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HLT-RADI64-08 · Lesson 3 · 25 clock hours · lab

Advanced Radiographic Positioning: Upper and Lower Extremities and Girdles

Objective. Students perform all ARRT-required upper and lower extremity and girdle projections on a partner or phantom, demonstrating correct anatomy inclusion, joint alignment, and exposure parameters.

⚠ 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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Advanced Radiographic Positioning: Upper and Lower Extremities and Girdles

Mastering extremity positioning is essential for every radiologic technologist. The ARRT expects you to produce diagnostic-quality images across a wide range of joints and bones, adapting your technique for both routine and trauma situations. This lesson consolidates the upper extremity (hand, wrist, elbow, shoulder, and shoulder girdle) and lower extremity (foot, ankle, knee, hip, and pelvic girdle) into a unified framework of principles you can apply to any projection.

Core Positioning Principles

Every extremity image shares four fundamentals: correct patient and part alignment, appropriate central ray (CR) direction and centering, adequate anatomy inclusion, and proper exposure technique.

Alignment means the long axis of the part should generally run parallel to the long axis of the image receptor (IR), unless anatomy dictates otherwise (e.g., an oblique wrist). Joints must be aligned to the CR so the joint space opens cleanly without superimposition of adjacent structures.

CR placement determines which anatomy is demonstrated and how much distortion is introduced. For most extremity projections the CR is perpendicular to both the part and the IR. Exceptions include the axial calcaneus (angled posteriorly), the tangential patella (Merchant view), and several shoulder projections that require specific angulation to clear overlapping structures.

Anatomy inclusion means every projection must capture the required structures. For example, a PA hand must include all phalanges through the distal carpals, with the third metacarpal aligned to the long axis of the forearm. A lateral knee must include the distal femur, full patella, proximal tibia, and fibular head without rotation.

Exposure technique for extremities typically uses lower kVp (in the mid-50s to mid-60s range for small parts, higher for large parts such as the hip and pelvis) to produce high contrast images that reveal fine trabecular bone detail. Use the technique chart posted in your lab as your starting point, then apply clinical judgment for patient size and pathology.

Upper Extremity and Shoulder Girdle

Hand and fingers: Standard series = PA, lateral, and oblique. The PA hand is taken with the palm flat. Individual digit studies use the affected digit placed parallel to the IR. The lateral finger must show no rotation — nail beds should superimpose.

Wrist: PA, lateral, and oblique (semi-pronation) are routine. The scaphoid (navicular) view adds ulnar deviation and may use a CR angle toward the elbow to open the scaphoid waist. Position the wrist flat; do not allow the wrist to pronate on the lateral.

Elbow: PA (full extension), lateral (90° flexion), and internal/external obliques. If the patient cannot extend, use two AP axial projections — one for the distal humerus, one for the proximal forearm — to avoid distortion.

Shoulder: AP internal rotation, AP external rotation, and inferosuperior axial (Garth, Lawrence, or West Point) are common. The scapular Y (lateral scapula) locates glenohumeral joint dislocations without moving a traumatized arm. The AC joints require bilateral weight-bearing AP projections for comparison when indicated.

Clavicle and scapula require AP and oblique projections; breathing technique on the lateral scapula blurs overlying ribs.

Lower Extremity and Pelvic Girdle

Foot: AP (dorsoplantar), oblique, and lateral. The AP foot angles the CR 10° posteriorly (toward the heel) to reduce foreshortening. The lateral foot must include the entire calcaneus and all five metatarsals.

Ankle: AP, mortise (15–20° internal rotation to demonstrate the full talar dome and mortise joint), and lateral. The CR is centered to the ankle joint.

Knee: AP, lateral (5° CR angle cephalad to open the joint space), and obliques. The tunnel (intercondylar fossa) view demonstrates the posterior intercondylar eminence and is taken with the knee flexed.

Hip: AP pelvis (both hips for comparison), AP hip, and frog-leg lateral (modified Cleaves). For trauma, never move a suspected fractured hip into the frog-leg position — substitute the cross-table lateral instead.

Pelvis: AP pelvis uses gonadal shielding on male patients whenever it does not obscure the anatomy of interest; follow your department protocol and current ALARA guidelines for female patients.

