Image Production - Imaging Equipment CT9

Which of the following focal spot sizes should be used when doing macro radiography?

.3 mm. Macroradiography is magnifying an object. It is often used in angiography and mammography. The smaller the focal spot size the less unsharpness. 0.1 mm focal spots are used in mammography.

Which of the following will produce a lower contrast in a radiograph? 1. High kVp 2. Improper collimation 3. Outdated film

1, 2 & 3 High kVp will penetrate more parts producing a longer scale of contrast (low contrast); improper collimation will produce more scatter radiation; and outdated film will have fog.

How does magnification affect image quality? 1. Decreases recorded detail/spatial resolution 2. Decreases brightness 3. Lowers contrast

1. Decreases recorded detail/spatial resolution

The SID should be reduced by 1 inch for every _______ degrees of CR angle.

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Why is contrast needed in a radiographic image? 1. Makes detail visible 2. Increases sharpness of detail 3. Decreases need for distortion A. 1 only B. 2 only C. 3 only D. 1 & 2 only

A. 1 only Density/brightness and contrast are needed to make the details on a radiograph visible. The higher the contrast, the better the visibility of details.

A light radiograph may be caused by which of the following? 1. Grid cutoff 2. SID too low 3. Grid ratio too low A. 1 only B. 2 only C. 3 only D. 1 & 3 only

A. 1 only Grid cutoff is when the grid is misaligned with the x-ray beam and it absorbs the primary x rays, causing the image to be much lighter than expected.

Which of the following imaging plates should be selected to produce an image with the best spatial resolution? A. 18 cm x 24 cm (8 x 10) B. 24 cm x 30 cm (10 x 12) C. 30 cm x 35 cm (11 x 14) D. 35 cm x 43 cm (14 x 17)

A. 18 cm x 24 cm (8 x 10) The CR reader samples at a frequency of 2000 x 2000 no matter what the size of the imaging plate. Therefore, a smaller plate would be sampled more often which produces more samples per millimeter. Hence, better spatial resolution.

A detector element (DEL) size of 200 microns will produce how much spatial resolution? A. 2.5 line pairs per millimeter B. 5.0 line pairs per millimeter C. 7.5 line pairs per millimeter D. 10 line pairs per millimeter

A. 2.5 line pairs per millimeter A micron is 1/1,000,000 of a meter. There are 1,000 microns in a millimeter. Five, 200 micron detectors, could fit in a millimeter. It takes two detectors to make a line pair, so the spatial resolution would be 2.5 line pairs per millimeter.

What is the magnification factor if an object measures 4 cm but the radiographic image is 8 cm? A. 2X B. 3X C. 4X D. 6X

A. 2X Divide the image size by the object size to determine how many times larger the image is than the object.

When an object is placed halfway between the tube and the image receptor the image will be how many times larger? A. 2X B. 3X C. 4X D. 8X

A. 2x If the SID is 40" and the object is placed half way between the tube and the image receptor it would be placed at 20" SOD. Magnification = SID/SOD or 40"/20" = 2.

Which of the following techniques will produce a radiograph with the highest contrast? A. 50 mAs, 50 kVp B. 30 mAs, 60 kVp C. 15 mAs, 70 kVp D. 10 mAs, 80 kVp

A. 50 mAs, 50 kVp The lower the kVp, the more x rays will be absorbed and the less that will be scattered. This combination of high absorption and low scatter produces a high contrast image.

Which of these is the best method to reduce scatter radiation which causes fog? A. Collimation B. Filtration C. Compression D. High speed screens

A. Collimation By reducing the size of the collimated area, less tissue is exposed and less scatter radiation will be produced. Compression also helps reduce scatter radiation on a large person.

What is the greatest advantage of digital imaging? A. Contrast resolution B. Spatial resolution C. Decreased exposure D. Less distortion

A. Contrast resolution Contrast resolution is the ability to differentiate between two similar tissue densities. Digital imaging's wide dynamic range allows for this advantage over film-screen imaging.

Even though it is considered a primary factor, why should kVp NOT be used to control radiographic density? A. Contrast will also change B. Detail will also change C. It will cause motion D. The tube will overload

A. Contrast will also change kVp affects density and contrast. Therefore, if a radiographer uses it to change density, contrast will also change.

Tube angulation will produce which of the following types of shape distortion? A. Elongation B. Foreshortening C. Magnification D. Minification

A. Elongation By angling the tube the part is elongated. It will look longer than it actually is. This is shape distortion

If the central ray is perpendicular to the image receptor, but the part is angled, what will be the result? A. Foreshortening B. Elongation C. Minification D. Loss of density

A. Foreshortening Anytime the part is angled and the image receptor is not parallel to the part and the tube is not perpendicular to the part and image receptor, foreshortening will result.

Which of the following describes a short scale of contrast? A. High contrast B. Low contrast C. High number of density differences D. Greater film latitude

A. High contrast Scale of contrast refers to the number of different densities seen on a radiograph. The shortest scale would be black and white. This would be a great difference between densities or a high contrast.

Which of the following would increase the contrast-to-noise ratio (CNR)? A. Increase x-ray intensity B. Increase scatter radiation C. Increase electronic noise D. Increase background noise

A. Increase x-ray intensity As the number of x rays increases, noise decreases. This increases the contrast-to-noise ratio.

As contrast lowers, how is the number of densities in an image affected? A. Increases B. Decreases C. Remains the same D. Varies from image to image

A. Increases Lower contrast means a longer scale of contrast. Scale of contrast refers to the number of different densities seen in the radiograph. A long scale means there are several densities visible.

