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RAD 255
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| Question | Answer |
|---|---|
| Energy cannot be created or destroyed (T or F) | True |
| The speed of an object in a given direction is known as | Velocity |
| A roller coaster sitting at the top of the hill on a track represents what type of energy | Potential |
| Force x Distance = | Work |
| Energy can neither be destroyed or created describes the "Law of _____ __ ______ | conservation of energy |
| The tendency of a moving body to remain in motion and a resting body to remain at rest | Inertia |
| The product of mass x velocity | Momentum |
| The mass per unit volume of a substance | Density |
| The ratio of the density of any substance to the density of water | Specific Gravity |
| A quantity of matter of indefinite shape and size (not the same as weight) | Mass |
| The speed of ___________ is 186,000 miles/second | Light |
| How many centimeters in 1 inch | 2.54 |
| 1 meter= _________ millimeters | 1000 |
| Electrification is the addition or removal of _________ from an object | electrons |
| Ways an object can be electrified | Friction Induction Contact |
| The nucleus of an atom contains | Protons & Neutrons |
| If an atom contains 24 protons, 24 neutrons, and 23 electrons, what is the atomic number? | 24 |
| If an atom contains 24 protons, 24 neutrons, and 23 electrons, what is the atomic mass number? (Elemental mass) | 48 |
| In which orbital shell do the electrons have the greatest binding energy? (N, K, L, M?) | K shell |
| In which orbital shell do the electrons have the greatest potential energy? (N, K, L, M?) | N shell |
| The smallest division of an element or matter is the | Atom |
| The nucleus of an atom has a net ____ charge | Positive |
| Which of the following K-shell electrons would have the highest binding energy? Sodium Atom - Atomic number = 11 Tungsten Atom - Atomic Number = 74 Barium Atom - Atomic Number = 56 Carbon Atom - Atomic Number = 6 | Tungsten Atom - Atomic Number = 74 |
| An atom with more electrons than protons will have what charge? | Negative |
| Ohm's Law expresses the relationship between Current, voltage, and____ | Resistance |
| The flow of electrons in a conductor would be classified as : | electrodynamics |
| One coulomb flowing by a given point each second is equal to | 1 ampere |
| What happens to current as resistance increases | It decreases |
| Which of the following will have the least resistance? Large cross section / short length Small cross section / long length Large cross section / long length Small cross section / short length | Large cross section / short length |
| What is the fundamental difference between conductors and insulators? | Conductors have many free electrons |
| What is the purpose of a fuse in an electric circuit? | Protect against circuit overload |
| All of the following terms can be used interchangably to describe the pressure or force of electrons through a circuit EXCEPT: Amperage Voltage Electromotive Force (EMF) Potential Difference | Amperage |
| What is the material called that will attract small pieces of iron? | magnet |
| Every magnet has two poles. What are they called? | north and south |
| What are the magnetic lines called that surround a magnet? | flux lines |
| What determines the strength of a magnetic field? | the number of flux lines in an area |
| How would cutting the distance between two magnets in half effect the attraction force between them? | it would increase four times |
| What surrounds every electrical current? | magnetic field |
| In which direction do magnetic flux lines travel? | north pole to south pole |
| What are materials called that are strongly attracted to a magnet? | ferromagnetic |
| How are the north poles of two magnets going to affect each other? | they will repel |
| Materials that are easily magnetized and demagnetized are said to have a high_______. | permeability |
| How will the north pole and the south pole of two magnets affect each other? | they will attract |
| Materials that are difficult to magnetize and demagnetize are said to have a high_________. | retentivity |
| A coil of wire rotating through a magnetic field produces an electric current. What does this describe? | generator |
| The number of cycles per second that are associated with an alternating current is expressed in the term ____________? | hertz |
| In a 60 Hz alternating current, how many pulses (alterations) occur every second? | 120 |
| How are alternating current values usually expressed? | RMS values |
| An electric current that continually changes directions is known as what type of current? | alternating |
| A simple electric generator produces what type of current? | AC |
| When the AC sine wave passes over the zero voltage line, what happens in the circuit? | electrons come to a stop & electrons are preparing to reverse directions in the circuit there is no voltage in the circuit |
| If a step-down transformer has a turns ratio of 1:10, what will the output voltage be if the input voltage is 220 V? | 22 V |
| If the peak kilovoltage on a single phase unit is set on 100 kVp, what will the R.M.S. value be? | 70kV |
| An electric generator converts ____________ energy to ______________ energy. | mechanical electrical |
| What is the current carrying coil of wire called? | solenoid |
| What is it called when a solenoid has an iron core in its center? | electromagnet |
| Which of the following happens when a wire moves through a magnetic field? 1. an electric current is induced in the wire 2. the resistance in the wire increases 3. the magnetic field disappears | 1. an electric current is induced in the wire |
| Maximum induction will occur when a conductor cuts a magnetic field at what angle? | 90 degrees |
| How can voltage be induced into a conductor? | move a wire through a magnetic field 2. move a magnetic field across a wire 3. place a wire in a varying magnetic field |
| What is it called when a current is induced in a secondary coil by passing alternating current through in the primary coil placed in close proximity? | mutual induction |
| What type of transformer has more turns of wire in the secondary side than in the primary side? | step-up |
| What type of transformer core is most widely used in radiographic equipment? | shell type |
| What determines the transformer ratio? | turns of wire |
| What type of transformer core is most efficient? | shell type |
| If the voltage is stepped-up, what happens to the current in the secondary side of the transformer? | decreases |
| As a magnetic domains rearrange in a transformer, heat is produced. What is the energy loss called? | hysteresis losses |
| Which material would make the best transformer core? | soft iron |
| What are the swirling currents called that are induced in transformers and produce heat losses? | eddy currents |
