Prepared by:-

KAMARUL AMIN BIN ABDULLAH @ ABU BAKAR

At the end of lesson, the student should able to:-

1. List type of mobile x-ray units.

2. Briefly explain type of generators in mobile x-ray units.

3. List the advantages and limitation of the generators.

4. Briefly explain the principle operation of mobile x-ray units.

5. List the advantages and limitation of mobile x-ray units.

6. Briefly explain the special consideration for mobile x-ray units.

7. Briefly explain the safe handling for mobile x-ray units.

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What is mobile x-ray units?

Mobile radiographic units consist of awheeled cart that transports :-

1. x-ray generator

2. x-ray tube

3. tubestand

4. collimators

5. film-cassette or flat-panel detector

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It is equipment which can be moved from one place to another and used at the patient’s bedside or in operation theatre.

There are TWO (2) types of mobile x-ray units:-

1. Mobile Radiography Unit

2. Mobile C-arm (II) Unit

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x-rays are produced by the

x-ray tube

collimators confines the

primary beam

capture images using a

film/screen or flat panel detector

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Where are they commonly used?

1. Patient’s rooms or wards

2. Emergency Department, Resuscitation Unit

3. ICU, CCU, HDU/W

4. Surgery and Recovery Rooms (OT)

5. Nursery and Neonatal units

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MOBILE X-RAY (RADIOGRAPHY)

MOBILE C-ARM (II)

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Used at patient bedsides.

Requires Radiographer’s skills and expertise.

Procedures should be performed using as standard a method as possible.

Manual technique is generally used.

Ordinary factors such as distance, grids, and technique can become a challenge.

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Battery powered uses two sets of lead-acid, or nickel-cadmium batteries.

One set powers driving of the machine. One set provides power to the x-ray tube.

recharging is necessary after a number of exposures.

Capacitor discharge does not operate on batteries. It can produce x-ray from

energy stored in, then discharged from a capacitor. carries two metal plates that hold electrical charge.

High Frequency converts hf AC to DC - resulting in high voltage ripple

60Hz-500 Hz techniques are equivalent to 3Ø 12 p

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12 VOLT BATTERIES

CAR BATTERY

Silver or Nickel Cadmium

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DIGITAL UNITS

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Advantages:1. This machine can be used freely, provides wide

range of satisfactory kVp & mAs.2. This machine could be recharging less frequently

that the capacitor one.3. Some machine allows you to take up to 500

exposures without re-charging.

Disadvantages:1. It needs special care and maintenance.2. This machine is heavy and hard to control.

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Advantages1. Lightweight, smaller and easier to maneuver.2. Require much less time to charge than battery

units.3. The production and quality is consistence.4. No battery usage.

Disadvantages1. Can’t handle thick body parts due to voltage drop

during exposure.2. Must be charged prior to each use.

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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 +

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

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 medical x-ray units

These models are designed

for use in nursing homes,

private homes, correctional

facilities, field clinics,

hospitals, or anywhere an x-

ray machine must be

brought to a patient.

maximum of 80 mAs

70 lbs

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Portables can be the “ultimate test” of skill, competency and resourcefulness

Compounded with the urgency and tension of the Emergency Room , Intensive Care Unit and/or Operating Room

Patient’s inability to cooperate for positioning

Technical Considerations - varying SID, grid alignment, patient positioning

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More acutely ill and/or unable to transport

Cardiac Monitoring Lines, tubes, ventilators and traction Pt may be conscious or unconscious

cooperative or uncooperative Show courtesy to the patient - even the

one who may not appear to be able to hear or understand* *remember Phil Ballingers’ Story

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Before entering, park machine outside of room and go in and talk to the patient (establish rapport, check for correct patient)

Rearrange equipment/furniture if necessary - remember to put it back when done!

Radiographer’s responsibility to return all items to their original locations

Locks on bars, bed rails, etc

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Get patient’s permission to do the exam Explain the procedure Move items that will be in the way

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 Unconscious patients Surgery/Emergency Room/ICU

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Watch out for:

Equipment power supplies

Oxygen tubing

Intravenous lines

Catheters, etc.

EKG wires

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Caution with blocker - Side up of cassette

Proper labeling of cassettes

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CHEST – PLACE C/R ± TO STERNUM –

or ANGLE 5° CAUDAL FROM ± TO CASSETTE

C/R TOO CEPHALIC = APICAL LORDOTIC

C/R TOO CAUDAL = CLAVICLES IN MIDDLE OF THE CHEST

CONSIDER YOUR PATIENT’S BODY HABIUTS

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Maintain typical positioning for examinations

Perform chest radiography in semi-erect position whenever possible

Check with the nurse forCritically ill patients

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When checking for air-fluid levels : 2 exposures may be necessary

1 - horizontal beam to see level

1 - C/R ± to sternum “anatomically correct”

CHECK FOR ARTIFACTS

Grid alignment - low ratio grids used

(see coconut for fluid levels pg 525 Carltons)

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Kilovoltage

Milliampere-seconds

Distance

Grids

Film/screen combinations

Other factors

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SAME RULES APPLY AS IN RAD ROOM

AP CHEST – SCREEN OR GRID *

(REMEMBER: 4x LESS FOR SCREENS*)

BODY PARTS OVER 12 CM = GRID

SID – VERY IMPORTANT TO MEASURE

CHEST USUALLY DONE AT 62 – 72”

ALL OTHER DONE AT 40” * SEE MERRILLS BEGINNING AT PG 212

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Must be measured accurately –

For technique

40”

56”

63” (at feet)

72”

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Consider direction of grid lines to tube

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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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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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Lower grid ratio = CR is more sensitive to scatter

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RADIATION SAFETY

CONSIDER THE PATIENT

YOURSELF

AND OTHERS IN THE AREA

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It’s your duty to protect the patient, yourself and others (healthcare professional, family members)

Politely ask whoever can, to leave the area

Provide aprons to those who cannot leave -always carry 2 aprons with you on the machine (for you and the patient)

Announce your intent to make an exposure and give time for others to leave (but they shouldn’t “run” away)

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Never place your hand or other body part in primary beam

Provide gonadal protection for the patient

Achieve maximum distance from the patient and tube (stand 90° from the patient- SEE Merrills – pg 212)

Minimum 6 foot exposure cord for radiography

Label and handle cassettes carefully

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Increased possibility of artifacts

Remove all radiopaque objects

Move lines from imaging field if possible

Limit coverings to single, smoothed layer

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Move artifactswhen possible

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Pathology vs artifact ?

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BASIC TYPES OF MOBILE RADIOGRAPHY

Battery Powered Unit

Capacitor-discharge Unit

High Frequency Units

Mobile Fluoroscopic ( C-ARM)

More on this later this semester

& in RT 244………..

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C-ARM UNIT - Carltons pg 547

Tube at one end - I.I. at other end

TV Monitor control cart separate from unit

Uses Digital Fluoroscopy

Last Image Hold, Image Enhancement

Save for hard copies from disk, Video

Photographic Magnification, Subtraction

Static (pulsed) and continuous fluoro

Maneuverable and Versatile

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What is the largest amount of scatter caused from?

How to reduce this?

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RADIOGRAPHIC

6 ‘ exposure cord

Minimum source to skin distance = 12”

Preferred SID of 40”to 72”+ (mag detail)

Distance from tube and patient

At least .25mm lead apron

FLUOROSCOPIC

Minimum source to skin distance = 12”

Preferred SSD OF 18”

Distance from tube and patient

5 min Audible Alarm

At least .25mm lead apron to be worn

5 R/min - 10 R/min

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?? QUESTIONS??

Portable Equipment