• Four-sided collimation: Collimate to the area of interest with a minimum of two collimation parallel borders clearly demonstrated on the image. Four-sided collimation is always preferred if study allows it.

• Accurate centering: It is important that the body part and the central ray be centered to the IR.

• Grid use with cassette-less systems: Anatomy thickness and kV range are deciding factors for whether a grid is to be used. With cassette-less systems it may be impractical and difficult to remove the grid. Therefore, the grid is commonly left in place even for smaller body parts measuring 10 cm or less. If the grid is left in place, it is important to ensure that the CR is centered to the grid for all projections.

Collimation and Shielding

A general rule for protective shielding states that it should be used whenever radiation-sensitive areas lie within or near the primary beam. Red bone marrow and gonadal tissues are two of the key radiation-sensitive regions. However, a good practice to follow, in addition to close collimation to the area of interest, is to use gonadal shields on youth and patients of childbearing age for all lower limb procedures. This provides assurance to the patient that he or she is being protected from unnecessary exposure.

Multiple Exposures per Imaging Plate

Multiple images can be placed on the same IP. When doing so, careful collimation and lead masking must be used to prevent pre-exposure or fogging of other images.

AP Toes^*

Alternative routine may include entire foot on AP toe projection for possible secondary trauma to other parts of foot (see AP foot).

Fig. 4-1 AP 2nd digit, CR 10°–15° posteriorly.

• 18 × 24 cm C.W. (8 × 10″)

• Nongrid

• Lead masking with multiple exposures on same IR

Position

• Supine or seated on table with knee flexed, plantar surface of foot resting on IR

• Align long axis of affected toe(s) to portion of IR being exposed.

Central Ray:

• CR angled 10°–15° to calcaneus (⊥ to long axis of digits)

• CR centered to MTP joint(s) of interest

SID:

40–44″ (102–113 cm)

Collimation:

Collimate on four sides to area of interest to include soft tissues.

AP Oblique Toes^*

• 18 × 24 cm C.W. (8 × 10″)

• Nongrid

• Lead masking with multiple exposures on same IR

Position

• Supine or seated on table, foot resting on IR

• Align long axis of affected toe(s) to portion of IR being exposed

• Oblique foot 30°–45° medially for 1st to 3rd digits, and laterally for 4th and 5th digits. Place support under foot as shown

Fig. 4-2 Medial oblique (1st digit).

Fig. 4-3 Lateral oblique (4th digit).

Central Ray:

CR ⊥, centered to MTP joint(s) of interest

SID:

40–44″ (102–113 cm)

Collimation:

Collimate on four sides to area of interest to include soft tissues

AP and AP Oblique Toes

Fig. 4-4 AP toe.

Fig. 4-5 AP oblique toe.

Evaluation Criteria

Anatomy Demonstrated:

AP and AP Oblique:

• Entire digit and minimum of ½ of affected metatarsal

Position:

• AP: No overlap of surrounding digits and metatarsals; no rotation, equal concavity on both sides of shafts of phalanges and metatarsals

• AP oblique: Increased concavity on one side of phalangeal shaft

Exposure:

• Optimal density (brightness) and contrast; no motion

• Soft tissue and sharp cortical margins clearly demonstrated

Lateral Toes^*

Fig. 4-6 Lateromedial (1st digit).

Fig. 4-7 Mediolateral (4th digit).

• 18 × 24 cm C.W. (8 × 10″)

• Nongrid

• Lead masking with multiple exposures on same IR

Position

• Seated or recumbent on tabletop

• Carefully use tape and/or radiolucent gauze to help isolate unaffected digits as shown:

1st to 3rd digits—lateromedial projection (1st digit down)

4th to 5th digits—mediolateral projection (1st digit up)

Central Ray:

CR ⊥, to IP joint for 1st digit, and to PIP joint for 2nd to 5th digits

SID:

40–44″ (102–113 cm)

Collimation:

Collimate closely to digit of interest to include soft tissues

Toes—Sesamoids^*

(Tangential Projection)

Fig. 4-8 Patient prone.

Fig. 4-9 Alternative supine position.

• 18 × 24 cm C.W. (8 × 10″)

• Nongrid

• Lead masking with multiple exposures on same IR

Position

• Patient prone with foot and great toe carefully dorsiflexed so the plantar surface forms a 15°–20° angle from vertical if possible (adjust CR angle as needed)

Alternative Supine Position:

This may be a more tolerable position for patient to maintain if in great pain.

