RTBC Advanced Exposure Factors
Which two of the following statements are true concerning a higher ratio grid compared to a lower ratio grid? (Select two) -High ratio grids demonstrate increased efficiency (contrast improvement) -High ratio grids absorb less scatter radiation -High ratio grids require increased milliampere-seconds (mAs) to maintain receptor exposure -High ratio grids require decreased milliampere-seconds (mAs) to maintain receptor exposure
-High ratio grids demonstrate increased efficiency (contrast improvement) -High ratio grids require increased milliampere-seconds (mAs) to maintain receptor exposure
A radiograph is acquired using 450 milliamperes (mA) and an exposure time of 0.1 seconds (s). What new exposure time must be used to obtain the same receptor exposure if the radiograph is repeated with 300 mA? 0.044 s 0.15 s 0.23 s 0.66 s Start by calculating the original mAs: 450 mA x 0.1s = 45 mAs. Calculate the new mA by dividing the mAs by the new exposure time: 45 mAs/300 mA = 0.15 seconds
0.15 s
If the patient dose is 1 milligray (mGy) at a 40-inch (102 cm) source-to-image distance (SID), what is the patient dose at a 72-inch (183 cm) SID using the same technical factors? 0.3 mGy 0.55 mGy 1.8 mGy 3.25 mGy
0.3 mGy Start with the original patient dose (1), multiply by the original distance squared (40squared), and divide by the new distance squared (72squared). 1 x 40squared / 72squared = 0.3 milligray
If the patient dose is 0.5 milligray (mGy) at a 50 inches (127 cm) source-to-skin distance (SSD), what is the patient dose at a 64 inch (162 cm) SSD using the same technical factors? 0.26 mGy 0.31 mGy 0.39 mGy 0.64 mGy
0.31 mGy 0.5 x 50squared / 64squared = 0.31 mGy
If an optimal radiograph is acquired at 72 inches (183 cm) with an air kerma of 1 milligray (mGy), what will the air kerma be if the distance is reduced to 60 inches (152 cm)? 0.69 mGy 0.83 mGy 1.44 mGy 1.59 mgy
1.44 mGy 1 x 72squared / 60squared = 1.44 mGy
Radiographic grids are recommended when the anatomic part reaches which of the following thicknesses? 2 cm 4 cm 8cm 10 cm
10 cm Once an anatomical part reaches 10 cm thick a radiographic gris is recommended.
A radiographer typically uses 80 kilovoltage peak (kVp) and 3 milliampere-seconds (mAs) on a portable chest exam without a grid. If the radiographer uses and 8:1 grid on a portable chest, what new mAs would be required to compensate for the grid? 6 mAs 9 mAs 12 mAs 15 mAs Formula: mAs1 / mAs2 = Grid Factor1 / Grid Factor2
12 mAs
A radiograph is acquired using 500 milliamperes (mA) and an exposure time of 100 milliseconds (ms). What new mA must be used to obtain the same receptor exposure if the radiograph is repeated using 400 ms? 0.8 mA 31.25 mA 125 mA 2000mA
125 mA The receptor will remain the same when the milliamperage (mA) is changed to 125 mA. This ensures that the new milliampere-seconds (mAs) is the same as the original mAs. Start by converting the exposure times from milliseconds (ms) to seconds (s). The original exposure time is: 100 ms/1000 = 0.1 s The new exposure time is: 400 ms/1000 =. 0.4 s Next, calculate the original mAs: 500 mA x 0.1 s = 50 mAs Finally, calculate the new mA by dividing the mAs by the new exposure time: 50 mAs/0.4 s = 125 mA
An x-ray exposure at 40 inches (102 cm) results in a beam intensity of 200 microgray (μGy). What is the new intensity for an x-ray exposure at 50 inches (127 cm)? 128 μGy 160 μGy 250 μGy 312 μGy
128 μGy 200 x 40squared / 50squared = 128 μGy
