Foot Imaging Flashcards
(30 cards)
Foot/Toes exposure factors and rationale
50 kVp - low kV for high image contrast, large attentuation differences
100 mA - fine focus for image detail
0.04 s and 4 mAs (Foot) - provides required mAs for appropriate image density
0.02 s and 2 mAs (Toes) - provides required mAs for appropriate image density
Lateral foot - 55 kVp, 100 mA, 0.05 s, 5 mAs - slightly higher as more penetrative power required to get through lat foot
ALL NO grid
Imaging techniques for foot/toes projections
Dorsi-plantar (DP) Foot
* affected leg bent and plantar of foot in contact with IR
* ensure knee is straight, medial aspect of foot in contact with IR
- beam angled cranially 10-15 degrees so beam is perpendicular to metatarsal
- centre over base of 2nd metatarsal
- collimate all phalanges, metatarsals, tarsals
DP Oblique Foot
- start in DP, internally rotate foot approx. 30 degrees medially
- put radiolucent pad under to support
- vertical tube, no angle
- centre over the base of third metatarsal
**Lateral Foot **
- lying on affected side, either straighten knee or rol knee internally so that medial aspect in contact with IR, 5th metatarsal on IR
- centre over middle of tarsal bones
Weightbearing Lateral Foot
- patient standing on the foot on floor
- ensure patient is stable and has adequate support
- horizontal central ray
- centre over tubercle of 5th metatarsal
**Toes **
- same as DP foot except centre at metatarsophalangeal joint of toe of interest
- collimate to include distal half of metatarsal and all phalanges of affected toe
Imaging techniques for calcaneum projections
Lateral
- same as lat ankle
centre to middle of calcaneum, below medial malleolus
- collimate calcaneum, ankle joint, navicular, soft tissues
Axial
- patient on table legs extended
- posterior aspect of heel is placed on IR
- foot is dorsiflexed, toes pointed towards head, can be pulled towards trunk
- malleoli are equidistant
- angled 40 degrees cranially
- centre midway on plantar aspect of heel to pass thru malleoli
- if patient can’t dorsiflex, increase angle 40-45 degrees
Fractured Toes
fracture in the toes
What projections for Fractured Toes? Explain rationale for each
DP - to see the fracture line and which metatarsal is affected
Oblique - used to see if there are any other fractures that are not visible in DP
Lateral - to assess if there is any anterior/posterior displacement
Radiographic appearance of fractured toes
- fracture lines in toe/s
Avulsion/Corner Fracture
small corner fracture where the tendon attached to the bone pulls a fragment off a bone
What projections for Avulsion/Corner Fracture? Explain rationale for each
DP - to see overall foot anatomy, where the fragment has detached
Oblique - can show fractures that are not visible in DP or lateral views
Lateral - fragment more clear than in DP, as may appear overlapped in other views, alignment
Radiographic appearance of Avulsion/Corner fracture
- fragment has been pulled of the corner of the bone
- clear fracture line
Gout
inflammatory arthritis that results in build up of urate crystals causing swelling and pain in the metatarsophalangeal joints
What projections for Gout? Explain rationale for each
DP - see any bone erosions and foot anatomy and soft tissue swelling
Oblique - additional view
Lateral - see if any anterior/posterior displacement of the foot
need to use beam filtration to examine foot with gout to even out attenuation and density of foot since the foot is swollen but the toe isnt causing overexposure
Radiographic appearance of gout
- bone erosion
- swollen mass at the metatarsophalangeal joints
Hallux Vagus/ Bunions
deformity of the first metatarsophalangeal joint
What projections for Hallux Vagus/Bunions? Explain rationale for each
Weightbearing Lateral Foot - to see joint spaces, the arch of the foot under pressure, any other deformities
Weightbearing DP - to see the alignment of the 1st metatarsophalangeal joint, weightbearing to see the deformity clearly, medial deviation of small toe, lateral deviation of big toe
Radiographic appearance of hallux vagus/bunions
- lateral deviation of hallux (big toe)
- medial deviation of 1st metatarsal
Lisfranc injury
dislocation of the lisfranc joint complex, requires beam filtration to even out density of the foot
What projections for Lisfranc injury? Explain rationale for each
DP
Oblique
Lateral
Radiographic appearance of Lisfranc Injury
- fracture line or dislocation of the Lisfranc complex
- soft tissue swelling around foot but not in the toes
Fractured metatarsals
fracture in the metatarsals caused by direct impact
What projections for fractured metatarsals? Explain rationale for each
DP - to see overall foot anatomy and where the fracture line is
Oblique - provides alternate view, find any fractures that are not visible in DP
Lateral - to assess if there is any posterior or anterior displacment of the fragments or the joints
Radiographic appearance of fractured metatarsals
- comminuted fractures
- clear fracture lines
- displacement or angulation of fragments
- soft tissue swelling
Jones’ Fracture
fracture through the 5th metatarsal and through the neck of the 5th metatarsal
What projections for Jones’ Fracture? Explain rationale for each
DP - to see where the fracture line is and to see the overall foot anatomy
Oblique - to demonstrate shaft and base of 5th metatarsal better as it it can be blocked in DP view, reduces bony overlap, fracture line more clear
Lateral - to see if there is any displacement
Radiographic appearance of Jones’ Fracture
fracture in the shaft of the 5th metatarsal
