PortableMobile Equipment and

Applications

RTEC 124 – WEEK 12SPRING 2011

1

Portable Objectives

2

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

3

4

First “Portable “ Unit

Portable - DDR

5

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

6

MOBILE XRAY UNIT

7

Basic Types of Mobile Radiography

• Battery Powered Unit• Capacitor-discharge Unit • High Frequency Units• Mobile Fluoroscopic ( C-ARM)

8

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)

9

10

BATTERY POWERED

11

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

12

13

14

“PLUG –IN” :

Capacitor DISCHARE UNIT

Plug in – Light weight Cap. Discharge

15

16

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

17

Generators• Capacitor discharge

– Constant potential output

• Battery operated – 3 phase output

• THEREFORE– Technique is consistant

with x-ray room

• Grid is different18

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)

19

20

This paddle with one or two cells Placed behind the patient and cassette

Position of cells critical

Control PanelSelection of density back up time cells

AEC and Portables

NEW – Mobile DIGITAL UNITS

21

22

DIGITAL UNITS

23

24

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

25

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

26

27

MinXray High Frequency Portable Units

28

•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

29

“PREP”GETTING READY

FOR EXAMS

YOUR PATIENT

THE ROOMYOURSELF

30

Special Patient Considerations• Communication• Manipulating equipment• Positioning and pathology

31

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

32

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?

33

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

34

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

35

GRIDS: lower ratio / more latitude

36

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

37

Watch positioning of CR to grid

Cassettes with Grid Caps38

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

39

40

KUB With and Without GRID

41

CR GRIDS

42

Lower grid ratio = CR is more sensitive to scatter

Special Technical Factor Selection Considerations

• Kilovoltage• Milliampere-seconds• Distance• Grids• Film/screen combinations• Other factors

43

Distance

• Measurements • For technique

– 40”– 56”– 63” – 72”

44

ALARA• Patient• You• Staff• Friends and family

45

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

46

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

47

48

MOVE ARTIFACTS WHEN POSSIBLE

49

Artifact under pt abd

50

Move artifacts when possible

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) 51

52

?? QUESTIONS??