The head of the fibula is located at its proximal end and has a pointed apex laterally. Distally, the fibular features the lateral malleolus.
The articulations between the two leg bones are discussed on Screen 1.13.
Knee…..
The knee joint is the articulation between the femoral condyles and the tibial plateaus. Numerous soft tissues support and reinforce the knee, including the:
Menisci Cruciate ligaments Collateral ligaments
These supporting soft tissue structures are enclosed in a common joint capsule.
The knee joint is of the hinge type, capable of flexion and extension only. The anterior knee joint is protected by the patella and patellofemoral joint.
The patella is the largest and most constant sesamoid bone. It develops in the quadriceps femoris tendon between the ages of 3 and 5 years. The anterior distal surface of the femur has a shallow triangular depression, the patellar surface between the two condyles for articulation with the patella. This articulation is termed the patellofemoral joint. This synovial gliding joint protects the knee joint.
Femur….
1.12 Femur
The femur, the bone of the thigh region of the lower limb, is the longest, strongest bone in the human body. It has several anatomical features of note. Click to enlarge the illustration and see whether you can locate the following landmarks:
Head Neck Greater trochanter Lesser trochanter Body Lateral epicondyle
Note that some of these features are only seen on either the anterior or posterior view of the femur. It is useful to try describing the location of each anatomical feature as a means of studying and understanding femoral anatomy.
Knee Joint…
Six articulations are formed by the bones of the lower limb. The most distal, the ankle mortise, is discussed on Screen 1.6. The most proximal, the hip joint, will be studied in the next module. The remaining four are:
Proximal tibiofibular jointo Synovial diarthrosis gliding type
Distal tibiofibular jointo Fibrous syndemosis
Knee jointo Articulation between the femoral condyles and the tibial plateauso Synovial diarthrosis hinge type
Patellofemoral jointo Patella and patellar surface of anterior, distal femuro Synovial diarthrosis, gliding type
Positioning Steps Results/Rationale
Patient is seated with leg extended and affected posterior surface resting on IR or supine with leg and foot in position described above.
Provides AP projectionMaximizes patient comfort and cooperation
IR is centered to lower leg. Centers anatomy of interest to IR
Lower limb is in anatomic position.Tibial condyles are parallel to IR.
Provides true AP of tibia and fibula
Foot is dorsiflexed to right angle.Plantar surface is perpendicular to IR.
Demonstrates ankle joint without superimposition of calcaneus
Perpendicular CR enters center of lower leg. Places lower leg and both joints in center of IR and collimated fieldLonger limbs may require two exposures to image entire limb and adjacent joints.
Collimate to 1 inch (2.5 cm) on the sides and 11⁄2 inches (4 cm) beyond the ankle and knee joints.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
Lateral Projection: Tibia and Fibula
Positioning Steps Results/Rationale
Patient is seated with leg extended.Lateral side of affected limb rests on IR or patient is supine with leg and foot in position described above.
Provides mediolateral projectionMaximizes patient comfort and cooperation
IR is centered to lower leg. Centers anatomy of interest to IR
Tibial condyles are perpendicular to IR.Malleoli are superimposed and perpendicular to IR.
Provides true lateral of tibia and fibula
Foot is dorsiflexed to right angle. Demonstrates ankle joint without superimposition of calcaneus
Perpendicular CR enters center of lower leg. Places lower leg and both joints in center of IR and collimated field
Longer limbs may require two exposures to image entire limb and adjacent joints.