| What is the major reason for using alternating current? | transformers cannot operate without it |
| Transformers are ______% efficient | 90-95 |
| A transformer has a turns ratio of 10 which is 10 windings on the primary side and 100 windings on the secondary side. If the input voltage is 70, what will the voltage induced on the secondary side be? (consider 100% efficiency) | 700 |
| The induced current in a wire will be the strongest when the wire intersects the magnetic field at what angle? | 90 degrees |
| All moving charges are surrounded by a: | magnetic field |
| True or false? 1 watt is equal to 1 ampere of current across a potential of 1 volt. | True |
| Two coils of wire are placed near each other. AC is passed through the first wire and a current is induced in the second wire. This describes: | mutual induction |
| What impacts the magnitude of an induced current? | The strength of the magnetic field The angle of the conductor to the magnetic field The velocity of the magnetic field as it moves past the conductor The number of turns in the conductor |
| Use Ohm’s Law to calculate the resistance in a circuit if there are 12 volts of potential difference and 6 amps of current flowing through a circuit. | 2 ohms |
| Current which travels in only one direction in a circuit is called: | direct current (DC) |
| The number of protons in an atom’s nucleus is reflected in its: | atomic number (Z#) |
| The term R.M.S. or “root - mean square” is used to express the _______ voltage in a circuit. | effective |
| If the peak kilovoltage on a single phase unit is set on 110 kVp, what will the R.M.S. value be? | 77 kV |
| An electromagnetic device used to change the magnitude of voltage and current in an AC circuit is a: | transformer |
| You go to Europe on a traveling radiologic technologist assignment where AC is 50 Hz. How many pulses occur every second? | 100 |
| True or false? In a 60 Hz system, one entire cycle of the AC sine wave takes place in 1/60 of a second. | True |
| Left Hand generator rule- Thumb | Direction of wire motion |
| Left Hand generator rule- Index finger | Direction of magnetic flux from north to south |
| Left Hand generator rule- Middle finger | Direction of induced current |
| A transformer has 2400 windings on the primary side and 600 windings on the secondary. Is this a step- up or step-down transformer? | Step-down transformer |
| True or false? Transformers do not create energy; they only change current or voltage from high to low or low to high while maintaining power of the circuit according to the Law of Conservation of Energy. | True |
| An autotransformer is supplied with 440 volts of electricity has 5000 windings on the primary side and 10000 windings on the secondary side. The amperage will: | Decrease |
| An autotransformer is supplied with 440 volts of electricity has 5000 windings on the primary side and 10000 windings on the secondary side. If 440 V and 20 A are supplied to the primary side of this transformer, what will the voltage be on the secondary? | 880V |
| A transformer has 2400 windings on the primary side and 600 windings on the secondary. What is the turns ratio? | 1:4 |
| True or false? A transformer with a turns ratio greater than 1 is a step - down transformer. | False |
| What determines the transformer ratio? | turns of wire |
| In which orbital shell do the electrons have the least potential energy? (N, K, L, M) | k-shell |
| In order for a current to be induced in a wire by a magnet, the magnetic field must be: | changing or fluctuating |
| A simple electric generator produces what type of current? | AC |
| Leakage radiation is reduced by the housing to: | 1 mGya/hr |
| The housing serves to do all of the following except: Thermal cushion Electrical insulator Maintain vacuum Mechanical support | Maintain vacuum |
| Tungsten is used as a target material primarily because of which of the following? 1. High Melting Point (thermal capacity) 2. Electrical capacity 3. High Atomic Number (Complex Atom) | 1 and 3 only |
| What is the primary advantage of the rotating anode? | Increased heat load capacity |
| Which part of the induction motor is inside the glass envelope? | Rotor |
| A decrease in the anode target face angle (line focus principle), will decrease the size of the: | Effective focal spot |
| Which end of the beam has the most intense x-ray photons? | Cathode |
| Higher techniques are better tolerated by which filament size? | Large |
| All of the following are needed to produce x-rays in the x-ray tube except: Source of electrons Large potential difference Place for electron interaction Way to cool electrons | Way to cool electrons |
| How many heat units are produced using a three-phase, 12-pulse machine and the following factors for 5 exposures: 90 kVp, 400 mA, .02 sec.? | 5076 |
| By what process does a transformer change voltage? | Electromagnetic Induction |
| Filament heating is precisely controlled by which of the following? | Rheostat or Variable Resistor |
| A step-down transformer is used in what section? | Filament |
| Devices that in effect convert AC to DC are located in which section? | Secondary |
| Power from the step-down transformer will next enter the: | Filament |
| The DURATION over which the filament is heated is controlled by | Exposure Timer |
| The mA meter is located in the ________________ circuit, and measures milliamperage during the actual exposure under load conditions. | High Voltage or Tube Circuit |
| The mA selection is controlled by what circuit component? | Rheostat or Variable Resistor |
| Voltage exiting the step-up transformer will pass through what component next? | Rectifiers |
| Which component of the general x-ray circuit makes rectifiers necessary? | x-ray tube |
| Voltage to the filament circuit comes from which of the following? | Autotransformer |
| Which component of the primary circuit automatically adjusts incoming power? | Line compensator |
| Which part of the autotransformer allows for selection of secondary turns to be used? | Taps |
| The high current which passes through the filament circuit is needed to_____________. | -heat the filament -provide thermionic emission |
| The process of heating the x-ray tube filament to red hot temperatures, and the subsequent boiling off of electrons is known as_____________. | thermionic emission |
| The target of x-ray tube is composed primarily of _______ because of its _________ . | tungsten/high atomic number |
| Which part of the x-ray circuitry is responsible for adjustment of the KVP through the use of moveable taps? | autotransformer |
| The primary purpose of rotating anode is: | to provide a large area for heat distribution during the exposure |
| The device which adjusts the incoming voltage to precisely 220 volts for the purpose of providing consistent x-ray output is known as the: | line voltage compensator |
