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newSchoolWorks.com › VoTechWorks › Health & Personal Services › Limited X-Ray / Radiologic Technology › Anatomy & Positioning for Radiographic Practice › Lesson 3
HLT-RADI64-03 · Lesson 3 · 28 clock hours · lab

Positioning the Upper Extremity — Fingers Through Shoulder

Objective. Students will accurately position a cooperative partner or phantom for the standard PA, lateral, and oblique projections of all upper extremity segments, aligning the central ray and collimating correctly for each projection.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed clinician in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it to make decisions about any patient or medication. Always follow your instructor, your supervising professional, and current official references and regulations.

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Introduction: Why Upper Extremity Positioning Matters

The upper extremity — fingers, hand, wrist, forearm, elbow, humerus, and shoulder — is among the most frequently radiographed regions in any clinical setting. Accurate positioning ensures diagnostic image quality, minimizes repeat exposures, and protects the patient from unnecessary radiation. A limited-scope or radiography student must know each projection's centering point, central ray (CR) angle, source-to-image-receptor distance (SID), and the anatomical structures that should be demonstrated.

General Safety and Practice Principles

Before any exposure, confirm the patient's identity and the clinical indication. Always place the correct R or L lead marker in the primary beam, within the collimated field but away from anatomy of interest. Collimate tightly to the area of clinical interest — this reduces patient dose and scatter, improving image contrast. Use the lowest exposure factors consistent with diagnostic quality. Ensure the patient is not pregnant before thoracic or abdominal scatter reaches a fetus; even for distal extremities, ask about pregnancy as departmental policy requires. Wear a dosimetry badge and offer a lead apron to any patient not being imaged through the trunk.

Fingers and Hand

PA Hand: The hand is placed palm-down, flat on the image receptor (IR). Fingers are spread slightly. The CR is perpendicular and centered to the third metacarpophalangeal (MCP) joint. SID is typically 40 inches (102 cm). This projection demonstrates all phalanges, metacarpals, and carpals in a PA orientation.

Oblique Hand: From the PA position, the hand is rotated 45° laterally (thumb side up). A positioning sponge supports the elevated side. CR remains perpendicular, centered to the third MCP joint. The oblique separates the metacarpals and shows the medial carpals without superimposition.

Lateral Digit: A single finger is isolated and placed in a true lateral position, with the other fingers folded back or supported. CR is perpendicular to the proximal interphalangeal (PIP) joint of the finger being imaged. This shows anterior-posterior displacement of fractures.

Norgaard Method ("Ball Catcher"): Both hands are imaged simultaneously in a 45° supinated oblique. It demonstrates early erosive changes at the MCP joints. The CR is perpendicular, centered midway between both hands.

Wrist

PA Wrist: Wrist is placed palm-down on the IR, elbow flexed 90°. CR is perpendicular, centered to the midcarpal area (at the level of the proximal row of carpals). SID 40 inches.

Lateral Wrist: The wrist is in a true lateral position, thumb side up. CR is perpendicular, centered to the wrist joint. The lateral shows the carpal alignment and distal radius in profile.

Scaphoid (Ulnar Deviation) View: PA wrist with the hand deviated toward the ulnar (little finger) side. This opens the scaphoid for visualization. CR may be angled 10–15° proximally (toward the elbow) or a modified angle may be used per department protocol. This view is clinically important because scaphoid fractures are often occult on routine projections.

Forearm and Elbow

AP Forearm: The arm is fully extended, hand supinated. CR perpendicular, centered to the mid-forearm. Both joints should be included.

AP Elbow: Arm fully extended, hand supinated, CR perpendicular to the elbow joint, centered at the midpoint of the antecubital fossa. SID 40 inches.

Lateral Elbow: Elbow flexed 90°, in a true lateral position. CR perpendicular, centered to the lateral epicondyle. This demonstrates the fat pads and the olecranon process in profile.

Humerus and Shoulder

AP Shoulder: Patient erect or supine. CR perpendicular, centered to the glenohumeral joint (approximately 1 inch inferior to the coracoid process). The hand may be in external or internal rotation to profile different aspects of the proximal humerus — external rotation profiles the greater tubercle laterally.

Grashey Method (AP Oblique, Glenohumeral Joint): The patient is rotated 35–45° toward the affected side so the glenohumeral joint space opens up in profile. CR is perpendicular, centered to the glenohumeral joint. This is the best method for visualizing the true joint space.