Collimate to 1 inch (2.5 cm) on the sides and 11⁄2 inches (4 cm) beyond the ankle and knee joints.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
Chapter 6, Essential Projections of the Knee, pp. 286-297, 300-302, and 304-305
1. What degenerative conditions of the knee are best demonstrated with weight-bearing projections?
2. How does patient size affect knee radiography?
Chapter 6, Essential Projections of the Intercondylar Fossa Projections, pp. 306-309
1. How many variations are there for the PA axial—Holmblad projection for intercondylar fossa?
2. How is the degree of central ray angulation determined for the Camp-Coventry method?
Chapter 6, Essential Patella and Patellofemoral Joint Projections, pp. 311-312 and 316-317
1. What amount of knee flexion is optimal in demonstrating the patella in a lateral position?
2. What is the relationship between flexion of the knee and the appearance of the patellofemoral joint space?
3. What is the primary disadvantage of the tangential (Settegast method) in demonstrating the patellofemoral joint space?
Chapter 6, Essential Projections of the Femur, pp. 318-321
1. How is the angle of the femoral body affected by the width of the pelvis?
AP Projection: Knee
Positioning Steps Results/Rationale
Patient is seated or supine, with leg extended. Provides AP projectionMaximizes patient comfort and cooperation
Table bucky is centered to knee joint.(Located ½ inch [1.3 cm] below patellar apex.)
Centers anatomy of interest to IRReduces distortion
Lower limb is in anatomic position.Tibial condyles are parallel to IR.
Provides true AP of knee joint
CR is directed to a point ½ inch (1.3 cm) inferior to the patellar apex.Angle varies, depending on the measurement between the anterior superior iliac spine (ASIS) and the tabletop, as follows:
<19 cm = 3 to 5 degrees caudad (thin pelvis) 19 to 24 cm = 0 degrees >24 cm = 3 to 5 degrees cephalad (large pelvis)
Aligns CR to open knee joint
Collimate to 10 x 12 inches (25 x 30 cm) field size. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motionClose Window
Lateral Projection: Knee
Positioning Steps Results/Rationale
Patient is recumbent, turned on affected side with lateral surface of knee on table.Knee is abducted, with unaffected limb behind.
Provides mediolateral projection Maximizes patient comfort and cooperationRemoves opposite limb from anatomy of interest
Table bucky is centered to knee joint.
Centers anatomy of interest to IR
Knee is in lateral position with tibial condyles perpendicular to IR.Knee is flexed 20 to 30 degrees.
Provides true lateral position of knee jointDegree of flexion relaxes muscles to demonstrate maximum volume of joint cavity
CR angle is 5 to 7 degrees cephalad.Enters knee joint 1 inch (2.5 cm) distal to the medial epicondyle.
Aligns CR to open knee jointSlight angle on the CR prevents the joint space from being obscured by the magnified image of the medial femoral condyle.
Collimate to 10 x 12-inch (25 x 30-cm) field size.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure.
Reduces possibility of motion
Close Window
AP Projection: Knees, Standing
Positioning Steps Results/Rationale
Patient stands upright, back against vertical grid device. Provides AP weight-bearing projection
Vertical grid device is centered to knee joints (located ½ inch [1.3 cm] below patellar apex).
Centers anatomy of interest to IRReduces distortion
Weight is equally distributed on both feet, which are facing forward.
Provides weight bearing to demonstrate joint narrowingReduces risk of rotation or distortion
Horizontal CR is directed perpendicular and enters ½ inch (1.3 cm) inferior to the patellar apices.
Centers knees to collimated field
Collimate to a 14 x 17-inch (35 x 43-cm) field size. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
AP Oblique Projection: Knee, Lateral Rotation
Positioning Steps Results/Rationale
Patient seated or supine with leg extended Provides AP oblique projectionMaximizes patient comfort and cooperation
Table bucky is centered to knee joint (located ½ inch [1.3 cm] below patellar apex).
Centers anatomy of interest to IR & reduces distortion
Lower limb is rotated laterally 45 degrees; elevate and support unaffected limb, if necessary.
Provides oblique position of knee joint
CR is directed to a point ½ inch (1.3 cm) inferior to the patellar apex.Angle varies, depending on the measurement between the ASIS and the tabletop:
<19 cm = 3 to 5 degrees caudad (thin pelvis) 19 to 24 cm = 0 degrees >24 cm = 3 to 5 degrees cephalad (large pelvis)
Aligns CR to open knee joint
Collimate to 10 x 12-inch (25 x 30-cm) field size. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion.
