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Radiography > Quiz 1 > Flashcards

Quiz 1 Flashcards

1
Q

Radiology

X-Ray

Photons

A

Branch of medicine aiding in visulizing interior of body

Electromagnetic Radiation

  1. Particles
  2. Waves

Bundles of energy in x-ray beam. Rides the wave. Has no mass or electrical charge

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2
Q

Electromagnetic spectrum

A

Radiowaves - Microwaves - Infrared - Visible Light - Ultraviolet - X-rays - Gamma rays

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3
Q

X-ray properties

A
  1. Invisble
  2. cannot be felt
  3. type of electromagnetic radiation
  4. interacts with electrons
  5. penetrates matter
  6. ionizes atoms
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4
Q

Wavelength vs Frequency

A

Wavelength: Distance from point A to point B

Frequency: cycles per second

Longer the wavelength = Frequency decreases

Shorter the wavelength = Frequency increases

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5
Q

X-ray tube

A

Anode:

  • Positive
  • (Tungsten target)
  • Temp. can exceed 1000 C. Use of copper base and oil to conduct heat away

Types:

  • Stationary: Low xray production, can’t take a lot of heat.
  • Rotating: Disk shape

Cathode:

  • Negative
  • (Filament)

Cathode + Anode = 99% Heat & 1% X ray

** Cathode side x ray beam is more powerful. Place thicker body parts on cathode side.**

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6
Q

Waves

Absorption

A

Longer the wavelength = Frequency decreases = has less energy = travels shorter/does not penetrate well

Shorter the wavelength = Frequency increases = has more energy = travels further/penetrates deeper

Absorption varies on:

  • Atomic number
  • Density of the object
  • Enerrgy of the x ray
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7
Q

Postive vs Negative

A

Positive

Invisible images that is made visible via chemical or digital processing

Negative

Damaging and altering living tissue via:

  • Excitiation - Photon strikes and excites electron in orbit causing it to move to a higher orbit causing biological changes
  • Ionization - Photon displaces an electron in orbit by striking it and also causing biological changes.
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8
Q

Wilhelm Conrad Roentgen

A

Credited in discovering X rays

Used vaccum tubes to pass electrons from cathode to anode

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9
Q

Milliamperage (mA)

Kilovoltage (KVP)

Santes’ rule

A

mA

  • Milliamperes
  • measures the circuit that heats up the filament
  • measures electric current

mA x 1/sec = mAs (milliamperage-seconds)

increase in mA allows shorter exposure time

KVP

  • Kilovoltage peak
  • mA is boosted by KVP to produce enough speed
  • Measures pressure

Santes’ Rule: used to estimate KVP

(2 x thickness cm) + 40 = KVP

**increase kVP by 10 allows you to half the mAs or maintain mA with half the exposure time**

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10
Q

Focal Spot

A

Hits the target area

Smaller the focal point = Sharper the picture

** too small and it can’t stand the heat**

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11
Q

Failures

Electrical Components

A

Failures

Cathode Failure

  • Filament evaporates if exposed to too much heat and time of use
  • Does not get hot until you hit “pre exposure” button
  • Turn off machine if not using.
  • mA meter doesn’t move = filament is gone

Anode Bearings

  • holding “pre-exposure” button down to long can overheat bearings
  • Unusual noise is a problem
  • no noise is sign of failed bearings

Target Damage

  • Use low mA settings and high KVP to keep heat low.

Glass Envelope

  • If air gets into

Electrical Components

High Voltage Circuits

Provides High electrical potential to move electrons from cathode to anode

  • Autotransformer
  • Step up transformers

Low Voltage Circuits

Provides electricity to heat filament

  • Step down transformers
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12
Q

Collimator

A

Prevents scatter radiation

Restricts beams

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13
Q

Retification

A

Changes alternating to Direct current
so that constant electron flow is maintained

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14
Q

Control Panel

A
  • On/Off button
  • Voltmeter
  • Kilovolt selector
  • Milliampere selector
  • Timer
  • Exposure button
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15
Q

Radiation Damages & Exposure

A

Somatic

Damges to body tissue within person’s lifetime

Genetic

Damage to reporductive cells via genetic mutation

Hereditary damages

MPD (Maximum Permissible Doses)

ALARA (As Low As Reasonably Achievable)

Measured in Grays. 1 Gys = 100 rads (Radiation absorbed doses)

Absorbed Dose X Quality factor = Sieverts (Sv)

