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RAD106_Final
| Question | Answer |
|---|---|
| X-rays transmitted without interaction contribute to _______ | The radiographic image |
| At energies below 40 keV, the predominant x-ray interaction in soft tissue and bone is ________ | Photoelectric absorption |
| Pair production is an interaction between an x-ray and a(n) _________ that causes the x-ray to disappear and causes two electrons to take its place. | Nuclear Electric Field |
| Photodisintegration is an interaction that takes place at which energy level? | Energies higher than 10 MeV |
| If 5% of an incident beam is transmitted through a body part, then 95% of that beam was ________ | Attenuated |
| Compton scattering is an interaction between an x-ray and a(n) _________ electron that results in ionization and loss of energy | outer-shell |
| Coherent scattering is an interaction between _______ x-rays and atoms | low-energy |
| The photoelectric effect is an interaction between an x-ray and a(n) _________ electron that results in total x-ray absorption. | inner-shell |
| High kVp techniques reduce ________ | patient dose |
| Compton interactions, photoelectric absorption, and transmitted x-rays all contribute to _____________ | Differential absorption |
| Differential absorption in diagnostic imaging is primarily caused by _________ | pair production |
| A negative contrast agent is ___ | air |
| The two primary forms of x-ray interaction in the diagnostic range are __________ | Compton scattering and photoelectric absorption |
| Barium is a good contrast agent because of its __________ | High atomic number |
| An incident x-ray interacts with an atom without ionization during _________ | coherent scattering |
| Only at energies above 10 MeV can _______________ take place | photodisintigration |
| In ________________, there is complete absorption of the incident x-ray photon | photoelectric interation |
| Attenuation is caused by ___________ | absorption and scattering |
| K-shell binding energy increases with increasing _______ | atomic number |
| The scattered x-ray from a Compton interaction usually retains _____ of the energy of the incident photon. | most |
| _________ occurs only at the very high energies used in radiation therapy and in nuclear medicine P.E.T. imaging. | pair production |
| Differential absorption is dependent on all of the following, except _____________ | mAs of the exposure |
| When the mass density of the absorber is __________, it results in __________ Compton scatter. | increased;increased |
| The use of contrast agents increases the amount of ______ | differential absorption, Compton scatter and photoelectric absorption |
| An outer-shell electron is ejected and the atom is ionized during _________ | compton interations |
| As kVp ___________, the probability of photoelectric absorption ____________ | increases;decreases |
| Compton scatter is directed at _____ angle from the incident beam | any |
| Which x-ray interaction involves the ejection of the K-shell electron? | photoelectric absorption |
| Because of differential absorption, about _____% of the incident beam from the x-ray tube contributes to the finished image | 1% |
| X-ray intensity is directly proportional to _____. | mAs |
| The main purpose of added filtration is to reduce ____________. | Patient Dose |
| Increasing kVp increases the _________ of an x-ray beam. | energy |
| When SID is increased, ______ must be increased by _____ to maintain constant exposure to the image receptor. | mAs; SID^2 |
| A compensating filter is used to create ________ exposure with a body part of _________ thickness. | uniform;non-uniform |
| X-ray intensity is proportional to ____. | kVp^2 |
| X-ray beam energy is improved by ____________. | increasing filtration |
| X-ray quantity is _______ proportional to the ________ of the distance from the source. | inversely; square |
| The HVL is lowered by a decrease in ________. | kVp |
| Added filtration will ______ beam energy and ______ HVL. | increase; increase |
| The penetrability of an x-ray beam is called x-ray ________. | quality |
| An increase of 15% in kVp is equivalent to increasing mAs _____. | 100% |
| Grays, or milligrays, in air are the measurement for x-ray _________. | quantity, exposure and intensity |
| The inverse square law has the same effect on x-ray ________ and x-ray _________. | intensity; exposure |
| The number of x-rays in the useful beam defines x-ray ________. | Intensity |
| X-ray intensity is proportional to ______. | kVp^2 |