| The heat units produced in an x-ray tube during an exposure of 75 KVP and 200 mAs on a three-phase twelve pulse machine would be___________. | 21,150 |
| The autotransformer is supplied with ______ current. | alternating |
| Which component is used to change the alternating current supplied by the high voltage transformer into direct current, which is needed to operate the x-ray tube? | rectifiers |
| The high voltage transformer is a/an transformer. | step-up |
| The component in the x-ray circuitry whose job is to supply varying magnitudes of voltage to other parts of the circuit is: (the tube and filament circuits connect into this component) | the autotransformer |
| The device incorporated in parallel which allows voltage to be monitored before the exposure is made is the: | pre-reading voltmeter |
| Tungsten atoms are slowly vaporized from the filament and plate out inside the tube on the glass envelope: | this may eventually cause tube failure (cracked tube) through a process known as spark over |
| Reduction of the anode angle from 20o to 10o will result in: | better detailed images & creation of a smaller effective focal spot |
| A cloud of electrons forms around the filament of the x-ray tube, making it difficult for the filament to emit more electrons due to the negative charge of the cloud. This phenomenon is called: | the space charge effect |
| The heel effect states that: | the radiation intensity on the cathode side of the x-ray field is higher than that on the anode side |
| The portion of the x-ray tube consisting of two filaments surrounded by a metal cup is known as the: | cathode |
| The electron flow through an x-ray tube is in which direction? | cathode to anode |
| When the electrons strike the anode to produce x-rays, approximately what percent of the electrons actually turn into x-rays? ( the other percent is turned into heat) | 1 or below |
| Diagnostic x-ray tubes containing two filaments are known as________. | dual focus tubes |
| The primary voltage (the voltage going into the step-up transformer) is measured in ? | Volts |
| Thermionic emission in the x-ray tube_________. | provides electrons for x-ray production |
| The rectifiers in an x-ray circuit are located__________. | between the secondary of the step-up transformer and the x-ray tube |
| The heat units produced in an x-ray tube during an exposure of 75 KVP and 200 mAs on a single-phase machine would be___________. | 15,000 |
| By slightly angling the anode (the target angle decreased), the line focus principle accomplishes which of the following? | effective focal spot size is smaller than the actual focal spot size |
| The device which measures the actual amount of current that is flowing through the x-ray tube is known as the_______and is located in the_________. | mA meter / high voltage or tube circuity |
| An x-ray tube should be "warmed up"____________. | if the tube has not been used during the previous 60 minutes (or longer) |
| If proper "warm-up" procedure is not followed, which of the following types of damage is most likely to occur? | cracked anode |
| The average speed of a rotating anode in a general purpose tube is about | 3,400 rpms |
| mA or filament current is controlled by a device which varies the amount of in the filament circuit. | resistance |
| The anode target face is coated with an alloy of___________. | tungsten-rhenium |
| The x-ray tube filament is composed of ______. | thoriated tungsten |
| The "gassy" tube will exhibit which of the following symptoms___________. loud embarrassing noise 50% output consistently inconsistent output excessive leakage radiation vibrations during exposures | inconsistent output |
| The x-ray tube must be supplied with______for most efficient operation. | DC |
| The exposure timer and switch mechanisms are usually located on the side of the circuit. | low voltage (control panel) |
| The mA meter can NOT be safely placed on the operating console because it is grounded. (T or F) | False |
| The rectifiers and mA meter are located in the section of the x-ray circuitry. | high voltage |
| The motor that powers the rotor in an x-ray tube with a rotating anode works on the principle of: | electromagnetic induction (induction motor) |
| As the target angle decreases (becomes steeper), the recorded detail will increase. (T or F) | True |
| As the target angle decreases (becomes steeper), the effective focal spot becomes smaller. (T or F) | True |
| As the target angle decreases (becomes steeper), the anode heel effect increases. (T or F) | True |
| As the target angle decreases (becomes steeper), the radiation intensity on the anode side of the beam becomes less intense. (T or F) | True |
| As the target angle decreases (becomes steeper), the heat loading capacity of the x-ray tube increases. (T or F) | True |
| Excessive holding of the rotor switch which engages the booster circuit will | decrease the life expectancy of the tube and evaporate the filament at a faster rate |
| An x-ray tube is usually immersed in oil for the purpose of | electrical protection & aids in heat dissipation (helps to cool) |
| The protective tube housing serves which purposes | absorbs leakage radiation & protects against electrical shock |
| what is needed in order for the space charge electrons to be accelerated across the x-ray tube | a high voltage must be applied through the "tube-circuit" & the exposure switch must be activated |
| If the heat capacity of an x-ray tube is exceeded, which things may occur? | pitting and melting of the target may occur & ball bearing damage if the anode heat becomes excessive |
| Which of the mechanisms are used to aid in the dissipation of heat (cooling) from the x-ray tube housing? | air blower & heat exchanger |
| The "heat unit" is obtained for a three-phase (6 pulse) unit by the formula: kVp x mA x seconds x ________ | 1.35 |
| The auto transformer has one winding and one core (T or F) | True |
| Certain components, such as the minor and major KVP, connect directly into the auto transformer through what? | taps |
| What is NOT a part of the operating console? line compensator Step-up transformer KVP meter Timers | Step-up transformer |
| What meter can make accurate measurements of exposures less than 1/10 second? | Ballistic Meter |
| Exposure timers are usually located on the low or high voltage side? | low |
| Which timer can NOT be used for serial exposures because they must reset after each exposure? | Synchronous timer |
| The ammeter did nothing to prevent the "space charge limited region", so modern equipment have replaced ammeters with what? | Space-charge compensators |
| Where is the mA meter physically located? | High-voltage section |
| The average turns ratio for a step-up transformer | 500:1 |
| Why is tungsten used in a filament? | High melting point |
