"Rad Review - 4.1 Image Acquisition and Technical Evaluation (282)"

The exposure factors of 400 mA, 70 ms, and 78 kV were used to produce a particular receptor exposure. A similar radiograph can be produced using 500 mA, 90 kV, and

(28ms)

What pixel size has a 2,048 × 2,048 matrix with a 60-cm FOV? A 0.3 mm B 0.5 mm C 0.15 mm D 0.03 mm

(A) 0.3 mm since the answer is expressed in millimeters, first change 60 cm to 600 mm. Then 600 divided by 2,048 equals 0.29 mm

If the required technique is 10 mAs, 70 kVp, and the mA station is 500 mA, which of the following exposure times would be needed? A 20 ms B 33 ms C 50 ms D 100 ms

(A) 20 ms

Which of the following groups of exposure factors will produce the shortest scale of contrast? A 200 mA, 0.25 s, 70 kVp, 12:1 grid B 500 mA, 0.10 s, 90 kVp, 8:1 grid C 400 mA, 0.125 s, 80 kVp, 12:1 grid D 300 mA, 0.16 s, 70 kVp, 8:1 grid

(A) 200 mA, 0.25 s, 70 kVp, 12:1 grid

Which of the following fluoroscopic modes delivers the smallest patient dose? A 30 cm field B 25 cm field C 12 cm field D 9 cm field

(A) 30 cm field Larger input phosphor field sizes (A) produce little or no magnification of the anatomical areas being evaluated, and with decreased patient dose.

Which of the following groups of exposure factors would be most appropriate for a sthenic adult IVU? A 300 mA, 0.02 s, 72 kVp B 300 mA, 0.01 s, 82 kVp C 150 mA, 0.01 s, 94 kVp D 100 mA, 0.03 s, 82 kVp

(A) 300 mA, 0.02 s, 72 kVp Low kilovoltage (about 70 kVp) is usually used to enhance the photoelectric effect and, in turn, to better visualize the renal collecting system. High kilovoltage will produce excessive scattered radiation and obviate the effect of the contrast agent.

Of the following groups of analog exposure factors, which is likely to produce the shortest scale of image contrast? A 500 mA, 0.040 second, 70 kV B 100 mA, 0.100 second, 80 kV C 200 mA, 0.025 second, 92 kV D 700 mA, 0.014 second, 80 kV

(A) 500 mA, 0.040 second, 70 kV The most important factor regulating radiographic contrast in analog imaging is kilovoltage. The lower the kilovoltage, the shorter is the scale of contrast. All the milliampere-seconds values in this problem have been adjusted for kilovoltage changes to maintain receptor exposure, but just a glance at each of the kilovoltages is often a good indicator of which will produce the longest scale or the shortest scale contrast. In this case, the lowest kV will produce the shortest scale (highest) contrast

Which of the following absorbers has the highest attenuation coefficient? A Bone B Muscle C Fat D Air

(A) Bone

Which of the following devices is used to overcome severe variation in patient anatomy or tissue density, providing more uniform radiographic density? A Compensating filter B Grid C Collimator D Protective filter

(A) Compensating filter

If a lateral projection of the chest is being performed on an asthenic patient and the outer photocells are selected, what is likely to be the outcome? A Decreased receptor exposure B Increased receptor exposure C Scattered radiation fog D Motion blur

(A) Decreased receptor exposure If a lateral projection of the chest is being performed on an asthenic patient and the outer photocells are selected incorrectly, the outcome is likely to be an underexposed image.

Which of the following techniques is used to evaluate the dynamics of a part? A Fluoroscopy B Stereoscopy C Tomography D Phototiming

(A) Fluroscopy The dynamics, or motion, of a part must be studied during a "real-time" examination such as fluoroscopy affords. Stereoscopy is a technique used to produce a radiographic third dimension. Tomography produces sectional images of body parts by blurring superimposed structures above and below the section, or level, of interest. A phototimer is one type of AEC device.

Which of the following terms/units is used to express the resolution of a diagnostic image? A Line pairs per millimeter (lp/mm) B Speed C Latitude D Kiloelectronvolts (keV)

(A) Line pairs per millimeter (lp/mm)

Which of the following factors are considered geometric factors that affect radiographic image quality? (select the three that apply) A Magnification B Kilovoltage C Contrast resolution D Distortion E Focal-spot blur F Exposure time

(A) Magnification (D) Distortion (E) Focal-spot blur

A technologist prepares to perform an exam on an x-ray machine they have never used before. Which of the following three patient factors should be considered in the selection of appropriate kVp and mAs for an optimal image of the projections involved? A Patient habitus B SID C Estimated part thickness D Part composition E Voltage waveform of the equipment F Measured part thickness G Beam filtration

(A) Patient habitus (D) Part composition (F) Measured part thickness

The movement of the IP through the transport system of a CR reader is referred to as the: A Slow-scan direction B Charge-coupled direction C Nyquist direction D Fast-scan direction

(A) Slow-scan direction

SID affects spatial resolution in which of the following way A Spatial resolution is directly related to SID. B Spatial resolution is inversely related to SID. C As SID increases, spatial resolution decreases. D SID is not a spatial resolution factor.

(A) Spatial resolution is directly related to SID.

When performing an axial projection, which of the following is NOT true? A The amount of elongation distortion is affected by focal spot size. B The amount of elongation distortion is affected by the alignment of the long axis of the object to the direction of the angle. C The amount of elongation distortion is proportional to the size of the angle. D The amount of elongation distortion is proportional to the object's OID.

(A) The amount of elongation distortion is affected by focal spot size.

How would the introduction of a 6-in. OID affect image contrast? A Contrast would be increased. B Contrast would be decreased. C Contrast would not change. D The scale of contrast would not change.

(A) contrast would be increased

If a radiograph, made using AEC, is overexposed because an exposure shorter than the minimum response time was required, the radiographer generally should A decrease the milliamperage B increase the milliamperage C increase the kilovoltage D decrease the kilovoltage

(A) decrease the milliamperage

Which of the following is most likely to produce a radiograph with a long scale of contrast? A Increased photon energy B Increased OID C Increased mAs D Increased SID

(A) increased photon energy

X-ray energy is directly controlled by which of the following factors? A kVp B mAs C SID D OID

(A) kVP Increased kilovoltage in the x-ray circuit produces higher kinetic energy filament (projectile) electrons bombarding the anode of the x-ray tube. The increased kinetic energy results in the production of bremsstrahlung x-rays that are of higher energy (shorter wavelength) and can therefore penetrate the inherent and added filtration of the tube and collimator assembly, penetrate the patient, and expose the image receptor.

All the following are related to spatial resolution except A milliamperage B focal-spot size C source-to-object distance D OID

(A) milliamperage The milliamperage is unrelated to spatial resolution; it affects the quantity of x-ray photons produced and thus receptor exposure and patient dose

The CR should be directed to the center of the part of greatest interest to avoid A rotation distortion B magnification C foreshortening D elongation

(A) rotation

An exposure was made at 40-in. SID using 5 mAs and 105 kVp with an 8:1 grid. In an effort to improve image contrast, the image is repeated using a 12:1 grid and 90 kVp. Which of the following exposure times will be most appropriate, using 400 mA, to maintain the original receptor exposure? A 0.01 s B 0.03 s C 0.1 s D 0.3 s

(B) 0.03 s

Of the following groups of technical factors, which will produce the greatest receptor exposure? A 10 mAs, 74 kV, 44-in. SID B 10 mAs, 74 kV, 36-in. SID C 5 mAs, 85 kV, 48-in. SID D 5 mAs, 85 kV, 40-in. SID

(B) 10 mAs, 74 kV, 36-in. SID

Suppose a radiographer would normally use 5 mAs and 65 kVp on a neonate mobile AP abdomen radiograph using a non-grid DR detector array. However, upon arriving to the NICU, it is discovered that the neonate's abdomen is significantly distended due to ascites. The radiographer decides to use an 8:1 slip-on grid to reduce the amount of scatter radiation reaching the IR. Based on the condition of the patient and the use of an 8:1 grid, which of the following would be the best selection of technical factors the radiographer should use to maintain the desired exposure to the IR? A 20 mAs, 65 kVp B 10 mAs, 75 kVp C 10 mAs, 65 kVp D 12.5 mAs, 65 kVp

(B) 10 mAs, 75 kVp A non-grid exposure is assigned a factor of 1, since no grid is used. An 8:1 grid is assigned a factor of 4. Therefore, 4/1 × 5 mAs = 20 mAs and the original kVp would normally remain the same. However, ascites is an additive pathology, which would require an increase in kVp to properly penetrate the abdomen. By applying the 15% rule, the radiographer can half the mAs and add 10 kVp to ensure proper penetration and the desired IR exposure (B). While the grid factor calculation would normally require technical factors of 20 mAs, 65 kVp, this technique would not consider the additive pathological condition of the patient and the need for a more penetrating x-ray beam (A).

