Chapter 18 Foot Radiography

1
Chapter 18 Foot Radiography

• Fractures are characterized by involvement of the
  subtalar joint (75) and not involving the
  subtalar joint.
• Stress fractures are common in runners but
  typically not seen on radiographs.
• Stress fractures , plantar fascitis or heel spurs
  are common repetitive use conditions.

2
Foot or Heel Radiography

• Views of the foot and calcaneus are totally
  different.
• If a heel injury is suspected, take heel views
  and not foot views.
• A 30 degree medial oblique view can be useful.
  The oblique and lateral will demonstrate the
  subtalar joint.

3
Foot Radiography

• Foot view must include the tarsal bones,
  metatarsals and phalanges.
• A tube angle is used to open the tarsal bone
  articulations on the A-P view.
• If the patient is flat footed, no tube angle
  would be needed.

4
Foot Radiography

• The medial oblique view is particularly useful.
  It provides
• A clear view of the tarsal bone including the
  calcaneus.
• The 4th 5th metatarsals
• Intertarsal joints
• Detail of the 5th metatarsal

5
Foot Radiography

• The basketball foot is a traumatic medial
  subtalar dislocation resulting from landing on an
  inverted foot.
• The Jones fracture is an avulsion fracture off
  the base of the 5th metatarsal.
• Stress fractures of the metatarsals are generally
  transverse resulting from marching or jumping.

6
Toe Radiography

• Toe radiography can be particularly challenging.
• The natural curve of the toes toward the plantar
  surface of the foot results in foreshortening and
  closure of the interphalangeal joint spaces.
• Besides the A-P, an angled axial view is used to
  open the joint spaces.

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18.4 Foot A-P

• Measure A-P at base of third metatarsal
• Protection Apron
• SID 40 Table Top
• Tube Angle 10 cephalad
• Film 1/2 of 10 x 12 Extremity Cassette I.D. up

8
Foot A-P

• Patient seated or lying on table with the long
  axis of the affected foot centered to table.
• Place cassette on table.
• Have patient place foot flat on cassette.
• Horizontal CR base of third metatarsal

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Foot A-P

• Vertical CR long axis of foot.
• Collimation Top to Bottom distal tibia to tips
  of toes.
• Collimation Side to Side soft tissue of foot
• Instructions Remain still
• Make exposure and let patient relax

10
Foot A-P Film

• Should demonstrate toes , metatarsals and most of
  the tarsal bones. The talus and calcaneus will
  not be seen.
• The tube angle will help open the tarsal joint
  spaces.

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18.5Foot Oblique

• Measure A-P at base of third metatarsal
• Protection Apron
• SID 40 Table Top
• No Tube Angle
• Film 1/2 of 10 x 12 Extremity Cassette I.D. up

12
Foot Oblique

• Patient seated or lying on table with the long
  axis of the affected foot centered to table.
• Place cassette on table.
• Have patient place foot flat on cassette.
• The foot is medially rotated 30 to 40
• A sponge may be used under the plantar surface of
  the foot.

13
Foot Oblique

• Horizontal CR base of third metatarsal
• Vertical CR long axis of foot.
• Collimation Top to Bottom distal tibia to tips
  of toes.
• Collimation Side to Side soft tissue of foot
• Instructions Remain still
• Make exposure and let patient relax

14
Foot Oblique Film

• Should demonstrate toes , metatarsals and most of
  the tarsal bones. The talus and calcaneus will
  not be seen.
• The calcaneus will be well visualized
• Tarsal joint spaces should be open.

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18.6 Foot Lateral

• Measure Lateral at base of first metatarsal
• Protection Lead Apron
• SID 40 Table Top
• No Tube Angle
• Film 8 x 10 or 10 x 12 Extremity depending
  on foot size.

16
Foot Lateral

• Patient lies on the affected side with lower leg
  in lateral position.
• The foot should be dorsiflexed until the plantar
  surface is perpendicular to ankle.
• The plantar surface of foot is perpendicular to
  film.

17
Foot Lateral

• The film may be turned diagonally or the foot
  placed diagonally on film to fit the entire foot
  on the film.
• Horizontal CR base of 1st metatarsal
• Vertical CR base of first metatarsal

18
Foot Lateral

• Collimation Top to Bottom to include ankle to
  plantar surface soft tissue
• Collimation Side to Side to include from heel to
  tips of toes.
• Instructions Remain still
• Make exposure and let patient relax.