Central Ray:

CR ⊥, or angled as needed to be 15°–20° from plantar surface of foot, centered to head of 1st metatarsal

SID:

40–44″ (102–113 cm)

Collimation:

Collimate closely to area of interest; include distal 1st, 2nd, and 3rd metatarsals for possible sesamoids

Lateral Toes

Evaluation Criteria

Anatomy Demonstrated:

• Entire digit, including proximal phalanx

Position:

• No superimposition of adjoining digits

• Proximal phalanx visualized through superimposed structures

Exposure:

• Contrast and density (brightness) sufficient to visualize soft tissue and bony portions; no motion

Fig. 4-10 Lateral second digit.

Tangential Projection

(Sesamoid Bones)

Evaluation Criteria

Anatomy Demonstrated:

• Sesamoid bones in profile

Position:

• No superimposition of sesamoids and 1st to 3rd distal metatarsals in profile

Exposure:

• Optimal density (brightness) and contrast; no motion

• Soft tissue and sharp cortical margins clearly demonstrated

Fig. 4-11 Tangential sesamoids.

AP Foot^*

(Dorsoplantar Projection)

• 24 × 30 cm L.W. (10 × 12″)

• Nongrid

• Lead masking with multiple exposures on same IR

Fig. 4-12 AP foot, CR 10° posteriorly.

Position

• Supine or seated with plantar surface of foot flat on IR, aligned lengthwise to portion of IR being exposed

• Extend (plantar flex) foot by sliding foot and IR distally while keeping plantar surface flat on IR. (Support with sandbags to keep foot and IR from sliding farther.)

Central Ray:

CR ⊥, to metatarsals, which is about 10° posteriorly (toward heel), centered to base of 3rd metatarsal

SID:

40-44″ (102-113 cm)

Collimation:

Four sides to margins of foot

AP Oblique Foot^*

• 24 × 30 cm L.W. (10 × 12″)

• Nongrid

• Lead masking with multiple exposures on same IR

Fig. 4-13 30°–40° medial oblique.

Position

• Supine or seated with foot centered lengthwise to portion of IR being exposed

• Oblique foot 30°–40° medially, support with 45° radiolucent angle block and sandbags to prevent slippage

• Note 1: A higher arch requires nearer 45° oblique and a low arch “flat foot” nearer 30°.

• Note 2: A 30° lateral oblique projection will demonstrate the space between 1st and 2nd metatarsals and between 1st and 2nd cuneiforms.

Central Ray:

CR ⊥, centered to base of 3rd metatarsal

SID:

40-44″ (102-113 cm)

Collimation:

Four sides to margins of foot and distal ankle.

AP and AP (Medial) Oblique Foot

Fig. 4-14 AP foot.

Fig. 4-15 Medial oblique foot.

Evaluation Criteria

Anatomy Demonstrated:

• AP and AP medial oblique: Tarsals, metatarsals, and phalanges

Position:

AP:

• No rotation with tarsals superimposed

AP Medial Oblique:

• 3rd to 5th metatarsals free of superimposition

• Cuboid clearly demonstrated; base of 5th metatarsal seen in profile

Exposure:

• Optimal density (brightness) and contrast; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

Lateral Foot^*

• 18 × 24 cm L.W. (8 × 10″) or

• 24 × 30 cm L.W. (10 × 12″) for large foot

• Nongrid

Fig. 4-16 Mediolateral foot.

Position (Mediolateral)

• Recumbent, turned on affected side, knee flexed with unaffected leg behind to prevent overrotation

• Place support under affected knee and leg as needed to place plantar surface of foot perpendicular to IR for a true lateral.

Fig. 4-17 Lateromedial foot.

Lateromedial Projection:

May be easier to achieve a true lateral if patient’s condition allows this position.

Central Ray:

CR ⊥, centered to area of base of third metatarsal

SID:

40-44″ (102-113 cm)

Collimation:

Four sides to margins of foot and distal ankle

Lateral Foot

Fig. 4-18 Lateral foot.

Evaluation Criteria

Anatomy Demonstrated:

• Entire foot with ≈1″ (2.5 cm) of distal tibia-fibula

Position:

• True lateral with tibiotalar joint open

• Distal metatarsals superimposed

Exposure:

• Optimal density (brightness) and contrast; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

Weight-Bearing Feet AP and Lateral^*

Lateral projection is most common for longitudinal arch (flat feet), AP demonstrates alignment of metatarsals and phalanges.

