Essential Radiography Terms: Patient Dose & Distortion Study Set

The conscientious radiographer can reduce the patient dose by at least ____ in most examinations by choosing appropriate exposure factors.

a. 100 percent

b. 75 percent

c. 50 percent

d. 25 percent

c. 50 percent

The maximum exposure received by the patient is at the

a. anatomy of deepest penetration.

b. area of interest.

c. gonads.

d. skin entrance to the body.

d. skin entrance to the body.

Which of the following radiographic procedures delivers the lowest entrance skin exposure?

a. hip

b. pelvis

c. lumbar spine

d. elbow

d. elbow

The Food and Drug Administration (FDA) sets an entrance skin exposure limit of ____ R/min for fluoroscopic systems in the United States.

a. 11.5

b. 20.2

c. 35.1

d. 42.7

a. 11.5

The radiation intensity from a diagnostic x-ray unit will vary in a/an

a. direct relationship with mAs.

b. direct relationship with the square of the kVp.

c. inverse relationship with the square of the distance.

d. all of the above.

d. all of the above.

To reduce patient exposure, the __________ consistent with image quality should be selected.

a. highest mAs

b. highest kVp

c. shortest distance

d. highest mAs and lowest kVp

b. highest kVp

Which x-ray generator will substantially decrease the patient entrance skin exposure?

a. single-phase, unrectified

b. single phase, rectified

c. three-phase, 6-pulse

d. three-phase, 12-pulse

d. three-phase, 12-pulse

Patient entrance skin exposure decreases as

a. source-to-image receptor distance (SID) decreases.

b. SID increases.

c. source-to-object distance (SOD) decreases.

d. object-to-image receptor distance (OID) increases.

b. SID increases.

When the primary-beam field size ____, the patient exposure ____.

a. increases; decreases

b. decreases; decreases

c. decreases; increases

d. increases; is unchanged

b. decreases; decreases

Each of the following is a type of gonad shield EXCEPT

a. flat contact.

b. shadow.

c. collimator.

d. shaped contact.

c. collimator.

The use of a radiographic grid will

a. decrease patient exposure.

b. increase patient exposure.

c. have no effect on patient exposure.

d. increase kVp.

b. increase patient exposure.

An effective method of reducing patient exposure is to use

a. reduced x-ray beam filtration.

b. a medium-speed image receptor.

c. a grid.

d. a high-speed image receptor.

d. a high-speed image receptor.

Entrance skin exposure is considered a/an ____ exposure.

a. maximum

b. minimum

c. average

d. composite

a. maximum

Skull radiography routinely includes a posterior-anterior (PA) projection. This is intended to

a. reduce dose to the lens of the eye.

b. reduce dose to the cerebellum.

c. reduce dose to the paranasal sinuses.

d. reduce dose to the thyroid.

a. reduce dose to the lens of the eye.

The approximate entrance skin exposure (ESE) for a radiographic study taken at 90 kVp and 23 mAs is

a. 57.5 mR.

b. 67 mR.

c. 103.5 mR.

d. 2.7 R.

c. 103.5 mR.

When patient SID or SOD increases,

a. patient ESE decreases.

b. patient ESE increases.

c. patient ESE increases by the square of the distance.

d. there is no relationship between ESE and distance.

a. patient ESE decreases.

When comparing ESE and actual dose to an area of interest,

a. actual dose is higher than ESE.

b. ESE and actual are equal.

c. the actual dose and ESE are inverse.

d. actual dose is lower than ESE.

d. actual dose is lower than ESE.

In an effort to reduce dose, the recommended SID for routine radiography is

a. 36-38 inches.

b. 40-42 inches.

c. 44-48 inches.

d. 56 inches.

c. 44-48 inches.

In an effort to minimize patient dose,

a. longer SOD's should be used.

b. high-speed anode rotation should be used.

c. beam filtration should be minimum.

d. lower kVp's should be used to reduce scatter.

a. longer SOD's should be used.