| Why is Rhenium used in the face of the anode disk? | Provides mechanical strength at high rpm's High atomic number of 75 Prevents surface erosion |
| What controls x-ray QUANTITY? | tube current |
| The "heat unit" is obtained for a three-phase (12 pulse) unit by the formula: KVp x mA x seconds x (provide the number only as your answer) | 1.41 |
| Which part of the induction motor is located outside the tube? | stator |
| Which of the following voltage ripples is (are) produced by three-phase equipment? 1. 100% voltage ripple 2. 14% voltage ripple 3. 4% voltage ripple | 2 and 3 only |
| If an AP' hip technique required 84 kVp with single- phase x-ray equipment, what kVp would produce a comparable image with three-phase equipment? | 74 kVp |
| With three-phase equipment (6-pulse), have how many pulses per cycle: | 6 |
| In order to be used more efficiently by the x-ray tube, alternating current is changed to direct current by the | rectifiers |
| Circuit devices that will conduct electrons in only one direction are 1. resistors 2. valve tubes 3. solid state diodes | 2 and 3 only |
| The voltage ripple associated with a three-phase, twelve-pulse rectified generator is about | 4.0% |
| Which of the following generators creates a PULSED beam? | Single Phase Half Wave |
| When a beam is PULSED, the voltage ripple is _______. | 100% |
| A three-phase, 12 pulse x-ray generator will produce how many pulses per SECOND? | 720 |
| All single phase x-ray machines are characterized by 100% voltage ripple, whether they are half-wave or full wave rectified. (T or F) | True |
| A single-phase, fully rectified x-ray machine will produce a voltage output with ________ pulses per CYCLE. | 2 |
| A three-phase x-ray generator with a transformer configuration that incorporates 2 UNLIKE windings on the secondary side offers which advantages? | mA meter grounded at mid-point & Increases output from 6 to 12 pulses per cycle |
| How can the voltage ripple be reduced to 0% in an x-ray generator? | incorporation of a capacitor between the rectifier system and the x-ray tube |
| Semi-conductors are primary parts of which of the following? | Solid-state rectifier |
| The use of four rectifiers will create | Single-phase full-wave |
| The primary side of the transformer configuration always has a ___________ winding. | Delta |
| Which x-ray units will produce the least amount of voltage ripple? | High frequency |
| Which of the following is an advantage of the falling load generator? | reduced exposure time |
| A Half-Wave rectification is accomplished by incorporating how many rectifiers in the circuitry? | 2 |
| A ___________ is a device that stores electrons. | Capacitor |
| Where is a capacitor located in the x-ray circuitry? | between the rectifiers and the x-ray tube |
| A three-phase 12 pulse generator produces _________ pulses per second and _________ voltage ripple. | 720 / 4% |
| What best describes the purpose of rectifiers in the x-ray circuitry? | Converts AC to DC to enable the x-ray tube to function efficiently |
| Select 2 answers for this question. The two types of rectifiers are (one old type and one modern): Solid State Resistive type Tube type Inverse type | Solid State Tube type |
| The modern type of rectifiers are constructed of what material? | Silicone |
| The solid-state rectifier allows the current to flow through it only when the _______ side is positive. | P |
| When the negative and positive charges meet at the NP Junction in a solid-state rectifier, what happens? | Current is allowed to flow through the rectifier |
| Advantages of solid state rectifiers over the old type are: (choose 2 answers) | Longer life expectancy Smaller in size |
| The ability of a timer to correctly time short exposures is its: | Accuracy |
| A three-phase timer can be tested for accuracy using a synchronous spinning top. The resulting image looks like a | solid arc, the angle (in degrees) representative of the exposure time |
| The manual spinning top test can be used to evaluate: | timer accuracy |
| The device used to test the accuracy of the x-ray timer is the | spinning top |
| A device which measures and automatically controls the radiographic exposure? | phototimer/AEC |
| In the electronic timer, which part controls the current into the capacitor? | Variable Resistor |
| The spinning top is used for which type of equipment? | Single Phase |
| The time required for the timer to reset and be ready to make another exposure is its: | Recycle Time |
| If the spinning top is used and testing the accuracy of the timer results in dots, then the technologist can conclude that the beam is _________. | pulsed |
| Which type of exposure timer is the most accurate, and is capable of timing the shortest exposure times? | Electronic |
| Which type of exposure switch would most likely be used in conjunction with cine or angio equipment, or in cases where a fast exposure time is necessary? | Constant Potential Generators |
| Which type of timer has the slowest recycle time, and is not capable of fast exposure times? | Synchronous |
| Which switch is on the low voltage side? | Primary Switch |
| All of the following are types of primary switches EXCEPT: Electromechanical Electronic Triode Vacuum Tube Silicon Controlled Rectifier (SCR) | Triode Vacuum tube |
| An electronic switch is also known as __________ | Thyratrons |
| For a single phase generator, what is the minimum number of rectifiers needed to produce full-wave rectification? | 4 |
| Advantages of three-phase x-ray generators are: | shorter exposure times possible less heat produced in the x-ray tube |
| A newer mobile x-ray generator will most likely be: | full wave rectification or high frequency |
| Which of the following x-ray generators will produce voltage with the lowest voltage ripple? single phase; 2 pulse three phase; 6 pulse single phase; 1 pulse three phase; 12 pulse | three phase; 12 pulse |
| A device which can be described as a storage tank for electrons and is used to help provide x-ray output with virtually no voltage ripple is known as a: | capacitor |
| The type of rectification in which 1/2 of the AC cycle is deleted (or wasted) is called: | half-wave |
| A circuit that contains four valve tubes and converts the inverse portion of the AC cycle into usable current is: | full-wave rectification |
| A three-phase fully rectified x-ray unit with one Wye and one Delta in the secondary of the high voltage transformer, will deliver a waveform characterized by ___________ pulses per SECOND. | 720 |
| *Which of the following types of voltage waveforms will provide the most efficient x-ray production? | three-phase; full wave rectification (12 pulse) |
| If a lateral skull technique on a three-phase x-ray machine calls for 62 KVP, the same projection would require approximately ____ on a single phase machine. | 72 KVP |