19
Foot Lateral Film

• The foot and ankle should be in a lateral
  position.
• The metatarsals and toes will be superimposed.
• The distal fibula should overlie the distal
  tibia.
• The talotibial joint space should be open.

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18.7 Toes A-P Axial A-P

• Measure A-P at 3rd metatarsal phalangeal joint
  or affected toe
• Protection Lead Apron
• SID 40 Table Top
• Tube Angle A-P none
• Tube Angle Axial A-P 15 cephalad
• Film 1/4 of 10 x 12 Extremity

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Toes A-P Axial A-P

• A-P patient places foot flat on film.
• Horizontal Vertical CR 3rd M-P joint for all
  toes or M-P joint of the affected toe for
  individual toe series.
• A-P Axial tube angle same as above but with 15
  cephalad angle.

22
Toes A-P Axial A-P

• A-P Axial with Sponge a 15 sponge is placed
  under toes instead of angling the tube. Or
• The Sponge is placed under the cassette
• Horizontal Vertical CR 3rd M-P joint for all
  toes or M-P joint of affected toe.

23
Toes A-P Axial A-P

• Collimation top to bottom to include all M-P
  joints to tips of toes or M-P joint to tip of
  affected toe.
• Collimation Side to Side soft tissue of foot or
  individual toe.
• Instructions Remain Still
• Expose and let patient relax

24
Toes A-P Axial A-P Film

• A-P is upper right image.
• A-P Axial is upper left image. The phalangeal
  joints will be open on the axial view.
• Views must include all of the affected toe or
  toes.
• Note that collimation was too tight top to bottom.

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18.8 Toes Medial Oblique

• Measure A-P at metatarsal-phalangeal joints
• Protection Apron
• SID 40 Table Top
• No tube angle
• Film 1/4 of 10 x 12 or 8 x 10 Extremity
  Cassette

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Toes Medial Oblique

• Patient places distal foot on unexposed portion
  of cassette.
• Patient medially rotates lower leg until the
  plantar surface forms a 30 to 45 angle.
• Horizontal CR 3rd MTP joint or the affected toe.

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Toes Medial Oblique

• Vertical CR centered to long axis of foot or the
  affected toe
• Collimation top to bottom Distal metatarsal to
  tips of toes or affected toe
• Collimation side to side soft tissue of foot or
  affected toe.

28
Toes Medial Oblique

• Patient instructions Remain Still
• Make exposure and let patient relax.
• Note that a sponge may be placed under plantar
  surface of foot to control angle of view . It
  will also make it more comfortable for the
  patient.

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Toes Medial Oblique

• The joint spaces should be open.
• The distal metatarsal and tips of the toes should
  be visualized.

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18.8 Toes Lateral

• Measure Lateral across the metatarsal-phalangeal
  joints For individual toe use A-P measurement.
• Protection Apron
• SID 40 Table Top
• No tube angle
• Film 1/4 of 10 x 12 or 8 x 10 Extremity
  Cassette

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1st Toe Lateral

• Patient places distal foot on unexposed portion
  of cassette.
• For 1st through 3rd toes
• Patient medially rotates lower leg until the
  plantar surface forms a 90 angle.
• For 4th and 5th toes
• Patient laterally rotates foot until the plantar
  surface is perpendicular to film.

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2nd Toe Lateral

• For individual toes, tape and tongue depressors
  are used to clear the other toes out of the view.
• Without the use of tape and tongue depressors,
  there will be too much superimposition

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3rd Toe Lateral

• Horizontal CR 3rd MTP joint or the affected
  toe.
• Vertical CR centered to long axis of foot or the
  affected toe
• Collimation top to bottom Distal metatarsal to
  tips of toes or affected toe
• Collimation side to side soft tissue of foot or
  affected toe.

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4th Toe Lateral

• Patient instructions Remain Still
• Make exposure and let patient relax.
• Note that the lateral surface of the foot is next
  to the film.

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5th Toe Lateral

• Note that the lateral surface of the foot is next
  to the film.
• The toe need to remain parallel to the film.
• The 5th toe is the most challenging lateral toe
  view.

36
Toes Lateral Film

• The joint spaces should be open.
• The distal metatarsal and tips of the toes should
  be visualized.
• The affected toe should be free of
  superimposition.

