Mobile Imaging PPT Flashcards
What locations are mobile x‐ray
machines commonly used in?
Nursing Home ED PACU Post surgery ICU Neonatal Units
Historical overview
• Military for treating battlefield injuries during
WW1
• Small portable units carried (“portable”) by
soldiers and set up in the field
Who invented the 1st portable machine?
the product infield of refrigerator
Frederick Jones
Who got a Noble Prize-winning physicist & put money to portable machines into WW I ambulances?
Marie Curie
***What are the ranges for kVp on a mobile x-ray machine?
40 to 130 kVp
***What are the ranges for mAs on a mobile x-ray machine?
0.04 to 320 mAs
What is the total unit of power for a mobile x-ray machine?
Between 15 and 25 kW
What is an MOBILE X-RAY MACHINE?
•Preset anatomic programming with exposure
techniques based on selected exam
•Direct digital capability
•Flat panel detector
What are the two classifications of mobile x-ray machines?
Battery operated units
Capacitor discharge units
What is Battery operated units?
- 2 sets of batteries
- 10 to 16 12 volt batteries connected in a series
- One controls x‐ray power output
- Provides power for self‐propelling driving ability
Average walking speed
Battery operated units
2.5 to 3 mph
Maximum incline of Battery operated units is
7 degrees
***Battery operated units when fully charged
10 to 15 exposures
10 miles on level ground
8 hours charging time
Driving mechanism of Battery operated units
- Forward/reverse
- Deadman brake
- Machine instantly stops when handle is released
***Advantages of Battery operated units
- Cordless
* Constant kVp and mAs
What is CAPACITOR-DISCHARGE
UNITS?
•Do not operate on batteries
•Capacitor stores electrical energy & charges
briefly before each exposure
•Capacitor builds up a charge when the exposure
button is pushed; when the pre‐selected charge
is reached, capacitor sends charge to x‐ray tube
***What are the advantages of the capacitor-discharge unit?
- Smaller size
- Easy to move
- Lighter in weight
What are the disadvantage of the capacitor-discharge unit?
• kVp drops constantly during exposure
• kVp may start @ 100 and drop to 80 kVp by end of
exposure
***What are the three important technical factors for mobile imaging?
Grid
Anode heel effect
SID
***Grid must be
Level
Centered to CR
Correctly used @ recommended focal distance
The incorrect use of a grid can result in loss of density across all or part of an image. Grid cut-off can result from 4 factors:
- off-center grid
- off-level grid
- off-focus grid
- upside-down grid
***If a longitudinal grid tilts transversely such as when placing under a patient on a mattress, the CR forms an angle across the long axis of the grid resulting in:
“Grid cutoff” results or
A lost of image density
If a longitudinal grid Tilts longitudinally, CR is angled but through long axis resulting in
Image is distorted
NO grid cutoff
***Grid cutoff results if
CR is directed transversely off from midline of
grid by more than 1 to 1 ½”
The more CR is off centered
The greater the grid cutoff.
***What is Grid cutoff?
Decreases density on image
***What is the ratio range for most focus type grids?
6:1 or 8:1
What is the focal range for most focus type grids?
36 to 44” focal range
Recommended focal range
• Varies with grid ratio
•Projections taken@ distances greater or less than
recommended distance produces cutoff
• Reduced image density @ lateral margins
***What is the grid ratio for portable grid?
6:1 or 8:1
What is the grid ratio for bucky grid?
12:1
***What is the concept of the anode heel effect?
The intensity of radiation from the cathode end is greater than at the anode end.
***The heel effect causes
a decrease in image density @ anode end due to the greater absorption of x-rays.
A thicker body part @ …………….end
A thinner part @ …………. end.
Cathode
Anode
***The heel effect More defined as
- Short SID
- Large field size
- Small anode angle
***Mobile radiography produces some of the …………….. occupational radiation exposures for radiographers.
Highest
***Recommended minimal distance from mobile unit when making exposure is
6 feet
or length of the cord.
***The single most effective means of radiation protection is
Distance
***According to the Federal Safety Regulation, SSD or source-to-skin distance cannot be less than
12 inches
Maintained @ ………………. for most mobile exams
40 inches
Longer SIDs require ……………………………… to
compensate for additional distance
increased mAs
OTHER CONSIDERATIONS for mobile are
- Technique chart
- Calipers
- Radiation safety
***Stand @ a ……………….. to primary beam – least
amount of scatter radiation
right angle
CHEST – AP PROJECTION
• Internally rotate arms TO move Scapular away
• Ensure no rotation of upper torso
• Midsagittal plane centered to IR
• Top of IR 2” above relaxed shoulders
•CR perpendicular to IR and 3” below jugular
notch @ level of T7
AP or PA CHEST PROJECTION (LATERAL DECUBITUS)
- Lateral recumbent
- Place support under patient to elevate 2‐3”
- Coronal plane is vertical
- IR is placed 2” above shoulders
- CR is horizontal & perpendicular entering 3” below jugular notch
AP PROJECTION - ABDOMEN
- Position IR to include pubic symphysis to upper abdomen region
- Center MSP to midline of IR
- Center IR to level of iliac crest
- CR perpendicular along MSP @ level of iliac crest or 10th rib laterally
***AP or PA PROJECTION – Abdomen Left
Lateral Decubitus Position
• True Left lateral recumbent position with coronal plane vertical
• IR is centered 2” above iliac crest to include
diaphragm
• Before exposure, patient has been in lateral
recumbent position for @ least 5 minutes
• Air to rise/Fluid to settle
•CR horizontal & perpendicular to center of
IR along MSP
AP PROJECTION - PELVIS
• 14 x 17 crosswise
• Position IR under pelvis with center midway
between ASIS & pubicsymphysis (2” inferior to
ASIS & 2” superior to pubic symphysis)
•Center MSP to midline of IR
•Rotate patient’s legs medially 15 degrees
•Respiration: Suspend
•CR perpendicular to MSP entering 2” abovepubic symphysis & 2”below ASIS
AP PROJECTION – FEMUR (Distal)
• 14 x 17 lengthwise
• Place distal edge of IR low enough to include
fx site, pathologicregion & knee joint
• Elevate IR if necessary to ensure proper alignment with tube – IR parallel to femoral condyles
•Respiration: Suspend
•CR perpendicular to long axis of femur ¢ered to grid
• Structure: distal 2/3 of femur including knee jt
AP PROJECTION – FEMUR
Proximal
- 14 x 17 lengthwise
- Place under proximal femur & hip
- Top of IR @ ASIS to include hip jt
- CR is directed to center of IR and long axis of femur
LATERAL PROJECTION - FEMUR
• 14 x 17 lengthwise
• Include distal knee joint
• Elevate unaffected leg until femur is almost vertical
•CR perpendicular to long axis of femur entering @
midpoint
•Demonstrates distal 2/3 of femur
• Digital
• Measure through thickest part of femur to select appropriate kVp
• Position cathode over proximal femur to improve CR image
LATERAL – C-SPINE (Right or left
dorsal decubitus position)
• 10 x 12 lengthwise
• Top of IR 1” above EAM to center IR @ C4
( upper thyroid cartilage)
• Raise chin slightly (contraindicated – fx)
• Relax shoulders
•Respiration: Full expiration
• Depresses shoulders
• SID of 60 to 72”
•CR horizontal and perpendicular @ level of C4
• Ensure proper alignment of CR & IR to prevent grid cutoff
•Must include C7
AP PROJECTION – CHEST &
ABDOMEN - Neonate
Florida Hospital protocol does not include chest/abdomen as 1 view