Which of the following groups of analog exposure factors is most likely to produce the longest scale of contrast? A 200 mA, 0.25 second, 70 kVp, 12:1 grid B 500 mA, 0.10 second, 90 kVp, 8:1 grid C 400 mA, 0.125 second, 80 kVp, 12:1 grid D 300 mA, 0.16 second, 70 kVp, 8:1 grid

(B) 500 mA, 0.10 second, 90 kVp, 8:1 grid Because an increased kilovoltage and low-ratio grid combination would allow the greatest amount of scattered radiation to reach the IR, thereby producing more gray tones, B is the best answer. Group D also uses a low-ratio grid, but the kilovoltage is too low to produce as many gray tones as B.

Which of the following is most likely to produce a high-quality image? A Small image matrix B High signal-to-noise ratio (SNR) C Large pixel size D Low resolution

(B) High signal-to-noise (SNR)

From the following list, select the effective methods of reducing scatter radiation production in the patient (select the two that apply). A Using an air-gap technique B Increasing collimation C Using a high ratio grid D Using a direct conversion digital system E Placing a lead apron over the anatomy of interest F Using anatomical part compression

(B) Increasing collimation (F) Using anatomical part compression

For which of the following examinations might the use of a grid not be necessary in an adult patient? A Hip B Knee C Abdomen D Lumbar spine

(B) Knee

The anode heel effect results in variation of the intensity of the beam across the field of view. Select four items from the list that will reduce the appearance of this variation on the displayed image. A Smaller anode target angle B Larger anode target angle C Longer SID D Automatic rescaling E Flat fielding F Aligning a tapering body part so that the thicker portion is on the anode side of the beam G Aligning a tapering body part so that the thicker portion is on the cathode side of the beam

(B) Larger anode target angle (C) Longer SID (E) Flat fielding (G) Aligning a tapering body part so that the thicker portion is on the cathode side of the beam A larger anode target angle, longer SID, flat fielding, and aligning a tapering body part so that the thicker portion is on the cathode side of the beam will all reduce the appearance of the variation of beam intensity caused by the heel effect

A focal-spot size of 0.3 mm or smaller is essential for which of the following procedures? A Bone radiography B Magnification radiography C Tomography D Fluoroscopy

(B) Magnification radiography

Which of the following terms is used to express spatial resolution? A Kiloelectronvolts (keV) B Modulation transfer function (MTF) C Relative speed D Latitude

(B) Modulation transfer function (MTF) The degree of resolution transferred to the image receptor is a function of the resolving power of each of the system components and can be expressed in line pairs per millimeter (lp/mm), line-spread function (LSP), or modulation transfer function (MTF)

Which of the following pathologic conditions would require a decrease in exposure factors? A Empyema B Osteoporosis C Pleural effusion D Hemothorax

(B) Osteoporosis

Which of the following pathologies would justify a decrease in technique? A Ascites B Pneumothorax C Hydrocephalus D Atelectasis

(B) Pneumothorax

Receptor exposure decreases with an increase in (select the three that apply): A kV B SID C focal spot size D mAs E part thickness F grid ratio G field size

(B) SID (E) part thickness (F) Grid ratio

OID is related to spatial resolution in which of the following ways? A Spatial resolution is directly related to OID. B Spatial resolution is inversely related to OID. C As OID increases, so does spatial resolution. D OID is unrelated to spatial resolution.

(B) Spatial resolution is inversely related to OID.

Which of the following best describes the distance from the center of one pixel to the center of the adjacent pixel? A Pixel density B Pixel size C Pixel pitch D Pixel wide

(C) Pixel pitch

Which of the following pathologic conditions would require an increase in exposure factors? 1. Empyema 2. Osteoporosis 3. Pleural effusion

1 & 3 only

With milliamperage adjusted to produce equal exposures, all the following statements are true except A a single-phase examination done at 10 mAs can be duplicated with three-phase, 12-pulse at 5 mAs. B There is greater patient dose with three-phase equipment than with single-phase equipment. C Three-phase equipment can produce comparable radiographs with less heat unit (HU) buildup. D Three-phase equipment produces lower-contrast radiographs than single-phase equipment.

(B) There is greater patient dose with three-phase equipment than with single-phase equipment.

With milliamperage adjusted to produce equal exposures, all the following statements are true except A a single-phase examination done at 10 mAs can be duplicated with three-phase, 12-pulse at 5 mAs. B There is greater patient dose with three-phase equipment than with single-phase equipment. C Three-phase equipment can produce comparable radiographs with less heat unit (HU) buildup. D Three-phase equipment produces lower-contrast radiographs than single-phase equipment.

(B) There is greater patient dose with three-phase equipment than with single-phase equipment. If the same kilovoltage is used with single-phase and three-phase equipment, the three-phase unit will require about 50% fewer milliampere-seconds to produce similar radiographs

Which of the following best allows optimal visualization of both soft tissue and bony structures in a given image? A Narrow dynamic range B Wide dynamic range C Brightness gain D Structures recorded

(B) Wide dynamic range Since digital imaging provides a wider dynamic range than film-screen imaging and can adjust for exposure errors, a greater margin of error exists. Dynamic range is the range of exposure intensities that an image receptor can respond to and acquire image data. A narrow dynamic range is a much shorter range that should not be used in digital radiology (A)

What type of x-ray imaging uses an area beam and a photostimulable phosphor as the IR? A Film radiography B Computed radiography C Digital radiography D Cineradiography

(B) computed radiography

When involuntary motion must be considered, the exposure time may be cut in half if the kilovoltage is A doubled B increased by 15% C increased by 25% D increased by 35%

(B) increased by 15%

Compensating filters are radiographically useful in that A they prevent unnecessary characteristic radiation from being produced. B they provide more uniform exposure to anatomical parts having unequal thicknesses. C they eliminate the need for internal and external filtration in the x-ray tube housing and collimator. D they eliminate scatter production in the patient, thereby reducing image noise.

(B) they provide more uniform exposure to anatomical parts having unequal thicknesses.

Focal-spot blur is greatest A toward the anode end of the x-ray beam B toward the cathode end of the x-ray beam C directly along the course of the CR D as the SID is increased

(B) toward the cathode end of the x-ray beam

Which of the following will produce the greatest distortion? A AP projection of the skull B PA projection of the skull C 37° AP axial of the skull D 20° PA axial of the skull(

(C) 37° AP axial of the skull The 37° (caudad) AP axial projection of the skull, for example, projects the facial bones inferiorly so that the occipital bone can be visualized to better advantage.

Which of the following groups of exposure factors would be most appropriate to control involuntary motion? A 400 mA, 0.03 second B 200 mA, 0.06 second C 600 mA, 0.02 second D 100 mA, 0.12 second

(C) 600 mA, 0.02 second

Which of the following terms is used to describe unsharp edges of tiny radiographic details? A Diffusion B Mottle C Blur D Umbra

(C) Blur

Which of the following measures the percentage of x-rays absorbed by the detector? A FPD B PPI C DQE D DXR

(C) DQE

Which of the following combinations is most likely to be associated with quantum mottle? A Decreased milliampere-seconds, decreased SID B Increased milliampere-seconds, decreased kilovoltage C Decreased milliampere-seconds, increased kilovoltage D Increased milliampere-seconds, increased SID

(C) Decreased milliampere-seconds, increased kilovoltage Fast imaging systems using low-milliampere-seconds and high-kilovoltage factors are most likely to be the cause of quantum mottle

Breast tissue is compressed in mammographic procedures to improve contrast resolution by reducing the production of Compton scatter. Which of the following also reduces Compton scatter production? A Using a grid B Increasing kVp C Decreasing tissue density (mass/volume) D Increasing average atomic number of tissue irradiated

(C) Decreasing tissue density (mass/volume)

Which of the following technical changes would best serve to remedy the effect of very dissimilar tissue densities? A Use of short exposure time B Use of a high-ratio grid C High-kilovoltage exposure factors D High milliampere-seconds exposure factors

(C) High-kilovoltage exposure factors

All the following statements regarding CR IPs are true except A IPs have a thin lead foil backing. B IPs can be placed in the Bucky tray. C IPs must exclude all white light. D IPs function to protect the PSP.

