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Radiology > Lecture 1: Be a radiology tech in 2 years > Flashcards

Lecture 1: Be a radiology tech in 2 years Flashcards

1
Q

Bayesian Analysis plus clinical example

A

pretest probability affects post-test probability. If you have a strong clinical suspicion of fracture but XR is negative, request further testing.

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2
Q

x ray attenuation: definition, function of what 3 variables?

A

X ray photons are “absorbed” by matter; amount of attenuation depends on: thickness, density of material (function of atomic number), and x ray beam kVp (peak kilovoltage/energy)

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3
Q

Xray: does an object of high density appear darker or brighter?

A

Brighter

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4
Q

X ray radiolucency: define

A

Allows x ray to pass through without absorption, penetrates most easily. Appears dark on XR

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5
Q

X ray radiodensity: define

A

Absorbs x ray beams, appears bright on XR

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6
Q

Name a highly radiolucent material

A

Air, fat

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7
Q

Name a material class with high radiodensity

A

heavy metal

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8
Q

Which is more radiolucent: bone or water?

A

water

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9
Q

Which is more radiolucent: contrast or bone?

A

Bone

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10
Q

Which is more radiodense: contrast or bone?

A

contrast

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11
Q

Which is more radiodense: bone or fat?

A

bone

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12
Q

PACS-define

A

Picture archiving and communication system-a medical imaging technology which provides economical storage of and convenient access to images from multiple modalities (source machine types).

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13
Q

DICOM-define

A

Digital Imaging and Communications in Medicine (DICOM) is a standard for handling, storing, printing, and transmitting information in medical imaging. It includes a file format definition and a network communications protocol.

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14
Q

RIS-define

A

A radiology information system (RIS) is a computerized database used by radiology departments to store, manipulate, and distribute patient radiological data and imagery. The system generally consists of patient tracking and scheduling, result reporting and image tracking capabilities.

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15
Q

HIS-define

A

A hospital information system (HIS) is an element of health informatics that focuses mainly on the administrational needs of hospitals

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16
Q

satisfaction of search

A

phenomenon in which the detection of one radiographic finding interferes with that of others; just because you found something doesn’t mean you found everything

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17
Q

Hounsfield Units: what modality of imaging? Define.

A

Measure of attenuation of x ray beam in CT scan

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18
Q

Hounsfield units: reference values for water and air

A

water=0, air=-1000

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19
Q

Hounsfeld units: bone, blood, muscle, fat

A

bone=1000, blood=40, muscle=10-40, fat=-50–100

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20
Q

CT scan: 4 types of artifact

A

Motion, metal, partial volume averaging, beam hardening artifact

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21
Q

CT scan motion artifact: example

A

Cardiac motion (less of an issue with today’s fast multislice scanners)

22
Q

CT scan: Partial volume averaging artifact

A

More of an issue with thicker slices; a substance that occupies several voxels will get “averaged” and look larger and blurrier than it would if it was centered in 1 voxel

23
Q

CT scan: metal artifact

A

Radiodense structures limits evaluation of adjacent structures, can be minimized by increasing kvp

24
Q

CT scan: beam hardening artifact

A

Appears like an area of radiolucency (very dark area on scan), low energy portion of the spectrum filtered out,

25
Q

CT contrast

A

Makes structures more radiodense, therefore brighter and easier to discern on scan. Administered orally, rectally, or intravenously.

26
Q

CT contrast risks

A

allergic reactions (mild-rash; severe-HOTN, laryngeal swelling, CV collapse); renal failure (creatinine >1,5-1.8); contrast extravasation-contrast leaks out of a ruptured vessel

27
Q

CT scan for pts on dialysis

A

IV CT contrast OK but not MRI contrast

28
Q

CT scan advantages

A

fast, high resolution, can be reformatted after scan into 3D image in any plane (multiplanar reformatting MPR)

29
Q

CT scan disadvantages

A

artifact, risks of IV contrast, RADIATION

30
Q

ionizing radiation-define and risk

A

electromagnetic waves with the energy to knock an outer shell electron out of valence shell (creates an ion); can result in damage to DNA

31
Q

ALARA

A

as low as reasonably achievable

32
Q

radiation safety compromise

A

between dose and quality of image

33
Q

Inverse Square Law of Radiation and Distance

A

radiation dose decreases as a function of the distance from the source squared

34
Q

Linear No Threshold Model: assumption/stochastic effects

A

risk is directly proportional to the dose; sum of very small exposures have the same effect as one large exposure (e.g. 1 CT scan=100 XRs)

35
Q

T1 Pulse sequence: behavior in water, fat

A

Dark in water, bright fat

36
Q

T2 Pulse sequence: behavior in water, fat

A

Water and fat bright

37
Q

PD pulse sequence: behavior in water, fat

A

Water intermediate, fat bright

38
Q

STIR pulse sequence: behavior in water, fat

A

water bright, fat dark

39
Q

MRI contrast: substance used, how administered

A

Gandolinium, intravenous contrast, bright on imaging

40
Q

CT scan contrast:

A

Iodinated

41
Q

Risks of gandolinium

A

Nephrogenic systemic fibrosis: occurs in pts with severe kidney failure or dialysis; EGFR 30-60 borderline, Gandolinium absolutely contraindicated EGFR <30

42
Q

Gandolinium absolute contraindications

A

Pregnant women, pts with EGFR <30

43
Q

MRI advantages

A

no ionizing radiation, lots of soft tissue information, sensitive to contrast, 3D data, can get angiogramswithout contrast, gandolinium not as allergenic

44
Q

MRI disadvantages

A

long scan times, motion artifact, expensive, contraindications, claustrophobia

45
Q

MRI safety: zones

A

Magnet is always on at full strength; zones: 1-public accessible; 2-supervised access, screening by MRI staff; 3-restricted area, prescreened pts and staff only; 4-magnet room

46
Q

MRI dangers

A

missile effect, field interaction with medical devices, torque on implanted devices, acoustic noise, thermal effect from absorbed RF energy and induced currents, cryogens, gandolinium risks

47
Q

MRI contraindications

A

pacemaker, nonremoveable cochlear implant, metal in the eye, noncompatible aneurysm clip, implanted electronic devices-insulin pumps, neurostimulator units, etc

48
Q

MRI possible problems

A

metallic stents, previous projectile injury, penile implants, artificial limbs, tattoos, medication patches with metal, claustrophobia

49
Q

Ultrasound benefits

A

cheap, no ionizing radiation, real time, good soft tissue detail, no artifact from metal, vascular imaging, good for MR incompatible patients

50
Q

US drawbacks

A

limited penetration, operator dependent, doesn’t penetrate air or metal

51
Q

US uses

A

rotator cuff integrity, baby hips, tendon integrity, joint effusions, guidance for interventional procedures

Radiology (5 decks)

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