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Ch 12-13 review
| Question | Answer |
|---|---|
| When collimating significantly, the radiographer should __________ exposure to compensate for the decrease in the number of x-ray photons that otherwise occurs. a. increase b. decrease c. keep the same | a. increase |
| Which of the following has a disadvantage when the angle of the flange is greater than the angle of divergence of the primary beam? a. cylinders b. cones c. shutters | b. cones |
| Collimator misalignment should be less than how much percent of the SID used? a. 0.5 b. 1 c. 1.5 d. 2 | d. 2 |
| Insufficient mAs will result in which of the following problems with a digital image? a. high contrast b. excessive scatter c. noise d. excessive patient dose | c. noise |
| Which of the following refers to the relationship of the height of the lead strips to the distance between them? a. interspace material b. grid frequency c. grid ratio d. grid focus | b. grid ratio |
| Which of the following refers to the number of lead lines per unit length in inches, centimeters, or both? a. interspace material b. grid frequency c. grid ratio d. grid focus | b. grid frequency |
| Which type of grid has lead lines that are angled, or canted, to approximately match the angle of divergence of the primary beam? a. parallel b. non-focused c. focused d. wafer | c. focused |
| Which type of grid cut off occurs when the x-ray beam is angled across the lead strips? a. off-center b. off level c. upside down d. off focus | b. off level |
| Which type of grid cut off occurs when the CR of the x-ray beam is not aligned from side to side with the center of a focused grid? a. off-center b. off level c. upside down d. off focus | a. off-center |
| Which type of grid cut off occurs when using SID outside of the recommended focal range? a. off-center b. off level c. upside down d. off focus | d. off focus |
| Which of the following will decrease the amount of scatter radiation produced? a. increasing the x-ray field size b. decreasing the x-ray field size c. increasing the grid ratio d. decreasing the grid ratio | b. decreasing the x-ray field size |
| Which of the following is not a type of beam restrictor? a. aperture diaphragm b. positive beam-limiting device c. cylinder d. lead shield | d. lead shield |
| As collimation decreases, the quantity of scatter radiation decreases. a. True b. False | b. False |
| What type of beam-restricting device provides the most flexibility in adjusting the x-ray field size? a. cylinder b. aperture diaphragm c. collimator d. cone | c. collimator |
| What describes the number of lead lines per unit length? a. grid frequency b. grid pattern c. grid convergent point d. grid ratio | a. grid frequency |
| A image was created using a 12:1 grid and 70 kVp at 10 mAs. What technique change would maintain a similar exposure to the image receptor when converting to a 6:1 ratio grid? a 81 kVp, 5 mAs b 70 kVp, 16.7 mAs c 70 kVp, 6 mAs d 60 kVp, 20 mAs | c 70 kVp, 6 mAs |
| What type of grid has lead strips running parallel to the long axis of the grid? a. focused b. short dimension c. cross hatched d. long dimension | d. long dimension |
| Angling the x-ray tube along the long axis of a crossed grid would result in: a. increased scatter absorption. b. grid cutoff. c. Moiré effect. d. lateral decentering. | b. grid cutoff. |
| For the air gap technique to be effective in reducing scatter radiation reaching the image receptor, what must be increased? a. SID b. focal spot size c. kVp d. OID | d. OID |
| With exposure technique compensation, _____ the grid ratio will _____ patient radiation exposure. a. decreasing, increase b. increasing, decrease c. increasing, increase d. decreasing, will not affect | c. increasing, increase |
| Decreasing patient thickness while using an AEC device would result in a. decreased exposure time b. decreased film density c. increased mAs readout d. decreased image contrast | a. decreased exposure time |
| Which detector or combination is best for a left shoulder? a. Center. b. Left. c. Right. d. Right and left. | a. Center. |
| What type of exposure technique system varies the mAs for patient thickness? a. Fixed kVp. b. Variable kVp. c. Pre-programmed. d. None of the above. | a. Fixed kVp. |
| Which of the following is NOT an advantage to a variable kVp–fixed mAs chart a. most effective with pediatric pt b. effective with small extremities c. small changes in kVp more effective than changin mAs d. greater assurance of adequate penetration | d. greater assurance of adequate penetration |
| Which of the following special situations would NOT required a change in exposure technique? a. Plaster cast. b. Additive disease. c. Positive contrast medium. d. Fiberglass cast. | d. Fiberglass cast. |
| Automatic exposure control (AEC) devices work by measuring _____. a. attenuation of primary radiation by the patient b. radiation that exits the patient c. radiation that is absorbed by the patient d. radiation exiting the tube | b. radiation that exits the patient |
| Which of the following exposure system operates by ionizing air that creates an electrical charge? a. anatomically programmed technique b. phototimer c. ionization chamber d. none of the above | c. ionization chamber |