(C) IPs must exclude all white light IPs do not contain a lightsensitive material and, therefore, do not need to be light-tight. The photostimulable PSP is not affected by light.

Which of the following is most likely to result from the introduction of a grid with appropriate technical factor change? A Increased patient dose and increased scattered radiation fog B Decreased patient dose and decreased scattered radiation fog C Increased patient dose and decreased scattered radiation fog D Decreased patient dose and increased scattered radiation fog

(C) Increased patient dose and decreased scattered radiation fog

In which of the following examinations should 70 kV not be exceeded? A Upper GI (UGI) B Barium enema (BE) C Intravenous urogram (IVU) D Chest

(C) Intravenous urogram (IVU) The iodine-based contrast material used in IVU gives optimal opacification at 60 to 70 kV.

In which of the following examinations would a IR front with very low absorption properties be especially desirable? A Extremity radiography B Abdominal radiography C Mammography D Angiography

(C) Mammography

Which of the following can contribute to the image contrast? 1. Tissue density 2. Pathology 3. Muscle development

1, 2, & 3

A particular milliampere-seconds value, regardless of the combination of milliamperes and time, will reproduce the same receptor exposure. This is a statement of the A line-focus principle B inverse-square law C reciprocity law D law of conservation of energy

(C) Reciprocity law

Which of the following has the greatest effect on receptor exposure? A Aluminum filtration B Kilovoltage C SID D Scattered radiation

(C) SID

Recently, dual-sided reading technology has become available in more modern CR readers, in which two sets of photodetectors are used to capture light released from the front and back sides of the phosphor storage plate, or PSP (photostimulable phosphor). This technology enables improved: A Slow-scan direction speed B Modulation transfer function C Signal-to-noise ratio D Fast-scan direction speed

(C) Signal-to-noise ratio

Which of the following combinations will result in the most scattered radiation reaching the image receptor? A Using more mAs and compressing the part B Using more mAs and a higher ratio grid C Using less mAs and more kVp D Using less mAs and compressing the part

(C) Using less mAs and more kVp

Causes of overexposure using AEC include (select the three that apply) A insufficient backup time selected B selected photocell is under tissue less dense than area of interest C plus density control incorrectly selected D required exposure time more than minimum response time E selection of incorrect Bucky F selected photocell is under a radiopaque appliance/prosthesis

(C) plus density control incorrectly selected (E) selection of incorrect Bucky (F) selected photocell is under a radiopaque appliance/prosthesis

In preparing to use Automatic Exposure Control in combination with a PSP image receptor for an AP lumbar spine projection on a patient with a hypersthenic habitus, an optimal image can best be produced with which of the following changes to technical factors? A kVp is decreased to compensate for decreased patient size. B The outer cells of the AEC are active. C The AEC calibration is adjusted via the "+" density controls on the control panel, creating a longer exposure. D kVp is increased to compensate for increased part thickness.

(D) kVp is increased to compensate for increased part thickness.

Which of the following matrix sizes is most likely to produce the best image resolution? A 128 × 128 B 512 × 512 C 1,024 × 1,024 D 2,048 × 2,048

(D) 2,048 x 2,048

An x-ray image of the ankle was made at 40-SID, 200 mA, 50 ms, 70 kV, 0.6 mm focal spot, and minimal OID. Which of the following modifications would result in the greatest increase in magnification? A 1.2 mm focal spot B 36-in. SID C 44-in. SID D 4-in. OID

(D) 4-in. OID Although a decrease in SID will increase magnification, it does not have as significant an effect as an increase in OID. In general, it requires an increase of 7 in. SID to compensate for every inch of OID.

An exposure was made using 300 mA and 50 ms. If the exposure time is changed to 22 ms, which of the following milliamperage selections would most closely approximate the original receptor exposure? A 300 mA B 400 mA C 600 mA D 700 mA

(D) 700 mA

How is SID related to exposure rate and receptor exposure? A As SID increases, exposure rate increases and radiographic receptor exposure increases. B As SID increases, exposure rate increases and radiographic receptor exposure decreases. C As SID increases, exposure rate decreases and radiographic receptor exposure increases. D As SID increases, exposure rate decreases and radiographic receptor exposure decreases.

(D) As SID increases, exposure rate decreases and radiographic receptor exposure decreases

Which of the following conditions will require an increase in x-ray photon energy/penetration? A Fibrosarcoma B Osteomalacia C Paralytic ileus D Ascites

(D) Ascites Some conditions, such as osteomalacia, fibrosarcoma, and paralytic ileus (obstruction), result in a decrease in body tissue density. In conditions such as ascites, where body tissue density increases as a result of the accumulation of fluid, x-rays will not readily penetrate the body tissues; that is, there is less x-ray penetrability.

Which of the following pathologies would justify an increase in technique? A Multiple myeloma B Pneumothorax C Emphysema D Atelectasis

(D) Atelectasis Multiple myeloma (A), Pneumothorax (B), and Emphysema (C) are all destructive conditions that require a decrease in technique. Atelectasis makes the area of interest more difficult to penetrate

Which of the following is not considered a radiographic geometric factor? A Magnification B Focal spot size C OID D Beam filtration

(D) Beam filtration

Which of the following represents the image acquisition contrast resolution? A Pixel B Pixel size C Pixel pitch D Bit depth

(D) Bit depth

Which of the following is NOT true of spatial resolution, FOV, and matrix size as they relate to each other? A Increasing matrix size with no change to FOV will improve spatial resolution. B Changing FOV has no effect on matrix size. C Decreasing FOV with no other changes will improve spatial resolution. D Changing matrix size has no effect on spatial resolution.

(D) Changing matrix size has no effect on spatial resolution. Small pixels mean better spatial resolution. Therefore, it is not true that changing matrix size has no effect on spatial resolution

A patient is being positioned for a particular radiographic examination. The x-ray tube, image recorder, and grid are properly aligned, but the body part is angled. Which of the following will result? A Grid cutoff at the periphery of the image B Grid cutoff along the center of the image C Increased receptor exposure at the periphery D Image distortion

(D) Image distortion

Which of the following best describes the number of pixels per unit area? A Pixel size B Pixel pitch C Pixel wide D Pixel density

(D) Pixel density An image consisting of a greater number of pixels per unit area or pixel density provides improved spatial resolution (D). Pixels are measured per inch; a higher pixel density per inch allows for more sharpness and clarity for the image.

Underexposure of a radiograph can be caused by all the following except insufficient A milliamperage (mA) B exposure time C Kilovoltage D SID

(D) SID

Which of the following can minimize magnification seen in a radiographic image? 1. Long SID 2. Short OID 3. Compression

1, 2, & 3

A radiograph made with a parallel grid demonstrates decreased receptor exposure on its lateral edges. This is most likely due to A static electrical discharge B the grid being off-centered C improper tube angle D decreased SID

(D) decreased SID The lead strips in a parallel grid are parallel to one another and, therefore, are not parallel to the x-ray beam. The more divergent the x-ray beam, the more likely there is to be cutoff/decreased receptor exposure at the lateral edges of the image. This problem becomes more pronounced at short SIDs. If there were a centering or tube angle problem, there would be more likely to be a noticeable receptor exposure loss on one side or the other.

Each manufacturer's software system determines the gray scale available for when the x-ray image is displayed. Which of the following terms best describes this definition? A Modulation transfer function B Detective quantum efficiency C Exposure latitude D Dynamic range

(D) dynamic range Dynamic range determines the gray scale available for the image

All the following affect the exposure rate of the primary beam except A milliamperage B kilovoltage C distance D field size

(D) field size The size of the x-ray field determines the volume of tissue irradiated, and hence the amount of scattered radiation generated, but is unrelated to the exposure rate

All the following have an impact on radiographic contrast except A photon energy B grid ratio C OID D focal-spot size

(D) focal-spot size

Which combination of exposure factors most likely will contribute to producing the shortest-scale contrast? A mAs: 10; kV: 70; Grid ratio: 5:1; Field size: 14 × 17 in. B mAs: 12; kV: 90; Grid ratio: 8:1; Field size: 14 × 17 in. C mAs: 15; kV: 90; Grid ratio: 12:1; Field size: 11 × 14 in. D mAs: 20; kV: 80; Grid ratio: 10:1; Field size: 8 × 10 in.

