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Comprehensive Radiology Review > Mosby Review > Flashcards

Flashcards in Mosby Review Deck (216)
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1

1004 - Early somatic effects of a substantial dose of ionizing radiation include:

1. Nausea

2. Epilation

3. Formation of solid malignant tumors

1 and 2 only

Although these two effects can occur early, it takes a high dose of radiation to cause them. Tumors are a long-term effect.

2

1006 - Which of the following must be increased to increase the quality of the x-ray beam?

1. Filtration

2. kVp

3. mAs

1 and 2 only

Both kVp and filtration affect the wavelength of the beam, and consequently the quality of the beam. Because either or both is increased, beam quality increases. mAs affect the intensity of the beam, that is, the number of rays.

3

1008 -  Which of the following are classified as controlled areas?
1. Radiographic room
2. Hallway
3. Unattended elevators

1 only 

In the radiographic room, personnel are instructed in the use of radiation and wear dosimeters. The other areas are generally populated only by the general public.

4

1010 - Protective shielding, which includes lead apron, curtain, and Bucky slot cover, provides:

maximum protection for the radiographer during fluoroscopy.

5

1011 - One of the purposes of the backup timer used with automatic exposure control (AEC) devices is to:

prevent excessive exposure to the patient

The backup timer will terminate the exposure when it goes beyond a safe level.

6

1012 - Two x-ray photons from the primary beam have interacted with atoms in a patient's body. After the interaction, one of the two photons was absorbed and the other photon scattered in a direction away from the image receptor. Both of these photons may now be classified as:

attenuated photons

Attenuation is any change in the beam as it traverses the patient. Hence both of these photons have been attenuated, one by photoelectric interaction and the other by Compton interaction

7

1016 - The age of the radiographer in years multiplied by 10 mSv may be used to determine:

cumulative exposure for occupationally exposed individuals

This calculation is used for lifetime accumulated dose for occupationally exposed individuals. In traditional units of measurement this would be the age of the radiographer multiplied by 1 rem.

8

1017 - Which of the following is not effective in reducing exposure to the patient during a diagnostic examination?

Decreasing kVp

For ALARA (as low as reasonably achievable) purposes, the lowest doses are high kVp, low mAs techniques.

9

1021 - Which of the following will not provide radiation protection for the radiographer?

OSL dosimeter

The dosimeter records the dose received, but does not contribute to Safety.

10

1025 - Which of the following is essential for protection of the radiographer who is performing a mobile radiographic examination?
1. Protective lead apron

2. Primary protective barrier

3. Six-foot exposure cord

1 and 3

A primary protective barrier is one that is struck by the primary beam. In this example, there is no need for a primary protective barrier. A lead apron should always be worn for mobile examinations. Maximum use of the 6-foot cord is essential

11

1027 - Which of the following devices should be used to reduce exposure to the mammary glands during a juvenile scoliosis examination?

Breast Shield

Although not used often, breast shields are very important to use for a scoliosis series.

12

1028 - A nonpregnant relative to a 2-year-old child volunteers to help restrain the child while AP and lateral radiographs are obtained in the upright position. This person should be provided with:

appropriate protective apparel

It is not necessary to monitor this person's dose, but all available protective apparel must be worn, and the individual should be kept out of the primary beam.

13

1046 - Computed radiography may be part of an integrated system of images and text called:

PACS

Picture archival and communication systems (PACS), the computer system used for digital imaging, is a digital communication network of many systems, not an imaging method in itself.

14

1053 - Which of the following grid errors will result in an image that shows normal IR exposure in the middle but decreased IR exposure on the sides and may follow removal and replacement of the grid?

Upside-down grid

This describes the error that occurs when a grid is positioned upside down during replacement. Grid-focus decentering results in the same type of problem on the radiograph, but this error is caused by a violation of the grid radius, not by incorrect positioning of the grid during replacement. An off-level grid will cause image-forming rays to be absorbed all across the radiographic field, with decreased density (cutoff) visible over the entire radiograph. Lateral decentering of the grid results in visible cutoff more to one side of the radiograph. Be sure to review grid errors.