  • Occupational - 0.05 Sv/yr
  • Non Occ. - 0.005 Sv/yr

Use Lead Apron: 0.5mm Lead

Use 2.5 mm aluminum filter b/t window and collimator

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16
Q

Vet Tech role

A

Knowledge of

  • x ray machine
  • film
  • cassettes
  • film processor
  • Safety requirments
  • Proper techniques for production of diagnostic radiograph
  • Evaluation of diagnostic quality
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17
Q

Rapidly dividing cells

A

Reporductive cells

Epithelial cells

Lymphoid cells

Hemopoietic

Fetal tissues

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18
Q

Density vs Contrast

A

Density

  • Degree of blackness
  • # of x rays reaching the film
  • penetrating power of radiation
  • development time/temp
  • High mAs = High density
  • High kVP = High density

High tissue thickness = less xrays reaching film = less density

Too Dark:

Decrease mAs: 30%-50%

Decrease kVp: 10%-15%

Too Light:

Increase mAs: 30%-50%

Increase kVp: 10%-15%

Contrast

  • Difference in brightness in 2 neighboring areas
  • High contrast = Short scale
  • Low contrast = Long scale = more grays
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19
Q

Grids

A

Absorbs scatter radiation

Placed b/t patient and film

Lead strips: absorbs xrays

Spacer material: allows primary x rays to reach film

Types

  • Focused: lead strips are angled
  • Unfocused: Lead strips are parallel
  • Pseudofocused: a compromise
  • Crossed or Linear

**Use bucky if patient measurement is greater than 10cm**

20
Q

SID

A

Source Image Distance

Distance b/t x ray tube focal spot and image receptor (Film)

Closer the distance = higher the intensity

Use constant 40 inches

21
Q

Limbs Position

A

Use Cranial & Cauldal

(Front & Back)

Use Dorsal & Palmar/Planter

(Top & Bottom)

22
Q

Nose to Ears

A

Rostral (cranial)

towards ears (Caudal)

23
Q

Frontal Plane

Sagittal Plane

Transverse Plane

Median Plane

A

Separates Dorsal/Ventral

Separates Lt/Rt sides

Separates Cranial/Caudal

Separates Lt/Rt Halves

24
Q

Technique Chart

A

Provides following information

  • X ray cassette
  • Placement of cassettes
  • mA, mAs, kVp setting

Based on tissue thickness

Anatomical part

Created by site via trial and error

5 charts

  • Extremity/Skull
  • Abdomen
  • Thorax
  • Pelvis/Spine
  • Avian/exotics
25
Q

Under Exposure vs Over Exposure

A

Under Exposure (Too Light) w. anatomic outlines (adequate)

Solution: Increase mAs 30-50%

Under Exposure (Too Light) w/o anatomic outlines (Inadequate)

Solution: Increase kVp 10-15%

Over Exposure (Too Dark) w. white bones (Adequate)

Solution: Decrease mAs 30-50%

Over Exposure (Too Dark) w. grey bones, low contrast b/t bone and tissue (Overpenetration)

Solution: Decrease kVp 10-15%

26
Q

Abdomen

A

Reasons for abdominal xrays

  • Trauma
  • Vomitting
  • Distention
  • Urinary Obstruction
  • Mass
  • General wellness

Long Scale Contrast (Low contrast - grays):

High kvp and low mAs

27
Q

Abdomen view

A

V/D views (Stomach side up)

  • Diaphragm to Femoral head
  • Expiratory phase
  • Beam center and measure on 13th rib
  • Use sandbags under thoracic & v-trough

Lateral views

  • Diaphragm to Femoral head
  • Expiratory phase
  • Beam center and measure on 13th rib
  • Use foam pads b/t femurs and under sternum
28
Q

Scapula

A

Scapula Lateral View

  • Beam center on middle of scapula
  • Measure thickest area of scapula

Scapula caudocranial View

  • Beam center on middle of scapula
  • Measure thickest area of scapulohumeral joint
  • VD position
  • Extend limb cranially
  • Rotate sternum away from scapula
29
Q

Humerus

A
  • Center beam on center of bone
  • Measure thickest area over shoulder joint
  • Lateral position, dorsal recumbency (caudocranial view), abduct limb away from midline
  • Include joints
30
Q

Elbow

A

Craniocaudal view

  • Beam center over joint
  • Measure thickest area
  • Position sternal recumbancy, head tilted away
  • Use foam pad under elbow

