Week 5 - humerus and Clavicle

Flashcards covering humerus and clavicle radiography, including positioning, central ray, and anatomy.

What is the central ray (CR) for an AP Humerus projection?

Perpendicular to the image receptor.

Where is the central point (CP) for an AP Humerus projection?

Midway between the elbow and shoulder joint.

What structures must be included in an AP Humerus image?

Entire humerus from shoulder to elbow joint, with collimation extended 1”-2” beyond each joint.

What are the respiration instructions for an AP Humerus projection?

Suspend respiration during exposure.

What is the patient positioning for an AP Humerus?

Patient stands with back to bucky, arm extended, humerus abducted and in contact with IR.

How should the arm be positioned for an AP Humerus?

Externally rotate the arm to place the humerus in true AP; palm supinated and elbow in AP.

How do you check for rotation in an AP Humerus?

Use the epicondyles to ensure they are parallel to the IR.

What joints should be included when collimating for an AP Humerus?

Both the shoulder and elbow joints.

What adjustment might be made to the collimator for an AP Humerus?

Tilt the collimator to align with the long axis (LA) of the humerus.

How should the hand be positioned for an AP Humerus?

In the AP position, similar to AP elbow/forearm positioning.

What is the central ray (CR) for a Lateral Humerus projection?

Perpendicular to the image receptor.

Where is the central point (CP) for a Lateral Humerus projection?

Midway between the elbow and shoulder joint.

What structures must be included in a Lateral Humerus image?

Entire humerus from shoulder to elbow joint, with collimation extended 1”-2” beyond each joint.

What are the respiration instructions for a Lateral Humerus projection?

Suspend respiration during exposure.

Where should the top of the IR be placed for a Lateral Humerus?

Approximately 2.5–4 cm above the shoulder.

What is the general positioning for a Lateral Humerus?

Patient in AP or PA; humerus abducted, in contact with bucky, centered to IR.

How is the arm positioned for a Lateral Humerus?

Flex the elbow, supinate the hand, and internally rotate the arm to make epicondyles perpendicular to the IR.

In a Lateromedial projection, where is the palm placed?

Against the thigh.

In a Mediolateral projection, how should the palm be positioned?

Palm should face upward.

What should be avoided in a Lateromedial lateral humerus projection?

Avoid rotating the body away from the affected side to prevent increased OID.

What should be avoided in a Mediolateral lateral humerus projection?

Avoid rotating the torso too much to prevent superimposition of the shoulder/back on the humerus.

What positioning error occurs if the arm is placed on the abdomen for a lateral humerus?

Epicondyles won't be perpendicular to the IR, resulting in an inaccurate lateral.

What two conditions must be met regardless of lateral view chosen?

The humerus must be in contact with the IR, and the epicondyles must be perpendicular to the IR.

What is the central ray (CR) for an AP Clavicle projection?

Perpendicular to the image receptor.

Where is the central point (CP) for an AP Clavicle projection?

Mid-clavicle.

What structures must be included in an AP Clavicle image?

Entire clavicle from the sternoclavicular (SC) joint to the acromioclavicular (AC) joint.

How do you locate the correct centering point for an AP Clavicle?

Palpate to identify the SC joint and AC joint, then center at mid-clavicle.

What is the recommended collimation for an AP Clavicle?

Tight collimation to include both the SC and AC joints.

What is the central ray (CR) angulation for an Axial Clavicle projection?

15–30 degrees cephalad.

Where is the central point (CP) for an Axial Clavicle projection?

2.5 cm inferior to mid-clavicle.

What is the patient positioning for an Axial Clavicle projection?

AP position with shoulders flat against IR/table, no slouching or rotation, and shoulders in the same transverse plane.

Why is more angulation used for thinner patients in Axial Clavicle imaging?

The clavicle lies closer to other structures, so more angulation is needed to project it above and away from them.

What angulation is typically used for a sthenic (average build) patient? (Axial Clavicle)

About 25–30 degrees cephalad.

What angulation is typically used for a hypersthenic (larger build) patient? (Axial Clavicle)

About 15–20 degrees cephalad.

Why is a lateral projection not used as the second clavicle view?

Too many overlying structures would obscure the clavicle, and a high kV would be needed.

What does the Axial Clavicle projection help demonstrate?

It projects most of the clavicle above the scapula and ribs, helps assess fracture angulation and dislocation, especially in the lateral 2/3.

What parts of the clavicle are most commonly fractured?

The middle and lateral thirds.

What is the central ray (CR) angulation for the alternative Axial Clavicle projection?

0–15 degrees cephalad.

Where is the central point (CP) for the alternative Axial Clavicle projection?

Mid-clavicle or slightly inferior, depending on the CR angle.

What structures must be included in the alternative Axial Clavicle image?

Entire clavicle from SC joint to AC joint.

What is the patient position for the alternative Axial Clavicle projection?

AP position, about 1 foot forward from the bucky, then leaning back into a lordotic position.

How should you support the patient during positioning for this view?

Support at the shoulders to help them lean back until the shoulders touch the bucky.

Why is the patient placed in a lordotic position for this projection?

To allow the clavicle to project above thoracic structures with less need for tube angulation.

What steps should be taken before final positioning in the lordotic view?

Estimate the angulation, return the patient upright, adjust the tube/collimation, then place the patient back in lordotic position.

What key alignment should be checked before taking the image?

Ensure the shoulders are relaxed, in the same transverse plane, and the body has no rotation or tilt.

What is palpated to confirm correct centering in the alternative axial clavicle view?

The entire clavicle from SC joint to AC joint.

What is the hand position for an AP Humerus (erect)?

Palm facing forward.

What is the hand position for a Lateral Humerus (Lateromedial, erect)?

Palm against the thigh, fingers pointing toward the knee.

What is the hand position for a Lateral Humerus (Mediolateral, erect)?

Palm facing up.

What is the hand position for an AP Humerus (supine)?

Palm facing up.

What is the hand position for a Lateral Humerus (supine)?

Back of the hand against the thigh.

Why is the hand position different in a lateral humerus when done supine?

Because rotating the hand this way achieves a true lateral (epicondyles perpendicular) without flexing the elbow.