Image Production-Image Acquisition and Technical Evaluation
Which of the following focal sizes should be used when doing macreo radiography? A. .3 mm B. 1.0 mm C. 1.5 mm D. 2.0 mm
A. .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.
The ablity of a digital system to display details (expressed as the number of line pairs per millimeter) is know 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.
The quality of an x-ray beam is determined by which of the following? A. mAs B. kVp C. SID D. Focal spot size
B. kVp Quality refers to the energy of the x-ray beam. kVp determines the energy of the x-ray beam.
If the SID is halved, which of the following changes must be made in order to maintain the same exposure? A. mAs halved B. mAs reduced by 4x C. mAs doubled D. mAs increased by 4x
B. mAs reduced by 4X Cutting the SID in half will increase the exposure to the image receptor by 4X. Therefore, mAs would have to be reduced by 4X to maintain the same exposure.
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.
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 Quantum noise is visible in an underexposed image. It should be repeated if the exposure is 50% less than needed. This is determined by the exposure indicator number.
Tube angulation will produce which of the following types of shape distortion? A. Elongation B. Foreshortening C. Magnification D. Minification
A. Elongation An angling the tube the part is elongated. It will look longer than it actually is. This is shape distortion.
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 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.
How does magnification affect image quality? 1. Decreases spatial resolution 2. Decreases receptor exposure 3. Lowers contrast A. 1 only B. 2 only C. 2 & 3 only D. 1, 2 & 3
A. 1 only Magnification decreases spatial resolution because the divergent xrays have a chance to spread out further before reaching the image receptor
Which of the following imaging plates should be selected to produce an image with the best spatial resolution? A. 18 cm x 24 (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 is 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 receptot 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.
The SID should be reduced by 1 inch for every ______________ degree of CR angle. A. 5 B. 10 C. 15 D. 20
A. 5 This will help maintain the original SID
How much should kVp be increased when radiographin a part in a fiberglass orthopedic cast? A. 5 kVp B. 10 kVp C. 15 kVp D. 25 kVp
A. 5 kVp Most of today's orthopedic casts are made of fiberglass. This material adds to the thickness of the part, therefore, kVp must be increased to penetrate it.
The image in an image receptor after exposure but before processing is known as what? A. Latent image B. A manifest image C. A visible image D. An imaginary image
A. A latent image The latent image is produced when the image receptor captures the x-ray image. This produces an invisible image.
What is a major benefit of a fixed kVp technique chart? A. Adequate part penetration B. Decreased exposure latitude C. Increased tube loading D. Increase in patient exposure
A. Adequate part penetration A fixed kVp chart uses more kVp than necessary to make sure all body parts will be penetrated.
Which of these is the best method to reduce scatter radiation which causes fog? A. Collimation B. Filtration C. Compression D. Speed class
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. Deceased 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.
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 brightness
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 brightness differences D. Greater film latitude
A. High contrast Scale of contrast refers to the number of different brightnesses seen on a radiograph. The shortest scale would be black and white. This would be a great difference between brightnesses or a high contrast
Contrast resolution is a major advantage of digital imaging. What determines high contrast resolution in a digital image? A. High exposure and low noise B. Low exposure and high noise C. High exposure and high resolution D. High resolution and low noise
A. High exposure and low noise Contrast resolution is the ability to distinguish between the various tissues of the acquired image. Known as the signal-to-noise ratio, a high exposure will produce low noise and allow the software to visualize the various tissues.
How will increasing SID affect the spatial resolution in a radiograph? A. Increase spatial resolution B. Decrease spatial resolution C. Eliminate spatial resolution D. Will have no effect on spatial resolution
A. Increase spatial resolution Increasing SID allows the radiographer to use more of the central part of the x-ray beam and collimate off the more divergent beam. The central, less divergent bea, produces a sharper image.
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 brightness 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 brightnesses seen in the radiograph. A long scale means there are several brightnesses 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 brightness area of the image B. Middle range brightness areas of the image C. High brightness areas of the image D. Maximum brightness areas of the image
A. Low brightness area of the image If the low brightness or white areas on the image are covered with, the image 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 spatial resolution. 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 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. Produces 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.