If an optimal radiograph is acquired at 72 inches (183 cm) with an air kerma of 4 milligray (mGy), what will the air kerma be if the distance is reduced to 40 inches (102 cm)? 1.23 mGy 4.6 mGy 7.2 mGy 13 mGy
13 mGy This question requires the inverse square calculation. 4 x 72squared / 40squared = 13 mGy
A radiograph is acquired using 200 milliamperes (mA) and an exposure time of 200 milliseconds (ms). What new exposure time must be used to obtain the same receptor exposure if the radiograph is repeated with 300 mA? 89 ms 133 ms 300 ms 450 ms
133 ms The receptor exposure will remain the same when the exposure time is changed to 133 milliseconds (ms). This ensures that the new milliampere-seconds (mAs) is the same as the original mAs. Start by converting the exposure time from milliseconds to seconds. The original exposure time is: 200 ms/1000 = 0.2 s. Next, calculate the original mAs: 200 mA x 0.2 s = 40 mAs Calculate the new exposure time by dividing the mAs by the new mA: 40 mAs/300 mA = 0.133 seconds Finally, convert the exposure time from seconds to milliseconds by multiplying by 1,000: 0.133 s x 1000 = 133 ms
If the patient dose is 1 milligray (mGy) at a 72 inch (183 cm) source-to-image distance (SID), what is the patient dose at a 40 inch (102 cm) SID using the same technical factors? 0.3 mGy 0.55 mGy 1.8 mGy 3.24 mGy
3.24 mGy
An exposure is made using 70 kilovoltage peak (kVp), 300 milliamperes (mA), and a 0.1 second (s) exposure time. Calculate the milliampere-seconds (mAs). 4 mAs 7 mAs 30 mAs 370 mAs
30 mAs The milliampere-seconds (mAs) is calculated by multiplying the milliamperage (mA) by the exposure time (in seconds [s]): 300 mA x 0.1 s = 30 mAs. The kilovoltage peak (kVp) is not used to calculate the mAs.
An x-ray exposure at 50 inches (127 cm) results in a beam intensity of 200 microgray (μGy). What is the new intensity for an x-ray exposure at 40 inches (102 cm)? 128 μGy 160 μGy 250 μGy 312 μGy
312 μGy 200 x 50squared / 40squared = 312 μGy
A patient has been brought to the imaging department for radiograph of his knee. Previously, the patient had a portable knee exam completed in the emergency department (ED), using 70 kilovolts (kV), 2.5 milliampere-seconds (mAs), and a 6:1 grid. The exposure will be completed with the image receptor (IR) in the Bucky tray with a 12:1 grid. What new mAs will be required for the exposure in the department to compensate for the higher ratio grid? 1.5 mAs 4.15 mAs 7.5 mAs 12.6 mAs
4.16 mAs The exam should be completed with 4.0 mAs. According to the grid conversion formula, the correct calculation for this problem is (2.5 x 5) / 3 = 4.0. The original mAs is multiplied by the new grid conversion factor, and then that product is divided by the original grid conversion factor. Since the grid ratio is higher in the x-ray room, mAs must be increased in order to maintain an appropriate receptor exposure. The grid conversion formula is: (mAs2) ./ (mAs2) = (GF1) / (GF2) (2.5) / (x) = (3) / (5) Solving for (x) this becomes (x) = (2.5) x (5) / (3) = 4.16 mAs
An exposure is made using 500 millliamperes (mA), and a 100 millisecond ( ms) exposure time. Calculate the milliampere-seconds (mAs). 5.2 mAs 9.6 mAs 50 mAs 596 mAs
50 mAs The milliampere-seconds (mAs) is calculated by multiplying the milliamperage (mA) by the exposure time (in second [s]). The exposure time in milliseconds [ms] must be converted to seconds by dividing by 1000: 100/100 =0.1 s. The exposure time MUST be in units of seconds to calculate the mAs: 500 x 0.1s = 50 mAs.