Of the choices below, the combination of exposure factors that would minimize patient dose would be

a. 24 mAs, 80 kVp, 8"x10" field size, 44" SID

b. 12 mAs, 92 kVp, 8"x10" field size, 40" SID

c. 6 mAs, 106 kVp, 8"x10" field size, 44" SID

d. 24 mAs, 80 kVp, 10"x12" field size, 40" SID

c. 6 mAs, 106 kVp, 8"x10" field size, 44" SID

Entrance skin exposure (ESE) is calculated

a. at the minimum SOD

b. on the underside of the collimator assembly

c. at the maximum kVp of the generator

d. with no beam filtration in place

a. at the minimum SOD

Size distortion in radiography can be ____ only

magnification

Distortion is controlled by (3)

SID, OID, radiographic distances

As size distortion decreases, the resolution of recorded detail

increase

The ____ the SID, the ____ the degree of magnification.

greater; smaller

Examinations of body parts with a large inherent OID warrant a ____ whenever possible.

large SID

As OID increases and SID remains constant, entrance skin exposure (ESE)

increases

Large patients receive a greater exposure than small patients because their

a.

SOD is decreased.

b.

OID is increased.

c.

entrance skin surface is closer to the source.

d.

all of the above.

d. all of the above

The magnification factor for a radiographic procedure is calculated at 1.25. It may be assumed that there is a ____ magnification of the object size.

125%

When the position of the patient is reversed, the direction of the tube angle must be ____ to maintain the relationship.

reversed

Because the x-ray beam is divergent

minification is impossible

X-ray tube angulations inherently

Change the SID and introduce magnification to some degree

In order to achieve a true SID of 40" with an x-ray tube angle of 30 degrees, the overhead scale should read

34.6 inches

Performing a routine chest radiograph in the anterioposterior (AP) projection will

produce improved resolution of the T-spine

A renal calculus that measures 0.2 mm in size

a.

cannot be visualized with an effective focal spot of 0.5 mm focal spot due to penumbral overlap.

b.

is best seen with magnification and a large focal spot.

c.

most likely will be visualized with a small radiographic tube angle using a large target angle.

d.

all of the above.

a.

cannot be visualized with an effective focal spot of 0.5 mm focal spot due to penumbral overlap.

Opening up the intervertebral joints of the cervical spine would best be accomplished with

Patient in AP with 40" SID

With digital image receptors (CR/DR)

a.

the geometric factors of distortion do not apply.

b.

EI#s are inaccurate due to elongation distortion.

c.

computer postprocessing corrects for shape distortion.

d.

none of the above.

d. none of the above

A radiographic magnification factor(MF) of −.15 indicates

a.

the object size and image size are nearly equal.

b.

nothing, since negative MF is not possible.

c.

the image size is smaller than the object size.

d.

a change in OID is needed.

nothing, since negative MF is not possible.

Enlargement of a digital radiographic image on the review monitor, is an example of

electronic magnification

Positioning patients is intended to eliminate anatomical superimposition, from a radiologist perspective. To optimize image resolution it is best to

a.

keep the central ray and receptor perpendicular to the patient's anatomy, and rotate the part.

Shape distortion is calculated

a.

as the ratio of SID and SOD.

b.

using the tube angle and OID.

c.

automatically in the computer postprocessing.

d.

none of the above.

d. none of the above

best seen with the patient supine

kidneys

MF

SID/SOD

SID/MF

SOD

The incident beam is significantly altered as it passes through the patient.

a. True

b. False

a. True

The beam emitted from the patient contains diagnostic information.

a. True

b. False

a. True

Subject density refers to the impact the patient has on the resulting image receptor exposure.

a. True

b. False

a. True

Subject distortion occurs naturally.

a. True

b. False

a. True

Accurate patient positioning has very little impact upon subject distortion.

a. True

b. False

b. False

Shape distortion can be the result of a patient's body habitus.

a. True

b. False

a. True

The patient has an impact on all the properties that affect radiographic quality.

a. True

b. False

a. True

The relationship between radiographic quality and the patient is termed image receptor exposure.

a. True

b. False

b. False

The relationship between image receptor exposure and the patient is termed subject density.

a. True

b. False

a. True

The relationship between radiographic contrast and the patient is termed subject contrast.

a. True

b. False

a. True

X-rays are attenuated

a. exponentially.

b. linearly.

c. based upon the direction of the central ray.

d. as a function of mAs.

a. exponentially.

