Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Imaging I
Imaging I Final
| Question | Answer |
|---|---|
| The larger the field size, the more scatter produced? | True |
| Increasing kVp has what effect? | Increases the amount of scatter |
| What is the goal of beam limitation technique? | To obtain good diagnostic images, reduce patient expose, and reduces film fog |
| A cone is a type of______? | Apeture diaphragm |
| Advantage(s) of collimation over apeture diaphragms include which of the following: | They reduce scatter more efficiently, they have a light to aid in positioning, and they are easier and quicker to use |
| The pair of shutters in collimators can be controlled independently to create which of the following: | Different field sizes |
| The light inside the collimator is used to do which of the following: | Help position the patient |
| What affects how much scatter is produced? | The size and thickness of the body area examined, the tissue density of the body being examined, the kVp selection |
| kVp can be lowered to reduce scatter, but this also can cause which of the following? | Reduced density |
| The basic parts of the collimator are which of the following? | light source, mirror, shutters |
| The second state shutters (farther from the tube) reduce which of the following? | Penumbra |
| What does the mirror in the collimator do? | Reflects the light beam to the same area as the radiation beam |
| Which of the following is true of a positive beam limitation device (PBL)? | It is required on all new fixed Radiographic equipment, it ensures the field size is never larger than the image receptor, it works automatically to determine film size used. |
| Penumbra is defined as: | The un-sharpness around the periphery of the image |
| When using and apeture diaphragm, the diaphragm field size can be calculated by using which formula? | SID x Diameter of diaphragm / Distance from focal spot to diaphragm. |
| Compared to an apeture diaphragm, circular and cylander cones are known to: | Reduce penumbra |
| Attenuation is defined as: | Reduction in the total number of x-ray photons reaching the film |
| The higher the atomic number of the material being irradiated, the _____ the percentage of attenuation. | Greater |
| Of the following listed which has the higher atomic number: | Air |
| Air absorbs fewer photons than fat. | True |
| Photons passing through a material with a low atomic number will produce a _____ radiographic density. | Greater |
| Fat has more tissue density than muscle. | False |
| Which of the following lists the basic substances of the body in the correct order of more dense to less dense. | Bone, muscle, fat, air |
| The atomic number of bone is: | 12.31 |
| When there is little differences in the absorption characteristics of the given body tissues within a part being examined, subject contrast will be_____ | Low |
| This will be altered by changes in the amount or type of tissue being irradiated. | Subject Density |
| Degree of differential absorption resulting from the differing absorption characteristics of the tissues in the body. | Subject Contrast |
| Dependent on the position of structures withing the body and the body's placement in relationship to the film. One primary factor that affects this is distance. | Subject Detail |
| Characterized by the position of the patient. If the patient is not positioned specifically to demonstrate a particular structure this may occur. | Subject Distortion |
| If motion is a problem, and 50 mAs is needed, what mA would be best selected? | 400mA |
| If motion were a problem, to maintain the same density, the time can be reduced by 1/2, if the kVp is increased by what percentage? | 15% |
| The amount of darkening seen on any radiograph is termed? | Density |
| The primary function of mAs during radiographic exposure is to: | Regulate density |
| The primary exposure factor that is used for regulating radiographic contrast is: | kVp |
| An image is said to possess excessive radiographic density. This would appear as: | Darker than normal |
| The greater the number of photons reaching the IR, the: | Greater the density |
| The density of a radiograph can be increased by employing a: | Higher mAs value |
| The principle controlling factor for the number of photons produced during and exposure is | mAs |
| An increase in image density can result from and increase in: | kVp and mAs |
| If you halved the time of exposure, how much would you change the mA to obtain the same density on the radiograph? | Double the mA |
| If a satasfactory radiograph is obtained at a SID of 40", using 40 mAs at 70kVp, what exposure factors will have to be used to maintian the density at 60"? | 90mAs at 70kVp |
| Which one of the following processes results in the complete absorption of a photon? | Photoelectric |
| If the incident and scattered photon have the same wavelength, the scattering process is said to be: | Coherent |
| The interaction in which an electron and a positron appear when a photon disappears is called? | Pair production |