(D) mAs: 20; kV: 80; Grid ratio: 10:1; Field size: 8 × 10 in. Review the groups of factors. First, because the milliampere-seconds value has no effect on the scale of contrast produced, eliminate milliampere-seconds from consideration by drawing a line through the column. Then check the two entries in each column that are likely to produce shorter-scale contrast. For example, in the kilovoltage column, because lower kilovoltage can produce shorter-scale contrast, place checkmarks next to the 70 and 80 kV. Because higher-ratio grids permit less scattered radiation to reach the IR, the 10:1 and 12:1 grids can produce a shorter scale of contrast than the lower-ratio grids; check them. As the volume of irradiated tissue decreases, so does the amount of scattered radiation produced, and consequently, the shorter is the scale of radiographic contrast; therefore, check the 11 × 14 and 8 × 10 in. field sizes.

Changes in milliampere-seconds can affect all the following except A quantity of x-ray photons produced B exposure rate C receptor exposure D spatial resolution

(D) spatial resolution The milliampere-seconds value has no effect on spatial resolution.

A radiograph made using 300 mA, 0.1 second, and 75 kVp exhibits motion unsharpness, but otherwise satisfactory technical quality. The radiograph will be repeated using a shorter exposure time. Using 86 kV and 500 mA, what should be the new exposure time?

0.03 second

If 100 mA were selected for a radiographic exposure, what exposure time would be required to produce 5 mAs?

0.05 sec

A satisfactory radiograph of the abdomen was made at a 42-inch SID using 300 mA, 0.06-second exposure, and 80 kVp. If the distance is changed to 38 inches, what new exposure time would be required?

0.05 second exposure maintenance formula: old mAs / new mAs = old D^2 / new D^2

The exposure factors of 300 mA, 0.07 second, and 95 kVp were used to deliver a particular analog receptor exposure and contrast. A similar analog x-ray image can be produced using 500 mA, 80 kVp, and

0.08 sec

Which of the following focal-spot sizes should be employed for magnification radiography? A 0.2 mm B 0.6 mm C 1.2 mm D 2.0 mm

0.2 mm A magnified image that is diagnostic can be obtained only by using a fractional focal spot of 0.3 mm or smaller.

What pixel size has a 1024 × 1024 matrix with a 35-cm FOV?

0.35mm the FOV is 35 cm; since the answer is expressed in millimeters, first change 35 cm to 350 mm. Then 350 divided by 1024 equals 0.35 mm.

What pixel size has a 2048 × 2048 matrix with an 80-cm FOV?

0.4 mm first change 80 cm to 800 mm. Then 800 divided by 2048 equals 0.4 mm. 80 cm = 800 mm

A grid is usually employed 1. when radiographing a large or dense body part. 2. when using high kilovoltage. 3. when less patient dose is required.

1 & 2 only

A grid usually is employed in which of the following circumstances? 1. When radiographing a large or dense body part 2. When using high kilovoltage 3. When a lower patient dose is required

1 & 2 only

An increase in kilovoltage will have which of the following effects? 1. More scattered radiation will be produced. 2. The exposure rate will increase. 3. Radiographic contrast will increase.

1 & 2 only

Cassette-front material can be made of which of the following? 1. Carbon fiber 2. Magnesium 3. Lead

1 & 2 only

Compared to a low ratio grid, a high ratio grid will 1. absorb more of the useful beam. 2. absorb more scattered radiation. 3. allow more centering latitude.

1 & 2 only

Disadvantages of using lower kilovoltage technical factors, with mAs compensated to maintain receptor exposure, include 1. insufficient penetration 2. increased patient dose 3. diminished resolution

1 & 2 only

For which of the following examinations can the anode heel effect be an important consideration? 1. Lateral thoracic spine 2. AP femur 3. Right anterior oblique (RAO) sternum

1 & 2 only

In comparison with 60 kV, 80 kV will 1. permit greater exposure latitude 2. produce more scattered radiation 3. produce shorter-scale contrast

1 & 2 only

Low-kilovoltage exposure factors usually are indicated for radiographic examinations using 1. water-soluble, iodinated media 2. a negative contrast agent 3. barium sulfate

1 & 2 only

Phosphors classified as rare earth include 1. lanthanum oxybromide. 2. gadolinium oxysulfide. 3. cesium iodide.

1 & 2 only

The effect that differential absorption has on radiographic contrast of a high-subject-contrast part can be minimized by 1. using a compensating filter. 2. using high-kilovoltage exposure factors. 3. increased collimation.

1 & 2 only

Which of the following can have an effect on radiographic contrast? 1. Beam restriction 2. Grids 3. Focal spot size

1 & 2 only

Which of the following is affected by the size of the x-ray field? 1. Amount of scattered radiation produced 2. Motion unsharpness 3. Patient dose

1 & 3 only

Which of the following methods can be used effectively to decrease differential absorption, providing a longer scale of contrast in the diagnostic range? 1. Using high peak kilovoltage and low milliampere-seconds factors 2. Using compensating filtration 3. Using factors that increase the photoelectric effect

1 & 2 only

Which of the following units is (are) used to express resolution? 1. Line-spread function 2. Line pairs per millimeter 3. Line-focus principle

1 & 2 only

Which one of the following is (are) used to control the production of scattered radiation? 1. Collimators 2. Optimal kV 3. Use of grids

1 & 2 only

With all other factors constant, as digital image matrix size increases, 1. pixel size decreases. 2. resolution increases. 3. pixel size increases.

1 & 2 only

Which of the following will improve the spatial resolution of image-intensified images? 1. A very thin coating of cesium iodide on the input phosphor 2. A smaller-diameter input screen/phosphor 3. Increased total brightness gain

1 & 2 only As the input screen/phosphor layer is made thinner, spatial resolution increases. Also, the smaller the input phosphor diameter, the greater is the spatial resolution. A brighter image is easier to see but does not affect resolution.

An increase in the kilovoltage applied to the x-ray tube increases the 1. percentage of high-energy photons produced. 2. beam intensity. 3. patient absorption.

1 & 2 only As the kilovoltage is increased, a greater number of electrons are driven across to the anode with greater force. Therefore, as energy conversion takes place at the anode, more high-energy photons are produced. However, because they are higher-energy photons, there will be less patient absorption.

An analog x-ray exposure of a particular part is made and restricted to a 14 × 17 in. field size. The same exposure is repeated, but the x-ray beam is restricted to a 4 × 4 in. field. Compared with the first image, the second image will demonstrate 1.less receptor exposure 2. more contrast 3.more receptor exposure

1 & 2 only Less scattered radiation is generated within a part as the kilovoltage is decreased, as the size of the field is decreased, and as the thickness and density of tissue decrease. As the quantity of scattered radiation decreases from any of these sources, the less is the total receptor exposure

Which of the following is (are) classified as rare earth phosphors? 1. Lanthanum oxybromide 2. Gadolinium oxysulfide 3. Cesium iodide

1 & 2 only Rare earth phosphors have a greater conversion efficiency than do other phosphors. Lanthanum oxybromide is a blue-emitting rare earth phosphor, and gadolinium oxysulfide is a green-emitting rare earth phosphor. Cesium iodide is the phosphor used on the input screen of image intensifiers; it is not a rare earth phosphor.

Disadvantages of moving grids over stationary grids include which of the following? 1. They can prohibit the use of very short exposure times. 2. They increase patient radiation dose. 3. They can cause phantom images when anatomic parts parallel their motion.

1 & 2 only patient dose is increased with moving grids. Since the central ray is not always centered to the grid because it is in motion, lateral decentering occurs (resulting in diminished density), and consequently, an increase in exposure is needed to compensate

Higher kVp settings can provide which of the following benefits? 1. Improved penetration 2. Patient dose reduction 3. Increased spatial resolution

1 & 2 only Increased spatial resolution is determined by such factors as the focal spot size, geometric unsharpness (penumbra), laser beam diameter in the CR reader, and pixel size (B, C, and D).