| If the intensity of a 70 kVp exposure at 20 mAs is 1.0 mGya, what would it be at 5 mAs? | 0.25 mGya |
| Beam energy is affected by ______________. | kVp and filtration |
| If an exposure is 0.5 mGya at an SID of 40 inches, what would the exposure be at an SID of 60 inches? | 0.222 mGya |
| f filter thickness is ________, then x-ray intensity is ________. | increased; reduced and reduced; increased |
| Image contrast is affected by ________. | beam quality and kVp |
| An x-ray beam that could pass through dense tissue would have high _____. | penetrability and quality |
| A 10% increase in kVp has ________ effect on x-ray intensity than/as a 10% increase in mAs. | much greater |
| A low-quality beam would also have low _____. | penetrability |
| Standard x-ray machines produce about _____ µGya/mAs at 70 kVp measured at 100 cm SID. | 50 |
| X-ray intensity increases in direct proportion to increases in __________. | mAs |
| The half value layer (HVL) of an x-ray beam is a measurement of beam _______. | energy |
| If a technologist changes the technique from 70 kVp @ 200 mAs to 70 kVp @ 400 mAs, the x-ray intensity will _________. | Double |
| If the quantity of electrons hitting the target is doubled, the x-ray intensity is __________. | increased by a factor of 2 |
| If the distance from the source to the image (SID) is reduced by half, how is the x-ray intensity at the image affected? | it is increased 4Xs |
| How does added filtration affect the emission spectrum? | Reduced amplitude and a shift to the right |
| Changes in _______ result in directly proportional changes in the amplitude of the emission spectrum. | mAs |
| A change in mA or mAs results in a proportional change in the ________ of the x-ray emission spectrum at all energies. | amplitude |
| The amplitude of the emission spectrum with a _________ generator is __________ it is with a three-phase generator. | single-phase; lower than |
| A 15% increase in kVp is equivalent to ______ | Doubling the mAs |
| Characteristic x-rays are emitted when an _________ electron fills an _________ void. | outer-shell; inner-shell |
| Bremsstrahlung x-rays are produced when a ________ electron is slowed by the _______ field of a target atom nucleus. | projectile; nuclear |
| The discrete portion of the x-ray emission spectrum would change position with a change in _______ | target material |
| Approximately _____ of the kinetic energy of electrons from the cathode is converted to heat. | 99% |
| A change in kVp affects both the ______ and the ______ of the x-ray emission spectrum. | amplitude;position |
| The efficiency of x-ray production is ___________ the tube current. | not affected by |
| The _____ of an x-ray beam is higher when the peak of the emission spectrum is further to the ______ | quailty; right |
| Bremsstrahlung x-rays are produced by _________ at the target. | slowing electrons |
| An increase in kVp would ________ the ________ of the emission spectrum. | increase; amplitude and position |
| The quantity of bremsstrahlung radiation increases proportionately with increased _____. | mAs |
| Approximately _____ of the kinetic energy of the projectile electrons is converted to x-rays at the target. | 1% |
| An exposure taken at 100 kVp would have a continuous emission spectrum with a maximum energy of _____ keV. | 100 |
| An increase in mAs would _________ the ___________ of the emission spectrum. | increase; amplitude alone |
| Projectile electrons travel from ______ | cathode to anode |
| Electron interactions at the inner shell of the target atoms produce _____ radiation. | characteristic |
| Most of the x-rays produced at the target are _______________. | bremsstrahlung |
| Most of the heat generated at the target is due to ___________. | outer-shell excitation |
| At 55 kVp, _____ of the x-rays produced are bremsstrahlung. | 100% |
| At the target, the projectile electrons interact with _______ | inner-shell and outer-shell electrons |
| Characteristic K-shell x-rays have an effective energy of _____ keV. | 69 |
| Characteristic x-rays are produced by _______ | released binding energy |
| The useful characteristic x-rays from tungsten targets are ___-shell x-rays. | K |
| The efficiency of x-ray production increases as ______ increases. | kVp |
| The production of heat at the anode is directly proportional to ________ | tube current |
| During an exposure, most of the ________ energy of the projectile electrons is converted to ________. | kinetic; heat |
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jetsetjes