• 24 × 30 cm L.W. (10 × 12″); 35 × 43 cm C.W. (14 × 17″) for bilateral study

• Nongrid

Fig. 4-19 AP—both feet CR 15° posteriorly.

Position

AP: Erect, weight evenly distributed on both feet, on one IR

Lateral: Erect, full weight on both feet, vertical IR between feet, standing on blocks, high enough from floor for horizontal CR (R and L feet taken for comparison)

Fig. 4-20 Lateral—left foot.

Central Ray:

AP: CR 15° posteriorly, CR to level of base of 3rd metatarsal, midway between feet

Lateral: CR horizontal, to base of 5th metatarsal

SID: 40-44″ (102-113 cm)

Collimation: Collimate to outer skin margins of the feet

Weight-Bearing AP and Lateral Foot

Evaluation Criteria

Anatomy Demonstrated:

• AP: Bilateral feet with soft tissue detail

• Lateral: Entire foot with 1″ (2.5 cm) of distal tibia-fibula

Fig. 4-21 AP weight-bearing foot.

Position:

• AP: Open tarsometatarsal joints; no rotation with approximately equal spacing of 2nd to 4th metatarsals

• Lateral: Dorsum to plantar surface demonstrated; heads of metatarsals superimposed

Exposure:

• Optimal density (brightness) and contrast

• Soft tissue and sharp bony trabeculation clearly demonstrated; no motion

Fig. 4-22 Lateral weight-bearing foot.

Plantodorsal Calcaneus^*

(Axial Projection)

Fig. 4-23 CR 40° to long axis of foot.

• 18 × 24 cm L.W. (8 × 10″)

• Nongrid (detail screens)

• Lead masking with multiple exposures on same IR

Position

• Supine or seated, dorsiflex foot to as near vertical position as possible. If possible, have patient pull on gauze as shown. (This may be painful for patient to maintain, don’t delay!)

• Center CR to part, with IR centered to projected CR.

Central Ray:

CR 40° to long axis of plantar surface (may require more than 40° from vertical if foot is not dorsiflexed a full 90°)

• CR centered to base of 3rd metatarsal, to emerge just distal and inferior to ankle joint

• Note: Important to place the calcaneus on the lower aspect of the IR closest to the x-ray tube because of the severe CR angulation

SID:

40-44″ (102-113 cm)

Collimation:

Collimate closely to region of calcaneus.

Lateral Calcaneus^*

• 18 × 24 cm L.W. (8 × 10″)

• Nongrid

• Lead masking with multiple exposures on same IR

Fig. 4-24 Lateral calcaneus.

Position

• Recumbent, on affected side, knee flexed with unaffected limb behind, to prevent over-rotation

• Place support under knee and leg as needed for a true lateral

• Dorsiflex foot so the plantar surface is near 90° to leg if possible.

Central Ray:

CR ⊥, to midcalcaneus, 1″ (2.5 cm) inferior to medial malleolus

SID:

40-44″ (102-113 cm)

Collimation:

Four sides to area of calcaneus, include ankle joint at upper margin

Plantodorsal (Axial) and Lateral Calcaneus

Evaluation Criteria

Anatomy Demonstrated:

• Plantodorsal: Entire calcaneus from tuberosity to talocalcaneal joint

• Lateral: Calcaneus in profile to distal tibia-fibula

Fig. 4-25 Plantodorsal calcaneus.

Fig. 4-26 Lateral calcaneus.

Position:

• Plantodorsal: No rotation with sustentaculum tali in profile medially

• Lateral: Partial superimposed talus and open talocalcaneal joint

Exposure:

• Density and contrast (brightness) sufficient to faintly visualize distal fibula through talus; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

AP Ankle^*

Fig. 4-27 AP ankle.

• 24 × 30 cm L.W. (10 × 12″)

• Nongrid

• Lead masking with multiple exposures on same IR

Position

• Supine or seated on table, leg extended, support under knee

• Align leg and ankle parallel to edge of IR.

• True AP, ensure no rotation, long axis of foot is vertical, parallel to CR (lateral malleolus will be about 15° more posterior than medial malleolus)

Central Ray:

CR ⊥, to midway between malleoli

SID:

40-44″ (102-113 cm)

Collimation:

Collimate to lateral skin margins; include proximal ½ of metatarsals and distal tibia-fibula.

