Transcript portable (mobile) radiography

Portable
Mobile Equipment and
Applications
RTEC 124 – WEEK 12
SPRING 2011
1
Portable
Objectives
1) Recommend methods for
accomplishing acceptable variations
of standard radiographic projections
2) Assess the radiation protection
rules for mobile radiography
2
Objectives Continued
3) Identify factors contributing to the difficulty
of mobile radiography
4) Explain appropriate communications methods
for mobile examinations
5) Describe items that must be considered when
arranging a patient room for a mobile
examination
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First “Portable “ Unit
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Portable - DDR
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THREE Basic types of Units
Portable - refers to a small hand held unit,
first designed by Picker for WW I
• 15 ma generator
• Chest & extremities
Mobile - Full powered institutional units
much heavier - motor or muscle driven
Fluoroscopic:
• C-arm and “Mini C-arm” or Fluoroscan
• PORTABLE is accepted terminology
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MOBILE XRAY UNIT
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Basic Types of Mobile Radiography
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Battery Powered Unit
Capacitor-discharge Unit
High Frequency Units
Mobile Fluoroscopic ( C-ARM)
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Portable Units - Special Features
• Battery Powered uses Ni-Cd rechargeable batteries,
DC high frequency pulsed power
• Capacitor-Discharged - uses 110 outlet. High voltage
transformer - Capacitor discharges at time of
exposure -voltage drops 1kv/mas during exposure
• High Frequency- converts hf AC to DC - resulting in
high voltage ripple 60hz-500 hz (square vs sine
wave)
• *Techniques are equivalent to 3Ø 12 p
(like in a standard Radiographic room)
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BATTERY POWERED
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12 VOLT BATTERIES
CAR BATTERY
Silver or Nickel
Cadmium
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Power Drive
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Self-propulsion for mobile unit
Dead-man switch
Must use caution when piloting equipment
Weight of Equipment
Areas:
– safe and not safe to use
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“PLUG –IN” :
Capacitor DISCHARE UNIT
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Plug in – Light weight Cap. Discharge
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Types of Equipment
• Power supplies
• Generators
• Power drive
• Power Supplies:
• Portable light duty units
– 220V or 110V outlet
• Full power mobile
institutional units
– Capacitor discharge
– Battery operated
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Generators
• Capacitor discharge
– Constant potential
output
• Battery operated
– 3 phase output
• THEREFORE
– Technique is consistant
with x-ray room
• Grid is different
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Milliampere-Seconds
• Low power units not capable of high mAs
techniques needed for grid radiography (300
mA)
• Double or triple exposure
– Be careful not to overload tube
– EX: X-table L5 S1 SPOT (in surgery)
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AEC and Portables
This paddle with one or
two cells
 Placed behind the patient
and cassette
Position of cells critical
Control Panel
Selection of density
back up time
cells
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NEW – Mobile DIGITAL UNITS
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DIGITAL UNITS
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COMPARISONS
• Battery Powered
• Uses 9 - 10 12V batteries (heavy)
• Battery supplies power for all
inst. operations
• Motor Driven
• Wt - +1,000 lbs
• ? Constant potential
• Some have AEC
• Needs recharging - holds 8 hr
charge
• 3Ø 12pulse techniques
• Can double expose +
• 110 V Capacitor DC
• Uses 110 outlet
• Capacitors stores up charge then exposure discharges
• “Muscle Driven”
• Wt - + 450 lbs
• ? Constant potential
• Some have programmed
memory
• Must be plugged in to store
up charge
• ? Not for large parts
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HIGH FREQUENCY UNITS
• Very Expensive –
– not many in use
• Smaller
– more compact units
• High voltage transformer 1/10 the size
• Minimal voltage ripple
– higher efficiency
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MinXray High Frequency Portable Units
•Designed for use in:
nursing homes, private
homes, correctional
facilities, field clinics, or
hospitals,
Maximum of 80 mAs
70 lbs
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SUMMARY
• Battery Powered Uses
batteries
3Ǿ 12p
(4%ripple)
• Capacitor Discharge Needs
wall outlet Constant
Potential
(1 % ripple)
• C-Arm Fluoroscopic Digital,
Subtraction, Last Image
Hold
“PREP”
GETTING READY
FOR EXAMS
YOUR PATIENT
THE ROOM
YOURSELF
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Special Patient Considerations
• Communication
• Manipulating equipment
• Positioning and pathology
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THE TECHNOLOGIST
• The “ultimate test” of skill, competency and
resourcefulness
• Urgency and Tension
• Patient’s inability to cooperate
• Technical Considerations –
– varying SID,
– grid alignment
– patient positioning
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THE PATIENT
• More acutely ill and/or unable to transport
• More lines and tubes
– Cardiac Monitoring
– Ventilators
– traction
– Respirators
• Levels of consciousness
• Can they hear you or understand you?
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Patient Considerations
• Pre- portable rapport
• Rearrange equipment/furniture
• Leave it the way it was before you got there
Locks on bars
– bed rails
– Table trays
– Chairs
– Pillows
– Blankets
– TV
– etc
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Other considerations
• Overhanging TV’s and the X-ray tube can be
hazardous to your head!
• Don’t bump the bed or your head
• Place cassette in a pillowcase when possible
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GRIDS: lower ratio / more latitude
Consider
direction of
grid lines to
tube
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Grid Ratio
• Higher grid ratio
– More efficient in
removing scatter
• Typical grid ratio range
is 5:1 to 16:1
Watch positioning of CR to grid
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Cassettes with Grid Caps
Grid Frequency
• The number of lead
strips per inch or cm
• Frequency range
– 60-200 lines/in
– 25-80 lines/cm
• Typically higher
frequency grids have
thinner lead strips
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KUB
With and Without GRID
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CR GRIDS
Lower grid ratio = CR is more sensitive to scatter
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Special Technical Factor Selection
Considerations
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Kilovoltage
Milliampere-seconds
Distance
Grids
Film/screen combinations
Other factors
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Distance
• Measurements
• For technique
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40”
56”
63”
72”
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ALARA
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Patient
You
Staff
Friends and family
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Legal Radiation Protection
• It’s your duty
• Politely ask whoever can, to leave the area
– Provide aprons to those who cannot leave
– Always carry 2
• Announce your intent to make an exposure
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Ethical Radiation Protection
• Never be in primary beam
• Achieve maximum distance from the patient and
tube
– stand 90° from the patient
• Minimum 6 foot exposure cord for radiography
• Label and handle cassettes carefully
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MOVE ARTIFACTS WHEN POSSIBLE
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Artifact under
pt abd
Move artifacts
when possible
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Types of Exams
• Chest
– AP, Lateral and LLD
• Abdomen
– AP or LLD
• Cross table Hip
• Extremities
– 2 VIEWS - 90°
• Cross table C-spine
• Cross table T-spine
• Shoulder (Y- view)
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?? QUESTIONS??
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