Greater latitude is available to the radiographer in which of the following circumstances? 1. Using high-kV technical factors 2. Using a low-ratio grid 3. Using low-kV technical factors

1 & 2 only High-kilovolt technical factors offer much greater margin for error; in the high-kV ranges, an error of a few kV makes little/no difference in the resulting image. Lower-ratio grids offer more tube-centering latitude than high-ratio grids.

Which two (2) of the following statements are true regarding image distortion? 1. The least amount of image distortion occurs along the path of the CR 2. CR alignment has little/no impact on image distortion 3. X-ray tube angle impacts shape distortion 4. The least amount of image distortion occurs at the periphery of the x-ray beam 5. SID impacts shape distortion as well as size distortion

1 & 3

An increase in the milliamperage (mA) setting increases 1. X-ray beam quantity 2. X-ray beam quality 3. Image receptor exposure

1 & 3 only

Filtration of the radiographic x-ray beam functions to do which of the following? 1. Reduce patient skin dose 2. Decrease average beam energy 3. Provide uniform exposure of an anatomical part with different thicknesses

1 & 3 only

If the x-ray image exhibits insufficient receptor exposure, this might be attributed to 1. Insufficient kilovoltage 2. Insufficient SID 3. grid cutoff

1 & 3 only

If x-ray beam filtration were not present, which of the following would be considered a negative effect? 1. Increased patient dose 2. Overexposure of the IR 3. Average energy of the x-ray beam would decrease

1 & 3 only

Which of the following imaging procedures do not require the use of ionizing radiation to produce an image? 1. Ultrasound 2. Computed axial tomography 3. MRI

1 & 3 only

Which of the following is (are) characteristic(s) of a 16:1 grid? 1. It absorbs more useful radiation than an 8:1 grid. 2. It has more centering latitude than an 8:1 grid. 3. It is used with higher-kilovoltage exposures than an 8:1 grid.

1 & 3 only

Which of the following will contribute to the production of longer-scale radiographic contrast? 1. An increase in kV 2. An increase in grid ratio 3. An increase in photon energy

1 & 3 only

Which of the following will improve the sharpness of the edges of small anatomical parts? 1. Small focal spot size 2. Increased OID 3. Increased SID

1 & 3 only

Which of the following function(s) to reduce the amount of scattered radiation reaching the IR? 1. Grid devices 2. Restricted focal spot size 3. Beam restrictors

1 & 3 only The use of grids helps clean up scattered radiation before it reaches the IR. The size of the tube focus has an impact on image geometry and spatial resolution, but it has no effect on scattered radiation.

An anatomical part calls for a kilovoltage (kVp) setting necessary to penetrate the part. If a lower than acceptable kVp were selected using a fixed milliampere-seconds (mAs) setting, this would result in which of the following? 1. Increased patient dose 2. Increased exposure to the image receptor 3. Decreased penetration of the anatomical part

1 & 3 only Decreased kilovoltage settings using a fixed mAs setting increases patient dose because of the increased number of photoelectric interactions.

If a radiograph exhibits insufficient receptor exposure, this might be attributed to 1. insufficient kVp. 2. insufficient SID. 3. grid cutoff.

1 & 3 only As kVp is reduced, the number of high-energy photons produced at the target is reduced; therefore, a decrease in receptor exposure occurs. If a grid has been used improperly (off-centered or out of focal range), the lead strips will absorb excessive amounts of the useful beam, resulting in grid cutoff and loss of rreceptor exposure. If the SID is inadequate (too short), an increased receptor exposure will result.

The factors that impact spatial resolution include 1. Focal spot size 2. Type of rectification 3. SID

1 & 3 only The method of rectification has no controlling effect on spatial resolution

Exposure rate increases with an increase in 1. mA. 2. kVp. 3. SID.

1 and 2 only

Which of the following factors impact(s) spatial resolution? 1. Focal spot size 2.Subject motion 3. SOD

1, 2, & 3

Which of the following is (are) associated with subject contrast? 1. Patient thickness 2. Tissue density 3. Kilovoltage

1, 2, & 3

Spatial resolution is directly related to 1. source-image distance (SID). 2. tube current. 3. focal spot size.

1 only

There is direct relationship between spatial resolution and 1. SID. 2. tube current. 3. focal-spot size.

1 only

What are the effects of scattered radiation on a radiographic image? 1. It produces fog. 2. It increases contrast. 3. It increases grid cutoff.

1 only

Which of the following is (are) characteristic(s) of a 5:1 grid? 1. It allows some positioning latitude. 2.It is used with high-kilovoltage exposures. 3.It absorbs a high percentage of scattered radiation.

1 only

Which of the following is (are) directly related to photon energy? 1. Kilovoltage 2. Milliamperes 3. Wavelength

1 only

An increase in kilovoltage with appropriate compensation of milliampere-seconds will result in 1. increased part penetration. 2. higher contrast. 3. increased receptor exposure.

1 only As the milliampere-seconds value is decreased to compensate for the increased kilovoltage, receptor exposure should remain the same

According to the line-focus principle, an anode with a small angle provides 1. improved spatial resolution. 2. improved heat capacity. 3.less heel effect.

1 only The line-focus principle states that as the target/focal track angle gets larger, the effective focal spot is larger. When the effective focal spot is larger, focal spot blur increases, and spatial resolution is decreased. With focal spot/track size (area of electron bombardment) unchanged, heat capacity remains unchanged. The smaller the anode angle, the more apparent the anode heel effect.

The functions of automatic beam limitation devices include 1. reducing the production of scattered radiation 2. increasing the absorption of scattered radiation changing the 3. quality of the x-ray beam

1 only Beam restrictors function to limit the size of the irradiated field.

Which of the following examinations might require the use of 70 kV? 1. AP abdomen 2. Chest radiograph 3. Barium-filled stomach

1 only It is appropriate to perform an AP abdomen radiograph with lower kilovoltage because it has such low subject contrast. Abdominal tissue densities are so similar that it takes high- or short-scale contrast (using low kilovoltage) to emphasize the little difference there is between tissues.

A positive contrast agent 1. absorbs x-ray photons 2. results in a dark area on the radiograph is composed of elements 3. having low atomic number

1 only Radiopaque contrast agents appear white on the finished image because many x-ray photons are absorbed. These are referred to positive contrast agents—composed of dense (i.e., high atomic number) material through which x-rays will not pass easily. Radiolucent contrast agents appear black on the finished image because x-ray photons pass through easily. An example of a radiolucent contrast agent is air.

Image resolution depends on all the following except 1. quantity of filtration. 2. anode angle. 3. OIDs.

1 only The factors that affect the resolution are focal-spot size, source-to-image receptor distance (SID), object-to-image distance (OID), and motion

In radiography of a large abdomen, which of the following is (are) effective way(s) to minimize the amount of scattered radiation reaching the image receptor (IR)? 1. Use of optimal collimation 2. Use of low mAs 3. Use of a low-ratio rather than high-ratio grid

1 only The mAs selection has no impact on scattered radiation production or cleanup. Low-ratio grids allow a greater percentage of scattered radiation to reach the IR

A decrease from 90 to 77 kVp will result in an increase in 1. wavelength 2. gray scale 3. scattered radiation

1 only As kilovoltage is decreased, fewer electrons are driven to the anode at a slower speed and with less energy. This results in production of fewer and lower energy, longer wavelength x-ray photons.

A technique chart should be prepared for each AEC x-ray unit and should contain which of the following information for each type of examination? 1. Photocell(s) used 2. Optimum kilovoltage 3. Backup time

1, 2, & 3

Acceptable method(s) of minimizing motion unsharpness is (are) 1. suspended respiration. 2. short exposure time. 3. patient instruction.

1, 2, & 3

For which of the following procedures must the radiographer carefully consider exposure time? 1. Patients who are unable to cooperate 2. UGI radiography 3. Lateral thoracic spine radiography

1, 2, & 3

Geometric unsharpness is influenced by which of the following? 1. Distance from object to image 2. Distance from source to object 3. Distance from source to image

1, 2, & 3

Geometric unsharpness will be least obvious 1. at long SIDs. 2. with small focal spots. 3. at the anode end of the image.

1, 2, & 3

Shape distortion is influenced by the relationship between the 1. x-ray tube and the part to be imaged. 2. body part to be imaged and the IR. 3. IR and the x-ray tube.

