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Tests & Measures Exam #2 > Medical Imaging > Flashcards

Medical Imaging Flashcards

1
Q

Why do Physical Therapists need to know how to view x-rays?

A
  • more comprehensive evaluation is obtained
  • PT will look at an x-ray for different reasons than a radiologist (alignment, fracture configuration, etc.)
  • APTA seeks to allow PT’s to be able to order musculoskeletal radiographs
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2
Q

Who discovered X-rays?

A

Wilhelm Roentgen in 1895

Marie Curie discovered radioactive elements in 1898

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3
Q

X-Ray Wavelength

A
  • Shorter the wavelength, the higher the energy and greater penetration of dense substances
  • Produces ionization of atoms and molecules (loss of electrons)
  • Results in a gray image on the radiograph
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4
Q

Production of a Radiograph

A

An x-ray beam source

A patient

A x-ray film or image receptor

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5
Q

X-Ray Tube

A

Cathode (negative) and anode (positive) enclosed in glass envelope which maintains a vacuum.

High voltage current passes through a vacuum

Electrons are driven from cathode and strike the anode

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6
Q

Attenuation

A
  • Gradual loss of intensity as a result of passing through a medium
  • How much attenuation depends on the density of the tissue
  • Air is darker, bone is whiter
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7
Q

Radiodensity

A
  • Refers to the amount of blackening on the radiograph
  • Determines how much radiation will be absorbed

1) Radiolucent
2) Radiopague

-NOT photographs, but actually densographs

75% film-reading is knowledge of anatomy

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8
Q

Radiolucent

A
  • Does not absorb much radiation
  • Appears dark grey or black
    ex) Air and Fat
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9
Q

Radiopaque

A
  • Absorbs a lot of radiation
  • Appears more white
    ex) Metal and bone and teeth
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10
Q

Radiodensity determined by…

A
  1. Atomic weight
    - Greater atomic weight = Greater radiodensity
    - Lead used as a shielding device (high atomic weight)
  2. Thickness of the object
    - Thick object = more radiation absorbed = more radiodense
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11
Q

Density of tissues

A
  • Greater density of tissue = less penetration of the x-rays
  • Higher density tissues appear white
    ex) Flat wedge vs. Upright wedge
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12
Q

Third Dimension Perception

A
  • Need more than one radiograph to get information about a structure
  • 2 projections are taken at 90° orientation (Minimizes 2D Error!)
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13
Q

Body Positioning

A
  • Specific protocol for every body part to give best visualization w/ lowest # of radiographs
  • Routine views: AP, lateral, & oblique
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14
Q

Anterioposterior (AP)

A

-Whiplash pts. to make sure Co & C2 are still intact

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15
Q

Posteroanterior (PA)

A

-Lung dysfunction

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16
Q

Tangetial

A

-Patella & Femur

aka “Sunrise” View

17
Q

Axial

A

-Straight down from the top of patient

18
Q

Viewing Radiographs

A

Place film on view box as if the viewer (you) are the x-ray beam

Consider the area x-rayed

Consider this area must be closest to the film to get an accurate picture

Consider the x-rays must pass through the person to get to the film

19
Q

Film Markers

A 
Patient ID
Anatomical Side Markers (L/R)
IR
ER
WB
Erect, upright
Decubitus (laying down)
INSP/EXP
Radiographers Initials
20
Q

Image Quality Factors

A
  • Controlled by varying the milliamperage (mA) & exposure time
  • Distance of body part from beam affects this as well
  • Underexposure: beam not on long enough
  • Overexposure: beam on too long (more intensity)
21
Q

Radiographic Contrast

A
  • Greater variation in anatomy = higher contrast
  • Chest = low contrast
  • Skeleton = high contrast
22
Q

Contrast

A
  • Controlled by: kilovoltage (kVp)
  • Higher kVp = greater energy of beam= greater penetration = more uniform picture = less variation in tissue absorption

From this, a low contrast radiograph occurs

23
Q

General Rule

A

Use the highest kVp and lowest mA

Will yield the best diagnostic information necessary for patient intervention

24
Q

Radiographic Distortion

A

Difference between the actual object and it’s recorded image

Radiographs are 30% larger than actual structure

25
Q

Shape Distortion

A

Unequal magnification of structure

Central ray accurate

More inclined the structure = greater distortion

26
Q

Size Distortion

A

Enlargement
Elongation
Shortening

Causes: Beam Source, Patient, Film, Alignment of the Body, Position of the Central Ray

27
Q

Superimposition

A
  • Anatomic structures are stacked on one another so the x-ray beam must penetrate multiple structures before arriving at the film plate.
  • May create artificial lines, shapes, and forms that appear unrecognizable or pathological in nature.
  • Again, 2-D representation of a 3-D structure
28
Q

Evaluating Plain Film Radiographs

A

ABCD’S

Alignment
Bone Density
Cartilage Space
Disc Space
Soft Tissue
29
Q

ABCD’S: Alignment

A
  • General structural architecture
  • General contour of bone
  • Alignment of bone relative to adjacent bones
30
Q

ABCD’S: Bone Density

A
  • General bone density
  • Texture abnormalities
  • Local bone density changes
    ex) Osteoporosis
31
Q

ABCD’S: Cartilage Space

A
  • Joint space width
  • Subchondral bone
  • Epiphyseal plates: can tell their age by what age the plates fuse together in life
32
Q

ABCD’S: Disc Space

A

-Only when valuating the cervical, thoracic, or lumbar spine

33
Q

ABCD’S: Soft Tissue

A
  • Muscles
  • Fat pads
  • Joint capsules
  • Periostreum
  • Mescellaneous soft tissue findings
34
Q

Contrast-Enhanced Radiographs

A
  • Radiolucent: Air

- Radiopaque: Barium sulfate or Iodide

Tests & Measures Exam #2 (7 decks)

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