AP Mortise Ankle^*

This is a frontal view of the entire ankle mortise and generally should not be a substitute for the routine AP or 45° oblique ankle.

• 24 × 30 cm L.W. (10 × 12″)

• Nongrid

• Lead masking with multiple exposures on same IR

Fig. 4-28 AP, to visualize entire ankle mortise (15°–20° medial oblique).

Position

• Supine or seated on table, leg extended, support under knee

• Rotate leg and long axis of foot internally 15°–20° so intermalleolar line is parallel to tabletop.

Central Ray:

CR ⊥, to midway between malleoli

SID:

40-44″ (102-113 cm)

Collimation:

Collimate to ankle region. Include distal tibia-fibula and proximal metatarsals in collimation field.

Note:

The base of the fifth metatarsal is a common fracture site and may be demonstrated in this projection.

AP Oblique Ankle^*

• 24 × 30 cm L.W. (10 × 12″)

• Nongrid

• Lead masking with multiple exposures on same IR

Fig. 4-29 45° medial oblique ankle.

Position

• Supine or seated, leg extended, support under knee

• Rotate leg and foot 45° internally (long axis of foot is 45° to IR).

Central Ray:

CR ⊥, to midway between the malleoli

SID:

40-44″ (102-113 cm)

Collimation:

Collimate to ankle region, include proximal metatarsals and distal tibia-fibula.

Note:

The base of 5th metatarsal is a common fracture site and may be visualized on oblique ankle projections.

AP, AP Mortise, and 45° Oblique Ankle

Fig. 4-30 AP ankle.

Fig. 4-31 AP mortise ankle.

Fig. 4-32 45° oblique.

Evaluation Criteria

Anatomy Demonstrated:

• AP: Distal ⅓ tibia-fibula, talus, and proximal metatarsals

• AP mortise: Entire ankle mortise with distal ⅓ tibia-fibula and base of 5th metatarsal; equal distance throughout the tibiotalar joint

• AP 45° oblique: Distal ⅓ tibia-fibula, talus, calcaneus, and base of 5th metatarsal

Position:

• AP: No rotation with superior-medial joint surfaces open.

• AP mortise: Open lateral, superior, and medial joint surfaces; malleoli in profile

• AP 45° oblique: Open distal tibiofibular joint, talus, and medial malleolus open with no or only minimal overlap.

Exposure:

• Density and contrast (brightness) sufficient to faintly visualize distal fibula through talus; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

Lateral Ankle^*

• 24 × 30 cm L.W. (10 × 12″)

• Nongrid (detail screens)

• Lead masking with multiple exposures on same IR

Fig. 4-33 Mediolateral ankle.

Position

• Recumbent, affected side down, affected knee partially flexed

• Dorsiflex foot 90° to leg if patient can tolerate.

• Place support under knee as needed for true lateral of foot and ankle.

Fig. 4-34 Lateromedial ankle.

Central Ray:

CR ⊥, to medial malleolus

Note:

May also be taken as a lateromedial projection if patient condition allows, may be easier to achieve a true lateral.

SID:

40-44″ (102-113 cm)

Collimation:

Four sides to ankle region. Include distal tibia-fibula and proximal metatarsals.

Lateral Ankle

Evaluation Criteria

Anatomy Demonstrated:

• Distal ⅓ of tibia-fibula with lateral view of tarsals and base of 5th metatarsal

Position:

• True lateral with no rotation, distal fibula superimposed over posterior half of tibia

• Tibiotalar joint open

Exposure:

• Density and contrast (brightness) sufficient to faintly visualize distal fibula through talus; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

Fig. 4-35 Lateral ankle.

AP Ankle—Stress Views^*

(Inversion and Eversion Positions)

Fig. 4-36 Inversion stress.

Fig. 4-37 Eversion stress.

Warning: Stress must be applied very carefully, either by a long gauze held by patient or handheld by qualified person wearing lead gloves and apron (may require injection of local anesthetic by a physician).

• 24 × 30 cm L.W. (10 × 12″) or 35 × 43 cm C.W. (14 × 17″)

• Nongrid

• Lead masking with multiple exposures on same IR

Position

• Supine or seated on table, leg extended

• Without rotating leg or ankle (true AP), stress is applied to ankle joint by first turning plantar surface of foot inward (inversion stress), then outward (eversion stress).