1, 2, & 3

The advantage(s) of high-kilovoltage chest radiography is (are) that 1. exposure latitude is increased 2. it produces long-scale contrast 3. it reduces patient dose

1, 2, & 3

Which of the following are potential undesirable effect(s) of scattered radiation? 1. Image fog 2. Increased patient dose 3. Increased radiographer dose

1, 2, & 3

Which of the following can affect histogram appearance? 1. Centering accuracy 2. Positioning accuracy 3. Processing algorithm accuracy

1, 2, & 3

Which of the following can affect radiographic contrast? 1. LUT 2. Pathology 3. OID

1, 2, & 3

Which of the following is (are) characteristic(s) of a 16:1 grid? 1. It absorbs a high percentage of scattered radiation. 2. It has little positioning latitude. 3. It is used with high-kVp exposures.

1, 2, & 3

Which of the following is likely to contribute to the radiographic contrast present on an analog x-ray image? 1. Atomic number of tissues radiographed 2. Any pathologic processes 3. Degree of muscle development

1, 2, & 3

Which of the following may be used to reduce the effect of scattered radiation on the radiographic image? 1. Grids 2. Collimators 3. Compression bands

1, 2, & 3

Which of the following pathologic conditions require(s) a decrease in exposure factors? 1. Pneumothorax 2. Emphysema 3. Multiple myeloma

1, 2, & 3

Factor(s) that impact receptor exposure include 1. milliamperage. 2. exposure time. 3. kilovoltage.

1, 2, & 3 Factors that regulate the number of x-ray photons produced at the target determine receptor exposure, namely milliamperage and exposure time (mAs). Receptor exposure is directly proportional to mAs; if the mAs is cut in half, the receptor exposure will decrease by one-half. Although kilovoltage is usually considered to regulate radiographic contrast (in analog imaging), it may also be used to impact receptor exposure in variable-kVp techniques, according to the 15% rule.

Geometric unsharpness is influenced by 1. OID 2. SOD 3. SID

1, 2, & 3 As OID increases, so does magnification—therefore, OID is directly related to magnification. As SOD and SID decrease, magnification increases—therefore, SOD and SID are inversely related to magnification.

Which of the following pathologic conditions are considered additive conditions with respect to selection of exposure factors? 1. Osteoma 2. Bronchiectasis 3. Pneumonia

1, 2, & 3 Bronchiectasis is a chronic dilatation of the bronchi with accumulation of fluid. Pneumonia is inflammation of the lung(s) with accumulation of fluid. Additional bony tissues and the pathologic presence of fluid are additive pathologic conditions and require an increase in exposure factors. Destructive conditions such as osteoporosis require a decrease in exposure factors.

In which of the following ways might higher image contrast be obtained in abdominal radiography? 1. By using lower kilovoltage 2. By using a contrast medium 3. By limiting the field size

1, 2, & 3 Higher/shorter scale contrast has few shades of gray between white and black. It is partly a result of lower energy photons (lower kVp). To produce higher contrast in abdominal radiography, lower kVp can be used. To better demonstrate high contrast within a viscus, a contrast medium such as barium, iodine, or air can be used. Restricting the size of the field will also function to increase contrast because less scattered radiation will be generated.

The effect described as differential absorption is 1. responsible for radiographic contrast 2. a result of attenuating characteristics of tissue 3. minimized by the use of a high peak kilovoltage

1, 2, & 3 The radiographic representation of these structures is referred to as radiographic contrast; it may be enhanced with high-contrast technical factors, especially using low kilovoltage levels. At low-kilovoltage levels, the photoelectric effect predominates and differential absorption is emphasized. High kV actors provide more uniform penetration of all tissues and minimizes the effect of differential absorption.

Which of the following factors is/are related to grid efficiency? 1. Grid ratio 2. Number of lead strips per inch 3. Amount of scatter transmitted through the grid

1, 2, & 3 only

Acceptable method(s) of minimizing motion unsharpness is (are) 1. suspended respiration 2. short exposure time 3. patient instruction

1, 2,& 3

A part whose width is 6 inches will be imaged at 44 inches SID. The part to be imaged lies 9 inches from the IR. What will be the magnification factor?

1.25 MF = SID/SOD Substituting known factors the equation becomes: MF = 44/35 MF = 1.257

A satisfactory radiograph was made using a 40-inch SID, 10 mAs, and a 12:1 grid. If the examination will be repeated at a distance of 48 inches and using an 8:1 grid, what should be the new mAs to maintain the original receptor exposure?

11.5

The use of which of the following is (are) essential in magnification radiography? 1. High-ratio grid 2. Fractional focal spot 3. Direct exposure technique

2 only

If 300 mA has been selected for a particular exposure, what exposure time would be required to produce 60 mAs?

1/5 sec

A satisfactory radiograph was made without a grid, using a 72-inch SID and 8 mAs. If the distance is changed to 40 inches and an 8:1 ratio grid is added, what should be the new mAs?

10 mAs

An exposure was made using 300 mA, 40 ms exposure, and 85 kV. Each of the following changes will cut the receptor exposure in half except a change to

10 mAs

Exposure factors of 100 kVp and 6 mAs are used with a 6:1 grid for a particular exposure. What should be the new milliampere-seconds value if a 12:1 grid is substituted?

10 mAs

A lateral radiograph of the cervical spine was made at 40 in. using 300 mA and 0.03 second exposure. If it is desired to increase the distance to 72 in., what should be the new milliampere (mA) setting, all other factors remaining constant?

1000 mA

In a PA projection of the chest being used for cardiac evaluation, the heart measures 15.2 cm between its widest points. If the magnification factor is known to be 1.3, what is the actual diameter of the heart?

11.7 cm

A satisfactory radiograph was made without a grid using a 72-in. SID and 8 mAs. If the distance is changed to 40 in. and an 12:1 ratio grid is added, what should be the new milliampere-seconds value?

12 mAs mAs1/mAs2 = D1^2/D2^2 and grid factor

In a posteroanterior (PA) projection of the chest being used for cardiac evaluation, the heart measures 14.7 cm between its widest points. If the magnification factor is known to be 1.2, what is the actual diameter of the heart?

12.25 cm

While using a digital radiography system, suppose a radiographer uses exposure factors of 10 mAs and 70 kVp with an 8:1 grid for an AP shoulder radiograph with acceptable anatomical part penetration and detector element (DEL) exposure. If the radiographer desires to increase scatter absorption using a 12:1 grid, what new exposure factors should be used to maintain the same DEL exposure?

12.5 mAs, 70 kVp

In order to double the x-ray quantity to the image receptor (IR) using kilovoltage-peak (kVp), the radiographer would need to raise the kVp by ______ percent.

15

Exposure factors of 110 kVp and 12 mAs are used with an 8:1 grid for a particular exposure. What should be the new mAs if a 12:1 grid is substituted?

15 12/x = 4/5 4x = 60 x = 15

Exposure factors of 90 kVp and 4 mAs are used for a particular nongrid exposure. What should be the new mAs if an 8:1 grid is added?

16 mAs

If a particular grid has lead strips 0.40 mm thick, 4.0 mm high, and 0.25 mm apart, what is its grid ratio?

16:1 4 mm / 0.25mm = 16

An exposure was made using 600 mA, 0.04 sec exposure, and 85 kVp. Each of the following changes will serve to reduce the receptor exposure by one-half except change to

18 mAs To cut the receptor exposure in half, the milliampere-seconds must be reduced to 12 mAs (not 18 mAs).

The average frequency of photons contained within the x-ray beam can be increased by 1. Increasing mAs 2. Increasing kVp 3. Increasing filtration 4. Decreasing kVp

2 & 3

A decrease from 80 mAs to 40 mAs will result in a decrease in which of the following? 1. Wavelength 2. Exposure rate 3. Beam intensity

2 & 3 only

Characteristics of high-ratio focused grids, compared with lower-ratio grids, include which of the following? 1. They allow more positioning latitude. 2. They are more efficient in collecting SR. 3 .They absorb more of the useful beam.2 &

2 & 3 only

For an AP projection of the knee, if the patient is unable to fully extend the lower extremity, what could the radiographer do to minimize magnification distortion? 1. Use a compression band to extend the lower extremity 2. Increase the SID 3. Perform a PA projection

2 & 3 only

Spatial resolution can be improved by decreasing 1. the SID 2. the OID 3. patient/part motion

2 & 3 only

Which of the following refers to anatomical shape distortion? 1. Magnification 2. Elongation 3. Foreshortening

2 & 3 only

The term differential absorption is closely related to 1. beam intensity 2. subject contrast 3. pathology

2 & 3 only The radiographic subject, the patient, is composed of many different tissue types of varying densities (i.e., subject contrast), resulting in varying degrees of photon attenuation and absorption.

