1. Mobile Radiography (Portables)
8/29/2012 Class ed.

2. Principles of Mobile Radiography
You bring imaging services to pt using transportable x-ray equipment
Where are they commonly used?
pt room ER
ICU
surgery and recovery rooms
nursery and neonatal units
When was mobile x-ray equipment first used?
battlefield WW1 -units were carried to field sites

3. Mobile X-Ray Machines
True or false? Portables are as sophisticated as stationary units?
False
Typical unit has what 2 controls?
kVp and mAs
What is the mAs range?
Generally 0.04 to 320 mAs
What is the kVp range?
-generally 40 to 130 kVp

4. Two basic types of Mobile X-Ray Machines
1. Battery powered
Uses two different sets of batteries (lead-acid, or nickel-cadmium )
One powers driving of machine
One set provides power to x-ray tube
Fully charged batteries:
- can make 10 to 15 exposures
- be driven reasonable distances
2. Capacitor discharge (obsolete)
No batteries
Carries two metal plates that hold electrical charge
Capacitor units must be charged prior to each use

5. Battery-operated Unit
Advantages:
Cordless
Provide constant kVp and mAs
Disadvantages:
- Heavy
- hard to control
What is “Deadman” type of brake?
stops machine instantly when push-handle released

6. Capacitor Discharge Units
Advantages?
lightweight, smaller and easier to maneuver
require much less time to charge than battery units
Disadvantages?
can’t handle thick body parts due to voltage drop during exposure
must be charged prior to each use

7. The Nomad For places with no electricity or chemical processors
Mainly for dental x-rays

8. 3 important technical factors that must be clearly understood to perform optimum mobile examinations:
Grid
Anode-heel effect
Source–to–image receptor (SID)

9. Grid Must be level! X-ray beam must be properly centered to grid
Correct focal distance must be used
(Best grids for mobile radiography have ratios of 6:1 or 8:1 and a focal range of inches)
Make sure grid is fastened to cassette properly (tape)

10. Anode Heel Effect
Correctly place anode-cathode (marked on tube housing) with respect to anatomy
Anode should be on thinner part (T-spine)
Heel effect increases with short SID, larger field sizes (more common in mobile radiography)
Beam travels through thicker part of target on anode side, thus attenuating beam more

11. SID- Mobile Units What is standard SID? 40
Possible problems with greater SID?
Need increased mAs, thus longer exposure time
Increases risk of imaging motion
Increased drain on battery
Possible grid cut-off

12. Performing Mobile Examinations
Plan ahead!
Gather all necessary devices to take with you
IR (bring extras!)
Grid
Tape
Markers
Sponges

13. Before Beginning Examination
Find pt’s x-ray order
Let nurse’s station know of your presence and purpose
Identify pt and introduce yourself with your title
Explain exam and ensure it is appropriate and correct
Politely ask any visitors to leave
Obtain assistance when necessary!

14. Interfering Devices
Watch out for orthopedic beds, fracture frames, tubes, wiring, etc., producing artifacts
Know which objects can be moved and which ones you have to work around
May have to perform with object in image
Ask if unsure whether an object can be moved

15. Portable Position
If exam in supine position, move base of machine to middle of bed
If seated upright, base at end of bed
Lateral and decubitus positions, place base parallel or perpendicular to bed

16. Performing Mobile Examinations
Make sure collimation is not open larger than IR size
Check CR and IR alignment to prevent distortion
Use consistent system for keeping exposed and unexposed IRs separate
Keep log of procedures, time of examination, technical factors for image ID

17. Technique Charts and Logs
Exposure for optimum exam!
Should be available for every machine
Should display standard technical factors for all projections performed with machine
Logbook of all recent pt exams and technique
Caliper should also be available for accurate patient measurement

18. Scatter Radiation and Mobile Radiography

19. Wear film badge at collar or waist outside lead protection
Mobile radiography produces some of highest occupational radiation exposure for radiographers!
Wear a lead apron!
Wear film badge at collar or waist outside lead protection
What is single most effective radiation protection measure?
Distance!
What is minimal safe distance ?
6 feet

20. Safest Place to Stand
Least exposure is at what angle to pt and primary beam?
Right angle

21. When should you shield pt’s gonads?
X-raying children
Person is of reproductive age
Pt requests
Gonads lie in or near useful beam
When shield will not interfere with anatomy of interest

22. Radiation Safety cont’d
What is minimum source-to-skin distance?
12
Have visitors leave area
Warn other personnel when you are about to make an exposure

23. Patient Mobility Never move pt or part without:
Assessing ability to move or ability to tolerate movement
Checking with staff obtain assistance and permission to move a part that has had surgery or fractured
Inappropriate movement can further injure pt!

24. Warn pt of potential discomfort from IR
Cold
Hard
IR can damage skin of older patient
Use cloth or paper cover to reduce risk of injury
Protect IR from contamination by use of appropriate impermeable cover

25. Assess Patient Condition
Be aware of any limitations to procedure!
Alertness
Respiration
Ability to cooperate
Language comprehension
Mobility
Fractures
Interfering devices
If in OR, don’t break sterile field!

26. Isolation Considerations
What are two types of pts in isolation?
Those who have contagious infectious microorganisms
you want to avoid them!
Those who must be protected from exposure to infectious microorganisms-
they want to avoid you!
This known as?
Reverse isolation!

27. Isolation Considerations cont’d
Wear all required protective apparel for specific situation
Wash hands before gloving
Protect IR with protective cover

28. Isolation Considerations cont’d
After procedure:
Discard of protective apparel according to protocol
Wash hands!
Wear clean gloves to clean equipment and use appropriate aseptic technique
Wash hands again after removing gloves

29. Most Common Portable Radiographic Exams
Chest
Abdomen
Pelvis
Femur
Cervical spine
Neonate

30. AP Chest Elevate head of the bed as pt condition permits
Pull pt to head of bed before elevating if condition permits
Make sure pt is not rotated
What if pt has respiration assistance?
watch pt chest to determine inspiratory phase (or respirator)

31. AP or PA Chest Lateral Decubitus Position
Place firm support under pt to elevate body and keep pt from sinking down in bed
Protect pt from rolling off of bed!

32. Lateral Decubitus Position Considerations
Fluid levels best imaged with?
affected side down
Air levels seen best with?
affected side up
How long should pts be in this position before exposure?
5 minutes
Why?
to allow fluid or air to settle

33. Orthopedic Examinations
How many images required?
at least 2 films at right angles to each other
Who do you obtain permission from prior to moving an injured pt?
pt’s nurse or physician
How do you position pts?
very carefully!

34. Lateral Cervical Spine
Dorsal decubitus position
CR horizontal
If there is a immobilization device when should you remove it?
NEVER or until Dr. gives permission

35. Neonate Move arms out of anatomy of interest Bring legs down
Who should hold infant in position?
Nurse- (provide lead apron)
Why do you leave head rotated?
to avoid advancing endotracheal tube too far
Collimate closely
Shield gonads

36. Neonate
AP projection of chest and abdomen often ordered and shot in one exposure
Infant is supine
Some bassinets equipped with tray to hold IR
If IR placed directly under infant- wrap with soft cover