AP Oblique Projection: Knee, Medial Rotation
Positioning Steps Results/Rationale
Patient is seated or supine with leg extended. Provides AP oblique projectionMaximizes patient comfort and cooperation
Table bucky is centered to knee joint (located ½ inch [1.3 cm] below patellar apex).
Centers anatomy of interest to IR & reduces distortion
Lower limb is rotated medially 45 degrees; elevate and Provides oblique position of knee joint
support affected limb, if necessary. Opens proximal tibiofibular joint
CR is directed to a point ½ inch (1.3 cm) inferior to the patellar apex.Angle varies, depending on the measurement between the ASIS and the tabletop:
<19 cm = 3 to 5 degrees caudad (thin pelvis) 19 to 24 cm = 0 degrees >24 cm = 3 to 5 degrees cephalad (large pelvis)
Aligns CR to open knee joint
Collimate to 10 x 12-inch (25 x 30-cm) field size. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motionClose Window
PA Axial Projection: Intercondylar Fossa (Holmblad Method)
Positioning Steps Results/Rationale
Patient may be examined in one of three positions:
1. Standing: Knee of interest is flexed and resting on a stool at the side of the table.
2. Standing at tableside: Affected knee is flexed and placed in contact with the front of the IR.
3. Kneeling on the table (original Holmblad method): Affected knee is over the IR (pictured above).
Consideration of patient safety in choice of positionProvides PA axial projection
Center IR to patella. Centers anatomy of interest to IR and reduces distortion
Flex knee 70 degrees from full extension. Opens intercondylar fossa
CR is perpendicular to the lower leg and centered to IR. Centers open intercondylar fossa to collimated field
Collimate to a 8 x 10-inch (18 x 24 cm) field size. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
PA Axial Projection: Intercondylar Fossa (Camp-Coventry Method)
Positioning Steps Results/Rationale
Patient is prone on table. Provides PA axial projection
Place tibial condyles parallel to IR. Reduces distortion
Flex knee to 40- or 50-degree angle.Provide proper support for lower leg and foot.
Opens intercondylar fossaReduces risk of motion
CR is perpendicular to the lower leg and centered to IR:
Angled 40 degrees when knee is flexed 40 degrees
Angled 50 degrees when knee is flexed 50 degrees
Centers open intercondylar fossa to collimated field
Collimate to a 8 x 10-inch (18 x 24 cm) field size. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
PA Projection: Patella
Positioning Steps Results/Rationale
Patient lies prone on table. Provides PA projection
Place patella parallel to IR (usually requires heel to be rotated 5 to 10 degrees laterally).
Reduces distortion
CR is perpendicular to midpopliteal area. Centers patella to collimated field
Collimate to a 6 x 6-inch (15 x 15-cm) field size. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
Lateral Projection: Patella
Positioning Steps Results/Rationale
Patient lies in lateral recumbent position.Lateral surface of affected knee rests on table.Unaffected leg is placed in front, resting on table for support.
Provides mediolateral projection
Flex knee 5 to 10 degrees, with femoral epicondyles superimposed.Place patella perpendicular to IR.
Opens patellofemoral joint space (too much flexion decreases joint space)Places patella in lateral position
CR is perpendicular to IR; enters the knee at the midpatellofemoral joint.
Centers patella to collimated field
Collimate to a 4 x 4-inch (10 x 10-cm) field size. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
Tangential Patella and Patellofemoral Joint (Settegast Method)
Positioning Steps Results/Rationale
Patient lies prone (preferred) or sits with knee flexed.
Do not flex knee until a transverse fracture of the patella has been ruled out with a lateral image.Patient comfort considered in choice of positionProvides tangential projection
Flex knee slowly until patella is perpendicular to IR if patient's condition permits.