The ____ the body part, the ____ the attenuation.

a. more dense; less

b. thinner; greater

c. thicker; less

d. thicker; greater

d. thicker; greater

Which of the following elements would attenuate a greater percentage of the x-ray beam?

a. hydrogen

b. calcium

c. oxygen

d. carbon

b. calcium (bone is made up of calcium)

Which of the following elements would attenuate a lesser percentage of the x-ray beam?

a. phosphorus

b. barium

c. iron

d. carbon

d. carbon

Attenuation is greater for elements with more ____ with which the photons may interact.

a. electrons

b. protons

c. neutrons

d. positrons

a. electrons

. Bone produces less image receptor ____ because it attenuates the x-ray beam more than soft tissue does.

a. detail

b. contrast

c. exposure

d. distortion

c. exposure

For the same exposure intensity, air produces

a. less exposure intensity to the receptor than other materials.

b. greater exposure intensity to the receptor than other materials.

c. the same exposure intensity to the receptor as other materials.

d. less exposure intensity due to the high degree of photoelectric absorption.

b. greater exposure intensity to the receptor than other materials.

Which of the following is the greatest attenuator of the x-ray beam?

a. pneumonic lung

b. pericardial fat

c. psoas muscle

d. perirenal fat

c. psoas muscle (best to worst attenuators: bone, muscle, fat, air)

Which of the following is the least attenuator of the x-ray beam?

a. aerated lung

b. pericardial fat

c. psoas muscle

d. perirenal fat

a. aerated lung

As subject density ____, image receptor exposure ____.

a. increases; remains the same

b. decreases; decreases

c. increases; increases

d. increases; decreases

d. increases; decreases

The degree of differential absorption is referred to as

a. material contrast.

b. subject contrast.

c. image receptor exposure.

d. subject density.

b. subject contrast.

The recorded detail of a structure is dependent on

a. its position within the body.

b. the placement of the body in relationship to the film.

c. the size of the part.

d. all of the above.

d. all of the above.

The recorded detail of a structure is dependent on

a. its position within the body.

b. the placement of the body in relationship to the film.

c. the size of the part.

d. all of the above.

d. all of the above.

Distortion is the misrepresentation of the ____ of an object.

a. length

b. width

c. shape

d. all of the above

d. all of the above

The primary source of radiation exposure for occupational personnel is due to

a. Compton scatter.

b. classical scatter.

c. photoelectric effect.

d. coherent scatter.

a. Compton scatter.

Because of its tissue composition, the human breast

a. is a high subject contrast structure.

b. yields a high contrast image.

c. is a low subject contrast structure.

d. is considered a high-attenuator of x-ray energy.

c. is a low subject contrast structure.

With the patient in the posterior-anterior projection of the abdomen (prone),

a. renal stones would have high resolution.

b. the lumbar vertebrae would have high resolution.

c. the psoas muscles would have high resolution.

d. the anterior ribs would have high resolution.

d. the anterior ribs would have high resolution.

All of the following refer to patient factors contributing to image quality EXCEPT

a. receptor contrast.

b. subject detail.

c. subject contrast.

d. tissue density.

a. receptor contrast.

With the perfusion of iodinated contrast material into the kidneys,

a. a greater degree of Compton scatter is produced from the kidneys.

b. the kidneys will demonstrate lower subject contrast.

c. a greater degree of photoelectric interactions will occur in the kidneys.

d. there is less distinction between kidney structures.

c. a greater degree of photoelectric interactions will occur in the kidneys.

All of the following are related EXCEPT

a. air.

b. barium.

c. fat.

d. bone.

b. barium.

All of the following are true of Compton scatter EXCEPT:

a. It contributes no meaningful information the final image.

b. Its production increases as tissue density increases.

c. It is a significant contributor to occupational radiation exposure.

d. It is not a factor of exposure technique selection.

b. Its production increases as tissue density increases.

Clinically speaking from a diagnostic viewpoint, the only useful radiation exposure is that radiation

a. absorbed in the patient.

b. produced from Compton interactions.

c. detected by the receptor.

d. that traverses through the grid.

c. detected by the receptor.

With a patient in the supine position, the anatomical structure that would demonstrate the greatest subject detail would be the

a. nasal bones.

b. sternum.

c. vertebral pedicles.

d. spinous processes.

d. spinous processes.

