Patella Tangential Projections Quiz

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Questions and Answers

What is the angle of knee flexion for the Hughston method?

90°

Greater than 90°

55° (correct)

45°

What is the SID for the Settegast Method?

40 to 48 inches (correct)

35 to 43 inches

65 to 70 inches

18 to 24 inches

How should the patient be positioned for the Inferosuperior Projection?

Supine position, legs together, with 40° to 45° knee flexion (correct)

Sitting position, greater than 90° knee flexion

Prone position, 90° knee flexion

Prone position, legs relaxed, with 55° knee flexion

What size IR is recommended for the Inferosuperior Projection?

35 × 43 cm (14 × 17 inches) crosswise Signup and view all the answers

What is the recommended kV range for nongrid analog systems in the Settegast Method?

65 ± 5 kV range Signup and view all the answers

Why is it not recommended for the patient to sit up to hold the IR in place for the Inferosuperior Projection?

To prevent neck injury from the x-ray beam Signup and view all the answers

In which position is the patient for the Hobbs modification superoinferior tangential method?

Sitting Signup and view all the answers

What angle of knee flexion is recommended for the Settegast Method?

90° Signup and view all the answers

What is the recommended IR size for a unilateral study in the Settegast Method?

18 × 24 cm (8 × 10 inches), lengthwise Signup and view all the answers

What is the recommended kV range for digital systems in the Inferosuperior Projection?

70 to 80 kV range Signup and view all the answers

Why is it important to rule out fracture of the patella before attempting the Settegast Method?

To prevent exacerbation of the fracture Signup and view all the answers

What is the major advantage of the Inferosuperior Projection method?

Does not require special equipment Signup and view all the answers

What is a potential problem with the Inferosuperior Projection method?

Potential difficulty in holding or supporting the IR Signup and view all the answers

What is a major disadvantage of the Hughston Method?

Image distortion caused by awkward part alignment Signup and view all the answers

What is the recommended knee flexion angle for the Hughston Method?

55° Signup and view all the answers

What is the recommended knee flexion angle for the Settegast Method?

40° to 45° Signup and view all the answers

What is the recommended IR size for the Inferosuperior Projection method?

18 × 24cm (8 × 10 inches), 24 L lengthwise Signup and view all the answers

What is the recommended kV range for digital systems in the Inferosuperior Projection method?

70 to 80 kV range Signup and view all the answers

Why is it important to flex the knee only 5° or 10° for the lateral knee technique?

To avoid overexposing the patella Signup and view all the answers

What is the minimum recommended SID for the Patella PA Lateral Tangential technique?

40 inches (102 cm) Signup and view all the answers

What is the recommended IR size for a smaller patient in the Patella PA Lateral Tangential technique?

18 × 24cm (8 × 10 inches), 24 L lengthwise Signup and view all the answers

What is the recommended shielding in the lateral knee technique?

Shield radiosensitive tissues outside the region of interest Signup and view all the answers

Why is it recommended to align and center the long axis of the patella to the CR and to the centerline of the table or IR in the lateral knee technique?

To achieve better image quality Signup and view all the answers

Study Notes

Knee Positioning Techniques

The angle of knee flexion for the Hughston method is generally recommended at 50 to 60 degrees for optimal visualization of the patella.
For the Settegast method, the recommended SID (Source-to-Image Distance) is 40 inches, ensuring adequate image quality.
The patient should be positioned supine for the Inferosuperior Projection, with the legs extended and the IR placed under the knee.
A 10 x 12 inch IR is recommended for the Inferosuperior Projection, allowing for sufficient coverage of the anatomy.

kV and Radiation Concerns

The kV range for nongrid analog systems in the Settegast Method is typically between 70 to 80 kV, providing good contrast.
For digital systems in the Inferosuperior Projection, the recommended kV range is 75 to 90 kV, optimizing image quality.
It is advised against having the patient sit up to hold the IR in place for the Inferosuperior Projection due to potential instability and increased difficulty in achieving a proper image.

Specific Method Recommendations

In the Hobbs modification superoinferior tangential method, the patient is positioned supine with the knee flexed.
The angle of knee flexion recommended for the Settegast method is also 90 degrees for effective visualization of the patella.
For a unilateral study in the Settegast Method, a 10 x 12 inch IR is ideal, accommodating the necessary anatomy.

Importance of Safety and Technique

Ruling out any fractures of the patella before attempting the Settegast Method is crucial as it prevents further injury and aids in accurate diagnosis.
The major advantage of the Inferosuperior Projection method is its ability to give a clear view of the patellofemoral joint space.
A potential problem with the Inferosuperior Projection method is that it can be difficult to obtain an image if the patient cannot flex the knee adequately.

Disadvantages and Techniques

A major disadvantage of the Hughston Method is the increased risk of discomfort for the patient due to the degree of knee flexion required.
The recommended knee flexion angle for the Hughston Method is typically at 45 degrees.
The importance of flexing the knee only 5° or 10° in the lateral knee technique is to minimize distortion of the patellofemoral joint.
The minimum recommended SID for the Patella PA Lateral Tangential technique is 40 inches, ensuring precise imaging.

Shielding and Alignment

The recommended IR size for smaller patients in the Patella PA Lateral Tangential technique is 8 x 10 inches, accommodating their anatomy.
Proper shielding in the lateral knee technique is essential to minimize radiation exposure, especially to reproductive organs.
Aligning and centering the long axis of the patella to the CR and the centerline of the table or IR in the lateral knee technique is recommended for accurate representation and reduced misalignment.

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Description

Test your knowledge of tangential (axial or sunrise/skyline) projections of the patella with this quiz. Explore four additional methods for capturing these projections, including inferosuperior, Hughston, Settegast, and Hobbs modification superoinferior tangential methods.