37
Accessory Testing

• Accessories include the cassettes, grids outside
  the Bucky, Lead Aprons and gonadal protection.
• The cassettes and screens are the primary
  concern.
• Screens should be cleaned monthly with screen
  cleaner. Keeping the darkroom clean is also
  important for screen cleanliness.

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23.4 Screen Contact Testing

• Procedure
• Clean screens and let them dry. Use screen
  cleaner design for the screen used.
• With a felt tip pen, write an identification
  number on the screen next to the I.D. and on the
  back of the cassette.
• Load cassettes.

39
Screen Contact Testing

• Procedure
• Set SID to 40 Table Top
• Place cassette on table.
• Place wire mesh tool on cassette.
• Set collimation to film size.
• Make exposure and process film.

40
Screen Contact Testing

• Procedure
• Hang film on view box.
• Step back 72 from view box and view film.
• Areas of increased density or loss of resolution
  indicates poor contact or stained screens.

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Screen Contact Testing

• Procedure
• The I.D. will help you find a cassette that
  needs to be cleaned or taken from service.
• Frequency of tests semiannual

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Poor Screen Contact

• There is a loss of detail in the thoracic and
  lumbar spine due to poor screen contact.
• This was a new cassette.

43
Poor Screen Contact

• Note the blurry image in the spine but sharp
  image of the ribs.
• The screens were not in proper contact in the
  middle of the cassette due to a bow in the
  cassette back.

44
Screen Cleaning

• Materials needed
• Screen Cleaner designed for type of screens used.
• 4 x 4 gauze or cotton balls
• Tape Pen

45
Screen Cleaning

• Procedure
• Unload cassette if contact is not being tested.
• Apply cleaner with gauze.
• Wipe excess off with dry gauze.

46
Screen Cleaning

• Leave open to air dry.
• Make sure cassette is still legible.
• After dry, reload cassette.

47
Screen Cleaning

• Record date on tape and place on back of
  cassette.
• By having each cassette identified, selected
  cassette can be cleaned as needed.

48
Screen Cleaning

• California Department of Radiologic Health
  recommends cleaning screens monthly.
• Should definitely be done quarterly and sooner as
  needed when artifacts are identified on films.
• Never use alcohol or detergents not designed for
  cleaning screens.

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Cassette Care

• Methods to get the maximum life from cassettes
• Avoid dropping the cassettes
• Open only far enough the change films
• Keep outside of cassette clean and dry.
• Keep screens clean
• Store on end.

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Dirty or Damaged Screens

• Dirty or damaged screen will cause white spots on
  the image.

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Dirty Damaged Screens

• The white spots on this film are the result of
  damaged or worn out screens.
• Never use alcohol or detergents to clean screens.

52
Speed Matching

• After looking for screen contact problems
• Measure speed of cassettes by reading density
  with the Densitometer. The density of the exposed
  area should not vary more than 0.05 OD.
• As screen age, they loose speed.
• Always make sure the light spectrum of the
  screens and film are matched.

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23.5 Apron and Gonad Shield Testing

• Lead aprons and shields should be tested
  semiannually for defects
• Aprons with defective lead provide little
  protection for the patient.

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Apron and Gonad Shield Testing

• Tools needed
• 14 x 17 cassette
• View Box
• Coat Apron Procedure
• Drape apron over Bucky
• Place cassette in Bucky make exposures in upper
  and lower Bucky slots.

55
Apron and Gonad Shield Testing

• Coat Apron Procedure
• Note that this is the same test as used for grid
  alignment.
• Process films
• View films on view box

56
Apron and Gonad Shield Testing

• Half Apron and Small Shield Procedure
• Place cassette on table
• Set SID at 40
• Place apron or shields on cassette.
• Make exposure and process the film.

57
Apron and Gonad Shield Testing

• Viewing the test films
• Note creases in the lead.
• Full holes will produce a black area on the film.
• If cracks or defects are in the area that should
  cover the gonads, replace apron.

58
Care of Aprons

• Never fold aprons
• Store flat or hung on apron rack
• Use only aprons with the lead equivalency of
  0.5mm for patient and staff protection.
• Do not use as lead blockers for extremity films.
• Protect from heat and direct sun light.

59
Grid Uniformity Testing

• Procedure is the same as testing the Bucky Grid.
• Place homogenous phantom or lead apron over grid
  that is taped to the top of the cassette.
• Make exposure and look for density changes and
  grid damage.