| Use of the AEC device, the time of exposure is inversely related to intensity of exit radiation is directly related to intensity of exit radiation has an inverse squ relationship to exit radiation has no relationship to the intensity of exit radiation | is directly related to intensity of exit radiation |
| What factors are important when using automatic exposure control (AEC) devices? 1. detector selection 2. centering part to detector 3. back-up mAs, if set a. 1 and 2 only b. 1 and 3 only c. 2 and 3 only d. 1, 2, and 3 | d. 1, 2, and 3 |
| Increasing patient thickness while using an AEC device would result in: a. increased exposure time. b. decreased brightness. c. decreased mAs readout. d. increased image contrast. | a. increased exposure time. |
| Which detector or combination is best for a right rip? a. center b. left c. right d. right and left | a. center |
| What is the primary goal of exposure technique charts? a. extend life of x-ray tube b. improve radiographer’s accuracy c. consistency in image quality d. increase patient work flow | c. consistency in image quality |
| What type of exposure technique system uses a fixed mAs regardless of patient thickness? a. fixed kVp b. variable kVp c. preprogrammed d. AEC | b. variable kVp |
| Of the following, which is most important when using a technique chart? a. same radiographer revises chart b. same chart used for all x-ray tubes c. accurately measure patient d. include a patient history | c. accurately measure patient |
| An advantage of the variable kVp technique chart is that it: a. produces lower contrast images. b. reduces patient exposure. c. makes a 2 kVp change sufficient with any kVp. d. makes smaller technique changes possible. | d. makes smaller technique changes possible. |
| Which of the following special considerations may require a decrease in mAs? a. bariatric patient b. soft tissue examination c. pediatric patient d. b and c only | d. b and c only |
| Which of the following special considerations may require an increase in mAs? a. contrast media b. bariatric patient c. tissue edema d. all of the above | d. all of the above |
| Why is a contrast agent an effective method? | Increases radiographic contrast in areas of low subject contrast |
| ______ contrast agents produce more brightness (less density), while _____ contrast agents produce less brightness (more density). | Positive; Negative |
| When it is desired or necessary to compensate for additive or destructive diseases, which exposure factor is best to manipulate? | kVp because it affects the penetrating ability of the beam. |
| What type of splint requires an increase in exposure factors? | None/All of them but only if they are in the way of the primary beam. |
| Which type of cast requires a change in exposure factors? | Plaster |
| What chart has the advantages of easier use, more consistency in production of quality radiographs, greater assurance of adequate penetration of all anatomic parts, uniform contrast, and increased accuracy? | Fixed kVp - Variable mAs technique chart |
| What happens if there is failure to maintain regular calibration? | Results in the lack of consistent and reproducible exposures to the detectors and could effect image quality. |
| What is the purpose of calibration? | To ensure that consistent and appropriate exposures to the image receptor are produced. |
| What is the most common cause of suboptimal film-screen image when AEC is used? | Centering |
| What detector has a greater effect on total exposure? | The detector that receives the greatest amount of exposure |
| Routinely using the plus or minus density settings to produce an acceptable radiograph indicates what problem? | An issue with the AEC device |
| At what kVp and mAs should the backup time be terminated if it is automatically controlled? | 600 mAs at ~/+ 50 kVp |
| What is the purpose of the backup time? | To act as a safety mechanism; it protects the patient from unnecessary exposure and protects the x-ray tube from reaching/exceeding its heat-loading capacity. |
| If the radiographer wants to decrease exposure time, would they increase or decrease the mA? | Increase the mA |
| What causes a shorter exposure time when using a higher kVp? | Because the detectors measure the quantity of radiation, the higher the kVp used the faster the quantity desired is reached. |
| The higher the kVp, the shorter the exposure time (T/F). | True |
| AEC controls on the _______ of radiation reaching the image receptor and therefore has no effect on other image characteristics such as _________. | Quantity; Contrast |
| What are the advantages of having the mAs from the mAs readout? | Allows to become more familiar with manual exposure technique factors, and be able to make exposure adjustments. |
| Why are ionization-chamber AEC devices considered entrance-type devices? | The detectors are positioned in front of the image receptor so that radiation interacts with the detectors just before interacting with the image receptor. |
| Why are phototimer AEC devices considered exit-type devices? | The detectors are positioned behind the image receptor so that radiation must exit the image receptor before it is measured by the detectors. |
Created by:
drocco25