Which of the following controls contrast in a digital system? A. Look-up table B. Histogram C. High-frequency laser D. Analog-to-digital converter

A. Look-up table Look-up tables convert the raw digital data to different numbers to determine the contrast in an image.

Fog will have the greatest adverse effect on which of the following? A. Low density areas of the image B. Middle range density areas of the image C. High density areas of the image D. Maximum density areas of the image

A. Low density areas of the image If the low density or white areas on the film are covered with fog, the film will lose contrast and details will be less visible (because the purpose of contrast is to make details visible).

Fractional focal spots are necessary for which of the following? A. Magnification radiography B. Stereoradiography C. Soft tissue radiography D. Tomography

A. Magnification radiography Increasing OID to magnify an object causes a loss of recorded detail. Focal spot sizes in the .3 mm range will compensate for some of the loss.

How well an imaging system reproduces the actual object is referred to as what? A. Modulation transfer function B. Resolving power C. Lines per inch D. Linear image transfer

A. Modulation transfer function (MTF) Modulation transfer function measures the information lost between the actual object and the recorded image. It is controlled by how well the x-ray image is converted into a visible image.

Which of the following defines image brightness? A. Pixel light intensity B. Difference in light intensity between pixels C. Sharpness of the pixels D. Visibility of the pixels

A. Pixel light intensity The intensity of the pixels in the display monitor determines the brightness of the digital image.

How will the use of radiographic grids affect the contrast of an image? A. Produce higher contrast B. Produce lower contrast C. Eliminate contrast D. Have no effect on contrast

A. Produce higher contrast Grids remove scatter radiation that causes fog. Without fog covering up the white areas on the image there will be a bigger difference between black and white or higher contrast.

Low energy radiation will result in which of the following? A. Short scale of contrast B. Medium scale of contrast C. Long scale of contrast D. Low scale of contrast

A. Short scale of contrast Low energy radiation will be absorbed by the tissues of the body and therefore produce a short scale of contrast. High energy radiation is scattered by the tissues and produces a long scale of contrast. A low scale of contrast is not a proper term to describe radiographic contrast.

What are the two types of distortion that can reduce the quality of a radiograph? A. Size and shape B. Size and contrast C. Brightness and contrast D. Long and short

A. Size and shape Like the definition states, "a misrepresentation of the size or shape of an object", the two types are size and shape.

The ability of a digital system to display details (expressed as the number of line pairs per millimeter) is known as what? A. Spatial resolution B. Quality assurance C. Detail factor D. Finite factor

A. Spatial resolution A display monitor must be able to display at least 2.5 line pairs per millimeter according the American College of Radiology's digital standards.

Which of the following will have the greatest effect on reducing motion on an abdomen radiograph? A. Suspend respiration B. Compression device C. High mA D. Increased SID

A. Suspend respiration Clear instructions to suspend respiration to a cooperative patient will reduce the risks of motion. Of course, there is very little that can be done with the uncooperative patient.

What determines the density of a radiograph? A. The number of silver halide crystals reduced by developer B. The number of silver halide crystals removed by fixer C. The brightness of the viewboxes D. The perception of the radiologist

A. The number of silver halide crystals reduced by developer The developer reduces the exposed silver halide crystals to black metallic silver, which produces the overall blackness (density) on the radiograph.

When radiographing a small part, recorded detail can be improved by which of the following? A. Using slow speed screens B. Increasing the OID C. Using a large focal spot D. Using the high speed rotor

A. Using slow speed screens The slower the screen speed, the better the recorded detail. That is because slow speed screens have a thinner active layer of phosphors, resulting in less divergence of the light photons.

Which of the following is considered the controlling factor for radiographic density? A. mAs B. kVp C. SID D. OID

A. mAs Since mAs affects density but does not affect contrast, distortion or recorded detail it is considered the controlling factor for density.

When motion is a problem, time can be reduced by 1/2 if the kVp is increased by what percentage? A. 5% B. 15% C. 25% D. 35%

B. 15% The 15% rule is practiced by most technologists.

Geometric unsharpness is directly proportional to which of the following? 1. SID 2. OID 3. SOD A. 1 only B. 2 only C. 1 & 3 only D. 1, 2 & 3

B. 2 only Directly proportional means as one factor increases the other increases. By increasing the OID, the unsharpness increases. That is why the part should always be as close to the image receptor as possible.

Most computed radiography (CR) readers scan the imaging plate at what frequency? A. 1000 x 1000 B. 2000 x 2000 C. 3000 x 3000 D. 4000 x 4000

B. 2000 x 2000 As the laser sweeps the imaging plate, light is released from the photostimulable phosphors. The intensity of that light is sampled at a frequency of 2000 x 2000 by a photodetector. That analog data is then digitized and stored in a 2000 x 2000 matrix in the computer so it can be reconstructed as a digital image.

How much must the mAs be increased before a noticeable change in density can be seen? A. 10% B. 30% C. 50% D. 75%

B. 30% Known as the 30% rule, it takes a change in density of at least 30% to be visible to the human eye.

Which of the following will produce the largest image? A. 40" SID, 3" OID B. 40" SID, 5" OID C. 72" SID, 3" OID D. 72" SID, 5" OID

B. 40" SID, 5" OID The magnification ratio = SID/SOD. A 5" OID will leave a 35" SOD (source-to-object distance) when using 40". This will produce an image 1.14 X larger. A = 1.08; C = 1.04; D = 1.07.