Lateral view

  • Center beam over joint
  • Measure distal humerus
  • Position with rope. Caudally push opposite limb back.
  • Use foam under metacarpal
    *
31
Q

Radius & Ulna

A

Lateral view

  • Center beam on middle of bones
  • Meausre over elbow

Craniocaudal view

  • Center beam on middle of bones
  • Measure at distal humerus
  • Sternal recumbency
32
Q

Carpus

A

Lateral view

  • Center beam on distal carpal bones
  • Measure on center of joint

Dorsopalmar

  • Center beam at middle of distal carpals
  • Measure at center of joint
33
Q

Metacarpus/Phalanges

A

Dorsopalmar view

Center beam on middle of metacarpal bones

Measure on middle of metacarpal bones

Lateral view

Cetner beam on center of digits

Measure on middle of phalanx

34
Q

Image receptor Parts

A
  • Film
  • Intensifying screens (Converts xrays into visible light)
  • Cassette (Lead backing)
35
Q

Screens

A

Pros

Lower radiation

Lower mAs

Less exposure to patient

Lower chance of motion

Cons

Causes slight blurring of image

Parts

  1. Base (support)
  2. Reflective layer
  3. Phosphor crystal layer
  4. Protective coat
36
Q

Screen Speed

A

Affected by:

  • Phospher type
  • crystal size
  • phospher layer thickness
  • reflective layer efficiency
  • Dyes in phosphor layer

Large crystals

Faster screens

Less detail

Grainy

greater light emission

Small Crystals

Slower screens

more detail

less grainy

larger amount of radiation used

Thick Phosphor Layer

Increases xray absorption

Increases light emission

Decreases detail

Reflective layer efficiency

Reflects light from phosphor layer to film

Slow speed

  • Optimal detail
  • Long exposure time

Medium speed

  • Good Resolution
  • Short exposure

Fast speed

  • Emits more light = Reduce exposure time = less detail
  • penetrates thick tissue
37
Q

Film Properties

A
  • Silver bromide or Halide - aborbs xrays and visible light to form image
  • 2 sided
  • Do not expose any side to light (foggy means it was exposed to light)
  • Will turn metallic silver once exposed
  • Will be clear if unexposed
  • Conversion makes film blacker
38
Q

Screen film vs Non screen film

A

Screen Film

  • Regular film: Blue sensitive
  • Rare Earth: Green sensitive
  • Sensitive to fluorescent light

Non screen film

  • Best for bones and teeth
  • More details
  • responds directly to xrays
  • More exposure
39
Q

Film Storage

A

Vertically

inside darkroom

in cool/dry place

store away from radiation or chemcial fumes

Use before expiration date

40
Q

Screen Speed

A

Efficiency in converting xrays to light

41
Q

Technique Charts

A

Help keep consistancy

Improves efficiency

42
Q

Chart factor

A

Screen speed & film

Age of screen

SID

beam filtration

temp/time of film processing

grid type

43
Q

mAs vs kVp

A

Increase mAs for more density

Increase kVp for short exposure time (10-15%)

Too light w. outlines - increase mAs 30-50%

Too light w/o outlines - increase kVp 10-15%]

Too much penetration: decrease kvp

Overexposure: decrease mAs

44
Q

Film processing

Dry side vs wet side

A

Dry side

place to place and remove film from cassettes

Storage bin for film

Wet side

For chemcial processing

  • Developer - Converts silver halide crystal to black metallic silver
  • water - to rinse, stop developing process, contamination
  • fixer - clears unexposed crystals
  • Wash bath - manual processing of stirring. (20-30 min.)
45
Q

Steps to film processing

A

Step 1

Preparation

  • chemicals should be at 68 degree
  • Dont use same paddle
  • Turn on safety lights

Step 2

Unload Cassette

  • Dont use fingernails
  • Shake film out
  • Hold film by edges
  • close cassette while labeling film

Step 3

Loading film to hanger

  • attach to clips
  • don’t touch the center of film

Step 4

Developing

  • Put film in developing tank
  • agitate a couple of times
  • close lid
  • set timer

Step 5

Rinsing

  • Remove film
  • Put in the rinse bath for 30 sec

Step 6

Fix it

  • Put in fix tank
  • agitate and set timer
  • fix for 10 mins.

Step 7

Washing

  • Remove film
  • Wash for 20-30 mins.

Step 8

Drying

  • hang film
  • cut edges of film
  • prevent dust on films
46
Q
A

Radiography (2 decks)

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