An x-ray exposure measured at 38 inches (97 cm) results in a beam intensity of 90 microgray (μGy). What is the new intensity for an x-ray exposure at 48 inches ( 122 cm)? 48 μGy 56 μGy 71 μGy 97 μGy
56 μGy This question requires using the inverse square calculation. Start with the original intensity (90), multiply by the original distance squared (38squared), and divide by the new distance squared (48squared). that 90 x 38squared / 48squared = 56 μGy
An exposure is made using 200 milliamperes (mA), and a 300 millisecond (ms) exposure time. Calculate the milliampere-seconds (mAs). 21 mAs 60 mAs 74 mAs 270 mAs
60 mAs The milliampere-seconds (mAs) is calculated by multiplying the milliamperage (mA) by the exposure time (in seconds [s]). The exposure time in milliseconds (ms) must be converted to seconds (s) by dividing by 1000: 300/1000 = 0.3 s. The exposure time MUST be in units of seconds to calculate the mAs: 200 x 0.3 s = 60 mAs
The back-up timer terminates the exposure when the total milliampere-seconds (mAs) has reached: 100 mAs 300 mAs 600 mAs 1,200 mAs
600 mAs The back-up timer stops the exposure at 150% of the expected exposure, or 600 milliampere-seconds (mAs). This is only likely to happen if the technologist activates the automatic exposure control (AEC) cells within the wrong bucky in the x-ray room. Please note that the back-up timer and maximum mAs can vary some between machines.
An exposure is made using 80 kilovotage peak (kVp), 250 milliamperes (mA), and a 0.25 second (s) exposure time. Calculate the milliampere-seconds (mAs). 3 mAs 20 mAs 63 mAs 330 mAs
63 mAs The mAs is calculated by multiplying the mA by the exposure time (in seconds [s]): 250 mA x 0.25 s = 62.5 mAs, which rounds up to 63 mAs. The kVp is not used to calculate the mAs.
An x-ray exposure measured at 60 inches (152 cm) results in a beam intensity of 100 microgray (μGy). What is the new intensity for an x-ray exposure at 72 inches (183 cm)? 69 μGy 83 μGy 120 μGy 144 μGy
69 μGy 100 x 60squared / 72squared = 69 μGy
A grid that has lead strips with a height of 4 mm that are spaced 0.5 mm apart will have a grid ratio of: 2:1 4:1 8:1 16:1
8:1 The grid has a ratio of 8:1. Grid ratio is determined by dividing the height of lead strips by the distance between them; 4/0.5 = 8
According to the inverse square law, changing the source-to-image distance (SID) while using a fixed technique will affect which two of the following? (SELECT TWO) Beam Energy Beam Intensity Patient dose Tube loading
Beam Intensity Patient Dose
A radiology department's routine protocol is to complete knee exams with the use of a grid. However, in a portable situation, the technologist does not have a grid and decides to complete the exam without a grid and without making and changes to the technique. Without the use of a grid, the quality of the image will demonstrate decreased: Receptor exposure Noise Contrast Spatial resolution
Contrast
The primary effect of scatter radiation on a radiographic image quality is decreased: Receptor exposure Contrast Brightness Spatial resolution
Contrast Scatter radiation decreases image quality by decreasing contrast. Scatter radiation adds a layer of gray fog over the image and contributes no meaningful information to image formation.
Which of the following grid types can't be used when tube angulation is required? Focused Grid Crossed Grid Linear Grid Parallel Grid
Crossed Grid Crossed grids must be perfectly positioned within the x-ray field. They can't be used if the x-ray beam requires any angulation. For this reason, crossed grids are not often used in a diagnostic x-ray. Tube angulation can be used for linear, parallel, and focused grids.
According to the inverse square law, if the source-to-image distance (SID) increases, the receptor exposure will: Increase Decrease Remain the same
Decrease
According to the inverse square law, when the distance between the x-ray source and the point of measurement (patient, worker, or receptor) increases, the beam quantity will: Increase Decrease Remain the same
Decrease
According to the inverse square law, if the source-to-image distance (SID) increases, the beam intensity will: Increase Decrease Remain the same
Decrease Assuming no other factors change, increasing the SID decreases the beam intensity. Increasing the distance, decreases the intensity.
A radiograph is acquired using a 40 inch (102 cm) source-to-image distance (SID). If the exposure factors remain the same but the SID is increased to 60 inches (152 cm), the receptor exposure will: Increase Decrease Remain the same
Decrease Increasing the source-to-image distance (SID) from 40 inches (102 cm) to 60 inches (152 cm) will result in decreased x-ray beam intensity. Moving the x-ray tube farther from the receptor results in a less concentrated x-ray beam, which is described as a decrease in intensity (quantity). Increasing the distance, decreases the intensity.