Trauma Adaptations

When a patient cannot assume the standard position, bring the IR and tube to the patient — never force a painful or potentially fractured limb. Horizontal beam (cross-table) laterals, reverse projections, and modified tube angles maintain two-view coverage of any joint while protecting the patient. Always clearly label trauma images with the patient's position (e.g., "cross-table lateral") so the interpreting physician understands the geometry.

Radiation Safety

Apply ALARA principles on every exposure. Collimate tightly to the anatomy of interest — extremity fields are small. Use gonadal and lead shielding per your facility policy. Keep ancillary personnel and the patient's other body parts out of the primary beam. Ensure the patient understands the procedure so they remain still, reducing repeat exposures. Place your lead marker (R or L) within the collimated field before every exposure.

Image Evaluation

After acquiring an image, evaluate it systematically: (1) correct anatomy included and centered, (2) adequate density and contrast, (3) no motion blur, (4) correct rotation or absence of rotation as required, (5) marker visible. If an image does not meet diagnostic standards, identify the specific error, correct it, and repeat with justification documented per department policy.

Key terms8

Central ray (CR)The center of the X-ray beam; its direction and point of entry determine which anatomy is demonstrated and the degree of distortion in the image.
Mortise viewAn AP ankle projection taken with the foot and leg internally rotated approximately 15–20° so the distal tibiofibular joint and full talar dome are visualized without bony overlap.
Scapular Y projectionA lateral shoulder view taken in the true lateral plane of the scapula; used to identify glenohumeral dislocations without requiring movement of a traumatized arm.
Cross-table lateralA horizontal-beam lateral projection performed with the patient supine and the IR placed vertically beside the part; used when the patient cannot be moved safely, especially for suspected hip fractures.
ALARAAs Low As Reasonably Achievable; the guiding radiation protection principle requiring that exposure to ionizing radiation be kept as low as possible while still producing a diagnostic image.
Image receptor (IR)The device that captures the X-ray image; may be a digital detector plate or computed radiography cassette, positioned to receive the remnant beam after it passes through the patient.
CollimationRestriction of the X-ray beam to the area of clinical interest using adjustable lead shutters; reduces patient dose and scattered radiation, improving image contrast.
Oblique projectionA projection in which the patient or part is rotated between the true frontal (AP/PA) and true lateral positions to demonstrate anatomy free of superimposition.
In class: Complete a timed positioning practical in which students produce five assigned extremity images — randomly selected from hand, wrist, elbow, shoulder, foot, ankle, knee, and hip — within a 30-minute window using the lab radiographic unit. · Critique a set of 20 clinical images provided by the instructor, identifying positioning errors, technical factor problems, and anatomy demonstrated, and writing a one-sentence corrective action for each suboptimal image. · Practice patient positioning for a non-weight-bearing trauma patient using a positioning mannequin, adapting standard projections for limited mobility while maintaining radiation protection and image quality standards.
Materials: Radiographic unit with extremity phantom and positioning mannequin, lead markers, positioning sponges, image critique worksheet, Bontrager's positioning text, technique chart
Check: Timed practical: all five images must score 8/10 or higher on positioning checklist; image critique worksheet must correctly identify the primary error and corrective action on at least 16 of 20 images — pass 80%.

Practice check8

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

Radiographic Procedures
1. A patient presents with wrist pain after a fall. The technologist suspects a scaphoid fracture. Which positioning modification best demonstrates the scaphoid waist with minimal foreshortening?
Radiographic Procedures
2. When performing a cross-table lateral hip on a trauma patient, where should the IR be placed?
Image Analysis / Critique
3. You are evaluating a lateral knee image and notice the posterior femoral condyles are not superimposed — the medial condyle projects posterior to the lateral condyle. This indicates:
Radiation Protection
4. Which of the following best describes the purpose of tight collimation when imaging a single finger?
Radiographic Procedures
5. A standard AP foot projection uses a CR angle of approximately 10° posteriorly (toward the heel). What is the primary reason for this angulation?
Radiographic Procedures
6. During a shoulder trauma series, the patient cannot abduct the arm. Which projection best evaluates glenohumeral joint alignment without requiring arm movement?
Radiation Protection
7. A technologist is about to expose a pelvis AP projection on a male patient. According to standard radiation protection practice, gonadal shielding should be applied:
Image Analysis / Critique
8. An image critique of an AP elbow shows the radial head, neck, and tuberosity are superimposed over the ulna. Which corrective action is most appropriate for the next projection?
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