A sampling frequency of 10 pixels per millimeter would produce how much spatial resolution? A. 1 line pair per millimeter B. 5 line pairs per millimeter C. 10 line pairs per millimeter D. 20 line pairs per millimeter

B. 5 line pairs per millimeter It takes 2 pixels to make a line pair, therefore, 10 pixels would produce 5 line pairs per millimeter.

Each cell of an image matrix is called what? A. A square B. A pixel C. An element D. A byte

B. A pixel Pixel stands for "picture element". In digital x-ray imaging the value of the pixel determines the pixel's brightness.

If the SID is increased the same as the OID, what will the resultant radiograph show? A. No change in size distortion B. An increase in size distortion C. A decrease in size distortion D. An elongated image

B. An increase in size distortion According to the magnification formula, SID/SOD, even if the SID is increased the same amount as the OID, the final radiograph will be larger than the actual object.

Luminance refers to the brightness of the light emitted from an image display monitor. What are the SI units for luminance? A. Joules per volt B. Candela per square meter C. Coulombs per meter squared D. Newtons per watt

B. Candela per square meter The American College of Radiology requires a brightness of at least 250 candelas per square meter, but newer monitors have brightnesses up to 1000.

Which of the following radiographic procedures requires a long scale of contrast? A. Lumbar spine B. Chest C. Myelography D. Angiography

B. Chest Chest radiography requires high kVp (140 kVp range) in order to penetrate the ribs and mediastinum to visualize the lung detail behind these structures. High kVp produces a long scale of contrast.

The difference in density/brightness between adjacent areas in a radiograph is a definition for which of the following? A. Resolution B. Contrast C. Distortion D. Recorded detail/spatial resolution

B. Contrast The greater the difference in density/brightness between adjacent areas, the higher the contrast.

How will an increase in radiographic fog affect contrast? A. Contrast will be higher B. Contrast will be lower C. Contrast will be eliminated D. Contrast will remain the same

B. Contrast will be lower Fog on a radiograph changes the white areas to gray areas. This lowers the contrast because instead of a big difference between black and white, now there is a smaller difference between black and gray.

How will increasing the OID affect the recorded detail/spatial resolution in a radiograph? A. Increase recorded detail/spatial resolution B. Decrease recorded detail/spatial resolution C. Eliminate recorded detail/spatial resolution D. Will have no effect on recorded detail/spatial resolution

B. Decrease recorded detail/spatial resolution Increasing OID will increase magnification, which will decrease recorded detail/spatial resolution.

How will increasing the focal spot size affect the recorded detail/spatial resolution in a radiograph? A. Increase recorded detail/spatial resolution B. Decrease recorded detail/spatial resolution C. Eliminate recorded detail/spatial resolution D. Will have no effect on recorded detail/spatial resolution

B. Decrease recorded detail/spatial resolution Increasing the focal spot size increases the divergent angle of the x-ray beam, which decreases recorded detail/spatial resolution.

If the mA is increased, how must the time be changed in order to maintain the same exposure? A. Increased B. Decreased C. Doubled D. Reduced by one half

B. Decreased mAs is the controlling factor for exposure. Therefore, if mA is increased, time must be decreased in order to maintain the same exposure.

Which of the following describes the blackness of a radiograph? A. Speed B. Density C. Gamma D. Fog

B. Density Density is defined as the overall blackness of a radiograph. It is the result of exposed silver halide crystals being reduced to black metallic silver by the developer.

Size distortion is affected by which of the following? A. Intrinsic factors B. Geometric factors C. Motion factors D. Technical factors

B. Geometric factors Geometric factors have to do with the angle the x-ray beam strikes the object. SID and OID are geometric factors. Intrinsic factors are screens and film; technical factors are kVp, mA, time.

Grid efficiency is determined by which of the following? A. Grid ratio and SID correct B. Grid ratio and grid frequency C. Grid focusing distance D. kVp and mAs

B. Grid efficiency is determined by which of the following?

Which of the following occurs when the OID is increased? A. Image size is reduced B. Image is magnified C. Image is elongated D. Image is foreshortened

B. Image is magnified Increasing the OID, reduces the SOD, which increases the magnification ratio (SID/SOD).

Which of the following will produce a longer scale of contrast? A. Increasing mAs B. Increasing kVp C. Increasing grid ratio D. Increasing SID

B. Increasing kVp Scale of contrast refers to the number of different densities on a radiograph. Increasing kVp penetrates more anatomical parts and therefore a larger number (longer scale) of densities will be seen.

Which of the following scales of contrast will produce a more consistent radiographic quality? A. Short scale B. Long scale C. Narrow scale D. Low scale

B. Long scale A long scale of contrast provides more exposure latitude which makes it easier to produce consistent quality radiographs.

After the values of interest have been determined from the histogram, which of the following is used to readjust those numbers to produce the proper contrast? A. Contrast chart B. Look-up table C. Values graph D. Number diagram

B. Look-up table Look-up tables convert the raw digital data to different numbers to determine the contrast in an image.

Which of the following describes a long scale of contrast? A. High contrast B. Low contrast C. Less film latitude D. Low number of density differences

B. Low contrast Contrast is described in two ways, a long scale contrast or low contrast and a short scale contrast or high contrast. A long scale of contrast has several densities/brightnesses with a small difference between densities/brightnesses. A short scale of contrast has few densities/brightnesses with a large difference between densities/brightnesses.

The ratio of SID to SOD represents which of the following? A. Distortion ratio B. Magnification ratio C. Definition ratio D. Shape ratio

B. Magnification ratio The magnification ratio determines how many times larger the image will be than the actual object. It is written SID/SOD.