| Characteristic or secondary x-ray photons: | Are emitted by an atom after a photoelectric interaction |
| When an electron having a binding energy of 200eV drops to an electron shell having a binding energy of 2000eV: | A characteristic photon having an energy of 1800eV is emitted. |
| The probability of photoelectric effect______ when the atomic number of matter ______. | Increases, increases |
| How does doubling the mAs affect the exposure quantity? | Doubles rate |
| How does increasing the kVp by 15% affect density? | Doubles density |
| Increasing the SID does what to density if all other factors are unchanged? | Decreases density |
| Contrast is defined as: | The difference between the adjacent areas of density on a radiograph |
| What is the result of scattered radiation reaching film? | Fog, more density, less contrast |
| The probability of photoelectric effect _______ when photon energy increase. | Increases |
| Of the three characteristics of x-rays which ones contribution is lease beneficial to the formation of an x-ray image? | Scatter |
| Which of these units of measurement refers to the measure of intensity of x-ray radiation? | A Roentgen |
| What does kVp settings control? | The kinetic energy of projectile electrons |
| Which shell has the greatest binding energy? | K shell |
| To reduce film fogging, the Compton effect should be: | Minimized |
| What will happen if the kVp setting remains the same and the mA setting is increased? | The electrons will have the same energy level. |
| A photoelectron is created when a photon: | Knocks an electron out of an atom |
| The probablity of photoelectric interactions is higher with: | Low-energy x-rays |
| In Compton scattering an x-ray photon: | Is diverted by hitting and electron |
| As the energy level of an incident x-ray increases, the probability of Compton scattering: | Increases |
| If the kVp setting is too high: | Too much penetration will occur |
| What is the mR/mAs for a calibration of 80kVp at 30mAs that produces a total exposure of 62mR? | 2.06mR/mAs |
| What is the approximate entrance skin dose for a fluoroscopic examination of the chest performed for 3.5min at 90kVp at 1.4R/min? | 4.9R |
| If decreased, _______ would cause a decrease in ESE? | mAs |
| Use of a grid (with technique compensation) increases ESE as compared to using a tabletop technique. | True |
| An AP chest lowers the patients breast dose compared to a PA chest. | False |
| If the kVp is changed from 50 to 100 with no change in mAs, the resultant density will be doubled. | False |
| If a radiograph was taken at 100kVp, and you wanted to double the amount of density, (with all other factors remaining the same), what kVp would you use? | 115kVp |
| 200mA and .05seconds is equivalent to how much mAs? | 10mAs |
| A radiograph is taken at 200mA .2 seconds at a 40" SID. You much change your distance to 20" SID. If you want to keep the same density what would your new mAs have to be? | 10mAs |
| What is the approximate entrance skin exposure during a barium enema exam for a patient measuring 21cm tht has a total intensity reading of 70mR, and an SID of 40"? | 112.2mR |
| Magnetic domains are: | Aligned atoms that produce a magnetic field |
| A permanent magnet placed within a coil is called a: | Electromagnet |
| Moving a wire through a magnetic field induces: | A current |
| In electrogmagnetic induction, current can be increased by increasing: | The strength of the magnet, speed of motion of the coil, and the number of coils |
| What is the process called when the current in one coil produces a current in another coil when the coils are not in direct contact with one another? | Mutual induction |
| The magnetic field created by a single electron is called a: | Dipole |
| What occurs as the poles of a magnet are stretched farther apart? | The magnets get weaker |
| A transformer requires______ to operate? | Alternating current |
| The transformer law states that there is a direct proportion between the ratio of wire turns on a coil and the ratio of: | Voltage |
| A rectifier works by allowing electrons to flow through it in: | One direction |
| A semiconductor rectifier is made by putting together n-type and p-type semiconductors. Joined together, what are these semiconductors called? | Diodes |
| From full wave rectification is produced a: | Pulsating direct current |
| In ferromagnetic material: | A majority of the magnetic dipoles are lying the in same direction and are greatly susceptible to magnetic induction |
| Diamagentic material are: | Repelled by a magnetic field |
| Given a closed loop of wire with no electron flow, an electric current can be induced if: | A changing magnetic field is present |
| An induction motor is used in an x-ray machine to: | Rotate the anode |
| A transformer changes electric: | Voltage |
| Electrons flow: | From cathode to anode |
| A rectifier converts ________ to _______. | AC to DC |
| Thermionic emission refers to: | Electron emission from a heated source |
