Hand X-rays Flashcards
What are sesamoids?
Where tendons and ligaments embed in the hand
What do sesamoids do?
They help with friction
What is the anatomy of the hand?
(4)
Phalanges
Metacarpals
Carpals
Sesamoids
What are the features of the carpal bones?
(4)
They’re wrist bones
They’re made up of 8 irregular shaped bones
They’re organised in 2 rows- proximal and distal
They’re included in the hand x-ray to ensure that we can see the metacarpals (since the carpals are below the metacarpals)
What are the features of the metacarpals?
(2)
They articulate with the carpal bones proximally
They articulate with the phalanges distally
What is the feature of the head of the metacarpals?
The head is rounded at the distal end
What are the features of the shaft of the metacarpals?
(2)
They’re long
The medial and lateral surfaces are concave
What are the features of the base of the metacarpals?
(2)
The base is flat at the proximal end
The styloid process is on the 3rd metacarpal
When are hand x-ray projections done?
For fractures
What are the 3 hand x-ray projections we can do?
Dorsi palmar (DP)
Oblique
Lateral
What does the DP hand projection look like?
(2)
The hand is flat, fingers extended
It’s the back of the hand to the palm
What does the oblique projection of the hand look like?
(2)
The thumb faces up (externally rotated to 45 degrees)
The fingers are extended
Why is the oblique hand projection important?
It opens up the metacarpals bones
What does the lateral projection of a hand look like?
(2)
The hand is rotated 90 degrees (the hand is on its side)
The thumb points up, away from the metacarpals
Why is the lateral projection of the hand important?
It allows us to see fractures of the metacarpals
What is the SID of a hand DP/oblique/lateral?
100/110cm
Is a grid/bucky used on a hand DP/oblique/lateral?
No
What is the detector size and orientation of a hand DP/oblique/lateral?
24cm x 30cm
Portrait
What is the centering point of a hand DP/lateral?
(2)
Perpendicular to detector
The 3rd metacarpal head is in the middle of the x-ray beam
What is the centering point for a hand oblique?
The 5th metacarpal head is in the middle of the x-ray beam
What is the collimation of a hand DP/oblique/lateral?
Top of fingers to wrist
What is the focal spot for a hand DP/oblique/lateral?
Why?
Less than 1.3mm
Because it’s a small body part being imaged
What do we always mean when we say exposure factors?
(2)
kV
mAs
What are the exposure factors of a hand DP/oblique/lateral?
60 kV
2 mAs
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What hand projection is this?
DP
What hand projection is this?
Oblique
Whenever we do a hand x-ray, what 2 projections do we always do?
DP
Oblique
What are the 2 joints in the fingers?
Interphalangeal joints (joints between phalanges)
Metacarpal phalangeal joints (joints between metacarpals and phalanges)
What is DP also known as?
PA
Why is DP positioning important for finger x-rays?
It demonstrates the phalanges and associated joint spaces
Why is lateral positioning important for finger x-rays?
It’s good for revealing dislocations and volar plate avulsions
What are the projections used in finger x-rays?
(2)
DP/PA
Lateral
Why are oblique projections not used for finger x-rays?
Because we only have 1 set of bones
How do we position the fingers when doing lateral projections?
The affected finger is put closest to the detector
What are volar plate avulsions?
When a bit of the bone gets ripped away (usually sporting injury)
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Why has the exposure of DP and lateral finger x-rays been reduced?
Because of the collimation
What are the 2 types of projections for a thumb x-ray?
AP
Lateral
Why is an AP projection used on the thumb?
To get the thumb close to the detector
What do we do if we can’t do an AP projection on the thumb?
Use a PA projection
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