Which of the following occurs when the image plate or flat-panel detector is grossly overexposed? A. Saturation B. Intensification C. Dynamic quantum D. Dynamic inefficiency
A. Saturation If the imaging plate or detector is grossly overexposed, anatomical information will be lost. This usually occurs in the low brightness and soft tissue areas of the image. These black areas are referred to as plate saturation.
What are the two types of distortion that can reduce the quality of a radiograph? A. Size and shape B. Size and contrast C. Receptor exposure 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 quantity of x-rays produced is dependent upon which of the following? A. mAs B. SID C. OID D. SOD
A. mAs mAs is the measurement of the number of electrons that will be produced during an exposure. The more electrons that are produced, the more x-rays will be produced.
If the mA is set at 400 and the mAs obtained is 80, what must the time be set at? A. .1 second B. .2 second C. .4 second D. .8 second
B .2 second To calculate time, you must divide the mAs by the mA. Seconds = 8/400 or .2
How could a KUB taken at 25 mAs, 70 kVp and a 400 speed film-screen system be properly converted for CR? 1. 25 mAs, 80 kVp 2. 50 mAs, 60 kVp 3. 50 mAs, 70 kVp A. 1 & 2 only B. 1 & 3 only C. 2 & 3 only D. 1, 2 & 3
B. 1 & 3 25 mAs at 80 kVp would reduce patient exposure and still produce a quality image. 50 mAs at 70 kVp would produce an optimum quality image.
Which of the following would be used to minimize size distortion? 1. Shortest possible OID 2. Smallest focal spot size 3. Longest focal spot size A. 1 only B. 1 & 3 only C. 2 & 3 only D. 1, 2, & 3
B. 1 & 3 only 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.
A technique of 300 mA, 1/10 second and 60 kVp is to be changed to 69 kVp, what would be the new time? A. 1/40 second B. 1/20 second C. 1/3 second D. 1/5 second
B. 1/20 second. A 15% incease in kVp will double the exposure to the image receptor. Therefore, you would have to cut your time in half to compensate. 1/2 of 1/10 is 1/20
Which of the following techniques will produce the highest contrast? A. 50 mAs, 80 kVp, 5:1 grid B. 100 mAs, 70 kVp, 8:1 grid C. 100 mAs, 80 kVp, 8:1 grid D. 200 mAs, 70 kVp, 5:1 grid
B. 100 mAs, 70 kVp, 8:1 grid The lowest kVp and the highest grid ratio will produce the highest contrast.
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.
Time can be decreased by 1/2 if the kVp is increased by what percentage? A. 10% B. 15% C. 25% D. 50%
B. 15% Known as the 15% rule, by increasing the kVp 15% the brightness of the radiograph will double. Therefore, the time can be reduced by 1/2 to maintain the same brightness. This is important to reduce motion and also to reduce the exposure to the patient (1/2 the mAs).
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.
What advantage is there to magnifying an object? 1. Spatial resolution increases 2. Small objects become visible 3. There is less distortion A. 1 only B. 3 only C. 1 & 2 only D. 1, 2, & 3
B. 2 only Just like a magnifying glass, magnification in radiography is used to make small objects more visible
Which of the following metric cassette sizes is equivalent to a 10x12 inch cassette? A. 18 x 24 B. 24 x 30 C. 30 x 35 D. 35 x 43
B. 24 x 30 To convert inches to centimeters you simply multiply the inches by 2.54. In this case 10"= 25.4 cm and 12"=30.48 cm. As you can see, 24 x 30 film and cassettes are smaller than 10 x 12 inches.
How could a knee taken at 4 mAs, 70 kVp and a 400 speed film-screen system be properly converted for CR? 1. 4 mAs, 80 kVp 2. 8 mAs, 60 kVp 3. 8 mAs, 70 kVp A. 1 only B. 3 only C. 1 & 3 only D. 1, 2, & 3
B. 3 only Since there are no vital organs in the knee, doubling to 8 mAs for the CR imaging plate would improve edge enhancement and visibility of details.
