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Rad Imag. 2
Ch 1-7
| Question | Answer |
|---|---|
| Matter is measured in | kilograms |
| The fundamental building blocks of matter are | atoms and molecules |
| The formula ___ is the basis for the theory that led to nuclear power | E-MC^2 |
| Electromagnetic energy includes | radiowaves, microwaves, ultraviolet, infrared, visible light, xray, gamma |
| A moving object has | kinetic energy |
| The removal of an electron from an atom is called | ionization |
| Ionizing radiation is capable of ___ electrons from atoms as it passes through matter | removing |
| Xray are forms of | electromagnetic energy |
| _____ exposure is the biggest source of man-made radiation | diagnostic xray |
| We are exposed to 20-90 mR/yr of ionizing radiation from | natural environment in the U.S. |
| The basic quantities measured in mechanics are | mass, length, time |
| Radiation exposure is measured in | grays |
| Today, radiology is considered a safe occupation because of elective | radiation protection |
| ALARA means | as low as reasonably achievable |
| Xray filtration is used to absorb | low energy xrays |
| The term atom was first used by the | Greeks |
| First person to describe an element as being composed of identical atoms was | John Dalton |
| The smallest particle that has the properties of an element is an | atom |
| A positively charged nucleus surrounded by negatively charged electrons in well-defined orbits is the | Bohr model of the atom |
| The fundamental particles of an atom are the | neutrons, protons, electrons |
| The chemical element is determined by the number of | protons in the atom |
| An atom in a normal state has an electrical charge of | zero; neutral |
| The binding energies or energy levels of electrons are represented by their | shells |
| Atoms with the same number of protons as another, but a different number of neutrons is an | isotope |
| When atoms of various elements combine they form | molecules |
| The losses or gain of one of more electrons is an | ionization |
| The number of electrons in an electron shell is calculated with the formula | 2n^2 |
| A neutral atom has the same number of | protons and electrons |
| The innermost electron shell is symbolized by the letter | K |
| The atomic number of an element is symbolized by the letter | Z |
| The atomic number equals the number of | protons in the atom |
| The difference between xrays and gamma rays is their | origin |
| The alpha particle is the least penetrating form of | particulates/particles |
| The properties of photons are | frequency, wavelength, velocity, and amplitude |
| The smallest quantity of any type of electromagnetic radiation is a | photon |
| The velocity of all electromagnetic radiation is | 3*10^8 m/s |
| The rate of the rise and fall of a sine wave is called | frequency |
| The ___ of electromagnetic radiation is constant | velocity |
| If the wavelength of a beam of electromagnetic radiation increases by a factor of 2, the frequency must decrease by | half |
| The intensity of radiation decrease in _______ to the square of the distance of the object from the source | inverse proportion |
| The reduction of radiation intensity due to scattering and absorption is called | attenuation |
| The intensity of radiation on an object is reduced with distance because the radiation is | spread out over a greater area |
| If intensity of light from a flashlight is 4 millilumens (m/m) at 3 ft using the inverse square law, what will it be at 6 ft? | I millilumen |
| The diagnostic range of xray energy is | 30-150 kVp |
| The energy of a photon is directly proportional to its | frequency |
| Xray are usually identified by their | energy (kVp) |
| The lowest energy range on the electromagnetic spectrum is | radiowaves |
| Gamma rays are produced in the | nucleus of the atom |
| Photons with the highest frequencies have the | shortest wavelengths |
| The smallest unit of electrical charge is the | electron |
| Electrification occurs only through the movement of | electrons only |
| A battery is a source of | direct current |
| When an electrical potential (voltage) is applied to a conductor, both a | current and a magnetic are produced |
| An alternating(AC) current is represented by a | sinusoidal line |
| A flashlight is battery operated, and is any example of using | direct current |
| Alternating current is produced by a | generator |
| Ohm's law formula is | V=IR |
| Electrical power is measured in | watts |
| Rubber and glass are ____ because they do not conduct electricity | insulators |