Recorded detail/spatial resolution can be improved by which of the following? A. Maximum OID B. Maximum SID C. Minimum SID D. Minimum SOD

B. Maximum SID SID is another geometric factor. The longer the SID, the more of the central part of the x-ray beam is used. The more angled x rays are absorbed by the collimator.

Which of the following defines radiographic density? A. Differences between blacks and whites B. Overall blackness of the radiograph C. Sharpness of the radiograph D. Visibility of the detail

B. Overall blackness of the radiograph The overall blackness of the radiograph is a result of exposed silver halide crystals being changed to black metallic silver by the developer.

Which of the following statements concerning fog density is true? A. The age of the film causes fog B. Overdevelopment causes fog C. Darkroom safelights cause fog D. Every film has the same base fog

B. Overdevelopment causes fog Overdevelopment means the developer is developing unexposed silver halide crystals, causing fog. Film over one year old may cause fog. Properly used safelights should not cause fog.

To avoid shape distortion, which of the following must be paid close attention to? A. SID B. Part angulation C. Part-to-table top distance D. SOD

B. Part angulation Any time the part is not parallel to the image receptor, shape distortion occurs.

How will high kVp techniques affect radiographic contrast? A. Produce higher contrast B. Produce lower contrast C. Produce higher contrast in obese patients D. Will have no effect on contrast

B. Produce lower contrast High kVp produces high energy x rays. High energy x rays are scattered by the tissues and produce lower contrast (long scale).

Even though it is considered a primary factor, why should the SID NOT be used to control density? A. Contrast will also change B. Recorded detail will also change C. It will cause motion D. The tube will overload

B. Recorded detail will also change SID affects density, but it also affects recorded detail and distortion. Whenever SID is changed, these radiographic qualities will change also.

Which of the following radiographic qualities determines the sharpness of detail in the finished radiograph? A. Recorded detail and contrast B. Recorded detail/spatial resolution and distortion C. Density and contrast D. Density and distortion

B. Recorded detail/spatial resolution and distortion Sharpness of detail is controlled by maximizing recorded detail/spatial resolution and minimizing distortion.

Which of the following is NOT one of the three elements that affect shape distortion? A. Central ray B. SID C. Object D. Image receptor

B. SID SID affects size distortion. Angling the CR, object or IR will cause shape distortion.

Which of the primary factors will always have an effect on recorded detail/spatial resolution? A. Seconds B. SID C. mA D. kVp

B. SID mA, time (which is mAs), kVp and SID are considered the primary factors because they are the first things to adjust to affect exposure to the image receptor. SID is also one of the geometric factors that affects recorded detail/spatial resolution.

Which of the following would NOT be used as contrast media in radiography? A. Air B. Saline C. Barium sulfate D. Sodium iodide

B. Saline Two types of contrast media are used in radiography, negative and positive. With negative contrast media (air) the x rays penetrate it very easily and produce a negative (dark) affect. Positive media (barium and iodine) absorbs the x rays and produces a light affect. Normal saline does neither of these.

Which of the following would be used to minimize size distortion? 1. Shortest possible OID 2. Smallest focal spot size 3. Longest SID A. 1 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

B. Shortest OID and Longest SID Size distortion is controlled by OID and SID. To minimize size distortion you want to get the part as close to the image receptor as possible and use the longest SID possible.

What type of distortion results from an increase in OID? A. Minification B. Size C. Elongation D. Shape

B. Size There are two types of distortion size and shape. Size distortion has to do with magnification. Increasing OID will magnify the object which misrepresents its actual size.

The measure of the amount of detail in a digital image defines which of the following? A. Recorded detail B. Spatial resolution C. Definition D. Detail

B. Spatial resolution Spatial resolution is measured in line pairs per millimeter.

What is the definition of recorded detail? A. The contrast in the image B. The sharpness of the structural lines C. The lack of distortion in the image D. All of the above are good definitions

B. The sharpness of the structural lines Recorded detail refers to the sharpness of the structural lines in a radiographic image.

Which of the following describes a radiograph that is lacking radiographic density? A. Overexposed B. Underexposed C. Overpenetrated D. Underpenetrated

B. Underexposed When defining a radiograph that is too light, the term underexposed would be appropriate.

Poor film-screen contact will cause which of the following effects? A. Gain of contrast B. Unsharpness C. Loss of density D. Gain of recorded detail

B. Unsharpness If there is not good film-screen contact the light diverges and a loss of recorded detail results.

The brightness of a digital image affects which of the following? A. Sharpness of detail B. Visibility of detail C. Distortion D. Exposure

B. Visibility of detail The image must be a certain brightness to make the details visible. A digital image can be too light or too dark.

Which of the following factors would be used to control contrast in a film-screen system? A. mAs B. kVp C. SID D. OID

B. kVp kVp is considered the controlling factor for contrast. This is because its penetrating ability determines how many different anatomical parts will be penetrated and visible on the radiograph.

The minimum monitor matrix size for an acceptable digital radiographic image is which of the following? A. 1000 x 1200 B. 1200 x 1600 C. 1536 x 2048 D. 2048 x 2560

C. 1536 x 2048 1536 x 2048 is the minimum, but a 2048 x 2560 matrix is necessary to produce an image sharp enough for an accurate diagnosis of chest details.

What is the spatial resolution of a 24 cm x 30 cm (10 x 12) imaging plate? A. 2 lp/mm B. 3 lp/mm C. 4 lp/mm D. 5 lp/mm

C. 4 lp/mm A 24 cm wide imaging plate is also 240 mm wide. If the plate is scanned at a frequency of 2000, then there would be 8 pixels/mm. It takes two pixels to make a line pair, so the spatial resolution would be 4 lp/mm.