Central Ray:

CR ⊥, to midway between malleoli

SID:

40-44″ (102-113 cm)

Collimation:

Collimate to lateral skin margins, including proximal metatarsals and distal tibia-fibula.

AP Leg (Tibia-Fibula)^*

Fig. 4-38 AP leg.

• 35 × 43 cm L.W. (14 × 17″) diagonal only if needed to include both ankle and knee joints.

• Nongrid

• Knee at cathode end to utilize anode heel effect

Position

• Supine, leg extended, ensure no rotation of knee, leg, or ankle

• Include ≈3 cm (1-1.5″) minimum beyond knee and ankle joints, considering divergent rays

Central Ray:

CR ⊥, to midshaft of leg (to mid-IR)

SID:

Minimum SID of 40″ (102 cm); may increase to 44–48″ (112–123 cm)

Collimation:

On four sides, to include knee and ankle joints

Lateral Leg (Tibia-Fibula)^*

Fig. 4-39 Lateral leg.

• 35 × 43 cm L.W. (14 × 17″) diagonal if needed to include both joints

• Nongrid

• Knee at cathode end (to utilize anode heel effect)

Position

• Recumbent, affected side down

• Place unaffected limb behind patient to prevent over-rotation.

• Place support under distal portion of affected foot as needed to ensure a true lateral position of foot, ankle, and knee.

• Include ≈3 cm (1-1.5″) minimum beyond knee and ankle joints considering divergent rays

Central Ray:

CR ⊥, to midshaft of leg (to mid-IR)

SID:

Minimum SID of 40″ (102 cm); may increase to 44–48″ (112–123 cm)

Collimation:

On four sides, to include knee and ankle joints

AP and Lateral Leg (Tibia-Fibula)

Fig. 4-40 AP lower leg.

Fig. 4-41 Lateral lower leg.

Evaluation Criteria

Anatomy Demonstrated:

• AP: Entire tibia-fibula with ankle and knee joints

• Lateral: Entire tibia-fibula with ankle and knee joints

Position:

• AP: No rotation, with femoral and tibial condyles in profile

• Slight overlap at both proximal and distal tibiofibular joints

• Lateral: Tibial tuberosity in profile

• Distal fibula overlaps posterior portion of tibia

Exposure:

• Near equal density (brightness) and contrast; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

AP Knee^*

Fig. 4-42 AP knee (CR ⊥, to film for average patient).

• 24 × 30 cm L.W. (10 × 12″)

• Grid >10 cm

• IR <10 cm

Position

• Supine, or seated on table, with leg extended and centered to CR and midline of table or IR

• Rotate leg slightly inward as needed to place knee and leg into a true AP. Center IR to CR.

Central Ray:

CR centered to 1.25 cm (½″) distal to apex of patella

CR Parallel to Articular Facets (Tibial Plateau):

Measure distance from ASIS to TT to determine CR angle.

• Thin thighs and buttocks (<19 cm ASIS to TT), 3°–5° caudad

• Average thighs and buttocks (19-24 cm), 0°, ⊥ IR

• Thick thighs and buttocks (>24 cm), 3°–5° cephalad

Collimation:

Sides to skin borders, ends to IR borders

AP Oblique Knee^*

Fig. 4-43 45° medial oblique.

Fig. 4-44 45° lateral oblique.

Medial oblique: Demonstrates fibular head and neck unobscured. (Lateral oblique may also be taken.)

• 24 × 30 cm L.W. (10 × 12″)

• Grid >10 cm

• IR <10 cm

Position

• Supine, leg extended and centered to CR and midline of table

• Rotate entire leg, including knee, ankle, and foot, internally 45° for medial oblique, and 45° externally for external oblique

• Center IR to CR.

Central Ray:

• CR ⊥, to IR on average patient (see AP Knee)

• CR to mid-joint space (1.25 cm or ½″ inferior to patella)

SID:

40-44″ (102-113 cm)

Collimation:

Sides to skin borders, ends to IR borders

AP and AP Medial and Lateral Oblique Knee

Fig. 4-45 AP knee.

Fig. 4-46 AP medial oblique.

Fig. 4-47 AP lateral oblique.

