Image Production- Image Acquisition & Evaluation (110 question exercise)

What is a major benefit of a fixed kVp technique chart?

adequate part penetration A fixed kVp chart uses more kVp than necessary to make sure all body parts will be penetrated.

Which of the following affects shape distortion?

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

When motion is a problem, time can be reduced by 1/2 if the kVp is increased by what percentage?

15% 15% RULE IS Practiced by most technolgists

How many milliseconds are in 0.05 seconds?

50 There are 1000 milliseconds in 1 second. To find how many milliseconds are in 0.05 seconds, multiply 1000 times .05 which equals 50.

Each cell of an image matrix is called what?

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

To avoid shape distortion, which of the following must be paid close attention to?

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

what is the greatest advantage of digital imaging?

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?

elegontaion 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 is an advantage of the air gap technique?

eliminates the need for a grid

Tube angulation will produce which of the following types of shape distortion?

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

When using AEC, which of the following methods can be used to control motion by reducing exposure time?

increase ma INCREASE Ma WITH AEC will result in a shorter exposure time. Decreasing kvp or increasing SID will result in a longer exposure time

How will increasing SID affect the spatial resolution on a radiograph?

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 beam produces a sharper image.

How are mA and seconds related to each other when used to maintain receptor exposure?

inversely proportional inversely proportional means that if one increases the other must decrease in to maintain the same exposure

In order to obtain the most spatial resolution the OID should be what?

-as short as possible 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.

Which of the following conditions would be considered "hard to penetrate"?

-edema -Paget;s disease -pneumonia

A technique of 400 mA, 0.25 seconds, non-grid could be converted to a technique of 200 mA, with an 8:1 grid and how many seconds?

0.2 400 x 0.25 = 100 mAs and no grid. An 8:1 grid requires 4X more mAs. 400 mAs divided by 200 mA = 2 seconds.

If the mA is set at 400 and the mAs obtained is 80, what is the exposure time?

0.2 second To calculate time, you must divide the mAs by the mA. Seconds = 80/400 or 0.2.

A misrepresentation of the shape of an object may be caused by which of the following?

1-An angled object, 2-an angled x-ray tube, or 3-an angled cassette 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 would be used to minimize size distortion?

1-shortest possible OID 3-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.

Which of the following can be used to reduce unsharpness?

1. Increase SID 2. Decrease focal spot size 3. Decrease OID Increasing SID and using a smaller focal spot produces a less divergent beam; less OID produces less magnification and less unsharpness. Continue

Which of the following effects will result from precise collimation?

1. Less biological tissue is exposed 2. Less scatter radiation is produced 3. Radiographic quality is improved Being confident in your positioning allows you to collimate to just the area of interest. This produces less exposure to the patient and produces a higher quality image.

What are the advantages of using high kVp techniques? 1. Less patient exposure 2. Longer tube life 3. All parts are well penetrated

1. Less patient exposure 2. Longer tube life 3. All parts are well penetrated 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 is lost.

Which of the following affect subject contrast?

1. Part thickness 2. kVp 3. Part density 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.

Which of the following types of information must be on all radiographs?

1. Patient's name 2. Date of exam 3. Right or left markers A radiograph is part of the medicolegal record of the patient, and like all legal documents they must be identifiable. They must contain the patient's name, date of the exam and which anatomical part had been radiographed.

Which of the following may be used to control motion during a radiographic examination?

1. Positioning sponges 2. Precise verbal instructions to the patient 3. Shortest possible exposure time Positioning aids, such as sandbags and sponges, are alright to use. However, it is not acceptable to restrain a patient without a doctor's orders.

Why is automatic exposure control (AEC) useful in controlling receptor exposure?

1. Receptor exposure remains constant based on patient thickness 2. AEC shuts off the beam when proper exposure is attained 3. Proper exposure reduces repeat rate 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.

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

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 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.

If a technique of 300 mA, 1/10 second and 60 kVp is to be changed to 69 kVp, what would be the new time?

1/20second A 15% increase 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 would be the most effective at absorbing scatter radiation?

12:1 grid High ratio grids absorb more scatter radiation than low ratio grids.

Time can be decreased by 1/2 if the kVp is increased by what percentage?

15% Known as the 15% rule, by increasing the kVp 15% the receptor exposure will double. Therefore, the time must be reduced by 1/2 to maintain the same exposure. This is important to reduce motion and also to reduce the exposure to the patient (1/2 the mAs).

Which of the following CR imaging plates should be selected to produce an image with the best spatial resolution?

18cm x 24cm (8x10) 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.