| When a group of dipoles are aligned, they create a | magnetic domain |
| In the United States, alternating current goes through a complete cycle every | 1/60 second |
| The Si unit of magnetic field strength is the | tesla |
| Ferromagnetic material can be made magnetic when placed in an external | magnetic field |
| Like magnets poles _____ and unlike magnetic poles | repel; attract |
| Water is a _____ (type of magnetic material) | diamagnetic |
| The magnetic intensity of an electromagnetic is greatly increased by the addition of an | iron core |
| The three main parts of an xray imaging system are the | operating console, high-voltage generator, tube |
| The operating console contains circuits that are | low voltage only |
| Variation in power distribution to xray machine are corrected by | line voltage compensators |
| The first component in the xray circuit is the | autotransformer |
| The autotransformer has | one winding |
| The ____ circuit provides electrons for the xray tube. | filament |
| The most accurate type of times is the | electronic timer |
| The automatic exposure control (AEC) terminates the exposure when sufficient radiation reaches the | image receptor |
| The step up transformer increases voltage | 500-1000 times |
| A diode allows electrons to flow from | cathode to anode |
| With half-wave rectification the current flows through the xray tube during the _____ part of the cycle | positive |
| Full-wave rectified, three-phase units provide an xray beam at ___ pulses per second | 360 |
| Voltage across the xray tube is most constant with | high voltage generators |
| Most mammography units operate with | high frequency generators |
| A single-phase waveform has ______ ripple | 100% |
| The principle disadvantage of three-phase equipment is | cost |
| The xray generator with the lowest power rating is the _____ imaging system | single phase |
| The most widely used support structure of the xray tube is the | ceiling support system |
| _____ coating within the tube can cause arcing | tungsten |
| The negative side of the xray tube is the | cathode |
| The cathode holds the | filament |
| The most common cause of tube failure is | tungsten vaporization |
| The filament is made of | tungsten |
| _____ emission at the filament creates a space charge | thermonic |
| The ___ motor works by electromagnetic induction to turn the anode | stator |
| When electron bombard the target ___ of their energy is converted to heat. | 99% |
| The target of the rotating anode is usually coated with a | tungsten alloy |
| The ___ is the source of radiation in the xray tube | focal spot |
| The size of the effective ___ decreases as the target angle decreases | focal spot |
| High capacity tube rotors revolve at | 10,000 rpm |
| The heel effect causes xray intensity to be greater on the ___side of the tube | cathode |
| The ___ side of the tube should be over the thicker part of the patient because of the heel node effect | cathode |
| Tube ____ can occur from long exposures | failure |
| The stators are ___ the glass envelope | outside |
| ___ or ___ radiation is produced from rebounding electrons | extrafocus; off-focus |
| The heel is caused by the ___ of the anode | angle |
| The effective focal spot size is smaller than the | actual focal spot |
| Localized ___ on the anode target can occur from a single excessive exposure | pitting |
| Projectile electrons travel from the filament to the | anode |
| During an exposure, most of the kinetic energy of the projectile electrons is converted to | heat |
| the production of heat at the anode is directly proportional to | tube current |
| The efficiency of xray production increases as kVp | increases |
| Approximately ___ of kinetic energy of the electrons is converted to xrays at the target | 1% |
| Electrons interaction at the inner-shell of the target atoms produce | characteristic radiation |
| The useful characteristic xrays from tungsten are | k shell xrays |
| Characteristic K-shell xrays have an effective energy of | 57 keV |
| Most of the xrays produced at the target are | bremsstrahlung |
| At 55kVp ___ of the xrays produced are bremsstrahlung | 100% |
| Bremsstrahlung xrays are produced by slowing electrons at the | nucleus |
| Characteristic xrays are produced by released binding | energy |
| The amplitude of the emission spectrum is lower with a ___ generator than with a three-phase generator | single phase |
| A 15% increasing kVp is equivalent to doubling the | mAs |
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