Spatial resolution is inversely related to 1. SID 2. OID 3. grid ratio

2 only OID is inversely related to spatial resolution because as OID increases, spatial resolution decreases. Grid ratio is not associated with spatial resolution

A lateral (analog) radiograph of the lumbar spine was made using 200 mA, 1/2 second exposure, and 90 kV. If the exposure factors were changed to 200 mA, 0.25 second, and 104 kV, there would be an obvious change in which of the following? 1. Receptor exposure 2. Scale of grays/contrast 3. Distortion

2 only The kilovoltage was increased (by 15%) to compensate for the receptor exposure loss and thereby increase the scale of grays.

If a duration of 0.05 second was selected for a particular exposure, what milliamperage would be necessary to produce 30 mAs?

600

If 85 kVp, 400 mA, and ⅛ s were used for a particular exposure using single-phase equipment, which of the following milliamperage or time values would be required, all other factors being constant, to produce a similar receptor exposure using three-phase, 12-pulse equipment?

200 mA

Of the following groups of exposure factors, which will produce the greatest receptor exposure? A 400 mA, 30 ms, 72-in. SID B 200 mA, 30 ms, 36-in. SID C 200 mA, 60 ms, 36-in. SID D 400 mA, 60 ms , 72-in. SID

200 mA, 60 ms, 36-in. SID

Using a 48-in. SID, how much OID must be introduced to magnify an object two times?

24-in OID To magnify an object to twice its actual size, the part must be placed midway between the focal spot and the IR.

An exposure was made using 600 mA and 18 ms. If the mA is changed to 400, which of the following exposure times would most closely approximate the original receptor exposure?

27 ms

A 3-inch object to be radiographed at a 36-inch SID lies 4 inches from the image recorder. What will be the image width?

3.3 inches

If 82 kVp, 300 mA, and 0.05 second were used for a particular exposure using 3-phase, 12-pulse equipment, what mAs would be required, using single-phase equipment, to produce a similar radiograph?

30 mAs When changing from single-phase to three-phase, 12-pulse equipment, only one-half of the original mAs is required. In this problem, we are changing from three-phase, 12-pulse to single-phase equipment; therefore, the mAs should be doubled (from 15 to 30 mAs).

If 0.05 second was selected for a particular exposure, what mA would be necessary to produce 15 mAs?

300 mA

If exposure factors of 85 kVp, 400 mA, and 12 ms yield an output exposure of 150 mR, what is the milliroentgens per milliampere-seconds (mR/mAs)?

31

Exposure factors of 80 kVp and 8 mAs are used for a particular nongrid exposure. What should be the new milliampere-seconds value if an 8:1 grid is added?

32 mAs No grid = 1 x original mAs 5:1 grid = 2 x original mAs 6:1 grid = 3 x original mAs 8:1 grid = 4 x original mAs 12:1 grid = 5 x original mAs 16:1 grid = 6 x original mAs

A radiograph made using 300 mA, 0.1 second, and 75 kV exhibits motion unsharpness but otherwise satisfactory technical quality. The radiograph will be repeated using a shorter exposure time. Using 86 kV and 400 mA, what should be the new exposure time?

37 ms

If 84 kV and 8 mAs were used for a particular abdominal exposure with single-phase equipment, what milliampere-seconds value would be required to produce a similar radiograph with three-phase, 12-pulse equipment?

4 mAs

If 300 mA has been selected for a particular exposure, what exposure time should be selected to produce 18 mAs?

60 ms

The exposure factors of 300 mA, 0.017 second, and 72 kVp produce an mAs value of

5

What is the spatial frequency of a digital system with a pixel pitch of 100 um?

5 lp/mm

A 5-in. object to be radiographed at a 44-in. SID lies 6 in. from the IR. What will be the image width?

5.7 in. Image Size / Object Size = SID / SOD

If 92 kV and 12 mAs were used for a particular abdominal exposure with single-phase equipment, what mAs would be required to produce a similar radiograph with three-phase equipment?

6

A satisfactory radiograph was made using a 36-in. SID, 12 mAs, and a 12:1 grid. If the examination will be repeated at a distance of 42 in. and using a 5:1 grid, what should be the new milliampere-seconds value to maintain the original receptor exposure?

6.5 mAs According to the exposure-maintenance formula, if the SID is changed to 42 in., 16.33 mAs is required to maintain the original radiographic receptor exposure: Thus, x = 16.33 mAs at 42 in. SID. Then, to compensate for changing from a 12:1 grid to a 5:1 grid, the milliampere-seconds value becomes 6.53 mAs:

The exposure factors of 400 mA, 17 ms, and 82 kV produce a milliampere-seconds value of

6.8

In an AP abdomen radiograph taken at 105-cm SID during an IVU series, one renal shadow measures 9 cm in width. If the OID is 18 cm, what is the actual width of the kidney?

7.5 cm IM/OS = SID / SOD (SOD = SID - OID)

In an AP abdomen taken at 105-cm SID during an IV urography series, one renal shadow measures 9 cm in width. If the OID is 18 cm, what is the actual width of the kidney?

7.5 cm image size / object size = SID / SOD (SID - OID)

A satisfactory radiograph of the abdomen was made at a 38-in. SID using 400 mA, 60-ms exposure, and 80 kV. If the distance is changed to 42 in., what new exposure time would be required?

73 ms

A part whose width is 6 inches will be imaged at 44 inches SID. The part to be imaged lies 9 inches from the IR. What will be the projected image width of the part?

8 inches IW / OW = SID / SOD

A particular radiograph was produced using 6 mAs and 110 kVp with an 8:1 ratio grid. The radiograph is to be repeated using a 16:1 ratio grid. What should be the new mAs?

9

Regardless of pixel size, which of the following factors influence spatial resolution? (select the two that apply) A Focal spot selection B kVp selection C Adding a grid, with a compensating change in mAs D Increasing collimation E Changing SID

A & E Utilizing a large focal spot and changing SID will affect the production of blur within the signal (A and E). kVp change, grid use, and collimation change will affect the amount of scatter radiation that reaches the IR (B, C, and D).

Which of the following are methods to prolong x-ray tube life? (select the three that apply) A Perform the x-ray tube warm-up procedure when the anode is cold B Use long exposure time settings C Limit exposure prep time D Avoid performing certain projections in the department's exam protocol E Reduce repeat radiographs F Keep the kVp setting constant for all exams

A, C, & E The radiographer should limit exposure prep time, when possible, as "boost-and-hold" causes anode-bearing wear and evaporation of the cathode filament (C)

Which of the following radiographic examinations can use the anode heel effect to best advantage? A AP foot B AP knee C PA skull D AP thoracic spine

AP thoracic spine the anode heel effect can only be used advantageously when the field size is large, such as that used when performing an AP thoracic spine radiograph

How is source-to-image distance (SID) related to exposure rate and receptor exposure?

As SID increases, exposure rate decreases and receptor exposure decreases.

The reduction in x-ray photon intensity as the photon passes through material is termed

Attenuation

The exposure factors used for a particular nongrid x-ray image were 300 mA, 4 ms, and 90 kV. Another image, using an 8:1 grid, is requested. Which of the following groups of factors is most appropriate? A 400 mA, 3 ms, 110 kV B 400 mA, 12 ms, 90 kV C 300 mA, 8 ms, 100 kV D 200 mA, 240 ms, 90 kV

B 400 mA, 12 ms, 90 kV The addition of a grid will help to clean up the scattered radiation produced by higher kilovoltage, but the grid requires an adjustment of milliampere-seconds. According to the grid conversion factors listed here, the addition of an 8:1 grid requires that the original milliampere-seconds be multiplied by a factor of 4:

Which of the following is most likely to occur as a result of using a 30-in. SID with a 14 × 17 in. IR to radiograph a fairly homogeneous structure? A Production of quantum mottle B Receptor exposure variation between opposite ends of the IR C Production of scatter radiation fog D Excessively short-scale contrast

B Receptor exposure variation between opposite. Because shorter SIDs and larger IR sizes require greater divergence of the x-ray beam to provide coverage, the anode heel effect will be accentuated

What is the best way to reduce magnification distortion?

