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RadPhysics
Unit 4 RADT physics
| Question | Answer |
|---|---|
| The kinetic energy of the projectile electron in an x-ray tube | is about 1% efficient in the production of X-rays |
| useful characteristic x-rays are produced in tungsten | by removal of k-shell electrons |
| The shift of the characteristic x-ray spectrum to higher energy occurs because of which of the following? | An increase in target atomic number |
| What is produced when the projectile electron excites an outer-shell electron? | heat |
| The energy of characteristic x-rays increases with increasing | Atomic number of target material |
| X-rays are produced when | Projectile electrons interact with target atoms |
| When characteristic x-rays are produced, the energy of the x-rays is characteristic of | The atomic number of the target |
| The kinetic energy of a projectile electron can be measured in | Joules |
| The efficiency of x-ray production is: | Independent of the tube current |
| Bremsstrahlung radiation is produced by | Conversion of projectile electron kinetic energy to electromagnetic energy |
| When a bremsstrahlung x-ray is produced: | A projectile electron loses it's energy |
| In bremsstrahlung x-ray production: | The projectile electron is from the cathode |
| Bremsstrahlung x-rays are produced only at | Energies up to the projectile electron energy |
| Bremsstrahlung x-rays produced in a tungsten-targeted x-ray tube: | Outnumber characteristic x-rays |
| When a bremsstrahlung x-ray is emitted: | This results from the conversion of kinetic energy. |
| The wavelength of an x-ray: | Becomes longer as projectile electron kinetic energy is reduced |
| When projectile electron energy is increased: | More bremsstrahlung x-rays are produced |
| The efficiency of bremsstrahlung x-ray production increases with increasing: | Target atomic number |
| The output intensity of an x-ray tube | Is primarily due to bremsstralung x-rays |
| Which of the following projectile electron-target interactions results in x-ray emission? | Removal of inner shell electrons |
| When a projectile electron enters a target atom and interacts with the nuclear force field | It decreases in velocity |
| The characteristic x-ray emission spectrum principally depends on which of the following? | Target material |
| The continuous x-ray emission spectrum principally depends on which of the following? | Projectile electron energy |
| A diagnostic x-ray beam contains: | Mostly Bremsstrahlung x-rays, with some characteristic x-rays. |
| Which of the following factors principally accounts for the reduced x-ray intensity at low energy? | Added filtration |
| Characteristic x-radiation is related to the | Energy required to eject K-shell electrons |
| An increase in kVp results in an increase in | Radiation quality |
| An increase in mAs results in an increase in | Both characteristic and bremsstrahlung x-rays |
| Which of the following factors primarily affects the low-energy side of the x-ray emission spectrum? | Filtration |
| When the mAs is increased, x-ray quantity | increases proportionately |
| When the kVp is increased, x-ray quantity | increases |
| To maintain a constant optical density, what percentage increase in kVp should be accompanied by a reduction of one-half in mAs? | 15% |
| What is the most appropriate measure of x-ray beam quality? | HVL (half value layer) |
| it should be clear that mAs controls quantity and kVp controls: | quality |
| A minimum HVL is required for diagnostic x-ray beams because: | A lower HVL would result in an increased absorbed dose to the patient with no improvement in image quality |
| An x-ray beam can be made to have higher effective energy if what occurs? | filtration is added |
| Which of the following will enhance x-ray beam quality? a. Collimation b. Filtration c. mA d. mAs e. SID | filtration |
| Reducing kVp will do what? | Soften the x-ray beam |
| As the HVL of a beam increases, its penetrability | increases |
| Added filtration affects the x-ray beam in what way? a. Higher beam quantity b. Higher patient dose c. Increased beam hardening d. Poorer beam quality e. Reduced kVp | c. Increased beam hardening |
| The HVL is affected most by a change in what | kVp |
| The inherent filtration in a general purpose radiographic x-ray tube is usually equivalent to | 0.5 mm Al |