| A unit which does not incorporate rectifiers in the circuitry and the x-ray tube acts as the rectifier is known as: | self-rectification |
| *Which of the following statements are true of single-phase, full-wave rectification? | resulting x-ray beam is pulsed |
| Which term is used to describe the amount of fluctuation of the x-ray tube voltage waveform? | ripple |
| If you notice that your single phase, fully rectified radiographic equipment is producing radiation output about 50% less than normal, which of the following may you attribute it to? | faulty rectifier |
| The primary transformer winding of a three-phase radiographic unit is always a _____ configuration. | Delta |
| A three phase transformer which contains two like windings in the secondary instead of just one allows for which of the following advantages? | allows a space for the mA meter to be grounded so it can be safely mounted on the control panel |
| The valve tube-type rectifier will allow electrons to flow through the circuit only when the _____ is negative: | cathode |
| Advantages of the type of rectifier which is constructed of semi-conductive material? | longer life expectancy can withstand higher temperatures |
| Where is a capacitor located in the x-ray circuitry? | between the rectifiers and the x-ray tube |
| Full-wave rectification is _____ when compared to half-wave rectification. | twice as efficient |
| Circuit devices that will conduct electrons in only one direction are: (1) resistors (2) valve tube rectifiers (3) solid state rectifiers | 2 and 3 only |
| Which of the following voltage ripples is (are) produced by three-phrase equipment? (1) 100% voltage ripple (2) 14% voltage ripple (3) 4% voltage ripple | 2 and 3 only |
| What tool would you use to test a single phase x-ray machine for a faulty rectifier? | manual spinning top |
| What are the two basic types of rectifiers: (1 old type and 1 newer type) (select 2) | valve tube solid state |
| Which type of timer is a type of electronic timer, in which the technologist selects the total mAs for the unit to select the highest mA station and shortest exposure time available? | mAs timer |
| Which type of exposure timer is the most accurate, is capable of timing the shortest exposure times, and would most likely be used in conjunction with cine or interventional equipment? | Electronic |
| When the negative and positive charges meet at the P-N Junction in a solid-state rectifier, which of the following occurs? | Current is allowed to flow through the rectifier |
| 5 seconds is equivalent to __________ milliseconds. | 5000 |
| 2000 milliseconds is equivalent to __________ seconds. | 2 |
| Testing a three phase unit, what arc degree should be seen with a 1 second exposure time? | 360 degrees |
| Testing a single phase full-wave unit, how many dots should be seen with a 0.5 second exposure time? | 60 dots |
| The component which must be incorporated into battery operated portable units to convert the DC to AC is the: | solid-state inverter |
| Advantages of battery-powered mobile x-ray units include 1. very low amount of voltage fluctuation 2. can make exposures independent of external power supply 3. lightness and ease of maneuverability | 1 and 2 only |
| Concerning capacitor discharge mobile x-ray units; 1. the KVP drops during the exposure 2. produces good output and good reproducibility 3. capacitor must be charged right before the exposure | 1, 2 and 3 |
| Which type of mobile x-ray generators is the least reliable in terms of reproducibility? | single phase |
| Which type of mobile generator obtains its power directly from the main AC supply outlet ( must be plugged in to 220 V), and must be equipped with a main impedance compensator to stabilize any voltage fluctuations? | single phase |
| What type of radiation is produced when the x-ray tube voltage is below 70 kVp? | Bremsstrahlung |
| As kilovoltage is applied, the electrons are accelerated toward which part of the x-ray tube? | Anode |
| Which of the following increases the penetrating power of the x-ray beam? | Kilovoltage |
| When electrons strike the target of an x-ray tube, most of their energy is converted to what? | Heat |
| What determines the quantity of electrons that will be accelerated across the x-ray tube? | Heating of the filament |
| What is the purpose of the anode in an x-ray tube? | Decelerates electrons |
| What effect will increasing the kVp have on the production of x-rays? | Their energy will increase |
| Which of the following is NOT needed to produce x rays? Availability of electrons Electrons set in high speed motion Electrons stopped suddenly Rotating anode | Rotating anode |
| When electrons strike the anode of an x-ray tube, how much of their energy is converted to x-ray? | Less than 1% |
| During an exposure, what electrical charge is placed on the anode? | Positive |
| What is the process of "boiling off" electrons called? | Thermionic emission |
| What type of radiation is produced when the L-shell electron moves down to fill the k-shell vacancy in a tungsten atom? | k-characteristic |
| What type of radiation is produced when the electron is slowed down when approaching the nucleus of the tungsten atom? | bremsstrahlung |
| The energy of a Bremsstrahlung radiation photon will increase as: | The electron passes closer to the nucleus and is braked or slowed down |
| The three-dimensional volume of tissue that is represented in each pixel is known as what? | A voxel |
| When referring to digital imaging, what does the term digital mean? | using numbers to generate images |
| The quality of a digital image depends on which of the following? 1. spatial resolution 2. brightness 3. contrast | 1, 2 & 3 |
| What does it mean to direct capture a digital image? | The x-ray image is captured directly by a detector array |
| Which term is used to describe long-term storage of digital images and documents? | archive |
| A universal standard that allows various digital imaging devices to work together within a network no matter who the manufacturer. | DICOM |
| Which system captures the x-ray image, converts it to light, and then releases electrons to be stored as a latent image? | indirect digital imaging |
| Flat-panel detectors use TFTs in an array to capture the x-ray image. What does TFT stand for? | Thin-film transistor |
| RIS stands for: | Radiology information system |
| What does CCD stand for? | Charged-couple device |
| Visually, dynamic range (aka bit depth) refers to | The number of shades of gray that can be represented |
| PACS stands for: | picture archiving and communication system |
| Undesirable fluctuation in image densities, resulting in images with a grainy, or sandlike, appearance is called __________. | Image Noise |
| How many shades of gray can be displayed with a bit depth of 10 bits? | 1024 |
| Which of the following is an advantage of digital imaging over film-screen imaging? less exposure time less noise more resolution more exposure latitude | more exposure latitude |
