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RA 102 Chapter 7
Projections
Term | Definition |
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Foot AP / AP Axial central ray: | (1) Axial: 10 degrees toward the heel entering the base of the third metatarsal (2) AP: perpendicular to the IR and entering the base of the third metatarsal |
Foot AP / AP Axial structures shown: | an AP (dorsoplantar) projection of the tarsals anterior to the talus, metatarsals, and phalanges |
Foot AP / AP Axial evaluation criteria: | - Anatomy from toes to tarsals; may include portions of talus and calcaneus - Axial projection resulting in improved demonstration of IP, MTP, and TMT joint spaces |
Foot AP Oblique Medial / Lateral rotation central ray: | perpendicular to the IR and entering the base of the third metatarsal |
Foot AP Oblique Medial / Lateral rotation structures shown: | - the interspaces of the cuboid and the calcaneus - the cuboid and the 4th and 5th metatarsals - the cuboid and the lateral cuneiform, and the talus and the navicular bone - the cuboid and sinus tarsi is shown in profile |
Foot AP Oblique Medial / Lateral rotation evaluation criteria: - Sinus tarsi - Lateral TMT and intertarsal joints | - entire foot, from toes to heel - 3rd through 5th MT free of superimposition - 1st and 2nd MT superimposed on medial and intermediate cuneiforms - navicular, lateral cuneiform, and cuboid with less superimposition - tuberosity of the 5th MT |
Foot LATERAL Mediolateral central ray: | perpendicular to the base of the third metatarsal |
Foot LATERAL Mediolateral structures shown: | the entire foot in profile, the ankle joint, and the distal ends of the tibia and fibula |
Foot LATERAL Mediolateral evaluation criteria: | - entire foot and distal leg - superimposed plantar surfaces of the MT heads - fibula overlapping the posterior portion of the tibia - tibiotalar joint |
Calcaneus Axial Plantodorsa central ray: | - the central ray enters near the base of the 3rd MT - directed to the midpoint of the IR at a CEPHALIC angle (entering the plantar surface and toward the heel) of 40 degrees to the long axis of the foot |
Calcaneus Axial Plantodorsa structures shown: | an axial projection of the calcaneus |
Calcaneus Axial Plantodorsa evaluation criteria: | - calcaneus and subtalar joint - the 1st or 5th MT not projected to the sides of foot - anterior portion of the calcaneus with brightness similar to the posterior portion; otherwise, two images may be needed for the two regions of thickness |
Calcaneus Axial Dorsoplantar central ray: | - enters the dorsal surface of the ankle joint - directed to the midpoint of the IR at a CAUDAL angle (enters posterior surface and toward the heel) of 40 degrees to the long axis of the foot. |
Calcaneus Axial Dorsoplantar structures shown: | an axial projection of the calcaneus and the subtalar joint |
Calcaneus Axial Dorsoplantar evaluation criteria: | - calcaneus and the subtalar joint - sustentaculum tali - calcaneus not rotated—the 1st or 5th MT not projected to the sides of the foot - anterior portion of the calcaneus with brightness similar to the posterior portion |
Calcaneus Lateral Mediolateral central ray: | - perpendicular to the calcaneus - center about 1 inch distal to the medial malleolus - this places the central ray at the subtalar joint |
Calcaneus Lateral Mediolateral structures shown: | the ankle joint and the calcaneus in lateral profile |
Calcaneus Lateral Mediolateral evaluation criteria: | - calcaneus, including ankle joint and adjacent tarsals - no rotation of the calcaneus - tuberosity in profile - sinus tarsi open - calcaneocuboid and talonavicular joints open |
Ankle AP central ray: | perpendicular through the ankle joint at a point midway between the malleoli |
Ankle AP structures shown: | a true AP projection of the ankle joint, the distal ends of the tibia and fibula, and the proximal portion of the talus |
Ankle AP evaluation criteria: - no overlapping of the medial talomalleolar joint | - medial and lateral malleoli - talus with proper brightness - normal overlapping of the tibiofibular articulation with the anterior tubercle slightly superimposed over the fibula - talus slightly overlapping the distal fibula - tibiotalar joint space |
Ankle Mediolateral central ray: | perpendicular to the ankle joint, entering the medial malleolus |
Ankle Mediolateral structures shown: | a true lateral projection of the lower 3rd of the tibia and fibula; the ankle joint; and the tarsals, including the base of the 5th metatarsal |
Ankle Mediolateral evaluation criteria: - 5th MT base and tuberosity should be seen to check for Jones fracture | -distal tib/fib, talus, calcaneus, and adjacent tarsals - ankle in true lateral position - tibiotalar joint well visualized, with the medial and lateral talar domes superimposed - fibula over the posterior half of the tibia |
Ankle Lateromedial central ray: | perpendicular through the ankle joint, entering 12 inch (1.3 cm) superior to the lateral malleolus |
Ankle Lateromedial structure shown: | a lateral projection of the lower third of the tibia and fibula, the ankle joint, and the tarsals |
Ankle Lateromedial evaluation criteria: | -distal tib/fib, talus, calcaneus, and adjacent tarsals - ankle in true lateral position - tibiotalar joint well visualized, with the medial and lateral talar domes superimposed - fibula over the posterior half of the tibia |
Ankle AP Oblique Medial rotation central ray: | perpendicular to the ankle joint, entering midway between the malleoli |
Ankle AP Oblique Medial rotation structure shown: | - the 45-degree medial oblique projection shows the distal ends of the tibia and fibula, parts of which are often superimposed over the talus - the tibiofibular articulation also should be shown |
Ankle AP Oblique Medial rotation evaluation criteria: | -ankle joint centered to exposure area - distal tibia, fibula, and talus - proper 45-degree rotation of ankle - tibiofibular articulation open - distal tibia and fibula overlap some of the talus |
Ankle Mortise Joint AP Oblique Medial rotation central ray: | Perpendicular, entering the ankle joint midway between the malleoli |
Ankle Mortise Joint AP Oblique Medial rotation structures shown: | - the entire ankle mortise joint should be shown in profile - the 3 sides of the mortise joint should be visualized |
Ankle Mortise Joint AP Oblique Medial rotation evaluation criteria: | - distal tibia, fibula, and talus - proper 15- to 20-degree rotation of ankle - talofibular articulation open - tibiotalar articulation open - no overlap of the anterior tubercle of the tibia and the superolateral portion of the talus with the fibula |
Ankle AP Oblique Lateral rotation central ray: | - perpendicular, entering the ankle joint midway between the malleoli |
Ankle AP Oblique Lateral rotation structures shown: | the lateral rotation oblique projection is useful in determining fractures and showing the superior aspect of the calcaneus |
Ankle AP Oblique Lateral rotation evaluation criteria: | - distal tibia, fibula, and talus - tibiotalar joint - calcaneal sulcus (superior portion of calcaneus) |