| A full wave rectified signal may be obtained from an AC circuit that contains ______diodes. | 4 |
| A single diode in a circuit having an AC power sources produces a ____ wave rectified signal. | Half |
| At what point in the x-ray circuit is the rectification circuit located? | Between the step-up transformer and the x-ray tube. |
| Which line current permits the potential difference to drop to zero with every change in the direction of current flow? | Single phase power |
| The part of the x-ray circuit that supplies the filament (cathode) of the x-ray tube with properly modified power is the ________ circuit. | Filament |
| Single phase generators with full wave rectification produce a voltage ripple of: | 2 pulses per Hz |
| The generator mentioned above, single phase with full rectification produces a voltage ripple of ___% | 100% |
| A three phase, six-pulse generator with full wave rectification produces a ripple of 13-25%. This meas that the voltage in the x-ray tube never falls below: | 87-87% |
| Which type of AEC device used a capacitor placed below the patient, tabletop and cassette that terminated the exposure after absorption of a predetermined amount of electrons that established a charge. | Photo-timer |
| What device in the x-ray circuit controls the mA? | Filament transformer |
| An electric generator converts _____ energy into ______ energy. | Mechanical to electrical |
| Unit for magnetic flux density is: | Gauss or Tesla |
| Which component of x-ray equipment requires a step down transformer? | Filament circuit |
| Wye, Star, and Delta are all examples of: | Three phase power connections |
| A low voltage ripple system is energized at 110kVp, 100ms. The maximum tube current possible is 900 mA. What is the power rating? | 99watts |
| A single-phase unit has a maximum capacity of 100 ms at 240kVp and 60mA. What is the power rating? | 10.08 watts |
| Electrons in the atoms: | travel around the nucleus, all have the same charge, and are in shells |
| What is classified as nucleons? | Neutron and proton |
| What unit has a positive charge? | Protons |
| In which shell do electrons have the greatest binding energy? | K shell |
| Which shell will hold the fewest electrons? | K |
| As the atomic number of an element gets larger: | Their atomic weight increases, number of nucleons increases, and they have more electrons |
| To calculate the number of neutrons in the nucleus from the A and Z values: | (A-Z) |
| What is the atomic number of an atom with three protons, five neutrons, and five electrons? | 3 |
| Which part of an atom has the least mass? | Electrons |
| What electrical charge do stable atoms have? | Neutral |
| In an electrically stable atom there is an equal number of: | Protons and electrons |
| What fundamental particle has an atomic mass number of 0? | Electron |
| Atomic mass number is measured by: | Sum of protons and neutrons |
| According to the Octet Rule the outermost shell of an atom can have a maximum of _____ electrons. | 8 |
| What electrical charge does an atom with an extra electron have? | Negative |
| Atoms that have eight electrons in their outermost shell: | Are considered inert |
| Atoms in each period of the Periodic Table of Elements have the same number of: | Electron shells |
| Frequency is determined by: | The number of waves in a 1 second period |
| Frequency increase as the: | Wavelength shortens |
| What does frequency times wavelength equal? | Velocity |
| What is the SI unit for frequency? | Hertz |
| The height of a wave is called? | Amplitude |
| The measurement from the top of one wave to the top of the next is called: | Wavelength |
| An isoptope of Boron has 5 protons and 6 neutrons. The atomic number of Boron is _____? | 5 |
| What is the range of wavelengths called that includes x-rays, radio waves, and visible light? | Electromagnetic spectrum |
| The longer the wavelength the _______the frequency | lower |
| The amount of energy carried in a wave increases as the ________ increases. | Frequency |
| What is the term that refers to the principles of nonmoving electric fields? | Electrostatics |
| Electric flow is the movement of: | Electrons |
| What is created when electrons are bumped into our out of electron shells? | Ions |
| Electrification that occurs when one object is rubbed against another is which of the following? | Friction |
| What is the term for the principles of electric charge in motion? | Electrodynamics |
| Potential energy is: | The ability to do work |
| The difference in electric charge between two points is measured in: | Volts |
| The SI for electrons flowing per second is: | Amperes |
| What is the SI for electric power? | Watts |
| Power in watts equals amperes times _______? | Volts |
| What is the pathway of an electric current called? | Electric circuit |
| As resistance increases, current in an electric circuit ______? | Decreases |
| What is the SI unit for resistance? | Ohm |
| Current that reverses direction in a circuit many times per second is called: | Alternating current |