When changing from non-grid to an 8:1 grid, how much would the mAs have to be increased? A. 2X B. 3X C. 4X D. 5X

C. 4X An 8:1 ratio grid will absorb 4X more scatter radiation than no grid at all, and therefore the radiograph will be 4X underexposed. The mAs would have to be increased 4X in order to compensate for the use of the grid.

If the kVp is increased 15%, how much must the mAs be reduced in order to maintain the same exposure to the image receptor? A. 15% B. 25% C. 50% D. 100%

C. 50% Known as the 15% rule, a 15% increase in kVp will double the exposure to the image receptor. This will require a 50% decrease in mAs in order to maintain the same exposure to the image receptor.

When using iodinated contrast agents and high-frequency x-ray equipment, the kVp should NOT exceed what? A. 50 kVp B. 60 kVp C. 70 kVp D. 80 kVp

C. 70 kVp The idea of contrast media is to absorb x rays and produce contrast between adjacent anatomical areas. The binding energy of iodine's K shell electrons is only 33 keV. As x-ray energy increases, less x rays are absorbed and more are scattered. Very few of the x rays will get absorbed when the kVp is above 70.

Which of the following statements is true? A. A long grayscale has few shades of gray B. A long grayscale is high contrast C. A long grayscale has several shades of gray D. High contrast has several shades of gray

C. A long grayscale has several shades of gray Grayscale refers to the number of shades of gray in a digital image. A long grayscale would have several shades of gray.

Which of the following can be done to help compensate for an angled part? A. Angle the tube in the opposite direction B. Angle the image receptor in the opposite direction C. Align the tube, part and image receptor D. Have the patient bend over

C. Align the tube, part and image receptor To prevent distortion, the image receptor has to be parallel to the part and the central ray has to be perpendicular to the image receptor and part. Good radiographers take time to align the tube, part and image receptor.

Size distortion can be used to an advantage for which of the following radiographic procedures? A. Gastrointestinal B. Skeletal C. Angiographic D. Neurological

C. Angiographic Magnification does make small things bigger, just like a magnifying glass, which makes them easier to see. Angiography uses magnification techniques to see small vessels easier.

In order to obtain the most recorded detail/spatial resolution the OID should be what? A. The same for every image B. As long as possible C. As short as possible D. Equal to the SID

C. As short as possible All radiographers know that it is important to get the OID (object-to-image receptor distance) as short as possible. In other words, get the part as close to the image receptor as possible.

Scatter radiation will have the greatest effect on which of these radiographic qualities? A. Recorded detail B. Density C. Contrast D. Distortion

C. Contrast Scatter radiation covers up the white or light areas on a radiograph. This means there will be less difference in density/brightness between areas causing lower contrast.

Which of the following determines the visibility of detail in a film-screen radiograph? A. Density and distortion B. Contrast and recorded detail C. Density and contrast D. Density, contrast and recorded detail

C. Density and contrast How visible the details are in a radiograph is determined by the density and contrast. How sharp the details are in a radiograph is determined by the recorded detail and distortion.

Misrepresentation of the true size or shape of an object is the definition of which of the following? A. Recorded detail B. Elongation C. Distortion D. Magnification

C. Distortion A radiographer's job is to try to get the object they are radiographing as close as possible to its true size and shape. If the radiographic image is not exact, it is said to have distortion.

Recorded detail/spatial resolution can be improved by reducing which of the following? A. SID B. SOD C. Focal spot size D. Patient size

C. Focal spot size Focal spot size is considered the controlling factor for recorded detail/spatial resolution because the small focal spot will produce twice as much detail as the large focal spot will (resolving power measurement).

Accurate centering of the central ray is critical for which type of grid? A. Crossed B. Parallel C. Focused D. Perpendicular

C. Focused Off-center grid cut-off is more likely with a focused grid.

Which of the following directly influences radiographic contrast? A. mA B. SID C. Grid ratio D. Exposure time

C. Grid ratio Radiographic grids remove scatter radiation before it reaches the image receptor to cause fog. This decrease in fog provides a higher contrast radiograph.

How would an image with just a few, wide density differences be described? A. High density B. Low distortion C. High contrast D. Low recorded detail

C. High contrast High contrast means there is a big difference in density between adjacent areas. An image with a few, wide density differences would be considered high contrast.

An H & D curve that demonstrates a steep curve represents a film with which of the following? A. Low fog B. High speed C. High contrast D. Low density

C. High contrast The steeper the slope of the curve, the higher the radiographic contrast.

Which of the following will affect recorded detail the most? A. Increase SID by 5 inches B. Increase SOD by 5 inches C. Increase OID by 5 inches D. Increase field of view by 5 inches

C. Increase OID by 5 inches Increasing the OID will increase magnification, which will cause a loss in recorded detail.

Which of the following will keep size distortion to a minimum? A. Increase kVp B. Increase grid ratio C. Increase SID D. Increase focal spot size

C. Increase SID The magnification formula is magnification = SID/SOD. By increasing SID, SOD is increased and the ratio is decreased. This is why radiographers use 72" for lateral cervical spines.

How will decreasing the focal spot size affect recorded detail/spatial resolution? A. It will increase blur B. It will increase unsharpness C. It will decrease unsharpness D. It will decrease recorded detail

C. It will decrease unsharpness Decreasing the focal spot size decreases the divergence of the x-ray beam. The less the divergence of the x-ray beam, the less the unsharpness.