What technical change is required to decrease receptor exposure when using automatic exposure control (AEC) Increased milliamperage (mA) Decreased kilovoltage peak (kVp) Increased back-up timer Decreased density setting
Decrease density setting Decreasing the density setting is the primary way to decrease receptor exposure when using AEC.
Increasing the distance from the x-ray source results in which of the following? Increased beam energy Decreased beam energy Increased beam intensity Decreased beam intensity
Decreased beam intensity Increasing the distance from the x-ray source will cause a decrease in beam intensity. Changes in distance affect the beam intensity, or quantity, according to the inverse square law. Changes in the distance have no effect on the beam energy or quality.
Which of the following effects is observed when using automatic exposure control (AEC) to image a hyposthenic patient? Decreased spatial resolution Increased contrast resolution Increased receptor exposure Decreased exposure time
Decreased exposure time
Which effect will occur when using an automatic exposure control (AEC) system to image a hyposthenic (small body habitus) patient? Decreased spatial resolution Increased contrast resolution Increased receptor exposure Decreased exposure time
Decreased exposure time Imaging a hyposthenic patient with an automatic exposure control (AEC) system will result in a decreased exposure time. A hyposthenic patient is small or less robust. Which allows the ideal receptor exposure in a shorter amount of time.
What is the advantage of a focused grid as compared to a parallel grid? Increased image contrast Decreased grid cut-off Increased recorded detail Decreased distortion
Decreased grid cut-off There is less grid cut-off with the focused grid. There is less absorption of useful radiation by the grid because the lead strips are angled to match the divergence of the beam.
When using automatic exposure control (AEC), which of the following technical changes will increase the total exposure time without increasing the receptor exposure? Decreased milliamperage (mA) Increased kilovoltage peak (kVp) Decreased back-up timer Increased density setting
Decreased milliamperage (mA) When using automatic exposure control (AEC), decreasing the milliamperage (mA) will result in an increased exposure time. Decreasing the mA decreases the exposure RATE, so it takes more time to reach the desired exposure level at which the system terminates the exposure. Changes to mA affect the exposure RATE and the exposure TIME, but the total receptor exposure remains the same.
An off-center grid error results in which of the following? Decreased receptor exposure on the outer edges of the radiograph Decreased receptor exposure across the entire radiograph Increased receptor exposure on the outer edges of the radiograph Increased receptor exposure across the entire radiograph
Decreased receptor exposure across the entire radiograph An off-center grid error results in decreased receptor exposure across the entire radiograph. Grids do not increase the receptor exposure.
An upside-down grid error results in which of the following? Increased receptor exposure on the outer edges of the radiograph Increased receptor exposure in the center of the radiograph Decreased receptor exposure in the center of the radiograph Decreased receptor exposure on the outer edges of the radiograph
Decreased receptor exposure on the outer edges of the radiograph
What is the primary advantage of using a grid for a radiographic procedure? Reduced scatter production Increased recorded detail Decreased scatter reaching the image receptor Decreased image contrast
Decreased scatter reaching the image receptor Grids decrease the amount of scatter radiation reaching the image receptor. The function of the grid is to absorb the scatter radiation coming from the patient before it hits the image receptor, therefore increasing the image contrast.
The inverse square law defines the relationship between what two factors? Distance and beam energy Distance and beam quality Distance and beam penetrability Distance and beam intensity
Distance and beam intensity
The automatic exposure control (AEC) system communicates with which portion of the x-ray circuit when the optimal receptor exposure has been achieved? Filament circuit Exposure timer Autotransformer Milliampere (mA) selector
Exposure timer The purpose of the AEC is to control the receptor exposure by controlling the exposure time. The exposure timer is within the low voltage, or primary, portion of the x-ray circuit.
