Image Evaluation Portable Medial Oblique Knee

By: Jenna Wood

HIPAA Compliance • This image is HIPAA compliant • There is no information provided

on this image that could identify a patient or an imaging facility

• It does not violate patient confidentiality

Marker and Patient ID • An anatomical marker is visible on

this image

Marker and Patient ID • The correct right anatomical marker should

be placed on the lateral side of the patient’s body, indicating it is a right knee, so it is displayed on the viewer’s left side

• Marker should include the technologist’s identification

• It should not superimpose any pertinent anatomy

• A portable marker should have been used along with the time in some hospital protocols

• The image is now displayed correctly based on my marker placement

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Radiation Hygiene • An image must have a minimum of three

sides of beam restriction and (1) of these sides should be closest to the patient’s gonads

• This is especially true while doing portables (Technologist’s should also wear a minimum of 0.25 mm/Pb eq)

• Gonadal shielding is required if the gonads are within 5 cm of the primary beam

• This image does not display appropriate beam restriction and is only clearly visible on two sides of the border

• There is no evidence of primary or additional shielding

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Completeness of Position/Projection• Routine imaging of the knee includes:

• AP projection, posterior position• 45° AP (medial/internal) oblique• 45° AP (lateral/external) oblique• Mediolateral projection

• Additional images depending on hospital/facility protocol:

• PA/AP axial intercondylar fossa projection • Tangential patella projection

• This image is a routine projection and all anatomical parts are visualized on the image, but not correctly positioned

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Artifact Identification

• There appears to be no preventable physical artifacts present on the image

• There appears to be no body parts superimposed over the image

• There appears to be no hospital paraphernalia present

• There appears to be no patient clothing visible

• There appears to be no indwelling artifacts/foreign bodies visible on this image

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Artifact Identification • There appears to be no

excessive fog affecting the quality of the image

• There appears to be no CR/DR artifact on the image

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Image Sharpness• There appears to be no

gross voluntary motion visible on the image

• There appears to be no excessive quantum mottle present in the image

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Image Sharpness• There appears to be no

evidence of a double or previous exposure

• Grid lines, grid artifact, &/or grid cut-off are not visible on the image because a grid might not have been used &/or a high frequency could have been used since it was done portably

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Image Sharpness• Size distortion does not appear to be greater than

expected for this image because OID is minimal in this position

• The CR is not properly centered to femorotibial joint space, but less than 1 cm

• There is evidence of slight shape distortion due to the CR/part misalignment

• Due to the insufficient 5 degree cephalic angle that should have been used because the patient’s thigh thickness appears to be >25 cm the tibial plateau does not appear to be perpendicular to IR

• The patellar apex sits closer to the upper joint space also indicating the CR was not proper angled

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Accurate Part Position • The part does appear to be

aligned parallel to the image media

• The part is slightly off-centered to the image media

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Accurate Part Position • The CR is off centered slightly laterally to the

femorotibial joint space, but within 1 cm of the anatomical part

• The CR is adequately aligned to the image media • The CR’s alignment does not appear to conform

to an acceptable IR exposure recognition field due to the lack of only two sides of collimation

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Accurate Part Position According to Kathy McQuillen Martensen’s Radiographic Image Analysis and Merrill’s Atlas:• 40” SID and 10 x 12” IR

• Position the patient supine, with the knee joint centered to the IR

• Internally rotate the leg until the femoral epicondyles are at a 45 degree angle with the IR

• Angle the CR to align it parallel with the tibial plateau

• To do so measure the patient from the ASIS to the table after the patient has been accurately positioned to determine the correct CR angulation (use a caliper and do not include abdominal tissue in measurement)

• 5 degree caudal if ASIS to tabletop measurement is 18 cm below• Perpendicular if ASIS to tabletop is between 19-24 cm • 5 degrees cephalic angle if ASIS to tabletop is 25 cm or greater** It is not uncommon to require a cephalic angle for the AP medial oblique when a perpendicular or caudal angle was used for an AP projection because the patients hips are elevated

• Center the CR to the midline of the knee 1 inch distal to the medial epicondyle (Martensen)

• Center the CR to the knee joint at ½ inch distal to the patellar apex (Merrill’s)

• Longitudinally collimate to include ¼ of the distal femus and proximal lower leg

• Transversely collimate to 0.5 inch of the knee skin line

• Table bucky and a grid should be used if the knee is greater than 10 cm part thickness, however when done portable a stationary grid would be used

Accurate Part Position According to Kathy McQuillen Martensen’s Radiographic Image Analysis and Merrill’s Atlas:Evaluation Criteria:• Fibular head is seen free of tibial superimposition (Martensen)• Lateral femoral condyle is in profile without superimposing the medial

condyle • Knee joint space is open: when correct obliquity is used (Bontrager)• The anterior and posterior condylar margins of the tibia are aligned • Fibular head is approximately 0.5 in distal to the tibial plateau• Knee joint is at the center of the exposure field• Tibia and fibula should be separated at their proximal articulations• Posterior tibia should be visible • ¼ of the distal femur and proximal lower leg included• Margin of the patella projecting slightly beyond the medial side of the

femoral condylar leg and the surrounding knee soft tissue are included with the exposure field

Accurate Part Position Evaluation• A minimum of three sides of beam restriction should be

demonstrated

• The CR is centered slightly laterally to the femorotibial joint

• The CR appears to have been directed perpendicular causing the tibial plateau to not appear perpendicular to the IR, therefore a 5 degree cephalic angle should have been used due to the patient’s thigh thickness >25cm

• The anterior and posterior condyles of the tibia are not superimposed due to incorrect CR angulation

• The patellar apex sits closer to the upper joint space also indicating the CR was not proper angled

• The knee does not appear to be sufficiently rotated to 45 degrees because the tibia is superimposed over the fibula head and also demonstrating a partially closed tibiofibular articulation

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Accurate Part Position Evaluation• All pertinent anatomy is included on

the image• The anatomical part is not positioned

correctly based on my assessment of the evaluation criteria

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Accurate Part Position Evaluation• The most radiolucent structure is

the surrounding soft tissue and knee joint (which should be open) and it is visible on the image

• The most radiopaque structure is the bony cortex and it is visible on the image time

Judicious Exposure Technique• Assessment of Image Contrast

(Window Width) • Contrast is determined by the

number of grays produced on an image

• Extremities should be displayed with short scale contrast, showing many shades of gray

• The image appears to have adequate contrast

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Judicious Exposure Technique• Assessment of Image’s Brightness

(Window Level)• The image’s brightness is the

balance between light and dark areas on the image and it appears to be acceptable because you are able to visualize the soft tissue, bony trabeculi and cortex

• I would expect the overall EI value to be within normal range

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Accept/Reject?This image should be repeated because it does not meet minimal established standardsRequired corrections: • Use a correctly placed right marker with technologist

identification and a portable marker along with the time the exposure was taken

• Include a minimum of three sides of collimation• Center the CR to the femoroibial joint space • Rotate the knee internally to 45 degrees so the tibia does

not superimpose over the fibula head articulation• Angle to CR approximately 5 degrees cephalically to

ensure the tibial plateau is perpendicular to the IR • Aligning the anterior and posterior condyles of the tibia to

superimpose one another • Angulation will also rotate the patellar apex superiorly and medially

away from the joint space

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Sources Frank, E, Long, B, & Smith, B. Merrill’s atlas of radiographic

positioning and procedures. 12th ed. St. Louis, MO: Mosby, 2012.

McQuillen-Martensen, K. (2015). Radiographic image analysis. Vol 4. St. Louis, MO: Elsevier

Saint Mary’s Medical Center