When an object is placed halfway between the tube and the image receptor the image will be how many times larger?

2 times 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.

What is the magnification factor if an object measures 4 cm but the radiographic image is 8 cm?

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

If 50 mAs provides an optimum exposure at 40" SID, how much mAs is necessary at 80" SID?

200mAs According to the inverse square law, if the distance is doubled, radiation intensity is 1/4 of the original value. Therefore, the mAs must be increased 4 times in order to maintain the same receptor exposure.

Which of the following techniques will produce the greatest image receptor exposure?

300 mA, 0.33 second, 80 kVp The highest mAs and the highest kVp will produce the greatest exposure.

A non-grid exposure requires 15 mAs. How much mAs is needed if a 5:1 ratio grid is used?

30mas A 5:1 ratio grid requires 2X more mAs to compensate for the loss of exposure because of the scatter radiation and some of the primary beam that is absorbed.

How much mAs will be generated if the control panel is set at 200 mA and 1/5 second?

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?

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

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

5 this will help maintain the original SID

How much should kVp be increased when radiographing a part in a fiberglass orthopedic cast?

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.

A sampling frequency of 10 pixels per millimeter would produce how much spatial resolution?

5 line pairs per millimeter -it takes 2 pixels to make a line pair, therefore, 10 pixels would produce 5 line pairs per millimiter

f the kVp is increased 15%, how much must the mAs be reduced in order to maintain the same receptor exposure?

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 distances (SID) would produce the least distortion?

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. Increased OID C. Patient motion 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.

Which of the following can be done to help compensate for an angled part?

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.

If the SID is increased the same as the OID, what will the resultant radiograph show?

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.

Which of the following is of the three elements that affect shape distortion?

Angling the CR ,object or, IR will cause shape distortion

The idea of the air gap technique is to move the patient away from the image receptor so scatter radiation will miss the image. If no scatter radiation reaches the image there is no need for a grid.

D. Eliminates the need for a grid

How would an image with just a few shades of gray be described?

High contrast High contrast means there is a big difference between light and dark areas. An image with only a few shades of gray would be considered high contrast.

spatial resolution is not affected by ?

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

The quality or energy of an x-ray beam is determined by which of the following?

KVP quality refers to the energy of the x-ray beam. kvp determines the energy of the x-ray beam

Spatial resolution can be improved by which of the following?

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.

How well an imaging system reproduces the actual object is referred to as what?

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.

Geometric unsharpness is directly proportional to which of the following?

OID 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.

Which of the following is the most important factor in controlling size distortion?

OID Get the part as close to the IR as possible

Which of the following will have the greatest effect on size distortion?

OID The farther the part gets from the image receptor the larger the image will be. This is why the heart will appear larger on an AP chest x-ray compared to a PA projection.

Which of the primary factors will always have an effect on spatial resolution?

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 is NOT one of the three elements that affect shape distortion?

SID affects size distortion

Which of the following may be the cause of an overexposed image?

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. Continue

What type of distortion results from an increase in OID?

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.

Which of the following factors is the best for reducing the risks of motion?

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 advantage is there to magnifying an object?

Small objects become visible

Which of the following radiographic qualities determines the sharpness of detail in the finished radiograph?

Spatial resolution and distortion The sharpness of detail is controlled by maximizing spatial resolution and minimizing distortion.

Which of the following radiographic procedures requires a long scale of contrast?

chest Rib radiographs should have a short scale of contrast to demonstrate the bones; chest images should have a long scale of contrast to visualize the lungs.

Which of these is the best method to reduce scatter radiation which causes fog?

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.

Scatter radiation will have the greatest effect on which of the following?

contrast Scatter radiation covers up the white or light areas on a radiograph, lowering the contrast resolution of the image.

The difference between light areas and dark areas in a radiograph is a definition for which of the following?

contrast The greater the difference between light and dark areas, the higher the contrast.

How will an increase in radiographic fog affect contrast?

contrast will be lower Fog or scatter radiation on an image 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.

Which of the following technique adjustments should be made when radiographing a geriatric patient with osteoporosis?

decrease KVP osteoporosis is easy to penetrate. Using KVP that is appropriate for an average patient would reduce an image that is overexposed

How will increasing the OID affect the spatial resolution on a radiograph?

decrease spatial resolution increase OID will increase magnification, which decrease spatial resolution

How will increasing the focal spot size affect the spatial resolution on a radiograph?

decrease spatial resolution increase the focal spot size increases the divergent angle of the x-ray beam, which decreases spatial resolution

If the mA is increased, how must the time be changed in order to maintain the same receptor exposure?