Which of the following grid types uses a specific source-to-image distance (SID) range? Crossed grid Parallel grid Focused grid Virtual grid
Focused grid Focused grids are designed for specific source-to-image distance (SID). The SID range is specified to match the divergence of the beam at a specified distance such as a 30 - 50 inches (76 - 127 cm) or 40 - 80 inches (102 - 203 cm). The specified SID range is termed "focal distance".
Which of the following terms is described as, the absorption of the primary (useful) beam caused by a misalignment of the radiographic grid? Grid conversion factor Grid efficiency Grid Ratio Grid cutoff
Grid cutoff Grid cutoff occurs when there is a misalignment of the radiographic grid.
An artifact introduced to a radiographic image from misusing a grid is known as: Grid ratio Grid cleanup Grid error Grid frequency
Grid error An artifact introduced to a radiographic image from misusing a grid is known as a grid error.
Compared to a stationary grid, the main advantage of using a moving grid is that the: Grid lines will be more visible with a moving grid Grid lines will be blurred and not visible with a moving grid Moving grid is more efficient at absorbing scatter radiation Moving grid will produce higher contrast images
Grid lines will be blurred and not visible with a moving grid
The height of the lead strips within a radiographic grid compared to the distance between them is described as the: Grid conversion Grid frequency Grid ratio Grid efficiency
Grid ratio The grid ratio is the height of the lead strip compared to the width, or distance, between them. This is calculated by dividing the height (H) of the lead strips by the distance (D) between the strips: H/D. Grid ratio is directly related to the efficiency of a grid.
Which grid error results in grid cut-off and loss of exposure on the outside edges of the image receptor?
Incorrect source-to-image distance (SID) with a focused grid
According to the inverse square law, if the source-to-image distance (SID) decreases, the patient dose will: Increase Decrease Remain the same
Increase Assuming no other factors change, decreasing the source-to-image distance (SID) increases the patient dose, the concentration of radiation absorbed by the patient. Bringing the x-ray tube closer to the receptor results in a more concentrated x-ray beam and increases the number of photons striking the patient.
According to the inverse square law, if the source-to-image distance (SID) decreases, the receptor exposure will: Increase Decrease Remain the same
Increase Decrease the distance, Increases the intensity.
A radiograph of the lumbar spine is produced using automatic exposure control (AEC). The exposure results in optimal contrast but low receptor exposure. What is the ideal way to increase receptor exposure? Increase milliamperage (mA) Increase kilovoltage peak (kVp) Decrease grid ratio Increase density setting
Increase density setting Increasing the density setting is the primary way to increase receptor exposure when using AEC
When using a radiographic unit with automatic exposure control (AEC), which of the following can be employed to reduce patient motion while maintaining proper receptor exposure? Increase milliamperage (mA) Decrease kilovoltage peak (kVp) Increase back-up timer Decrease density setting
Increase milliamperage (mA) When using AEC, a reduced patient motion may be achieved by increasing the milliamperage (mA). Increasing the exposure RATE, and decreases the exposure TIME. Decreasing the exposure time helps to minimize the effect of motion blur on a radiograph.
In an extreme case of off-focus grid error, which of the following may result? Decreased brightness and quantum mottle at the edges of the image Decreased brightness and quantum mottle at the center of the image Increased brightness and quantum mottle at the edges of the image Increased brightness and quantum mottle at the center of the image
Increased brightness and quantum mottle at the edges of the image
The technical change is required to increase receptor exposure when using automatic exposure control (AEC) Increased milliamperage (mA) Increased density setting Decreased kilovoltage (kVp) Decreased back-up timer
Increased density setting Increasing the density setting is the primary way to increase receptor exposure when using automatic exposure control (AEC)
Which effect will occur when using an automatic exposure control (AEC) system to image a hypersthenic (large body habitus) patient? Increased spatial resolution Increased exposure time Decreased contrast resolution Decreased receptor exposure
Increased exposure time
A technologist is performing an anteroposterior (AP) abdomen radiograph on a geriatric patient using an automatic exposure control (AEC) system. Which of the following changes will be noted if the technologist decreases the kilovoltage peak (kVp)? Decreased patient dose Increased receptor exposure Decreased contrast Increased exposure time
Increased exposure time Decreasing the kVp will result in increased exposure time; decreasing the kVp results in fewer photons in the beam and less penetrating ability.