Decrease OID

When describing the overall efficiency of CR photostimulabe phosphor plates converting x-ray signals into a useful image, which of the following terms best fit this definition?

Detective quantum efficiency Detective quantum efficiency or DQE, describes the overall efficiency of converting x-ray signals into a useful image. Ideally the CR system would reach a DQE of 1.0 or 100 percent (B)

A graphic diagram of signal values representing various absorption properties within the part being imaged is called a

Histogram

A technologist is about to perform a trauma cross-table cervical spine on a hypersthenic patient who is short of breath. As the technologist is setting up for the projection, it becomes clear that the patient will not be able to hold their breath through the exposure. How should the technologist adjust technique to preserve image quality?

Increase kVp by 15% and divide exposure time by 2.

Grids improve the radiographic image by reducing the amount of scattered radiation fog. How does the use of grids impact exposure factors?

It increases exposure factors

Quantum mottle manifests within an image because

a poor signal was captured by the image receptor.

What is the single most important factor controlling size distortion?

OID Shape distortion (foreshortening, elongation) is caused by improper alignment of the tube, part, and image receptor. Size distortion, or magnification, is caused by too great an object-image distance or too short a source-image distance. OID is the primary factor influencing magnification, followed by SID.

For a radiographic exposure of the femur, how should the anode heel effect be properly applied?

Place the cathode end of the x-ray tube over the proximal femur.

If insufficient x-ray quantity is supplied to a digital image receptor, which of the following will be seen on the final radiographic image? A Decreased image brightness B Increased contrast (shorter grayscale) C Decreased spatial resolution D Quantum mottle (noise)

Quantum mottle (noise)

A radiograph exposed using a 12:1 ratio focused grid may exhibit a loss of receptor exposure at its lateral edges because the

SID was too great If the SID is above or below the recommended focusing distance, the primary beam at the lateral edges will not coincide with the angled lead strips.

If a radiograph exposed using a 12:1 ratio grid exhibits a loss of receptor exposure at its lateral edges, it is probably because the

SID was too great If the SID is above or below the recommended focusing distance, the primary beam will not coincide with the angled lead strips at the lateral edges

The radiographer receives an x-ray order for a 1-year-old child. Without adequate immobilization techniques or accessories such as a Pigg-O-Stat™, which of the following image qualities could be affected?

Spatial Resolution

If a 6-in. OID is introduced during a particular radiographic examination, what change in SID will be necessary to overcome objectionable magnification?

The SID must be increased by 42 in to compensate for every 1 in. of OID, an increase of 7 in. of SID is required. Therefore, an OID of 6 in. requires an SID increase of 42 in.. This is why a chest radiograph with a 6-in. air gap usually is performed at a 10-ft SID.

As grid ratio is decreased,

The scale of contrast becomes longer Because lead content decreases when grid ratio decreases, a smaller amount of scattered radiation is trapped before reaching the IR. More grays, therefore, are recorded, and a longer scale of contrast results. Receptor exposure would increase with a decrease in grid ratio. Grid ratio is unrelated to distortion

A technologist setting a manual technique on a DR imaging system is contemplating changing mA from 300 down to 150, with no other changes to other factors. Which of the following effects will happen as a result of this change?

The signal-to-noise ratio will decrease.

Occasionally, it is difficult for the radiographer to obtain a diagnostic image of the odontoid (dens) process using the open-mouth technique. An alternative method, called the Fuch's method, may be used where the patient extends their head to place the mental and mastoid plane perpendicular to the image receptor. However, if the patient is unable to obtain the full extension needed, a cephalic angulation of the x-ray tube may be warranted. What would be the potential disadvantage(s) of such an angulation of the tube?

The tube angulation would foreshorten the odontoid process and therefore may superimpose the borders of a fracture gap in such a way that the fracture may go undetected.

If an acceptable image is obtained utilizing 20 mAs, 75 kVp at a 40-in. SID, what adjustment must be made to mAs with a 35-in. SID to maintain image receptor exposure?

Use 15 mAs, 75 kVp

When the collimated field must extend past the edge of the body, allowing primary radiation to strike the tabletop, as in a lateral lumbar spine radiograph, what may be done to prevent excessive receptor exposure owing to undercutting?

Use lead rubber to absorb tabletop primary radiation.

Geometric unsharpness is most likely to be greater

at the cathode end of the image The x-ray tube anode is designed according to the line focus principle, that is, with the focal track beveled (see the figure below). This allows a larger actual focal spot to project a smaller effective focal spot, resulting in improved spatial resolution with less blur. However, because of the target angle, penumbral blur varies along the longitudinal tube axis, being greater at the cathode end of the image and less at the anode end of the image.

The best way to control voluntary motion is

careful explanation of the procedure.

In amorphous selenium flat-panel detectors, the term amorphous refers to a

crystalline material lacking typical crystalline structure.

Decreasing field size from 14 × 17 in. to 8 × 10 in., with no other changes, will

decrease receptor exposure and decrease the amount of scattered radiation generated within the part

Decreasing field size from 14 × 17 into 8 × 10 inches will A decrease receptor exposure and increase the amount of scattered radiation generated within the part. B increase receptor exposure and increase the amount of scattered radiation generated within the part. C increase receptor exposure and decrease the amount of scattered radiation generated within the part. D decrease receptor exposure and decrease the amount of scattered radiation generated within the part.

decrease receptor exposure and decrease the amount of scattered radiation generated within the part.

A 15% increase in kVp accompanied by a 50% decrease in mAs will result in

decreased patient dose

Radiographic contrast is the result of

differential absorption

Exposure values arising from excessive kV, insufficient collimation, or thick anatomic structures are termed

fog Scattered radiation produces fog, which can add unwanted exposure values to the x-ray image and impair its diagnostic value. Scattered radiation production is encouraged at high kV, insufficient beam restriction, and thick anatomic parts. Scattered radiation can be removed from the remnant beam with the use of grid

The absorption of useful radiation by a grid is called

grid cutoff

Better resolution is obtained with

high SNR A high SNR (e.g., 1000:1) indicates that there is far more signal than noise.

A 15% decrease in kilovoltage accompanied by doubling the milliampere-seconds will result in a(n)

increase in patient dose

Using a short (25-30 in.) SID with a large (14 × 17 in.) IR is likely to

increase the anode heel effect Use of a short SID with a large-size IR (and also with anode angles of 10 degrees or less) causes the anode heel effect to be much more apparent. The x-ray beam needs to diverge more to cover a large-size IR, and it needs to diverge even more for coverage as the SID decreases

If a 4-inch collimated field is changed to a 14-inch collimated field, with no other changes, the image receptor will experience

increased receptor exposure

How are mAs and receptor exposure related in the process of image formation?

mAs and receptor exposure are directly proportional The milliampere-seconds value regulates the number of x-ray photons produced at the target and thus regulates receptor exposure.

To produce a just perceptible increase in receptor exposure, the radiographer should increase the

mAs by 30 % An increase or decrease in milliampere-seconds of at least 30% is necessary to produce a perceptible effect.

Misrepresentation of the true size of an anatomical structure is called

magnification Magnification, or size distortion, is the misrepresentation of the true size of the anatomical part being radiographed.

A focal-spot size of 0.3 mm or smaller is essential for

magnification radiography A fractional focal spot of 0.3 mm or smaller is essential for reproducing fine spatial resolution without focal-spot blurring in magnification radiography

An increase in kilovoltage in analog imaging is most likely to

produce a longer scale of contrast

The relationship between the height of a grid's lead strips and the distance between them is referred to as grid

ratio

Combinations of milliamperage and exposure time that produce a particular milliampere-seconds value will produce identical receptor exposure. This statement is an expression of the

reciprocity law

Radiation spreads from a source in an expanding sphere, the area given by 4/3πr34/3πr3. So long as the rate of emission is constant, the intensity of the radiation will reduce by a factor squared as an observer moves away from the source. This describes

the inverse square law

Misalignment of the tube-part-IR relationship results in

shape distortion

Compton scatter production and photoelectric absorption within the patient both increase at the same rate as

tissue thickness