| The equivalent added filtration provided by a conventional light-localizing, variable-aperture collimator is closest to | 1.0 mm Al |
| The purpose of a wedge filter in diagnostic radiology is to produce: | a uniform x-ray beam intensity at the image receptor |
| X-rays of higher maximum energy can be obtained by doing which of the following? a. Increasing filtration b. Increasing kVp c. Increasing mAs d. Reducing inherent filtration e. Using a higher Z target | increasing the kVp |
| When filtration is added to a normally filtered x-ray beam, the x-ray emission spectrum will | decrease in amplitude |
| helps harden the x-ray beam | Inherent filtration |
| protects the patient from unnecessary radiation | Added filtration |
| Inherent filtration is: | increased with tube age |
| When added filtration is increased- | x-ray quality is enhanced |
| Which of the following is not one of the five basic x-ray interactions with matter? a. Bremsstrahlung b. Classical scattering c. Compton scattering d. Photodisintegration e. Photoelectric effect | a. Bremsstrahlung |
| Which of the following x-rays would be most likely to undergo classical scattering? a. 5 keV b. 15 keV c. 35 keV d. 66 keV e. 85 keV | a.) 5 keV |
| Which of the interactions contributes to image noise? | Compton scattering |
| During the Compton effect, most of the incident x-ray energy is given to what? | Scattered x-ray |
| Compton interaction affects the image by increasing which of the following? a. Contrast resolution b. Latitude c. Noise (fog) d. Spatial resolution e. Speed | c.) Noise (fog) |
| The probability that an x-ray will interact with an outer-shell electron is influenced principally by: | the energy of the incident x-ray. |
| The probability that an x-ray will undergo Compton interaction: | Decreases with increasing x-ray energy. |
| What x-ray interaction that does not cause ionization? | Classical scattering |
| Compton-scattered x-rays: | Have lower energy than the incident x-ray |
| The photoelectric effect is principally associated with which of the following? a. Absorption of an x-ray b. Bremsstrahlung x-ray production c. Characteristic x-ray production d. Electron excitation e. Scattering of an x-ray | Absorption of an x-ray |
| Photoelectric interaction with soft tissue is most likely with which of the following x-rays? a. 0.3 keV b. 3.0 keV c. 30 keV d. 300 keV e. 3000 keV | a. 0.3 keV |
| During photoelectric interaction | An electron is emitted from the atom |
| The radiographic image is formed principally by which of the following? a. Classical scattering b. Compton scattering c. Off-focus radiation d. Photoelectric interactions e. Uniform distribution of remnant x-rays | d. Photoelectric interactions |
| As a result of photoelectric interaction: | An electron leaves the atom |
| The photoelectric effect is: | The complete absorption of an x-ray with the subsequent emission of an electron |
| Anatomic structures that readily transmit x-rays: a. Are called radiolucent b. Are called radiopaque c. Have a high effective atomic number d. Have a high probability for photoelectric effect e. Usually have high mass density | a. Are called radiolucent |
| Differential absorption, although a complicated process, is basically the result of differences between: | Photoelectric effect and transmission |
| When a radiograph is taken: | Low kVp is necessary when soft tissue is imaged because it leads to high photoelectric effect |
| Which of the following has the greatest mass density? a. Blood b. Bone c. Fat d. Lung e. Muscle | b. bone |
| Air-contrast studies such as a colon examination are successful principally for what reason? | There are differences in mass density |
| Differential absorption is: | The difference between those x-rays that are absorbed and those that are transmitted |
| Which process contributes most to the radiographic image? | Photoelectric effect |
| What will increase the energy of bremsstrahlung radiation? a. Filament current b. Exposure time c. SID d. Target material e. X-ray tube voltage | X-ray tube voltage |
| Compton interaction occurs with outer-shell electrons and results in: | Reduced grayscale |
| Compton interaction affects the image by increasing which of the following? a. Contrast resolution b. Latitude c. Noise d. Spatial resolution e. Speed | c. Noise |
| Is the difference between absorbed x-rays and transmitted x-rays | Differential absorption |
Created by:
mbromm