Positions patella and patellofemoral joint space for tangential projection
CR is perpendicular to patella and IR when patella is perpendicular.If not, angle CR into joint space, typically 15 to 20 degrees.CR enters the knee at the patellofemoral joint.
Centers patella and patellofemoral joint to collimated fieldOpens joint space
Collimate to 4 x 4-inch (10 x 10-cm) field size for unilateral image; 4 x 10-inch (10 x 25-cm) field is required for bilateral image.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
AP Projection: Femur, Proximal Portion
Positioning Steps Results/Rationale
Patient is supine, with no rotation of pelvis. Provides AP projection
Internally rotate limb 10 to 15 degrees. Positions femoral neck in profile
Top of IR (if used) is placed at level of ASIS. Includes entire hip joint and proximal femur
CR is perpendicular to midfemur and IR center. Centers proximal femur to collimated field
Collimate to 1 inch (2.5 cm) beyond medial and lateral skin shadows of thigh and 17 inches (43 cm) long.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
AP Projection: Femur, Distal Portion
Positioning Steps Results/Rationale
Patient is supine, with no rotation of pelvis. Provides AP projection
Position femoral and tibial condyles parallel. Positions femur in anatomic position
Bottom of IR (if used) is placed 2 inches distal to knee joint. Includes entire knee joint and distal femur
CR is perpendicular to midfemur and IR center. Centers distal femur to collimated field
Collimate to 1 inch beyond medial and lateral skin shadows of thigh and 17 inches (43 cm) long.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
Lateral Projection: Femur, Proximal Portion
Positioning Steps Results/Rationale
Patient lies in lateral recumbent on affected side, with unaffected limb placed behind affected limb for support.
Rotate unaffected side of pelvis posteriorly 10 to 15 degrees to prevent superimposition of hip of interest.
Positions femoral neck in lateral without superimposition of unaffected side
Top of IR (if used) is placed at level of ASIS. Includes entire hip joint and proximal femur
CR is perpendicular to midfemur and IR center. Centers proximal femur to collimated field
Collimate to 1 inch beyond skin shadows of thigh and 17 inches (43 cm) long.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold still in position for exposure. Reduces possibility of motion
Lateral Projection: Femur, Distal Portion
Positioning Steps Results/Rationale
Patient lies in recumbent lateral, resting on affected side, with pelvis in lateral position.Position unaffected limb in front of affected limb for support.
Image evaluation is a foundational skill for radiographers. Each projection has specific criteria that allow the radiographer to evaluate the image for evidence of proper positioning, as well as adequate image quality. A criterion common to all chest images are:
Visibility of legal identification and appropriate side marker
This criterion means that the institution and required patient information be a permanent part of the image, and that the correct side marker is visible, noting the right or left side of the patient.
Take time now to study the bulleted points under the heading "Evaluation Criteria" for each essential projection specified in the table below.
Readings from Merrill's Atlas of Radiographic Positioning & Procedures, vol. 1, 12th edition.
Chapter 6, Essential Projections: Toes - Ankle, pp. 242-243, 245-249, 252-257, 260-261, 271, 274, 279-281, 283-285 and 287
1. What is the appropriate size of the collimated field?
2. What anatomy is demonstrated in each projection?
3. How does the anatomy of interest appear on images when positioning is correct?
Chapter 6, Essential Projections: Leg - Knee, pp. 290-293, 296-297, 300-302, and 304-309,
Chapter 6, Essential Projections: Patella - Femur, pp. 311-312, 316-321
AP leg
Major critique criteria
Ankle and knee joints on one or more AP projections Ankle and knee joints without rotation Proximal and distal articulations of the tibia and fibula
moderately overlapped Fibular midshaft free of tibial superimposition Proper density and contrast evidenced by:
o Trabecular detail and soft tissue for the entire leg
The arrows in this image demonstrate the importance of including both the proximal and distal articulations on radiographic examinations of long bones. The distal tibia is fractured, as is the proximal fibula. Fractures at opposite ends are not uncommon.