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.

Which of the following conditions would be considered "easy to penetrate"?

degenerative arthritis Degenerative arthritis involves a deterioration of the joints. This destructive process makes the bony area easier to penetrate, so less kVp would be needed.

changing the shape of an object is called

distortion changing the shape or size of an object is called distortion

Misrepresentation of the true size or shape of an object is the definition of which of the following?

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. Elongation is shape distortion; magnification is size distortion.

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

doubled mAs is the controlling factor for receptor exposure. If time (s) is cut in half then mA must be doubled in order to maintain the same mAs and therefore, the same receptor exposure.

A fixed-kVp technique chart uses which of the following?

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.

Spatial resolution can be improved by reducing which of the following?

focal spot size Focal spot size is considered the controlling factor for spatial resolution because the small focal spot will produce twice as much detail as the large focal spot.

which of the following will NOT contribute to the underexposure of an image?

focal spot size too large focal spot size has no effect on receptor exposure

size distortion is affected by which of the following?

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.

An underexposed radiograph may be caused by which of the following?

grid cutoff 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 underexposed. Continue

Subject contrast will be the lowest with which of the following body types?

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.

which of the following occurs when OID is increased?

image is magnified increase OID reduces the SOD, which increase the magnification ration ( SID/SOD)

Which of the following will keep size distortion to a minimum?

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.

If it is impossible to get the part close to the image receptor, what can be done to compensate?

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 will decreasing the focal spot size affect spatial resolution?

it decreases 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

How will the use of radiographic grids affect the amount of scatter radiation reaching the IR?

less scatter will reach the IR How will the use of radiographic grids affect the amount of scatter radiation reaching the IR?

THE QUANTIY of x-rays production is dependent upon which of the following?

mAs

If the SID is halved, which of the following changes must be made in order to maintain the same exposure?

mAs reduced by 4X Cutting the SID in half will increase the exposure to the image receptor by 4X, per the inverse square law. Therefore, mAs would have to be reduced by 4X to maintain the same exposure.

the ration of SID represents which of the following?

magnification ratio the magnification ration determines how many times larger the image will be than the actual object. SID/SOD

In radiography, an object that is larger than its true size is said to be:

magnified

why is contrast needed in a radiographic image?

make details visible the higher the contrast the better the visibility details

How will beam filtration affect the primary beam?

make it more homogeneous Homogeneous means "of the same degree". Beam filtration filters out the low energy x rays in the primary beam producing a beam of mostly high energy x rays.

a wavy pattern that results when 2 geometrically parallel lines are superimposed is referred to as what?

moire effect moire effect occurs because the grid frequency matches the frequency of image plate that is being scanned in the CR reader

Which of the following conditions would be considered "hard to penetrate"?

osteosclerosis Osteosclerosis, meaning hardening (scler) of the bones (osteo) would make the bones denser, harder for the x-ray beam to penetrate, and would require an increase in kVp.

Changing the mAs controls which of the following?

quantity of the x-ray beam mAs stands for milliamperage-seconds, which measures the number of electrons that travel across the x-ray tube. More electrons = more x-ray production, so changing mAs changes the quantity of x-rays in the beam.

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?

receptor exposure Receptor exposure, the amount of radiation that strikes the image receptor, has replaced the term density.

What is the main reason why beam filters are used in radiography?

reduce 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.

Which of the following occurs when the imaging plate or flat-panel detector is grossly overexposed?

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

Spatial resolution can be improved by which of the following?

selecting the small focal spot 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.

Which of the following will occur when the tube angle is decreased?

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.

what are the 2 types of distortion that can reduce the quality of a radiograph?

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

Which of the following is NOT considered one of the geometric factors that control spatial resolution?

size of the object OID, SID and focal spot size all affect the angle of the x-ray beam, which affects spatial resolution

The quality or energy of an x-ray beam is determined by which of the following?

spatial resolution

A flat-panel detector's detector element (DEL) size determines which of the following?

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 have the greatest effect on reducing motion on an abdomen radiograph?

suspend respiration Clear instructions to a cooperative patient to suspend respiration will reduce the risks of motion. Choosing high mA with a short exposure time may be the only choice when working with an uncooperative patient.

which of the following will occur whne the OID is decreased?

the image is closer to the actual size you can never get image to be equal to the object's actual size, but decrease the OID will produce an image closer

Which of the following statements would define spatial resolution in digital imaging?

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

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

unsharpness unsharpness is the correct name for te loss of sharpness