Rad Positioning (Forearm and Elbow) 10-20-25

Which oblique best shows the coronoid process

medial (internal) oblique

Which oblique best shows the radial head neck and tuberosity

lateral (external) oblique

How many degrees should the elbow be flexed for a true lateral

90 degrees

What should you do if the patient cannot fully extend the elbow

Take two APs—one with the humerus parallel and one with the forearm parallel to the IR

Where do you center for the elbow routine (AP obliques lateral)

Mid-elbow joint through the epicondyles

The Jones method is used for what type of flexion

Acute flexion

Which two wrist fractures may be seen on a forearm image

Colles' and Smith's fractures

For the Coyle method of the radial head

angle 45° toward the shoulder with 90° flexion

For the Coyle method of the coronoid process

angle 45° away from the shoulder with 80° flexion

Difference in elbow flexion between Coyle's radial head and coronoid views

Radial head 90° flexion coronoid 80° flexion

If the arm is straight out that represents what flexion reference

Zero degrees

Which projection shows fat pads

lateral forearm or lateral elbow

What does a visible fat pad indicate

Possible occult fracture even if no line is seen

Why is a grid not used for forearm and elbow

Small body part under 10 cm and low kVp

What kVp and mAs are used for forearm and elbow

2@60

Internal versus external terminology for obliques

Internal = medial rotation ; External = lateral rotation

Bolded error for all projections

Keep shoulder elbow and wrist in the same plane to avoid distortion

Bolded error for laterals

Ensure true 90° flexion and do not clip posterior fat pads

Bolded reminder for lateral images

Do not clip posterior soft tissues of elbow ; include fat pads for fracture detection

Coyle for head mnemonic

Angle toward the head

Coyle for coronoid mnemonic

Angle away from the head

Three concentric arcs critique on lateral elbow

Trochlear sulcus → double ridges of capitulum & trochlea → trochlear notch of ulna

What does displaced fat pad visibility mean

There could be a small fracture even if unseen

May need to elevate wrist if elbow is large

To keep forearm and elbow on the same plane

Common error in positioning forearm

Not keeping shoulder and elbow in same plane causing distortion

Cassette orientation for AP forearm

14×17 lengthwise on the table

CR location for AP forearm

Mid-forearm

Required joint inclusion

At least 1 inch beyond wrist and elbow joints

Plane alignment requirement

Shoulder elbow and wrist must be in same plane

Hand position for AP forearm

Supinated palm up

Epicondyles position

Parallel to IR in profile

Distal radioulnar joint appearance

Slight if any superimposition

Reason PA forearm not performed

Proximal radius crosses over ulna

Common AP forearm error

Shoulder not same plane causes distortion

Technique and grid for AP forearm

2@60 kVp 40-48 in SID no grid

Marker placement recommendation

At wrist area

Exposure goal

Include soft tissue and both joints

Possible fractures visible

Colles' or Smith's fracture

How to correct magnification/distortion

Drop shoulder or raise table so arm is flat

Elbow angle for lateral forearm

Flex 90°

Hand position for lateral forearm

Thumb up — hand on side

CR location

Mid-forearm

Included anatomy

Carpals distal humerus soft tissue fat pads

If elbow larger than wrist

Elevate wrist with sponge to same plane

Distal radius and ulna appearance

Superimposed

Head of ulna and radius relationship

Head of ulna superimposed ; 1/3-½ of radial head superimposed

Humeral epicondyles relationship

Superimposed (stacked)

Technique and grid

2@60 kVp 40-48 SID no grid

Reason to open collimation posteriorly

To include posterior fat pads for fracture signs

Plane requirement again

Shoulder elbow and wrist same plane

Common lateral forearm error

Elbow not truly lateral or clipping fat pads

Purpose of including soft tissue

To evaluate for displaced fat pads or subtle fx

What indicates non-lateral positioning

Uneven superimposition of radius/ulna

Position of arm

Fully extended and supinated

Plane alignment

Shoulder elbow and wrist same plane

CR location

Mid-elbow joint

Included anatomy

Distal humerus and proximal radius/ulna (1-2 in above and below)

Epicondyles

Parallel to IR and in profile

Radial head/neck relationship

Only slightly superimposed by ulna

Technique

2@60 kVp 40-48 SID no grid

Marker placement

Within light field

Main evaluation error

Rotation or flexion > 0°

When used

Patient cannot fully extend arm

How many images taken

Two—one humerus parallel one forearm parallel

CR location

Mid-elbow

Why two images

To show both humerus and forearm true size without foreshortening

Technique

2@60 kVp no grid 40-48 SID

Collimation

2 in above and below joint

When used

Patient stuck in acute flexion > 90°

Number of images

Two—one perpendicular to humerus one to forearm

CR for humerus view

Perpendicular to humerus

Best seen for humerus view

Distal humerus true size ; forearm distorted

CR for forearm view

Perpendicular to forearm (angled toward humerus)

Best seen for forearm view

Proximal forearm true size ; humerus distorted

Angle degree specification

No fixed degree — just perpendicular to each segment

Technique

2@60 kVp 40-48 SID no grid

Purpose

Evaluates elbow when fully flexed and cannot extend

General rotation degree

45°

Plane requirement

Shoulder elbow wrist same plane

CR location

Mid-elbow

Technique

2@60 kVp 40-48 SID no grid

Collimation

2 in above and below joint to soft tissue

Lateral (external) oblique rotation

Rotate arm laterally 45°

Best seen on lateral (external) oblique

Radial head neck and tuberosity free of ulnar superimposition and capitulum in profile

Medial (internal) oblique rotation

Pronate and medially rotate 45°

What happens to radius and ulna on medial oblique

Radius crosses over ulna

Best seen on medial (internal) oblique

Coronoid process of ulna in profile

Lateral epicondyle appearance on external oblique

In profile

Reason patients roll body backward for external oblique

To achieve full 45° rotation if wrist mobility limited

When used

Patient cannot rotate arm due to trauma

Hand position

Hand flat on table not turned

Plane requirement

Shoulder elbow wrist in same plane

For coronoid process view

Flex elbow 80° and angle CR 45° away from shoulder

For radial head view

Flex elbow 90° and angle CR 45° toward shoulder

CR centering

Mid-elbow joint

Technique

2@60 kVp 40-48 SID no grid

Mnemonic

Head → toward the head ; Coronoid → away from the head

Purpose

Substitute for internal/external obliques in trauma

Result if performed correctly

Coronoid or radial head clearly separated from ulna

Position of arm

Flex elbow 90° thumb up