Lateral leg
Major critique criteria
Ankle and knee joints on one or more images Distal fibula lying over the posterior half of the tibia Slight overlap of the tibia on the proximal fibular head Ankle and knee joints not rotated Possibly no superimposition of femoral condyles because of
divergence of the beam Moderate separation of the tibial and fibular bodies or shafts
(except at their articular ends) Proper density and contrast, as evidenced by:
o Trabecular detail and soft tissue
AP knee
Major critique criteria
Open femorotibial joint space, with interspaces of equal width on both sides if the knee is normal
Knee fully extended if patient's condition permits Patella completely superimposed on the femur No rotation of the femur (femoral condyles symmetrical) and tibia
(intercondylar eminence centered) Slight superimposition of the fibular head if the tibia is normal Soft tissue around the knee joint Bony detail surrounding the patella on the distal femur
Lateral knee
Major critique criteria
Femoral condyles superimposedo Locate the adductor tubercle on the posterior surface of
the medial condyle to identify the medial condyle and to determine whether the knee is overrotated or underrotated.
Open joint space between femoral condyles and tibia Patella in a lateral profile Open patellofemoral joint space Fibular head and tibia slightly superimposed
o Overrotation causes less superimposition, and underrotation causes more superimposition.
Knee flexed 20 to 30 degrees All soft tissue around the knee Femoral condyles with proper density
AP knees, standing
Major critique criteria
No rotation of the knees Both knees Knee joint space centered to the exposure area Adequate IR size to demonstrate the longitudinal axis of the
femoral and tibial bodies or shafts
AP oblique knee, lateral rotation
Major critique criteria
Medial femoral and tibial condyles Tibial plateaus Open knee joint Fibula superimposed over the lateral half of the tibia Margin of the patella projected slightly beyond the edge of the
lateral femoral condyle Soft tissue around the knee joint Bony detail on the distal femur and proximal tibia
AP oblique knee, medial rotation
Major critique criteria
Open proximal tibiofibular articulation Posterior tibia Lateral condyles of the femur and tibia Both tibial plateaus Open knee joint Margin of the patella projecting slightly beyond the medial side of
the femoral condyle Soft tissue around the knee joint Bony detail on the distal femur and proximal tibia
PA axial intercondylar fossa (Holmblad)
Major critique criteria
Open fossa Posteroinferior surface of the femoral condyles Intercondylar eminence and knee joint space Apex of the patella not superimposing the fossa No rotation, evident by slight tibiofibular overlap Soft tissue in the fossa and interspaces Bony detail on the intercondylar eminence, distal femur, and
proximal tibia
PA axial intercondylar fossa (Camp-Coventry)
Major critique criteria
Open fossa Posteroinferior surface of the femoral condyles Intercondylar eminence centered in open femorotibial joint space Apex of the patella not superimposed on the fossa No rotation, as evidenced by slight tibiofibular overlap Soft tissue in the fossa and interspaces Bony detail on the intercondylar eminence, distal femur, and
proximal tibia
PA patella
Major critique criteria
Patella subject to complete superimposition by the femur Adequate penetration for visualization of the patella clearly
through the superimposed femur No rotation
The arrow points to a fracture line in the patella.
Lateral patella
Major critique criteria
Knee flexed 5 to 10 degrees
Open patellofemoral joint space
Patella in lateral profile Close collimation
Tangential patella and patellofemoral joint (Settegast)
Major critique criteria
Patella in profile Open patellofemoral
articulation Surfaces of the femoral
condyles Soft tissue of the
patellofemoral articulation Bony detail on the patella
and femoral condyles
AP proximal femur
Major critique criteria
Majority of the femur and the joint nearest the pathologic condition or site of injury
o A second projection of the other joint is recommended
Femoral neck not foreshortened on the proximal femur
Lesser trochanter not seen beyond the medial border of the femur, or only a very small portion seen on the proximal femur
Gonad shielding when indicated, but the shield not covering proximal femur
Any orthopedic appliance in its entirety
Trabecular recorded detail on the femoral shaft
AP distal femur
Major critique criteria
Majority of the femur and the joint nearest the pathologic condition or site of injury
o A second projection of the other joint is recommended.