Evaluation Criteria

Anatomy Demonstrated:

• AP: Open femorotibial joint space

• AP medial oblique: Open proximal tibiofibular joint; femoral and tibial lateral condyles in profile

• AP lateral oblique: Medial condyles in profile

Position:

• AP: No rotation evident by symmetric appearance of femoral and tibial condyles

• AP medial oblique: Proximal tibiofibular joint open; tibial lateral condyles demonstrated

• AP lateral oblique: Medial condyles of femur and tibia are in profile; proximal tibia and fibula are superimposed

Exposure:

• Optimal density (brightness) and contrast; outline of patella through distal femur; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

Lateral Knee^*

• 24 × 30 cm L.W. (10 × 12″)

• Grid >10 cm

• IR <10 cm

Fig. 4-48 Mediolateral knee, CR 5° cephalad.

Position

• Patient on affected side, knee flexed ≈20°, centered to CR and midline of table or IR

• Unaffected leg and knee placed behind to prevent over-rotation

• Place support under affected ankle and foot if needed and adjust body rotation as required for a true lateral of knee.

• Center IR to CR.

Central Ray:

• CR 5°–7° cephalad

• CR centered to ≈2.5 cm (1″) distal to medial epicondyle

SID:

40-44″ (102-113 cm)

Collimation:

Sides to skin borders, ends to borders of IR

Lateral Knee

Evaluation Criteria

Anatomy Demonstrated:

• Distal femur, proximal tibia-fibula, and patella in lateral profile

• Femoropatellar and knee joints open

Fig. 4-49 Lateral knee.

Position:

• True lateral with no rotation; femoral condyles superimposed

• Patella in profile and femoropatellar joint open

Exposure:

• Optimal density (brightness) and contrast; no motion

• Soft tissue (fat pads) and sharp bony trabeculation clearly demonstrated

Knees—AP or PA Weight-Bearing^*

• 35 × 43 cm C.W. (14 × 17″)

• Grid

Fig. 4-50 AP weight-bearing—bilateral, CR ⊥ to IR.

Position

AP:

• Erect, standing on step stool or footboard as needed (high enough to get x-ray tube low for horizontal beam)

• Feet straight ahead, knees straight, weight distributed evenly on both feet. Have patient hold onto table handles for support.

Alternative PA:

Patient facing the table or IR holder, with knees against table or vertical IR holder, knees flexed ≈20°

Central Ray:

CR to midpoint between knee joints, at level of ≈1.25 cm (½″) distal to apex of patellae

AP:

CR horizontal, ⊥ to IR on average patient (see AP Knee)

PA:

CR 10° caudad (if knees are flexed ≈20°)

SID:

40-44″ (102-113 cm)

Collimation:

To bilateral knee joint region

PA Axial Weight-Bearing Bilateral Knees^*

(Rosenberg Method)

• 35 × 43 cm C.W. (14 × 17″)

• Grid

Fig. 4-51 PA axial weight-bearing—CR 10° caudad.

Fig. 4-52 Rosenberg method.

Position

• Patient erect PA

• Weight evenly distributed

• Knees flexed to 45°

Central Ray:

10° caudad to mid-knee joints—½″ (1.25 cm) below apex of patella.

SID:

40-44″ (102-113 cm)

Collimation:

Bilateral knee joint region, including distal femora and proximal tibia

PA Axial Weight-Bearing Bilateral Knees

(Rosenberg Method)

Fig. 4-53 PA axial weight-bearing knees.

Evaluation Criteria

Anatomy Demonstrated:

• Distal femur, proximal tibia and fibula, femorotibial joint spaces, and intercondylar fossa

Position:

• No rotation of both knees evident by symmetric appearance

• Articular facets in profile

Exposure:

• Optimal density (brightness) and contrast; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

Knee for Intercondylar Fossa^*

Camp Coventry and Holmblad Methods (Tunnel View)

Fig. 4-54 PA axial projection (Camp Coventry).

Fig. 4-55 Alternative Holmblad method:

– Patient kneeling, leans forward 20°–30°

– CR ⊥ to IR

• 18 × 24 cm L.W. (8 × 10″)

• Grid

Camp Coventry:

Position:

• Prone, knee flexed 40°–50°, large support under ankle

• Knee centered to CR

• IR centered to projected CR

Central Ray:

CR 40°–50° caudad (⊥ to lower leg), centered to knee joint, to emerge at distal margin of patella

SID:

40-44″ (102-113 cm)

Collimation:

Four sides to area of interest

PA Patella^*

• 18 × 24 cm L.W. (8 × 10″)

• Grid

Fig. 4-56 PA patella.

Position

• Prone, knee centered to CR and midline of table or IR

• If patella area is painful, place pad under thigh and leg to prevent direct pressure on patella.