Scapular Y (Lateral Shoulder): The patient is positioned so the scapula is seen in a true lateral (Y-shape). The patient stands facing the upright bucky, obliqued approximately 45–60° with the affected side against the IR. CR is perpendicular, centered to the glenohumeral joint. The humeral head should sit in the center of the Y; displacement indicates dislocation.

Transthoracic Lateral Humerus: Used when the patient cannot move the injured arm. The unaffected arm is raised above the head. CR is horizontal, centered through the thorax to the surgical neck of the humerus. Breathing technique (using shallow respiration during a long exposure) blurs the ribs and lung markings, improving visualization of the humerus.

Collimation and Radiation Safety

Collimate to just beyond the area of clinical interest. For small parts (fingers, wrist), use close collimation. Confirm SID with a tape measure. Always label images before processing. After each supervised exposure, self-critique images for centering, rotation, collimation borders, density/contrast, and marker presence — these are the same criteria used in clinical competency evaluation and on credentialing examinations.

Key terms9

Central Ray (CR)The central, undeviated beam of x-rays from the tube; its direction and centering point define the projection geometry and must be documented for every view.
Source-to-Image-Receptor Distance (SID)The measured distance from the x-ray tube focal spot to the image receptor surface; standard SID for most extremity work is 40 inches (102 cm).
CollimationRestricting the x-ray field with lead shutters to the anatomical area of interest, reducing patient dose and scatter radiation.
Oblique ProjectionA view in which the part is angled (typically 45°) between a PA/AP and a lateral, used to separate overlapping structures.
Scaphoid View (Ulnar Deviation)A modified PA wrist projection with the hand in ulnar deviation and often a slight CR angle to profile the scaphoid bone, reducing superimposition by other carpals.
Grashey MethodAn AP oblique shoulder projection (patient rotated 35–45° toward the affected side) that opens the glenohumeral joint space for diagnostic evaluation.
Scapular Y ProjectionA lateral shoulder view where the scapula appears as a Y-shape; used to identify anterior or posterior glenohumeral dislocation based on humeral head position.
Lead MarkerA radiopaque R or L marker placed in the primary beam field on every image to permanently identify patient laterality; required for medicolegal and diagnostic accuracy.
Centering PointThe specific anatomical landmark to which the CR is directed; incorrect centering causes distortion, cut-off anatomy, and repeated exposures.
In class: Using positioning lab worksheets derived from Merrill's Atlas, students set up each projection (PA hand, oblique hand, lateral digit, PA wrist, lateral wrist, scaphoid view, AP elbow, lateral elbow, AP shoulder, scapular Y, transthoracic lateral humerus) on a classmate, calling out CR angle, centering point, and SID before instructor approval. · Perform supervised exposures on an energized radiographic unit for a minimum of six upper extremity projections, then print or display the images and self-critique using the departmental image critique checklist. · Watch and discuss video demonstrations of challenging positions (scaphoid, Norgaard method for fingers, Grashey method for glenohumeral joint), then repeat each setup on a partner until the instructor confirms correct alignment.
Materials: Radiographic positioning unit (energized), image receptors and grid, collimator, SID tape measure, positioning sponges and sandbags, lead markers (R/L), Merrill's Atlas, image critique checklist, protective aprons
Check: Instructor-observed positioning competency check: student must independently position for any three upper extremity projections called at random, achieving correct centering point (within 1 cm), CR direction, collimation, and marker placement on all three — all three must pass; repeat attempts permitted same session up to twice.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Radiographic Procedures / Positioning
1. For a PA projection of the hand, where is the central ray directed?
Radiographic Procedures / Positioning
2. Which projection is most appropriate for demonstrating the glenohumeral joint space in profile?
Radiographic Procedures / Positioning
3. A patient cannot abduct the injured arm for a standard lateral shoulder view. Which projection is the best alternative?
Radiographic Procedures / Positioning
4. When performing an oblique projection of the hand, what degree of rotation from the PA position is standard?
Radiation Protection / Patient Safety
5. Why is close collimation especially important when imaging small parts such as the fingers?
Radiographic Procedures / Image Evaluation
6. On the scapular Y projection, a normal humeral head should appear in what position relative to the Y?
Radiographic Procedures / Positioning
7. Which modification to the standard PA wrist projection best demonstrates the scaphoid with reduced superimposition?
Radiation Protection / Patient Safety
8. Before performing any radiographic exposure, which step is essential for patient identification and radiation safety?
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