| What type of energy conversions takes place in the x-ray machine? | Electrical to Radiant |
| EMF is measured in: | Volts |
| A negative charge is attracted to: | A positive charge |
| Electrification by ________ is the process of electrical fields acting on one another without physically coming together. | Induction |
| An element with ____ valence electrons is the best conductor. | 1 |
| A radiographer makes an exposure using a 40" SID. The intensity at this distance is measured at 5R. The same exposure is made at 45" SID. What is the radiation intensity at the new 45" distance? | 3.95R |
| Atomic number | Number of protons in an atom |
| Matter | It has shape, form, and occupies space |
| Weight | The force that an object exerts under the influence of gravity |
| Atom | The smallest particle of an element that still posses the characteristics of that element |
| Increases in value the closer the electron is to the nucleus. | Binding energy |
| Valence | Related to the number of electrons in the outermost shell |
| Molecule | Smallest particle of a compound that still posses the characteristics of the compound |
| Mass | Quantity of matter contained in an object and remains unchanged whether the matter of the object is on earth or the moon |
| Electrons are produced at the _____ and accelerated toward the ______. | Cathode, anode |
| The filament of an x-ray tube is a(n): | Coil of thin wire |
| Why is the anode usually made of Tungsten? | Has a high melting point |
| What is true when an x-ray machine is set at 100 kVp? | The most energetic x-rays have and energy of 100 keV |
| The fact that the effective focal spot is smaller than the actual focal spot size is known as: | The line focus principle |
| Which of the following interactions will create the x-ray with the lowest keV? | An electron passes relatively far away from the nucleus of an atom |
| When a projectile electron from the filament enters a target atom and interacts with the nuclear force field it will: | Decrease in velocity |
| _______is used as the main target material in mammography. | Molybdenum |
| The thickness of the absorbing material necessary to reduce the x-ray intensity to half it's original value is called: | Half-value layer |
| Diagnostic filtration is principally employed to reduce the ______ photons from reaching the patient. | low-energy |
| Uniform film density during radiography of structures unequal thickness can be accomplished with the use of an: | compensating filter |
| The diagnostic tube filtration from the composition of the x-ray tube with an equivalency of about .5-1.0mm Al is: | Inherent filtration |
| The most common filtering material for an x-ray beam in the diagnostic range is: | Aluminum |
| The amount of total filtration can be determined by finding the sum of: | |
| Which element is used in the filament of the cathode? | Tungsten |
| X-rays are produced when high-energy electrons strike the atoms of the: | Anode |
| Electrons boiling off the filament are directed by the: | Focusing cup |
| What is the charge of the focusing cup? | Negative |
| What element is used to conduct heat away from the anode target? | Tungsten |
| What was developed to reduce the heat build up caused by electrons hitting the same spot on the target? | Rotating anode |
| The sharpness of an x-ray image can be increased by: | Decreasing the size of the focal spot |
| The intensity of the hell effect depends on | the angle of the target, the distance between the film and x-ray tube, and size of radaigraphic film being used |
| Assume the binding energy of an L shell electron is 12 and that of an M shell is 2. What is the x-ray energy that results from the fall of the electron from the M shell to the L shell? | 10 |
| How does an electron lose its energy in the bremsstrahlung interaction? | By slowing due to the force of attraction between electron and nucleus |
| Leakage radiation refers to: | X-rays that escape through the protective housing |
| The protective housing of the x-ray tube: | Is made of tungsten and provides mechanical support for the tube |
| The oil in the protective housing around some x-ray tubes: | Serves as a thermal cushion and electrical insulator |
| What is the total filtration requirement for an x-ray tube that operates at 70kVp and above? | 2.5mm/Al eq |
| A phenomenon in which the electrons negative charges begin to oppose the emission of additional electrons at the filament is called: | Space charge effect |
| In a dual focus arrangement the filament for the small focal spot will: | Be shorter than the large focal spot filament |
| A smaller effective focal spot may be obtained by: | Decreasing the anode angle |
| The stator of the induction motor is located: | Outside the vacuum glass envelope |
| Over ______% of the total kinetic energy of the incident electrons is converted to ________. | 99, heat |
| Characteristic cascade | the progressive dropping of electrons into lower shells vacated during x-ray emission from ionization |
Created by:
paigemitich