• Rotate anterior knee approximately 5° internally or as needed to place an imaginary line between the epicondyles parallel to the plane of the IR.

• Center IR to CR.

Central Ray:

CR ⊥, centered to central patella region (at midpopliteal crease)

SID:

40-44″ (102-113 cm)

Collimation:

To area of patella and knee joint

Lateral Patella^*

• 18 × 24 cm L.W. (8 × 10″)

• Nongrid (detail screens—may use grid on large patient)

Fig. 4-57 Lateral patella.

Position

• Recumbent on affected side, opposite knee, and leg behind to prevent over-rotation

• Flex knee only 5°–10° to prevent separation of fractured fragments if present.

• Patellofemoral joint area centered to CR and midline of IR.

Central Ray:

CR ⊥, centered to mid-patellofemoral joint space

SID:

40-44″ (102-113 cm)

Collimation:

To area of knee joint, patella, and patellofemoral joint

Intercondylar Fossa, PA and Lateral Patella

Evaluation Criteria

Anatomy Demonstrated:

• PA axial: Intercondylar fossa shown in profile

• PA: Knee joint and patella outline through distal femur

• Lateral: Lateral patella in profile

Position:

• PA axial: No rotation evidenced by symmetric femoral condyles and intercondylar eminence centered under intercondylar fossa

• PA: No rotation, femoral condyles appear symmetric; patella appears centered to femur

• Lateral: Patella in profile and femoropatellar joint open

Fig. 4-58 PA axial—intercondylar fossa projection.

Fig. 4-59 PA patella.

Fig. 4-60 Lateral patella.

Exposure:

• Optimal density (brightness) and contrast; no motion

• Sharp bony trabeculation clearly demonstrated

Patella—Tangential Projection^*

(Merchant Bilateral Method)

• 24 × 30 cm C.W. (10 × 12″) or 35 × 43 cm (14 × 17″) C.W. for large knees

• Nongrid

• Adjustable leg and IR-holding device required

Fig. 4-61 Bilateral tangential.

Position

• Supine with knees flexed 45° on leg supports (important for patient to be comfortable with legs totally relaxed to prevent patellae from being drawn into intercondylar sulcus)

• Place IR on supports against legs about 30 cm (12″) distal to patellae, perpendicular to CR.

• Internally rotate both legs as needed to center patellae to midfemora.

Central Ray:

CR 30° from horizontal (30° from long axis of femora)

• CR to midpoint between patellae at patellofemoral joints

SID:

48-72″ (123-183 cm) greater SID reduces magnification

Collimation:

To bilateral patellae and patellofemoral joints

Patella—Tangential Projection^*

(Settegast and Hughston Methods)

Generally taken bilaterally for comparison purposes.

• 24 × 30 cm C.W. (10 × 12″)

• Nongrid

• Lead masking with multiple exposures on same IR

Fig. 4-62 Settegast:
– Knee flexed 90°
– CR 15°–20° to leg

Fig. 4-63 Hughston:
– Knee flexed 45°– CR 10°–15° to leg
Warning: Possible hot collimator, use pad.

Position

• Prone, knee flexed as shown

• Use long gauze or tape for patient to hold leg in position; for Hughston method, may support foot on collimator, use pad

Central Ray:

CR centered to patellofemoral joint space

Settegast:

CR 15°–20° cephalad to long axis of leg (knee flexed 90°)

Hughston:

CR 15°–20° cephalad to long axis of leg (knee flexed 45°) (recommended method)

SID:

40-48″ (102-123 cm)

Collimate:

Closely to patella region

Patella—Superoinferior Sitting Tangential^*

(Hobbs Modification)

Generally taken bilaterally for comparison purposes

• 35 × 43 cm C.W. (14 × 17″) or 18 × 24 cm (8 × 10″), C.W. (unilateral)

• Nongrid

Fig. 4-64 Tangential superoinferior (Hobbs modification).

Position

• Patient seated

• Knees flexed with feet placed under chair

• IR placed on footstool

Central Ray:

Perpendicular to IR centered to midway between femoropatellar joints

SID:

48-50″ (123-128 cm)

Collimation:

Bilateral knee joint region, distal femora, and patella

Tangential Bilateral Patella

(Hobbs Modification)

Fig. 4-65 Tangential sitting method.

