Mosby Random Test 1 Flashcards

1
Q

The process of scanning a phantom device of known density to improve the accuracy of CT attention measurement may be referred to as

A

calibration

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2
Q

after initiation of rapid bolus administration of an iodinated contrast agent, the hepatic venous phase of contrast enhancement occurs at approx ____

A

60-70 seconds

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3
Q

What are the 3 components of the uterine wall?

A
  1. perimetrium- outer layer of uterine wall
  2. myometrium- middle layer
  3. endometrium- innermost layer
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4
Q

The approx inherent filtration of the CT x-ray amounts to an aluminum equivalent of

A

3.0 mm

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5
Q

In a modern CT system, the total number of possible Hounsfield values that may be assigned to any one pixel is approx

A

4096

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6
Q

the degree of broadening, or point spread, that occurs along the z-axis during volumetric data acquisition

A

slice sensitivity profile (SSP)

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7
Q

What are the Agatston system ranges for coronary artery calcifications

A

minimal 1-10
mild 11-100
moderate 101-400
extensive >400

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8
Q

the system’s ability to differentiate objects with similar densities is called

A

contrast resolution

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9
Q

during CT angiography, images may be reconstructed using only the greatest density encounter along each ray. this type of image is called a(n)

A

MIP

maximum intensity projections

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10
Q

Severe reactions to IV iodinated contrast material occur in approx __% of all PTs

A

less than 1%

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11
Q

In PTs who are right handed, the posterior descending artery branches from the

A

right coronary artery

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12
Q

the abdominal aorta divides into the left and right common iliac arteries at approx what level?

A

L4

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13
Q

What does MTF stand for?

A

Modulation transfer function

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14
Q

the mathematical method of quantifying the spatial resolution of a CT scanner is ______

A

Modulation transfer function

MTF

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15
Q

Stop-motion capability of a CT system is referred to as

A

temporal resolution

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16
Q

quantifies the CT system’s ability to freeze motion and to provide an image free of blurring

A

temporal resolution

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17
Q

as a solid state CT detector measures transmitted radiation, it emits a proportional response in the form of a(n)

A

analog signal

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18
Q

examples of moderate adverse reactions to contrast are

A

severe vomiting, dyspnea, faintness, chest pain, and seizures
also known as intermediate

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19
Q

an abnormal connection between the intestine and an adjacent structure

A

fistula

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20
Q

two-dimensional representation a voxel

A

pixel

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21
Q

how do you calculate he dimensions of a voxel

A

pixel size X section width

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22
Q

term that refers to an excessive amount of nitrogenous materials in the blood and is a symptom of renal failure

A

azotemia

also known called uremia

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23
Q

the primary indication for CT perfusion of the brain is

A

acute stroke

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24
Q

ring artifacts are typically caused by

A

faulty detectors

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25
Q

the technique that provides the detail of the ouster potions of the 3D model while maintaining the typical CT detail of the lungs inside is called

A

surface rendering

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26
Q

the hallmark CT finding for focal nodular hyperplasia (FNH) of the liver is

A

central scar the remains hypodense after initial contrast agent administration

27
Q

the soft center of each intervertebral disk is called the

A

nucleus pulposus

28
Q

A CT image of a homogeneous material contains variations in CT number from pixel to pixel. This image is said to have

A

noise

29
Q

When doing a phantom, if an ROI measurement is made, the image noise corresponds to _______

A

standard deviation

30
Q

refers to the relationship between the x-ray tube and doctors during the scout

A

azimuth settings

31
Q

when choosing a window to display a CT image, the width defines the

A

range of pixel values that are included in an ROI

32
Q

In 1917, Austrian mathematician _____, proved that it was possible to reconstruct a 3D objects from the infinite set of all its projections.

A

J. Radon

33
Q

the pixel dimension may be calculated by

A

dividing the FOV by the matrix size. this two dimensional pixel size is then multiplied by the length of the voxel

34
Q

the role of CT during PET-CT is

A

anatomic location of tumor activity and attenuation correction of emitted photons

35
Q

the term beam hardening is used to describe what physical phenomena

A

increase in avg photon energy of a heterogenous x-ray beam

36
Q

propensity of a contrast agent to cause fluid to move from the extravascular space to the intravascular space is called

A

osmolality

37
Q

during CT colonography exams, tagged poop appears ___ on the image

A

white

38
Q

portion of the internal carotid artery as it enters the body skull and bifurcates into the anterior cerebral and middle cerebral arteries

A

carotid siphon

39
Q

differentiation between the duodenum and head of the pancreas is best accomplished with

A

oral contrast administered 30-45 minutes before scanning and placement of the PT in a right lateral decub before scanning

40
Q

coronal imaging through the paranasal sinuses are typically performed with the plane of imaging

A

perpendicular to the hard palate

41
Q

The ability of a CT scanner to image a small high-density object is controlled by the _______ of the scanner.

A

spatial resolution

42
Q

the type of compensating filter used at the x-ray tube of a CT scanner is called a

A

bow-tie filter

43
Q

occurs between the skull and the dura mater (outermost meningeal covering)

A

epidural hematoma

44
Q

occur between the dura mater and the arachnoid (inner layer of the meninges)

A

subdural

45
Q

the innermost layer of the meninges is called the

A

pia mater

46
Q

T/F the pt has the right to receive a copy of the diagnostic procedure performed

A

false

it’s at the discretion of the physicians involved

47
Q

the portion of the cardiac cycle in which the heart muscle is in relaxation is termed

A

diastole

48
Q

how is absorbed dose measured

A

grays (Gy)

49
Q

advantages of automatic CO insufflation for CT colongraphy include

A

better distention
lower risk of perf
improved pt comfort

50
Q

form of noise that occurs from an error during data acquisition or CT image display

A

artifact

51
Q

CT images that have been reconstructed from a portion of the data acquisition process in the hopes of reducing patient motion artifacts are called

A

segmented images

52
Q

a pixel may be defined as

A

a picture element

53
Q

the types of detectors used in CT are

A

gas ionization and scintillation

54
Q

newer MDCT systems utilized ______

A

solid-state scintillation

55
Q

the plasma half-life of IV administered iodinated contrast material is aprox

A

2 hours

56
Q

describes a device designed to remove scatter before it reaches the detector

A

pre-detector collimation

post-patient collimation

57
Q

a portion of a herniated intervertebral disk that has migrated from its normal position in called

A

a sequestered disk (or free fragment)

58
Q

in the cardiac cycle the term systole refers to

A

the contraction of heart muscle

59
Q

the component of the data acquisition system (DAS) responsible for strengthening the signal emitted from a detector is called the

A

preamplifier

60
Q

the iliac artery bifurcates into the external and internal iliac arteries at the level of

A

L5/S1

61
Q

the volume of a voxel may be calculated by multiplying the pixel dimension by the

A

section width

62
Q

the seminal vesicles are located

A

posterior to the bladder and anterior to the recutm

63
Q

the broadening of the slice sensitivity profile inherit to helical CT acquisition is said to negatively affect the

A

longitudinal spatial resolution

64
Q

Parts of a CT image containing abrupt changes in tissue density are electronically represented by

A

high spatial frequencies