15

1058 - When kVp is increased, which of the following happens?

Scale of contrast lengthens

An increase in kVp results in a lengthened scale of contrast because there is more uniform penetration of the part by shorter-wavelength rays. Decreased kVp results in increased contrast and decreased density. Recorded detail is not controlled by kVp.

16

1060 - The lowest contrast would be produced by which of the following sets of exposure factors?

A. 60 mAs, 80 kVp, 40-inch SID, 4-inch OID

B. 30 mAs, 92 kVp, 40-inch SID, 4-inch OID

C. 120 mAs, 92 kVp, 20-inch SID, 4-inch OID

D. 15 mAs, 100 kVp, 40-inch SID, 4-inch OID

D. 15 mAs, 100 kVp, 40-inch SID, 4-inch OID

kVp, rather than mAs or source-to-image distance (SID), is a controlling factor in the level of contrast. Higher kVp results in lower contrast; therefore, choice D, with the highest kVp, is correct.

17

1066 - mAs controls the:

quantity of x-rays produced at the anode

mAs controls the quantity of x-rays produced at the anode; this is proportional to the tube current. The quality of x-rays produced is controlled by kVp.

18

107 - This changes electric voltage and current into higher or lower values and operates on the principle of mutual induction, so it requires alternating current. This is called the:

transformer.

This describes the transformer, of which two are used in x-ray production. An autotransformer operates on the principle of self-induction. A rectifier converts AC to DC. The timer is used to regulate the duration of x-ray exposure.

19

1076 - kVp determines what aspect of the x-ray beam?

Penetrating ability

20

1079 - As the wavelength of the x-rays increases, penetrating ability

decreases

The relationship between wavelength and penetrating ability is inverse; longer-wavelength rays have decreased penetrating ability.

21

1080 - As the wavelength of the x-rays decreases, penetrating ability:

increases

The relationship between wavelength and penetrating ability is inverse; shorter-wavelength rays have increased penetrating ability.

22

1087 - The grid conversion factor for a 12:1 grid is:

5

For a 12:1 grid, multiply mAs by 5. Choice A is the grid conversion factor for a 5:1 grid; choice B, for an 8:1 grid; and choice D, for a 16:1 grid.

23

1093 - Differences in adjacent densities on a radiograph defines:

contrast

This is the simple definition of contrast. Density is the amount of blackness on a given area of a radiograph. Detail is the sharpness with which anatomic structures are displayed on the image receptor. Distortion is any misrepresentation that alters the size or shape of an anatomic structure on the image receptor.

24

1095 - An image with few gray tones, mainly black and white, is referred to as:

high contrast

A high-contrast image is mainly black and white, with few gray tones. High contrast is also known as a short-scale contrast.

25

1098 - An image with many gray tones is referred to as:

long-scale contrast.

An image with many gray tones is said to have long-scale contrast, also known as low, not high, contrast.

26

1105 - The portion of contrast represented by the anatomy and physiology is:

Subject contrast

is the portion of contrast that is inherent to the patient; that is, it already exists by nature of the patient's anatomy, physiology, and pathology.

27

1108 - Spatial resolution may also be known as:

1. sharpness.

2. definition.

3. image resolution

1, 2 and 3

Spatial resolution is also known as detail sharpness, definition, or image resolution. All of these terms refer to the same thing.

28

1124 - Magnification may be caused by:

short SOD

Short source-to-object distance (SOD), excessive (not short) object-to-image distance (OID), and insufficient (not long) SID can all cause magnification. Focal-spot size is a factor influencing recorded detail, not distortion. Be sure to keep all of these factors straight.

29

1140 - A focused grid must be used with specific ranges of:

SID

A focused grid must be used within specific ranges of source-to-image distance (SID). The distance between the source of radiation and the image receptor must be within this range so that the divergence of the beam coincides with angle of the strips.

30

1141 - The SID at which a focused grid must be used is called:

grid radius.

The source-to-image distance (SID) at which a focused grid must be used is called the grid radius (also called focal distance or focal range). Violating this distance will cause grid cutoff.