Which modifications may decrease the total exposure time when using an automatic exposure control (AEC) system? Increased milliamperage (mA) Decreased kilovoltage peak (kVp) Decreased back-up timer Increased density setting
Increased milliamperage (mA) When using automatic exposure control (AEC), increasing the milliamperage (mA) will result in a decreased exposure time.
Consider an x-ray examination that uses these technical factors: 300 milliamperes (mA), 100 milliseconds (ms), 75 kilovoltage peak (kVp), and 72 inches (183 cm) source-to-distance (SID). Changing the SID to 40 inches (102 cm) will result in which of the following? Increased x-ray beam energy Increased x-ray beam intensity Decreased x-ray beam energy Decreased x-ray beam intensity
Increased x-ray beam intensity
What component within the automatic exposure control (AEC) system measures the quantity of photons exiting the patient? Rectifier bridge Autotransformer Ionization chamber Exposure timer
Ionization Chamber An AEC system includes three or more ionization chambers that measure the quantity of photons exiting the patient and striking the image receptor.
When using automatic exposure control (AEC), the technologist can directly assign which three of the following parameters? (Select three) Kilovoltage peak (kVp) Milliampere-seconds (mAs) Source-to-image distance (SID) Object-to-image distance (OID)
Kilovoltage peak (kVp) Source-to-image distance (SID) Object-to-image distance (OID) The technologist can directly assign the kVp, SID, and OID. The technologist cannot directly assign the milliampere-seconds (mAs) when using an automatic exposure control system (AEC).
Which of the following projections may be improved by using a low-milliampere (mA), long-exposure time technique? Lateral thoracic spine Supine abdomen Decubitus chest Anteroposterior (AP) axial cranium
Lateral thoracic spine The lateral thoracic spine projection may be improved by using a low-milliampere (mA), long-exposure time technique, known as a "breathing technique".
Which of the following materials can't be used as interspace material inside a radiographic grid? Aluminum Lead Plastic Carbon Fiber
Lead
Which of the following statements is accurate regarding focused grids? Lead strips are angled to match the divergence of the x-ray beam Lead strips are perpendicular to each other Two sets of lead strips are present at 90 degrees to each other Lead strips are closer together in focused grids
Lead strips are angled to match the divergence of the x-ray beam Lead strips are angled to match the divergence of the x-ray beam in a focus grid. The angled lead strips allow more of the useful beam to penetrate through the grid without absorption, which prevents grid cut-off
The primary purpose of an automatic exposure control (AEC) system is to: Enhance image contrast Maintain optimal receptor exposure Increase radiographic spatial resolution Automatically modulate the kilovoltage peak (kVp)
Maintain optimal receptor exposure
Consider a technologist performing a lumbar spine series using an automatic exposure control (AEC) system. After acquiring the lateral radiograph, the technologist angles the beam to 5º caudal and collimates to the area of the L5- S1 joint. How should the technologist change the technical parameters to ensure the same receptor exposure as the lateral view? Increase kilovoltage peak (kVp) Increase milliamperage (mA) Decrease the source-to-image distance (SID) No change is required
No change is required When the beam angle and collimation are changed while using an automatic exposure control (AEC) system, the technologist should NOT make any changes to the technical parameters.
What type of grid error occurs when the x-ray beam is not aligned with the direction of the grid lines? Off-center Off-level Off-angulation Upside-down
Off-angulation Off-angulation grid errors occur when the x-ray beam is not aligned with the direction of the grid lines.
Which type of grid error occurs when the central ray is not aligned to the middle of the focus grid? Off-center Off-lever Off-angulation Upside-down
Off-center Off-center grid errors occur when the central ray is not aligned to the middle of a focused grid.
Which of the following terms is a type of grid error? Off-center Off-distance Center-angulation Upside-center
Off-center Off-center is a type of grid error. In addition to off-center, off-level, off-focus, off-angulation, and upside-down are also different types of grid errors.