Which of the following is the most important factor in controlling size distortion? A. Focal spot size B. SID C. OID D. Exposure time

C. OID Get the part as close to the image receptor as possible!

Changing the mAs controls which of the following? A. Penetrating power of the x-ray beam B. Quality of the x-ray beam C. Quantity of the x-ray beam D. Average photon energy of the x-ray beam

C. Quantity of the x-ray beam mAs stands for milliamperage-seconds, which measures the number of electrons that travel across the x-ray tube. The energy of these electrons is converted to x rays. The more mAs the more x rays.

An insufficient amount of mAs will produce a digital image with: A. distortion. B. loss of contrast. C. quantum noise. D. loss of brightness.

C. Quantum noise

Which of the following may be the cause of an overexposed image? A. mAs too low B. OID too high C. SID too low D. Grid ratio too high

C. SID too low

Which of the following will occur when the tube angle is decreased? A. The image will be foreshortened B. Contrast will be lower C. Shape distortion will decrease D. Size distortion will increase

C. Shape distortion will decrease The greater the tube angle the greater the elongation of the object. If the tube angle is decreased, the elongation will decrease which means shape distortion decreases.

A flat-panel detector's detector element (DEL) size determines which of the following? A. Dynamic range B. Detective quantum efficiency (DQE) C. Spatial resolution D. Speed class

C. Spatial resolution With DR flat-panels, the pixel size is determined by the detector element (DEL) size; with CR imaging plates the pixel size is determined by the sampling frequency.

Which of the following will occur when the OID is decreased? A. The image will be magnified B. The image will be minified C. The image is closer to actual size D. The image will be elongated

C. The image is closer to actual size You can never get the image to be equal to the object's actual size, but decreasing the OID will produce an image that is closer to the actual size.

Which of the following statements would define spatial resolution in digital imaging? A. The contrast in an image B. The lack of distortion in an image C. The measure of the amount of detail in an image D. The number of gray tones in an image

C. The measure of the amount of detail in an image Spatial resolution is measured in line pairs per millimeter.

Which of the following best describes grid ratio? A. The ratio of exposure with and without a grid B. The distance from the focus to the grid surface C. The ratio of the height of the lead strips to the distance between the lead strips D. The number of lines per inch

C. The ratio of the height of the lead strips to the distance between the lead strips The most common grid ratios are 5:1, 8:1, and 12:1.

Automatic exposure control (AEC) was used for an erect abdomen but the SID was left at 72" SID instead of moving it to 40". The image will be: A. underexposed. B. overexposed. C. properly exposed. D. fogged.

C. properly exposed. The AEC will remain on until the proper number of x rays have struck the ionization chamber. Or until the backup time is reached. In most cases, the result would be a properly exposed image.

The histogram is used to automatically rescale the image to the proper brightness. Which of the following could cause an error with the histogram analysis? 1. Exposure field NOT detected 2. Unexpected metal in the data set 3. Gross overexposure A. 1 & 2 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 Anything that would change the shape of the histogram could cause an error in the histogram analysis. When the exposure field is not detected or there is metal in the anatomy (e.g., prosthesis) the image will usually be too dark because the algorithm tries to automatically rescale the light areas to the proper tissue density.

Why is automatic exposure control (AEC) useful in controlling radiographic density? 1. Density must remain constant 2. Faulty density causes repeats 3. Density greatly affects quality A. 1 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 Density is an important part of radiographic quality. When the patient is positioned properly, AEC will reproduce a predetermined density and reduce the number of repeats.

Which of the following film characteristics can be determined from an H and D curve? 1. Speed 2. Contrast 3. Base plus fog A. 1 & 2 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 H & D curves are used to determine a film-screen's speed (the farther to the left the faster), contrast (the steeper the greater the contrast), and base plus fog (measured in the toe region).

What are the advantages of using high kVp techniques? 1. Less patient exposure 2. Longer tube life 3. All parts are well penetrated A. 1 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 High kVp allows for lower mAs to produce the same exposure, it is more efficient at producing x rays and it makes sure all parts are penetrated so no visibility of details are lost.

Which of the following may be used to control motion during a radiographic examination? 1. Immobilization devices 2. Precise verbal instructions to the patient 3. Shortest possible exposure time A. 1 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 Immobilization devices, such as sandbags and positioning sponges, are alright to use. However, it is not acceptable to restrain a patient without a doctor's orders.

Which of the following can be used to reduce unsharpness? 1. Increase SID 2. Decrease focal spot size 3. Decrease OID A. 1 & 2 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 Increasing SID and using a smaller focal spot produces a less divergent beam; less OID produces less magnification and less unsharpness.

A graphic representation of the relationship between density and exposure is called what? 1. D log E curve 2. H & D curve 3. Characteristic curve A. 1 & 2 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 Plotting density against the log of the exposure produces a curve that is characteristic of the factors used to produce the various densities. Hurter and Driffield (H & D) developed this curve.

Which of the following will decrease the recorded detail in a radiograph? 1. Increasing the focal spot 2. Increasing screen speed 3. Increasing OID A. 1 only B. 2 only C. 1 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 Recorded detail can be increased by using the smallest focal spot, the slowest speed screen and the least OID.

Which of the following affect subject contrast? 1. Part thickness 2. kVp 3. Part density A. 1 & 2 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 Subject contrast refers to the difference in tissue density between adjacent anatomical parts. All of the above will have an effect on how x rays are absorbed and scattered.

The size of the pixel produced when an imaging plate is read depends on which of the following? 1. The speed of the imaging plate as it passes through the reader 2. The frequency with which the data is sampled 3. The dimensions of the laser beam A. 1 only B. 1 & 2 only C. 1 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 The slower the imaging plate speed the better the spatial resolution. However, the slower the speed the longer it takes to acquire the image. The sampling frequency and the laser dimension also contribute to pixel size and therefore, spatial resolution.