| Monitor pixel size necessary for general interpretation by a Radiologist? | 1600 x 1200 |
| What is the technical name for a computed radiography imaging plate? | Photostimulable phosphor plate |
| What does the CR reader use to release the energy stored in the imaging plate? | Red laser light |
| The dynamic range of the human eye is about how many shades of gray _________. | 32 |
| Smoothing can be applied to a digital image to mask which of the following? | Noise |
| Edge enhancement can be applied to a digital image to improve which of the following? | The contrast along the edges of a structure |
| Digital fluoroscopy equipment only use an image intensifier. (T or F) | False |
| Thin film transistors (TFT) are found in which type of digital systems? Indirect digital flat-panel detectors Direct digital flat-panel detectors CR plates | Indirect digital flat-panel detectors & Direct digital flat-panel detectors |
| Arrange the following in the order they are layered, from top to bottom, in an indirect flat-panel detector. 1. Photodetector layer 2. Fluorescent layer 3. TFT layer | 2, 1 then 3 |
| _________ releases electrons when struck by light photons and _________releases electrons when struck by x ray photons. | Amorphous silicon, amorphous selenium |
| The time required for an AEC system to terminate the exposure after the proper amount of radiation has been sensed is known as: | reaction time (or minimum response time) |
| With the generator operating at 60 KVP, what percentage of the useful x-ray beam will be k_characteristic radiation? | 0% |
| The two basic types of AEC systems differ in the type of ______ that is used. | sensing device (sensor) |
| With the "ionization chamber" type of AEC, the sensor is placed: | in front of the image receptor |
| The function of the PM tube in the operation of a phototiming system is to measure __________ emitted from the ___________ and convert it to an electrical current. | light / fluorescent screen |
| When projectile electrons strike the anode of the x-ray tube, their kinetic energy is converted into: | x-ray & heat |
| Heat production in an x-ray tube varies ________ with mAs & KVP. | directly |
| When K- Characteristic radiation is produced, the K shell electron is ____________. | ejected from the shell |
| Unlike Bremsstrahlung radiation, Characteristic radiation consists of: discrete (specific) energy levels scatter energy attenuated photons heterogeneous energy levels | discrete (specific) energy levels |
| Which of the following electron transitions results in the most useful Bremsstrahlung x-ray? L to K M to K M to L none of these - Brems is not produced from the electron shells | none of these - Brems is not produced fron the electron shells |
| When a stream of fast-moving electrons interacts with the target of the anode, x-rays are generated by two different processes. They are: | Bremsstrahlung and Characteristic radiation |
| The constant excitation and restabilization of outer-shell electrons are responsible for the ___________generated in the anodes of x-ray tubes. | heat |
| A ______ x-ray is emitted when ionization of a K-shell electron occurs and the shell vacancy is filled by the dropping down of an L shell electron. | K-Characteristic |
| When an electron is attracted towards the nucleus of a tungsten atom and is deflected from its original direction with a loss of energy, the resulting radiation is called: | Bremsstrahlung |
| Which of the following characteristic x-rays contribute most to diagnostic radiographs? L to K transition M to L transition N to M K to nucleus O to N | L to K transition |
| The overall x-ray beam which is emitted from the x-ray tube can be described as: (consider that 2 types of radiation are mixed together when they emerge from the tube) discrete | heterogeneous |
| Which type of "switching" is preferred for use in conjunction with phototimers to allow for very short exposure time? | forced extinction |
| A main component of an AEC whose job is to compare the current flowing from the sensor to a refrence current and terminate the exposure is the: | comparator |
| The energy of a "Bremsstrahlung" x-ray photon equals: | the amount of lost kinetic energy of the electron as it is "braked" or deaccelerated upon approaching the nucleus |
| Bremsstrahlung radiation is characterized by a _______range of energies, while characteristic radiation consists of _______levels. | continuous / discrete |
| 90% of the radiation produced in the x-ray tube is: Characteristic Photoelectric Compton Classical Bremsstrahlung | Bremsstrahlung |
| in order for characteristic radiation to be produced, a KVP of at least ________ is required to overcome the binding energy of the K shell electron. | 70 |
| The energy of a K- Characteristic diagnostic x-ray photon is equal to: | the difference in the binding energy of the K and L shell electrons |
| Out of the 5 interaction with matter, which 2 does not occur in diagnostic Radiology? | Pair Production & Photodisintegration |
| The component which must be incorporated into battery operated portable units to convert the DC to AC is the _________. | solid-state inverter |
| Advantage of digital fluoro over conventional fluoro? real- time subtraction can be performed digital images contain more information using no radiation digital equipment is cheaper no image intensifiers are used in digital fluoroscopy | real- time subtraction can be performed |
| Digital imaging converts _________ information into ____________ form, and then displays this information as an image. | analog / digital |
| The first imaging modality to solely rely on a computer to produce the image: | CT |
| A digital image is displayed as a _______ of ___________. | matrix / pixels |
| *Which of the following combination of factors will produce a digital image that most closely resembles an analog image? | more shades of gray and more pixels |
| Which interaction does NOT involve the atom becoming ionized? | Coherent Scattering |
| Advantages of the DR method of obtaining a chest x-ray over that of the conventional chest radiograph | wider exposure latitude (less repeats) less patient exposure image obtained in a shorter period of time image can be enhanced to adjust contrast or density |
| A special application of "scanned projection radiography" known as _______ can be used to isolate either bone or soft tissue by utilizing a fluctuating high and low KVP. | dual- energy imaging |
| Advantages of battery-powered mobile units include their: 1. very low amount of voltage fluctuation 2. can make exposures independent of external power supply 3. lightness and ease of maneuverability | 1 & 2 only |
| Concerning capacitor discharge mobile x-ray units: 1. the KVP drops during the exposure 2. produces good output and good reproducibility 3. capacitor must be charged right before the exposure is made | 1, 2 & 3 |
