type of unit? | single phase radiographic unit |
| how many rectifiers are required to achieve full wave rectification? | 4 |
| how many overlapping pulses are generated in 1s for a 3 phase/12 pulse generator? | 720 |
| where would the rectifiers be physically located? | between the secondary side of step up transformer and xray tube |
| A 90/30 table would allow what? | a table to tilt 90 degrees towards the feet and 30 degrees towards the head. |
| what is responsible for providing protection at the level of the gonads during fluoro and has a Pb equivalency of .25 mm? | bucky slot cover |
| the output current of a step up transformer would be? | less than the input current |
| what part of a radiographic unit automatically selects the highest mA and shortest time for an exam? | falling load generator |
| what is the principle reason the high voltage generator is surrounded by oil? | electrical insulator |
| where is the autotransformer physically located? | operating console |
| what is true about AEC? | positioning is critical to correctly exposing patient. the back up time should be set 150% of the expected mAs |
| what is the principle difference between self induction and mutual induction? | mutual induction requires 2 coils and self requires 1 |
| a line voltage compensator is necessary to supplywhat? | the autotransformer with precisely 220 V |
| the filament operates at currents between? | 3-6 A |
| 3 phase/6 pulse voltage ripple | 13% |
| high frequency power voltage ripple | <1% |
| full wave rectified power voltage ripple | 100% |
| half wave rectified power voltage ripple | 100% |
| 3 phase/12 pulse voltage ripple | 4% |
| accurate to exposure as low as 1 ms and can be used for serial exposures? | electronic timer |
| minimum exposure time is 1/60th second? | synchronous timer |
| what terminates the exposure once it has received 1 mR of exposure? | AEC |
| what terminates exposure once the correct mAs has been achieved? | mAs timer |
| what is not accurate and can only be used for exposure > 250 ms? | mechanical timer |
| the xray tube housing helps to protect against radiation exposure and electrical shock? t/f? | true |
| the anode is powered by an induction motor? t/f? | true |
| the cloud of electrons surrounding the filament can be referred to as the space charge? tf? | true |
| a smaller target angle would result in a larger effective focal spot? t/f? | false |
| the 2 primary parts of the cathode are the filament and rotor? tf? | false |
| what type of transformer would be responsible for supplying current to the filament? | step down |
| what target angles is characteristic of a modern rotatin anode xray tube? | 10 degrees |
| what is true about the anode heel effect? | xray beam intensity can vary by up to 45% from cathode to anode |
| if the rotor of an anode fails to rotate, what is the most likely cause of tube failure? | pitted anode |
| what are functions of the anode? | supports the target, radiates heat, and conducts electricity |
| protective tube housings are designed to keep leakage radiation at what levels? | less than 100mR/hr at 1 m when operated at max. kV and mA |
| if a max exposure technique was applied to a cold anode what is the likely result? | cracked anode |
| what is true about the anode heel effect? | small anode angles result in larger heel effect position the thicker anatomy under the cathode side of the tube |
| what sex of exposure factors would be space charged limited? | low kVp and high mA |
| what is the focusing cup of the cathode negatively charged? | repels electrons and helps focus the electron beam towards the focal tract on the anode |
| according to the line focus principle, the effective focal spot is what compared to the actual focal spot? | smaller |
| modern xray tubes used for radiaography are? | dual focus tubes |
| why is tungsten the best material choice for xray tube targets? | high atomic number |
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