A misrepresentation of the shape of an object may be caused by which of the following? 1. An angled object 2. An angled central ray 3. An angled image receptor A. 1 & 2 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 To prevent shape distortion, the image receptor and object have to be parallel to each other and the central ray has to be perpendicular to the object and image receptor.

Which of the following types of motion must be considered when setting a radiographic technique? 1. Voluntary 2. Involuntary 3. Equipment A. 1 only B. 1 & 2 only C. 2 & 3 only D. 1, 2 & 3

D. 1, 2 & 3 Voluntary motion can be controlled by the patient (breathing), involuntary motion cannot be controlled by the patient (peristalsis) and motion may occur if the equipment moves.

Which of the following methods can be used to control motion by reducing exposure time? 1. Use highest mA station possible 2. Increase kVp 3. Decrease SID A. 1 only B. 1 & 2 only C. 2 & 3 only D. 1, 2 & 3

D. 1,2 & 3 Increasing mA or kVp and/or decreasing SID are ways of increasing exposure. Therefore, time can be reduced to maintain the proper exposure.

Which of the following factors affect radiographic density? 1. kVp 2. Anode heel effect 3. Pathology A. 1 only B. 1 & 2 only C. 2 & 3 only D. 1, 2 & 3

D. 1,2 &3 An increase in kVp will increase density. Because of the anode heel affect the image will be darker toward the cathode end. Pathologies can be additive or destructive, which will affect density.

What percentage increase is usually used for magnification radiography? A. 25% B. 50% C. 75% D. 100%

D. 100% Magnification radiography can produce an image twice as large as the object by putting the object halfway between the source and the image receptor (100%). Mammography magnification uses a 50% increase.

Which of the following grid ratios should be used to maintain contrast when using over 100 kVp? A. 5:1 B. 6:1 C. 8:1 D. 12:1

D. 12:1 100 kVp x rays will mostly scatter when passing through a patient. Therefore, a high ratio grid is needed to absorb this large amount of scatter radiation.

Which of the following screen speeds will produce the greatest density on a radiograph? A. 50 B. 100 C. 200 D. 400

D. 400 The higher the screen speed the thicker the active layer and the more phosphors there are to absorb x rays and convert them to visible light. The more light photons, the greater the radiographic density.

A typical digital radiograph contains _______ megabytes of information. A. .13 B. .52 C. 5.1 D. 7.5

D. 7.5 A MRI image requires .13 MB, a CT image requires .52 MB, a digital radiograph (1760 x 2140 x 2 bytes/pixel) = 7.5 MB. Storage capacity is an issue with PACS. Do not transmit more images than necessary.

Which of the following distances would produce the least distortion? A. 40" B. 55" C. 60" D. 72"

D. 72 The longer the SID the less the size distortion.

Which of the following is a reason for the loss of recorded detail/spatial resolution in a radiograph? A. Large focal spot B. OID C. Patient motion D. All of the above

D. All of the above The inability to get the part as close to the image receptor as possible causes the greatest loss of recorded detail/spatial resolution. Using the small focal spot whenever possible will reduce the amount of loss.

Density was the term used to describe the overall blackening of a conventional radiograph. What term is used in digital radiography to describe this radiographic quality? A. Window width B. Exposure C. Contrast D. Brightness

D. Brightness Brightness is used because digital images are viewed on a monitor.

Density was the term used to describe the overall blackening of a film-screen radiograph. What term is used in digital imaging to describe this radiographic quality? A. Window width B. Exposure C. Contrast D. Brightness

D. Brightness The brightness of the image displayed on the monitor can be too dark or too light, but it is usually just right.

Which of the following factors does NOT affect radiographic density? A. Screen speed B. Grid ratio C. Processing D. Film-screen contact

D. Film-screen contact Film-screen contact is not considered a factor that affects density. However, the film will be darker in those areas where there is poor film-screen contact.

Which of the following will NOT contribute to the underexposure of an image? A. mA set too low B. kVp set too low C. SID set too high D. Focal spot size too large

D. Focal spot size too large Focal spot size has no effect on radiographic exposure.

Subject contrast will be the lowest with which of the following body types? A. Sthenic B. Asthenic C. Hyposthenic D. Hypersthenic

D. Hypersthenic Subject contrast refers to the differences in tissue densities in the patient. Large patients (hypersthenic) have a higher fat content which creates smaller differences between tissues which produces a lower contrast radiograph.

Spatial resolution in digital imaging is determined by which of the following? A. Exposure to the image receptor B. Brightness and contrast C. Matrix size D. Matrix size and the size of the field of view

D. Matrix size and the size of the field of view The larger the matrix size and the smaller the field of view (display monitor), the better the spatial resolution.

Which of the following will have the greatest effect on radiographic contrast? A. Tube filtration B. Close collimation C. Focal spot size D. Reducing scatter radiation

D. Reducing scatter radiation Scatter radiation covers up the white or light areas on a radiograph. This means there will be less difference in density/brightness between areas causing lower contrast. Collimation helps prevent scatter radiation from large parts.

The number of density differences in a radiograph refers to which of the following? A. Subject contrast B. Object contrast C. Intrinsic contrast D. Scale of contrast

D. Scale of contrast Scale of contrast refers to the number of different densities seen on a radiograph. A few densities would be a short scale and several different densities would be a long scale.