No knee rotation of the distal femur
Gonad shielding when indicated, but the shield not covering proximal femur
Any orthopedic appliance in its entirety
Trabecular recorded detail on the femoral shaft
Lateral proximal femur
Major critique criteria
Majority of the femur and the joint nearest the pathologic condition or site of injury
o A second radiograph of the other end of the femur is recommended
Opposite thigh not over area of interest
Greater and lesser trochanters not prominent
Any orthopedic appliance in its entirety
Trabecular detail on the femoral body
Lateral distal femur
Major critique criteria
Majority of the femur and the joint nearest the pathologic condition or site of injury
o A second radiograph of the other end of the femur is recommended
Superimposed anterior surface of the femoral condyles
Patella in profile Open patellofemoral
space Inferior surface of the
femoral condyles not superimposed because of divergent rays
Any orthopedic appliance in its entirety
Trabecular detail on the femoral body
AP Oblique Projection: Leg in Medial Rotation
Positioning Steps Results/Rationale
Patient is seated or lying supine with leg extended.Posterior surface rests on IR (if used).
Provides AP oblique projection
Rotate lower limb medially 45 degrees. Demonstrates tibia and fibula in medial (internal) oblique positionDemonstrates the maximum interosseous space between the tibia and fibula
CR is perpendicular to center of IR. Centers tibia and fibula and adjacent joints on IR and collimated field
Collimate 1-inch (2.5-cm) border around shadow of skin on all sides Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold position for exposure. Reduces possibility of motion
AP Oblique Projection: Leg in Lateral Rotation
Positioning Steps Results/Rationale
Patient is seated or supine, leg extended.Posterior surface rests on IR (if used).
Provides AP oblique projection
Rotate lower limb laterally 45° Demonstrates tibia and fibula in
lateral (external) oblique positionDemonstrates fibula superimposed by tibia
CR is perpendicular to center of IR. Centers tibia and fibula and adjacent joints on IR and collimated field
Collimate 1-inch (2.5-cm) border around shadow of skin on all sides. Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills lethical responsibility
Instruct patient to hold position for exposure. Reduces possibility of motionAP oblique leg, medial rotation
Major critique criteria
Proximal and distal tibiofibular articulations included
Maximum interosseous space between the tibia and fibula
Ankle and knee joints demonstrated
o May require separate images on longer limbs
AP oblique leg, lateral rotation
Major critique criteria
Fibula superimposed by lateral portion of tibia
Ankle and knee joints included
o May require two images on longer limbs
PA Projection: Knee
Positioning Steps Results/Rationale
Patient lies prone with leg extended and toes resting on table. Provides PA projection
Femoral condyles are placed parallel to tabletop. Demonstrates knee joint without rotation
CR is directed at an angle of 5 to 7 degrees caudad to exit at a point ½ inch (1.3 cm) inferior to the patellar apex.
Centers knee joint to collimated field
Collimate a 1-inch (2.5-cm) border around shadow of skin on all sides.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold position for exposure. Reduces possibility of motion
PA Projection: Knees (Rosenthal Method)
Positioning Steps Results/Rationale
Patient stands facing vertical grid device, weight equally distributed on both feet.
Provides PA projection
Flex the knees to place the femurs at an angle of 45 degrees.Patient may grasp sides of grid device for support.
Demonstrates knee joint without rotationUsed to evaluate joint space narrowing and articular cartilage disease
Center IR to knee joints (½ in. or 1.3 cm inferior to patellar apices).
Demonstrates knee joint in center of image and collimated field
CR is horizontal and perpendicular to the center of the IR; enters perpendicular to the tibia and fibula, but a 10-degree
Demonstrates open knee joints in weight-bearing position
caudal angle is sometimes used.