All of the following pathological conditions would warrant an increase in exposure EXCEPT:

a. anorexia nervosa

b. osteopetrosis

c. ascites

d. bronchiectasis

a. anorexia nervosa

For most additive pathologies, an increase of _______ in kVp, is generally enough to compensate for the added attenuation.

a. 5%-15%

b. 20%-25%

c. 33%

d. none of the above

a. 5%-15%

When performing a KUB on a patient with ascites, using AEC and the proper detector combination, the responsible radiographer would:

a. decrease the kVp to reduce the amount of Compton

b. take a scout image using manual techniques, to establish a back-up time for the AEC

c. allow the AEC system to adjust the exposure for the patient condition

d. immediately increase the AEC sensitivity to +2

c. allow the AEC system to adjust the exposure for the patient condition

The primary purpose of using a radiographic grid is to

a. intercept remnant radiation.

b. remove undesired primary photons.

c. remove a percentage of scatter photons.

d. decrease skin exposure to patients.

c. remove a percentage of scatter photons.

A radiographic grid absorbs

a. primary radiation.

b. all scatter and secondary electrons.

c. scatter electrons.

d. scatter radiation.

d. scatter radiation.

When an x-ray beam passes through the body,

a. it will pass through the body unaffected.

b. it will be absorbed by the body.

c. it will interact with the body and change direction.

d. all of the above.

d. all of the above.

Photons that pass through the body unaffected produce

a. scatter radiation.

b. radiographic contrast.

c. secondary radiation.

d. radiographic distortion.

b. radiographic contrast.

Photon absorption within the body occurs as the result of

a. Compton interactions.

b. characteristic interactions.

c. photoelectric interactions.

d. Bremsstrahlung interactions.

c. photoelectric interactions.

The atomic interaction that produces scatter radiation is

a. Bremsstrahlung.

b. photoelectric.

c. Compton.

d. photodisintegration.

c. Compton.

As kVp increases,

a. secondary radiation increases.

b. scatter radiation increases.

c. image receptor exposure increases.

d. all of the above.

d. all of the above.

The greatest source of scatter during a radiographic examination is the

a. patient.

b. table top material.

c. image receptor.

d. AEC detector.

a. patient.

The amount of scatter radiation produced increases with a/an

a. increase in patient thickness.

b. larger field size.

c. decrease in atomic number of the tissue.

d. all of the above.

d. all of the above.

As a general rule, a radiographic grid is employed

a. for procedures below 60 kVp.

b. for part thicknesses above 10 cm.

c. for pediatric studies to improve contrast.

d. in order to improve positioning latitude.

b. for part thicknesses above 10 cm.

The use of a radiographic grid requires

a. attention to central ray angulation.

b. an awareness of the SID.

c. an increase in exposure factors.

d. all of the above.

d. all of the above.

Which statement about radiographic grids is incorrect?

a. Grids may have grid strips running in perpendicular directions.

b. A grid is a series of lead strips that alternate with radiopaque interspace strips.

c. The radiopaque strips are typically made of thin lead.

d. The interspace strips are usually made of aluminum.

b. A grid is a series of lead strips that alternate with radiopaque interspace strips.

The purpose of moving the grid during the radiographic exposure is to

a. activate the digital detector.

b. remove unwanted contrast.

c. blur out the radiopaque strips.

d. activate the AEC detectors.

c. blur out the radiopaque strips.

The radiopaque strips

a. absorb scatter.

b. are made of radiodense material.

c. have a high atomic number.

d. all of the above.

d. all of the above.

The ratio of the height of the lead strips to the distance between the lead strips is the grid

a. selectivity.

b. ratio.

c. frequency.

d. speed.

b. ratio.

Which grid would have the greatest distance between lead strips?

a. 15:1

b. 12:1

c. 8:1

d. 6:1

d. 6:1

Which grid would most effectively reduce scatter?

a. 6:1

b. 8:1

c. 12:1

d. 15:1

d. 15:1

The number of grid lines per inch is the grid

a. focus.

b. ratio.

c. frequency

d. speed.

c. frequency

As the lead content of a grid increases,

a. the contrast improvement factor decreases.

b. the ability of the grid to remove scatter increases.

c. the K-factor decreases.

d. exposure to the image receptor increases.

b. the ability of the grid to remove scatter increases.

When the lead strips run in a single direction in a grid, the grid pattern is described as

a. criss-cross.

b. linear.

c. cross-hatched.

d. Tangential.

b. linear.