Which of the following is NOT considered one of the geometric factors that control recorded detail/spatial resolution? A. OID B. SID C. Focal spot size D. Size of the object

D. Size of the object OID, SID and focal spot size all affect the angle of the x-ray beam, which affects recorded detail/spatial resolution

Contrast can be measured from an H & D curve by finding the slope of which of the following parts? A. Toe B. Shoulder C. Threshold D. Straight line portion

D. Straight line portion You can find the slope (tangent) of the straight line portion by the "rise over the run", or the vertical rise over the horizontal distance. This provides a number that represents the contrast on the film. The higher the number, the higher the contrast. A number 1 represents a 45 degree slope.

Which of the following affects shape distortion? A. SID B. OID C. Focal spot size D. X-ray tube angulation

D. X-ray tube angulation An angled x-ray tube will cause the image to be elongated compared to the actual object.

In radiography, an object that is larger than its true size is said to be: A. blown up. B. skewed. C. magnified. D. huge.

D. huge In radiography, the term is magnified.

Which of the following factors has the greatest effect on radiographic density? A. Focal spot sizes B. Grid ratios C. mAs D. kVp

D. kVp Doubling (100%) the grid ratio from 6:1 to 12:1 will decrease the density 166%. Doubling (100%) the mAs will increase the density 100%. But only a 15% increase in kVp will increase the density 100%. Focal spots sizes do not affect density.

Recorded detail/spatial resolution is NOT affected by which of the following? A. SID B. SOD C. OID D. kVp

D. kVp kVp will affect the visibility of detail by the amount of scatter radiation it produces. The higher the kVp the more scatter.

Changing the shape of an object is called what? A. Magnification B. Distortion C. Minification D. Definition

Distortion

If the exposure time is cut in half, how must the mA be adjusted to maintain the same exposure?

Doubled

Which of the following statements is true? A. High kVp, high contrast B. High kVp, low contrast C. High kVp, short scale D. High kVp, low density/brightness

High kvp, low contrast High kVp penetrates more anatomical parts and therefore a larger number (longer scale) of densities/brightnesses will be seen. This means there will be less density/brightness difference between these parts or lower contrast.

If it is impossible to get the part close to the image receptor, what can be done to compensate? A. Increase exposure time B. Increase SID C. Decrease kVp D. Decrease screen speed

Increase SID Having the part away from the image receptor creates magnification. The magnification ratio is SID/SOD. If the SID increases, the SOD will increase an equal amount which will reduce magnification.

How are mA and seconds related to each other when used to maintain exposure? A. Directly proportional B. Inversely proportional C. Mutually exclusive D. No relationship exists

Inversely proportional Inversely proportional means that if one increases the other must decrease in order to maintain the same exposure.

Patient motion can be used to an advantage in which of the following procedures? A. Chest radiography B. Coronary angiography C. Lateral thoracic spine D. Gastrointestinal radiography

Lateral T-Spine A breathing technique of at least three seconds will blur the ribs and lung markings to better view the lateral thoracic spine. One of the few times motion benefits radiography.

Which of the following will have the greatest effect on size distortion? A. SID B. OID C. Focal spot size D. Image size

OID

Which of the following accessories can be used to demonstrate a scale of contrast or test for contrast? A. Densitometer B. Penetrometer C. Rate meter D. Wire mesh

Penetrometer A penetrometer, also known as a step wedge, is used to produce a scale of contrast. This can be used to test kVp accuracy, mAs reciprocity and a number of other quality assurance tests.

How will an air gap technique affect radiographic contrast? A. Produce higher contrast B. Produce lower contrast C. Eliminate contrast D. Have no effect on contrast

Produce higher contrast The idea of an air gap technique is to move the part farther from the image receptor so the angled scatter radiation will miss the image receptor. This reduces the amount of scatter radiation reaching the image receptor which produces a higher contrast.

Which of the following factors affects radiographic density? 1. SID 2. OID 3. Focal spot size A. 1 only B. 2 only C. 1 & 3 only D. 1, 2 & 3

SID only According to the A.R.R.T. outline for their examination, only SID affects density. However, if you want to get technical, an air gap (OID) will allow scatter x rays to miss the image receptor, causing a decrease in density.

Which of the following occurs when the imaging plate or flat-panel detector is grossly overexposed? A. Saturation B. Intensification C. Dynamic quantum D. Dynamic inefficiency

Saturation If the imaging plate or detector is grossly overexposed, anatomical information will be lost. This usually occurs in the low density and soft tissue areas of the image. These black areas are referred to as plate saturation.

Recorded detail/spatial resolution can be improved by which of the following? A. Higher contrast B. Greater density C. Smaller focal spot size D. Air gap technique

Small focal spot size One of the geometric factors is the focal spot size. Its size has an effect on the angle of the x-ray beam. The smaller the focal spot size the less angle, therefore, the better the recorded detail/spatial resolution.

What advantage is there to magnifying an object? 1. Recorded detail increases 2. Small objects become visible 3. There is less distortion A. 1 only B. 2 only C. 1 & 2 only D. 1, 2 & 3

Small objects become visible. Just like a magnifying glass, magnification in radiography is used to make small objects more visible.

What is the correct name for the loss of sharpness due to the use of a large focal spot?

Unsharpness

One of the most important aspects of digital imaging is the ability of the computer to mathematically change the image's brightness and contrast. Which of the following controls image brightness? A. Window width B. Window level C. Digital filtering D. Image resolution

Window level A simple movement of the mouse can change the brightness. But it is not recommended because the original numbers will be changed as well, leaving the original image altered.

The quantity of x rays produced is dependent upon which of the following? A. mAs B. SID C. OID D. SOD

mAs