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Portable Mobile Equipment and Applications. RTEC 124 – WEEK 12 SPRING 2011. Portable Objectives. 1) Recommend methods for accomplishing acceptable variations of standard radiographic projections 2) Assess the radiation protection rules for mobile radiography. Objectives Continued.
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PortableMobile Equipment and Applications RTEC 124 – WEEK 12 SPRING 2011
Portable Objectives • 1) Recommend methods for accomplishing acceptable variations of standard radiographic projections • 2) Assess the radiation protection rules for mobile radiography
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
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
Basic Types of Mobile Radiography • Battery Powered Unit • Capacitor-discharge Unit • High Frequency Units • Mobile Fluoroscopic ( C-ARM)
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)
12 VOLT BATTERIES CAR BATTERY Silver or Nickel Cadmium
Power Drive • Self-propulsion for mobile unit • Dead-man switch • Must use caution when piloting equipment • Weight of Equipment • Areas: • safe and not safe to use
“PLUG –IN” : Capacitor DISCHARE UNIT
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
Generators • Capacitor discharge • Constant potential output • Battery operated • 3 phase output • THEREFORE • Technique is consistant with x-ray room • Grid is different
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)
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
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
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
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
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
Special Patient Considerations • Communication • Manipulating equipment • Positioning and pathology
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
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?
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
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
GRIDS: lower ratio / more latitude Consider direction of grid lines to tube
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
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
CR GRIDS Lower grid ratio = CR is more sensitive to scatter
Special Technical Factor Selection Considerations • Kilovoltage • Milliampere-seconds • Distance • Grids • Film/screen combinations • Other factors
Distance • Measurements • For technique • 40” • 56” • 63” • 72”
ALARA • Patient • You • Staff • Friends and family
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
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
Artifact under pt abd Move artifacts when possible