| type of mobile x-ray generators is the least reliable in terms of reproducibility? | single-phase |
| The 2 different types of "sensors" which can be used in AEC systems are: (one is exit type and one is entrance type) | ionization chamber and photomultiplier tube |
| *Which of the following would be considered a limitation of an AEC system? | can increase OID and reduce contrast due to placement of the sensor |
| Which type of QA tests would be done to check the consistency of an AEC system in producing proper film density? | repeatability test |
| Which type of mobile generator obtains its power directly from the main AC supply outlet (must be plugged into a 220V), and must be equipped with a main impedence compensator to stabilize any voltage fluctuations? | single phase |
| PACS stands for: | picture archiving and communication systems |
| Which interaction contributes to the white portion on the image due to the x-ray photon interacting with dense material? | Photoelectric Effect |
| In digital radiography, images can be enhanced to display diagnostic information more clearly without re-exposing the patient. The term that describes this capability is known as: | post processing |
| A digital image is displayed as various brightness levels ranging from +1000 to -1000. These brightness levels correlate to the density of imaginary squares of tissue in the body. The density or brightness level numbers and are referred to as __________. | hounsfield units (CT numbers) |
| Which of the following matrix sizes will provide the best spatial resolution? (consider the FOV or image receptor size is the same for each of these) 32 x 32 1024 x 1024 2028 x 2028 64 x 64 | 2028 x 2028 |
| The brightness (density) of a digital image can be changed once the exposure is made, by adjusting the: | window level |
| Decreasing or selection of a narrow "window width" will__________image contrast. | increase |
| Increasing the "window level" will: increase brightness (decrease density) increase contrast decrease brightness (increase density) decrease contrast | increase brightness (decrease density) |
| What is the best way to obtain the proper image brightness or exposure when performing digital radiography? | select the appropriate mAs |
| What is the best way to obtain the proper contrast when performing digital radiography? | select the appropriate KVP |
| What causes quantum mottle or image noise? | Insufficient technique |
| Which type radiography system is the most expensive? | DR |
| Which type of digital radiography system uses imaging plates instead of film cassettes, and can utilize the existing x-ray equipment (tube, table and bucky tray)? | CR |
| Which type of digital radiograph system can be used on portables? | CR and Wireless DR panels |
| The photostimulable phosper of an imaging plate is composed of ____________. | Barium fluorohalide |
| An image plate is scanned by ___________to release the stored energy (latent image), and then erased by ________ to prepare the plate for re-use. | a laser beam / visible light |
| For the Agfa CR System, an "LGM" number greater than the vendor's specified range an indication of: | overexposure |
| DR stands for __________radiography and replaces the film-screen cassette with a flat panel radiation detector. | direct capture or direct read out |
| PACS computers must be networked with _____ and _____so that images, patient data and reports can all be viewed simultaneously. | HIS and RIS |
| Which interaction with matter negatively affects the image? | Compton Scattering |
| If the radiologist you work with request a T V image with sharp detail, what type of T V camera would you recommend purchasing? | vidicon |
| How is the electron beam in a television camera tube produced? | thermionic emission |
| The electron beam in a television camera tube is controlled by which of the following? 1. steering coils 2. accelerator 3. control grid | 1, 2 & 3 |
| The target assembly of a television camera tube consists of which of the following? 1. window 2. signal plate 3. target plate | 1,2 & 3 |
| Which of the following is photoconductive? window signal plate target plate electron gun | target plate |
| Which component of the television monitor transfers the video signal into a visible image? | fluorescent screen |
| The advantages of using a lens system: 1. fluoro is not interrupted 2. Allows for auxillary imaging devices to be used 3. increases patient exposure | 1 and 2 |
| What is the purpose of fluoroscopy? | To view dynamic anatomy |
| In a stationary fluoroscopic unit, where is the fluoroscopic x-ray tube located? | under the table |
| What is the normal tube current during fluoroscopy? | 1 to 5 mA |
| What conversion occurs in the image at the input phosphor of an image intensifier tube? | X rays are converted to visible light |
| What conversion occurs in the image at the photocathode of an intensifier tube? | light is converted to electrons |
| What is photoemission? | the emission of electrons from photocathode |
| What conversion occurs in the image at the output phosphor of an image intensifier tube? | electrons are converted to visible light |
| At what stage of image intensified fluoroscopy is the number of photons lowest? | entering the input phosphor |
| Which comes first in image intensified fluoroscopy? | cesium iodide screen |
| Which comes last in image intensified fluoroscopy? | zinc cadmium sulfide screen |
| What is the process called when an image intensifier tube makes a dim image brighter? | brightness gain |
| What are the functions of the electrostatic lenses in an image intensification tube? 1. focus the electrons from the photocathode 2. increase the speed of the electrons 3. magnify the image | 1 only |
| Which of the following will affect the total brightness of an image intensification tube? 1. flux gain 2. minification gain 3. primary beam intensity | 1, 2 & 3 |
| The image intensifier's input phosphor differs from the output phosphor in what way? | it is much larger |
| The brightness level of the fluoroscopic image can vary with which of the following? 1. mA 2. Kvp 3. Patient size | 1, 2, & 3 |
| automatic brightness control (ABC) | the fluoroscopic system designed to maintain a constant image brightness |
| *Automatic brightness control (ABC) is designed to compensate for changes in which of the following? | patient part thickness |
| What happens when a multifocus image intensifier tube is operated in magnification mode? | the electron focal point is closer to the input phosphor |
| Single Phase half-wave rectification Pulses/cycle-? Pulses/second-? % Voltage ripple-? | P/C-1 P/S- 60 %VR- 100% |
| Single Phase Full-wave rectification Pulses/cycle-? Pulses/second-? % voltage ripple-? | P/C- 2 P/S- 120 %VR- 100% |