How much mAs will be generated if the control panel is set at 200 mA and 1/5 second? A. 20 mAs B. 40 mAs C. 80 mAs D. 100 mAs
B. 40 mAs To calculate the mAs you simply multiply the mA times the time. mAs = 200 mA x 1/5 second or mAs=40.
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
How many milliseconds are in .05 seconds? A. 5 B. 50 C. 500 D. 5000
B. 50 There are 1000 milliseconds in 1 second. To find how many milliseconds are in .05 seconds, you multiple 1000 times .05 which equals 50.
A 400 speed class requires how much less radiation than a 200 speed class? A. 25 % less B. 50 % less C. 100 % less D. 200 % less
B. 50 % less A 400 speed class requires 50% less radiation to achieve the same brightness.
The image after processing is known as what? A. A latent image B. A manifest image C. An invisible image D. An imaginary image
B. A manifest image The purpose of processing is to take the invisible (latent) image and make it visible (manifest) image.
Each cell of an image matrix is called what? A. A square B. A pixel C. A byte D. An element
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 amoutnas the OID, the final radiograph will be larger than the actual object
Where is the ionization chamber located in an automatic exposure control (AEC) device? A. Between the tube and the patient B. Between the patient and the image receptor C. Behind the image receptor D. Below the Bucky tray
B. Between the patient and the image receptor The ionizing chamber must be located between the patient and the image receptor so the number of x-rays can be measured before they reach the image receptor. Once the correct number of x-rays have passed through the patient the exposure will automatically shut off.
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 brightness between adjecent areas in a radiograph is a definition for which of the following? A. Receptor exposure B. Contrast C. Distortion D. Spatial resolution
B. Contrast The greater the difference in 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 an image changes the white area 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 focal spot size affect the spatial resolution in a radiograph? A. Increase spatial resolution B. Decrease spatial resolution C. Eliminate spatial resolution D. Will have no effect on spatial resolution
B. Decrease spatial resolution Increasing the focal spot size increases the divergent angle of the x-ray beam, which decreases spatial resolution
If the mA is increase, how must the time be changed in order to maintain the same receptor exposure? A. Increase B. Decreased C. Doubled D. Reduced by one half
B. Decreased mAs is the controlling factor for receptor exposure. Therefore, if mA is increased, time must be decreased in order to maintain the same receptor exposure
How will increasing the OID affect the spatial resolution in a radiograph? A. Increase spatial resolution B. Decrease spatial resolution C. Eliminate spatial resolution D. Will have no effect on spatial resolution
B. Decreases spatial resolution Increasing OID will increase magnification, which will decrease spatial resolution
Changing the shape of an object is called what? A. Magnification B. Distortion C. Minification D. Defintion
B. Distortion Changing the shape or size of an object is called distortion
A fixed-kVp technique chart uses which of the following? A. Fixed kVp and fixed mAs B. Fixed kVp and variable mAs C. Fixed mAs and variable kVp D. Variable mAs and variable kVp
B. Fixed kVp and variable mAs A fixed-kVp technique chart sets the kVp at a fixed amount to make sure all parts are penetrated. Then varies the mAs according to the part thickness.
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. Technical factors are kVp, mA and time.
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, reduced the SOD, which increases the magnification ratio (SID/SOD).
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 screeen speed
B. 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 receptor exposure? A. Directly proportional B. Inversely proportional C. Mutually exclusive D. No relationship exists
B. Inversely proportional Inversely proportional means that if one increases the other must decrease in order to maintain the same exposure
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 decribes a long scale of contrast? A. High contrast B. Low contrast C. Less film latitude D. Low number of brightness differences
B. Low contrast Contrast is descibed in two ways, a long scale of contrast or low contrast and a short scale of contrast or high contrast. A long scale of contrast has several brightnesses with a small difference between densities/brightnesses. A short scale of contrast has few brightnesses with a large difference between 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 writtenSID/SOD
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 will have the greatest effect on size distortion? A. SID B. OID C. Focal spot size D. Image size
B. OID The farther the part gets from the image receptor the larger the image will be. There is not much the radiographer can do to compensate for OID.