Evaluation Criteria

Anatomy Demonstrated:

• Tangential view of patella

• Femoropatellar knee joint

Position:

• Separation of patella and intercondylar sulcus

• Femoropatellar joint open

Exposure:

• Optimal density (brightness) and contrast; no motion

• Soft tissue and sharp bony trabeculation clearly demonstrated

Pediatric AP Lower Limb^*

• Size determined by patient size

• Nongrid (detail screen)

Note:

If foot is specific area of interest, AP and lateral projections of foot only may be required.

Fig. 4-66 AP lower limb.

Position—Shield Gonads

• Supine, include entire limb, shield over pelvic area

• A second IR of pelvis and/or proximal femur may be required (see Chapter 16 in the text)

• Immobilize arms and unaffected leg with sandbags.

• Use parental assistance only if necessary; provide lead gloves and apron.

Central Ray:

CR ⊥, centered to midlimb (mid-IR)

SID:

40-44″ (102-113 cm)

Collimation:

Four sides to area of interest

Pediatric Lateral Lower Limb^*

• Size determined by patient size

• Nongrid (detail screen)

Note:

If foot is specific area of interest, AP and lateral projections of foot only may also be required.

Fig. 4-67 Lateral lower limb (see Note).

Position—Shield Gonads

• Semisupine, include entire limb, shield over pelvic area

• Immobilize arms and unaffected leg with sandbags as needed

• Abduct (frog leg) affected limb into lateral position, immobilize with tape or compression band. (Do not attempt with hip trauma or hip disease.)

• If parental assistance is necessary, provide lead gloves and apron

Central Ray:

CR ⊥, centered to midlimb (mid-IR)

SID:

40″ (102 cm)

Collimation:

Four sides to area of interest

Pediatric—AP and Lateral Foot^*

(Congenital Clubfoot—Kite Method)

Fig. 4-68 AP foot.

Fig. 4-69 Mediolateral foot.

• 18 × 24 cm L.W. (8 × 10″)

• Nongrid (detail screens)

Note:

With Kite method, no attempt is made to straighten foot when placing on IR. The foot is held or immobilized for a frontal and side view (AP and lateral projections) 90° from each other. Both feet generally are taken for comparison.

Position

• AP: Elevate patient on support, flex knee, foot on IR

• Lateral: Patient and/or leg on side, affected side down, use tape or compression band

Central Ray:

• AP: CR ⊥, to IR, directed to midtarsals (Kite suggests no angle)

• Lateral: CR ⊥, centered to proximal metatarsal area

SID:

40-44″ (102-113 cm)

Collimation:

Closely on four sides to area of foot

^*Bontrager Textbook, 8th ed, p. 226.

^*Bontrager Textbook, 8th ed, p. 227.

^*Bontrager Textbook, 8th ed, p. 228.

^*Bontrager Textbook, 8th ed, p. 229.

^*Bontrager Textbook, 8th ed, p. 230.

^*Bontrager Textbook, 8th ed, p. 231.

^*Bontrager Textbook, 8th ed, p. 232.

^*Bontrager Textbook, 8th ed, pp. 233 and 234.

^*Bontrager Textbook, 8th ed, p. 235.

^*Bontrager Textbook, 8th ed, p. 236.

^*Bontrager Textbook, 8th ed, p. 237.

^*Bontrager Textbook, 8th ed, p. 238.

^*Bontrager Textbook, 8th ed, p. 239.

^*Bontrager Textbook, 8th ed, p. 240.

^*Bontrager Textbook, 8th ed, p. 241.

^*Bontrager Textbook, 8th ed, p. 242.

^*Bontrager Textbook, 8th ed, p. 243.

^*Bontrager Textbook, 8th ed, p. 244.

^*Bontrager Textbook, 8th ed, pp. 245 and 246.

^*Bontrager Textbook, 8th ed, p. 247.

^*Bontrager Textbook, 8th ed, p. 248.

^*Bontrager Textbook, 8th ed, p. 249.

^*Bontrager Textbook, 8th ed, pp. 251 and 252.

^*Bontrager Textbook, 8th ed, p. 254.

^*Bontrager Textbook, 8th ed, p. 255.

^*Bontrager Textbook, 8th ed, p. 256.

^*Bontrager Textbook, 8th ed, pp. 257 and 258.

^*Bontrager Textbook, 8th ed, p. 258.

^*Bontrager Textbook, 8th ed, p. 637.

^*Bontrager Textbook, 8th ed, p. 638.

Lower Limb (Extremity)