Which type of grid error is a "crooked grid"? Off-center Off-level Off-angulation Upside-down
Off-level Off-level grid errors are known as "crooked grid" errors. Off-center grid errors occur when the central ray is not aligned to the middle of a focused grid. Off-angulation grid errors occur when the x-ray beam is not aligned with the direction of the grid lines. Upside-down grid errors occur only when a focus grid is not placed right side up.
A patient presents to the imaging department on a stretcher for a shoulder exam. The technologist completes the exam with the patient on the stretcher and does not use a grid. However, the technologist fails to adjust the milliampere-seconds (mAs) typically used for a shoulder exam with a grid. Compared to typical shoulder images, failure to adjust the mAs without the use of a grid will result in an image that demonstrates: Higher contrast Decreased recorded detail Underexposure Overexposure
Overexposure The image created without a grid will be overexposed.
An important benefit of using an automatic exposure control (AEC) system is to minimize which of the following? Patient dose Patient motion Image artifact Heat accumulation in the tube
Patient dose
What position in the following x-ray beam illustration represents the area of highest intensity? Position A Position B Position C Position D
Position A Position A is the area of the highest beam intensity. According to the inverse-square law, the x-ray beam is most intense closest to the source of x-rays and becomes less intense as the distance from the source increases.
What is the primary function of the back-up timer? Prevent over-exposure to the receptor Prevent over-exposure to the patient Ensure adequate receptor exposure Ensure adequate image contrast
Prevent over-exposure to the patient The primary function of the back-up timer with an AEC system is to prevent over-exposure to the patient.
Which of the following projections may be improved by using a low-milliampere (mA), long-exposure time technique? Upright abdomen Anteroposterior (AP) axial clavicle Lateral chest Right anterior oblique (RAO) sternum
Right anterior oblique (RAO) sternum The right anterior oblique (RAO) sternum projection may be improved by using low-milliampere (mA), long-exposure time technique, known as "breathing technique".
In order to ensure optimal receptor exposure, the portion of the patient's anatomy that should be positioned over the active automatic exposure control (AEC) chamber is the: Structure of primary concern Structure of least concern Highest density structure Lowest density structure
Structure of primary concern The structure of primary concern should always be placed over the active automatic exposure control (AEC) cell(s).
Which of the following radiographic exam scenarios would utilize a moving grid? Portable chest radiograph Supine abdomen radiograph in the table bucky Tabletop hand radiograph Tabletop food radiograph
Supine abdomen radiograph in the table bucky Moving grids can only be used in conjunction with the x-ray table and wall bucky system. Moving grids can't be used in portable imaging, stationary grids are used in portable imaging. Tabletop imaging of a hand would not require a grid since it is a smaller extremity. Extremities such as a hand or foot are smaller in thickness, less than 10 cm.
Which of the following exposure factors is controlled by the automatic exposure control (AEC) system? Kilovoltage peak (kVp) Milliamperage (mA) Source-to-image distance (SID) Time
Time An automatic exposure control (AEC) system only controls the exposure time, and therefore the total produced milliamperage (mA) over a set amount of time, seconds (s), or mAs.
The total milliampere-seconds (mAs) is calculated as the product of which exposure factors? Tube potential and tube current Tube potential and exposure time Tube current and exposure time Tube current and filament current
Tube current and exposure time The total milliampere-seconds (mAs) is the product of the tube current or milliamperage (mA) and the exposure time in second (s). The mA multiplied by the exposure time (in seconds) equals the mAs
What is the main effect of grid cut-off? Overexposure of the image receptor Decreased image contrast Underexposure of the image receptor Reduced image spatial resolution
Underexposure of the image receptor Grid cut-off results in underexposure of the image receptor. Grid cut-off is the absorption of the useful x-ray beams, meaning that less radiation will reach the image receptor.
What type of grid error occurs only when a focus grid is not placed right side up? Off-center Off-level Off-angulation Upside-down
Upside-down
Which of the following is true about lead strips within the grid? Lead strips are oriented: Vertically and absorb none of the useful beam Vertically and absorb some of the useful beam Horizontally and absorb none of the useful beam Horizontally and absorb some of the useful beam
Vertically and absorb some of the useful beam