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.
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
B. 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.
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 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 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 xrays penetrate it very easily and produce a negative (dark) affect. Positive media (barium and iodine) absorbs the xrays and produced a light affect. Normal saline does neither of these.
Which of the following factors is the best for reducing the risks of motion? A. Low mAs B. Shortest possible exposure time C. Low ratio grid D. Highest practical kVp
B. Shortest possible exposure time Using the shortest possible exposure time is the best method for reducing the risks of motion. This is done by using the highest mA station 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 with misrepresents its actual size
The measure of the amount of detail in a digital image defines which of the following? A. Brightness B. Spatial resolution C. Definition D. Detail
B. Spatial resolution Spatial resolution is measured in line pairs per millimeter
Which of the following radiographic qualities determines the sharpness of detail in the finished radiograph? A. Spatial resolution and contrast B. Spatial resolution and distortion C. Receptor exposure and contrast D. Receptor exposure and distortion
B. Spatial resolution and distortion Sharpness of detail is controlled by maximizing spatial resolution and minimizing distortion.
Which of the following is the main determinant in selecting a focal spot size? A. The kVp used B. The mA used C. The equipment manufacturer D. The SID
B. The mA used A small focal spot cannot dissipate the heat generated from a high mA technique. Therefore, the radiographer must go to a larger focal spot or a low mA at a longer exposure time.
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
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
B. Window level A simple movement of the mouse can change the brightness. But it is not recommended because the orginal numbers will be changed as well, leaving the original image altered.
How will decreasing the focal spot size affect 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 techniques will produce the greatest image receptor exposure? A. 100 mA, .50 sec, 80 kVp B. 200 mA, .50 sec, 70 kVp C. 300 mA, .33 sec, 80 kVp D. 400 mA, .25 sec, 70 kVp
C. 300 mA, .33 sec, 80 kVp The highest mAs and the highest kVp will produce the greatest exposure. A= 50 mAs @ 80 kVp; B= 100 mAs @ 70; C= 99 mAs @ 80 kVp; D= 100 mAs @70 kVp
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
C. Lateral thoracic spine A breathing technique of at least 3 seconds will blur the ribs and lung markings to better view the lateral thoracic spine. One of the few times motion benefits radiography.
If the kVp is increased 15%, how much must the mAs be reduced in order to maintain the same receptor exposure? A. 15% B. 25% C. 50% D. 100%
C. 50% Known as the 15% rule, a 15% increase in kVP will double the receptor exposure. This will require a 50% decrease in mAs in order to maintain the same receptor exposure.
Which of the following statements is true? 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 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. Spatial resolution B. Receptor exposure 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 brightness between areas causing lower contrast
Misrepresentation of the true size or shape of an object is the definition of which of the following? A. Spatial resolution 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.
If the exposure time is cut in half, how must the mA be adjusted to maintain the same exposure? A. Cut in half B. Reduced 2 times C. Doubled D. Increased 4 times
C. Doubled mAs is the controlling factor for receptor exposure. If time (s) is cut in hald then mA must be doubled in order to maintain the same mAs and therefore, the same receptor exposure.
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 spatial resolution because the small focal spot will produce twice as must detail as the large focal spot
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 density C. High contrast D. Low spatial resolution
C. High contrast High contrast means there is a big difference in brightness between adjacent areas. An image with a few, wide brightness differences would be considered high contrast.
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.
What is the main reason why beam filters are used in radiography? A. Improves contrast B. Improves radiographic quality C. Reduces patient exposure D. Prolongs tube life
C. Reduces patient exposure Beam filters are used to reduce patient exposure by filtering out low energy x-rays that would have no chance of penetrating the patient and exposing the image receptor. They have not other affects unless they are too thick (more than 2.5 mm AL).