Collimate 1-inch (2.5-cm) border around shadow of skin on all sides.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold position for exposure. Reduces possibility of motion
AP Axial Projection: Intercondylar Fossa (Béclère Method)
Positioning Steps Results/Rationale
Patient is seated or supine, with no rotation in lower limbs.
Provides AP projection
Flex the knee enough to place the long axis of the femur at a 60-degree angle to long axis of tibia.Support knee with sandbags.
Demonstrates intercondylar fossa
Place IR under knee on top of sandbags.Center IR to the CR.
Demonstrates intercondylar fossa in center of image and collimated field
CR is perpendicular to the lower leg; enters ½ in (1.3 cm) inferior to the patellar apex.
Demonstrates open intercondylar fossa in AP axial projection
Collimate 1-inch (2.5-cm) border around shadow of skin on all sides.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold position for exposure. Reduces possibility of motion
Tangential Projection: Patella and Patellofemoral Joint (Hughston Method)
Positioning Steps Results/Rationale
Patient lies prone, without rotation.IR is under affected knee.
Reduces distortionReduces magnification
Knee is flexed to place tibia-fibula at 50- to 60-degree angle to table.Support ankle and foot as needed. (To avoid burns, make sure that the collimator is not hot!)
Positions patella to obtain a tangential projection
Make sure the leg is not rotated medially or laterally from the vertical.
Reduces distortion
CR is directed 45 degrees cephalad through the patellofemoral joint.
Demonstrates tangential projection of patella & joint space in the center of the collimated field
Collimate 1-inch (2.5-cm) border around shadow of skin on all sides.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold position for exposure. Reduces possibility of motion
Tangential Projection: Patella and Patellofemoral Joint (Merchant Method)
Positioning Steps Results/Rationale
Patient lies supine with knees at end of table.Support knees, lower legs, and IR in "axial viewer" device.
Holds legs and knees in desired position and relationship to IR
Using axial viewer device, elevate knees about 2 inches (5 cm) to place femora parallel to table.
Helps relax quadriceps femora muscles for optimal demonstration of the joint space
Knee is flexed 40 degrees. Positions patella to obtain a tangential projection
Place IR perpendicular to the CR and approximately 1 foot distal to the patellaeRest IR on thin foam pad on the patient's shins.
IR position aligned to central ray and patellae per Merchant methodFoam pad increases comfort.
CR is directed 45 degrees cephalad through the patellofemoral joint.
Demonstrates tangential projection of patella and joint space in the center of the collimated field
Collimate 1-inch (2.5-cm) border around shadow of skin on all sides.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold position for exposure. Reduces possibility of motion
Bilateral examination may be performed. Facilitates comparison
AP Projection: Lower Limbs
Positioning Steps Results/Rationale
Increase source-to-IR distance to 8 feet (244 cm). Required to provide long enough image field
Patient stands upright in anatomic position on riser. Insures demonstration of entire lower limbDemonstrates lower limbs and joints in anatomic position
Weight is equally distributed on feet. Reduces rotation/distortion
CR is perpendicular; enters midway between knees at level of knee joints.
Centers lower limbs in collimated field
Collimate 1-inch (2.5-cm) border around shadow of skin on all sides.
Demonstrates all anatomy of interestProvides radiation protectionImproves image quality
Provide gonadal shielding. Provides radiation protection/fulfills ethical responsibility
Instruct patient to hold position for exposure. Reduces possibility of motion
![Positioning and Timing Test Campaign Based on China Area ... · 1 Positioning and Timing Test Campaign Based on China Area Positioning System (CAPS) ZHANG Yang [1,2,3], [1,2,3]SU](https://static.documents.pub/doc/80x56/5fbc5ee60b748e3cc8468cc4/positioning-and-timing-test-campaign-based-on-china-area-1-positioning-and-timing.jpg)