| 3-phase 6-pulse Pulses/cycle-? Pulses/second-? % voltage ripple-? | P/C- 6 P/S-360 %VR-14% |
| 3-phase 12-pulse Pulses/cycle-? Pulses/second-?% voltage ripple-? | P/C- 12 P/S- 720 %VR- 4% |
| 3-phase 12-phase with capacitor Pulses/cycle-? Pulses/second-?% voltage ripple-? | P/C-12 P/S-720 %VR- 0% |
| High frequency Pulses/cycle-? Pulses/second-?% voltage ripple-? | P/C-6,500 P/S- 13,000 %VR- 1% or less |
| Disadvantages of using half-wave rectification | insufficient production of x-rays requires longer exposure times large amounts of heat are produced |
| Converts the inverse portion of the AC waveform into the positive phase so that the entire portion of the current is utilized | full wave rectification |
| full rectification is _____ as efficient as half-wave rectification | twice |
| (T or F) Three-phase power is always characterized by 100% ripple because voltage falls to the zero axis before it picks up again. | False |
| How many rectifiers needed for Half-wave rectification | 1-2 |
| How many rectifiers needed for full-wave rectification | at least 4 |
| three phase | 6-12 |
| (T or F) Three phase equipment have longer exposure times | False |
| If 1 rectifier out of the 4 malfunctions, the radiation output will be reduced by | 1/2 |
| The equipment to test rectifier failure in 3-phase units is more complicated. An electronic device with an ____ is used which produces a visual representation of the voltage output waveform. | oscilloscope |
| The most efficient arrangement for a transformer configuration for a 3-phase unit is | 1 wye and 1 delta |
| ripple% for 1 wye | 14% |
| ripple % for 2 wyes | 14% |
| ripple % for 1 wye and 1 delta | 4% |
| a storage tank for electrons (voltage) | capacitor |
| Adding a capacitor in the x-ray tube can produce ____ voltage ripple | 0% |
| which rectifier consists of air evacuated diode tube | valve tube |
| valve tubes are also known as | kinetron |
| most common type of solid state rectifier | silicon |
| the solid state rectifier's silicon is a semi-conductive material which means it acts as an | insulator |
| The solid state rectifier has a N-type and a ___ type | P |
| In the solid state rectifier, the 2 types of materials are joined together at a point known as the | n-p junction |
| slowest primary switch | electromechanical |
| old term for AEC | phototimer |
| detects the x-rays which have passed through the patient and produces a corresponding electrical current which is proportional to the amount of x-rays sensed | sensor |
| a device which "compares" the current flowing from the sensor to a predetermined reference current and terminates the exposure when the amount is reached | comparator |
| ionization chamber measures | ionization current |
| PM tube measures _______ intensity | light |
| The PM tube is located _____ the image receptor | behind |
| The ionization chamber is ______ of the image receptor | in front |
| The ionization chamber with gas that is ionized as radiation passes through it (T or F) | True |
| The largest portion of x-ray beam emerging from the target | Bremsstrahlung radiation |
| The total number of x-ray photons produced at the target is contingent upon | tube current target material square of the kilovoltage |
| In the production of Bremsstrahlung radiation, the incident electron | is deflected with resulting energy loss |
| In the production of characteristic radiation, the incident electron | eject an inner-shell tungsten electron |
| what occurs during bremsstrahlung radiation production | an electron approaching a positive nuclear charge changes direction and loses energy |
| The image intensifier's input phosphor is generally composed of | cesium iodide |
| The part of the image intensifier tube that functions to change the visible light image into an electron image is the | photocathode |
| The device that receives the remnant beam, converts it into light, then increases the brightness of that light is the | image intensifier |
| advantages of spot film cameras over cassette-loaded spot films include | -decreased patient dose -decreased fluoro tube heat load -shortened exam time |
| in order to maintain image clarity, the path of electrons flow from the photocathode to output phosphor is controlled by | electrostatic lenses |
| The image intensifiers input phosphor differs from the output phosphor in that the input phosphor | is much larger than the output phospor |
| the method used to record successive physiologic events occurring during fluoroscopy is | cinefluorogaphy |
| the total brightness gain of an image intensifier is a result of | -flux gain -minification gain |
| the largest application of cinefluorography is with | cardiac catheterization |
| (Jeopardy) Most common tube failure | spark over |
| (Jeopardy) solid state rectifier P-type dosed with | Arsenic |
| (Jeopardy) atom excited & returned to stable state produces | Heat |
| (Jeopardy) Increase or decrease in kvp or mA as part thickness brightness | ABC- automatic brightness control |
| (Jeopardy)year and company introduced CR | 1981 Fugi |
| (Jeopardy) what mobile x-ray generator requires a charge button | capacitor discharge |
| (Jeopardy) image intensifier brightness gain ranges from | 5,000-30,000 |
| (Jeopardy) interaction that creates light areas on x-ray | photoelectric effect |
| (Jeopardy)what's added to filament that increases thermionic emission efficiency by 1-2% | Thorium |
| (Jeopardy)Incoming x-ray bounces off atom loses energy and changes direction | coherent scatter |
| (Jeopardy) located on primary side of step down | mA selector/ Rheostat /ammeter |
| (Jeopardy) Device that helps x-ray equipment not operate in space charge limited region? | Space charge compensator (SCC) |
| (Jeopardy) target angle ranges from | 7-18 |
| (Jeopardy) indirect conversion detector converts light to electrical charge using | amorphous silicon |
| (Jeopardy)loss of brightness on peripheral edges | vignetting |
| (Jeopardy)another name for receptor size | FOV |
| (Jeopardy) which radiation is characterized as discrete | characteristic |
| (Jeopardy) side of the tube that contains focusing cup | cathode |
| (Jeopardy) activated the switch to open and close at pre-selected time intervals | timer |
| (Jeopardy) electrostatic focusing lens has what charge | negative |
| (Jeopardy) measures voltage provided by x-ray imaging system and adjusts voltage to 220v | line compensator |
| (Jeopardy) input phosphor converts x-rays to | light |
| (Jeopardy) which of the two rectifiers is air evacuated diode | valve tube |
| (Jeopardy) electric timer that automatically monitors mA & exposure timer | mAs timer |
| (Jeopardy) why is housing lined w/lead | electric shock protection and to absorb leakage radiation |
| (Jeopardy) photocathode converts light to | photoelectrons |
| (Jeopardy) input phosphor is made of | cesium iodide |
Created by:
anr296