Which of the following factors will NOT have an effect on contrast? A. Patient B. Grid ratio C. SID D. Radiation fog
C. SID SID affects brightness, spatial resolution and distortion but not contrast
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 It is always a good idea to double check the SID by making sure the tube is in detent or with the use of a tape measure
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.
Spatial resolution can be improved by which of the following? A. Higher contrast B. Greater brightness C. Smaller focal spot size D. Air gap technique
C. Smaller 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 spatial resolution.
A flat-panel detector's 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 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.
In radiography, an object that is larger than its true size is said to be: A. blown up B. skewed C. magnified D. huge
C. magnified In radiography, the term is magnification
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 (displau monitor), the better the spatial resolution.
Subject contrast will be the lowest with which of the following body types? A. Sthenic B. Asthenic C. Hypostheic D. Hypersthenic
D. Hypersthenic Subject contrast refers to the differences in tissue densities in the patient. Large patients (hpersthenic) have a higher fat content which creates smaller differences between tissues which produces a lower contrast radiograph.
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.
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 tha anatomy (e.g., prosthesis) the image will usually be too dark because the algorithm tried to automatically rescale the light areas to the proper tissue brightness.
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 produced less magnification and less unsharpness
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.
Why is automatic exposure control (AEC) useful in controlling receptor exposure? 1. Receptor exposure must remain constant 2. Faulty receptor exposure causes repeats 3. Receptor exposure greatly affects quality A. 1 only B. 1 & 3 only C. 2 & 3 only D. 1, 2, & 3
D. 1, 2, & 3 Receptor exposure is an important part of radiographic quality. When the patient is positioned properly, AEC will reproduce a predetermined receptor exposure and reduce the number of repeats.
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.
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 radio graphic 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.
The size of the pixel produced when a CR 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 bettwe 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.
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.
A technique of 400 mA, .25 seconds, non-grid could be converted to a technique of 200 mA, with an 8:1 grid and how many seconds? A. .50 B. .75 C. 1.0 D. 2.0
D. 2.0 400 x .25 = 100 mAs and no grid. An 8:1 grid requires 4X more mAs. 400 mAs divided by 200 mA = 2 seconds.
If 50 mAs provides an optimum exposure at 40", how much mAs is necessary at 80"? A. 12 mAs B. 25 mAs C. 100 mAs D. 200 mAs
D. 200 mAs According to the inverse square law, if the distance is doubled, the mAs must be increased 4 times in order to maintain the same brightness
What is the spatial resolution of a 24 cm x 30 cm (10x12) imaging plate? A. 2 lp/mm B. 3 lp/mm C. 4 lp/mm D. 5 lp/mm
D. 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 lm/mm.
Which of the following screen classes will produce the greatest brightness on a radiograph? A. 50 B. 100 C. 200 D. 400
D. 400 The higher the screen class the greater the brightness
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 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 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 film-screen 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.
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.
A wavy pattern that results when two geometrically parallel lines are superimposed is referred to as what? A. Grid lines B. Penumbra C. Image blur D. Moire
D. Moire In film-screen radiography the moire effect was present when a grid cassette would be put in a Bucky. The two grids would cause the moire effect. It now occurs because the grid frequency matched the frequency the imaging plate is being scanned.
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. Receptor exposure
D. Receptor exposure 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 will have the greatest effet 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 brightness between areas causing lower contrast. Collimation helps prevent scatter radiation from large parts.
Which of the following is NOT considered one of the geometic factors the control 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 spatial resolution.
Which of the following tests will determine the focal spot size? A. Safelight test B. Wire mesh test C. Wisconsin test cassette D. Star pattern test
D. Star pattern test Focal spot size can be determined by a pinhole camera or a star resolution pattern.
What is the correct name for the loss of sharpness due to the use of a large focal spot? A. Umbra B. Mottle C. Blur D. Unsharpness
D. Unsharpness Unsharpness is the correct name for the loss of sharpness.
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
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
