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a device that moves the grid during a radiographic exposure is called a
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a fixed kVp technique is fixed for a specific
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grids, filtration
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| Question | Answer |
|---|---|
| a device that moves the grid during a radiographic exposure is called a | Potter-Bucky diaphragm |
| a fixed kVp technique is fixed for a specific | range of part thickness |
| a grid absorbs | scatter radiation |
| a grid is used to improve | distortion |
| a Potter-Bucky diaphragm must move the grid___to the direction of the grid lines | perpendicular |
| a Thoreaus filter combines all of the following except; silver, copper, tin, aluminum | silver |
| air produces a ___image receptor exposure than any other body substance | greater |
| all filtration can be expressed in terms of the thickness of | Al/Eq |
| angulation across the long axis of a linear grid causes | grid cut-off |
| as a general rule, a grid is employed when the body part thickness exceeds___cm | 10 |
| as a general rule, a grid is employed when kVp exceeds | 60 |
| as kVp increases | scatter increases |
| as the lead content of a grid increases | the ability of the grid to remove scatter increases |
| attenuation is greater for elements with more___with which the photons may interacts | electrons |
| bone produces less image receptor___because it attenuates the x-ray beam more than soft tissue does | exposure |
| establishing the kVp steps in___cm increments permits simple halving or doubling of mAs to maintain density | 4 to 5 |
| filtration affects patient dose by | removing low-energy photons |
| filtration has what affect on patient dose | it decreases patient dose |
| filtration is the process of eliminating undesirable___by the insertion of absorbing materials into the primary beam | low-energy incident electrons |
| filtration permits the radiograper to___the photon emission spectrum into a more useful beam | narrow |
| fixed kVp systems | decrease patient dose, reduce x-ray tube wear, decrease time settings |
| fixed kVp systems | increase the consistency of image density, increase the consistency of image contrast, lengthen exposure latitude |
| fixed kVp systems | produce more scatter radiation than other systems |
| for a grid to be properly focused, the x-ray tube must be located along the___line | convergence |
| for a variable kVp exposure technique system, the kVp is primarily varied according to | measured body part thickness |
| how many half-value layers must be added to the primary beam to reduce its intensity to less than 20 percent of its original value | 3 |
| in a fixed kilovoltage system, the___is held constant | kVp |
| in a fixed kVp system, the kVp is held constant | for a given range of subject densities, contrasts, while the mAs is varied to achieve appropriate image density |
| in general, low-energy x-ray photons | are absorbed by the patient |
| in the early days of radiography, it was common practice to use a change of___kVp for every one cm of tissue thickness plus a constant | 2 |
| most of the inherent filtration of a typical x-ray equipment comes from the | wedge filter |
| once phantom images have been produced, they must be shown to | diagnosing radiologists and image quality control radiographers |
| photon absorption within the body occurs as the result of | photoelectric interaction |
| photons that pass through the body unaffected produce | radiographic contrast |
| steps formed for a variable kVp exposure system should be in groups of___cm increments | 5 |
| technique systems function best when a | large number of variables can be held constant, single factor is permitted to vary, method of consistency is used to produce a quality image |
| the advantages of the fixed kVp technique system include each of the following except; decreased contrast, decreased recorded detail, decreased mAs, max possible kVp | decreased contrast |
| the amount of material that will reduce the intensity of the primary beam to one-half its original value is the | half-value layer |
| the amount of scatter radiation increases with a/an | increase in patient thickness, larger field size, decrease in atomic number of the tissue |
| the collimator device is considered part of the___filtration | added |
| the degree of differential absorption is referred to as | subject contrast |
| the device used to measure part thickness is called a | caliper |
| the effective use of a variable kVp technique chart requires | precise part measurement |
| the greatest source of scatter during a radiographic exam is the | patient |
| the half-value layer is typically expressed in | Al/Eq |
| the higher the kVp, the | lower the patient dose |
| the interaction that produces scatter radiation is called___interaction | compton |
| the kVp has a profound effect on | contrast, type of interaction, average photon energy |
| the mAs values for a fixed kVp system must be set at minimum increments of ___percent | 30 |
| the most common filter material used is | aluminum |
| the number of grid lines per inch is the grid | frequency |
| the objective of optimal kVp is to determine the | highest kVp & lowest contrast |
| the optimal kVp must ensure | sufficient penetration of the subject, acceptable radiographic contrast, the availability of diagnostic information |
| the primary variable of a fixed kVp system is | mAs |
| the problem of unequal subject density is solved by a | Thoreaus filter |
| the purpose of moving the grid is to blur the | radiopaque strips |
| the radiopaque strips | absorb scatter, are made of dense material, have a high atomic number |
| the ratio of the height of the lead strips to the distance between the lead strips is the grid | ratio |
| the use of the max kVp as optimal causes a corresponding decrease in | mAs |
| the___the bidy part, the___the attenuation | thicker, greater |
| to reduce or eliminate the need for patient exposures, a___is used to develop a variable kVp exposure system | PEP |
| total filtration is equal to the sum of___filtration | inherent and added |
| variable kVp systems | produce higher contrast images than other systems do, enhance the visibility of detail, increase the perception of resolution |
| what term describes filtration that is part of the x-ray tube, the tube housing, and the collimation device | inherent |
| when AEC systems are used, the selection of___ factors is eliminated | time |
| when an x-ray beam passes through the body | it will pass throught the body unaffected, be absorbed by the body, interact with the body and change direction |
| when establishing a technique chart, the initial step involves | producing phantom images |
| when the lead strips run in a single direction in a grid, the grid pattern is described as | linear |
| when viewing phantom images, professionals are not asked to select the | single best image |
| which grid would have the greates distance between lead strips | 6:1 |
| which grid would most effectively reduce scatter | 15:1 |
| which of the following elements would attenuate a greater percentage of the x-ray beam; hydrogen, barium, oxygen, carbon | barium |
| which of the following elements would attenuate a lesser percentage of the x-ray beam; hydrogen, barium, oxygen, carbon | hydrogen |
| which of the following materials are used as a filter; glass, oil, aluminum | all of the above |
| ___ compensating filters is used most commonly in thoracic spine radiography | wedge |
| the thickest portion of the wedge filter is placed over the less dense part of the patient | true |
| a grid is a series of radiopaque strips that alternate with radiolucent interspace strips | true |
| which term best describes the filtration that occurs as the primary beam passes through the glass window of the x-ray tube | inherent |
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