Clark's Pocket Handbook for Radiographers (Clark's Companion Essential Guides)

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Insufficient dorsiflexion ⫽ calcaneum superimposed on lateral malleolus. Insufficient internal rotation ⫽ overlapping of the tibiofibular joint.

The image should be of comparable quality to that described for the postero-anterior chest projection. The patient sits or lies supine on the X-ray table with both limbs extended. The affected leg is rotated medially until both malleoli are equidistant from the image receptor. The ankle is dorsiflexed. The position is maintained by using a bandage strapped around the forefoot and held in position by the patient. The image receptor is positioned with its lower edge just distal to the plantar aspect of the heel. The patient should be made as comfortable as possible to assist immobilization. An erect holder, or similar device, may be used to assist the patient in supporting the image receptor. The X-ray beam should be collimated carefully to ensure that the primary beam does not extend beyond the area of the image receptor. The vertical central ray is directed through the proximal aspect of the humeral head. Some tube angulation towards the palm of the hand may be necessary to coincide with the plane of the glenoid cavity. If there is a large object-to-detector distance, it may be necessary to increase the overall focus receptor distance to reduce magnification. A true lateral will have been achieved if the lateral portions of the floors of the anterior cranial fossa are superimposed.Toes – Dorsi-plantar Toes Second to Fifth – Dorsi-plantar Oblique Wrist – Postero-anterior Wrist – Lateral Zygomatic Arches – Inferosuperior Maximum lung demonstration is lost due to the absence of the gravity effect of the abdominal organs, which is present in the erect position. A pleural effusion or a pneumothorax is not as well demonstrated compared with the erect projections. An FRD of at least 120 cm is essential to reduce unequal magnification of intrathoracic structures.

RADiographers Charles Sloane MSc DCR DRI Cert CI Principal Lecturer and Radiography Course Leader, University of Cumbria, Lancaster, UK Ken Holmes MSc TDCR DRI Cert CI Senior Lecturer, School of Medical Imaging Sciences, University of Cumbria, Lancaster, UK Craig Anderson MSc BSc Clinical Tutor, X-ray Department, Furness General Hospital, Cumbria, UK A Stewart Whitley FCR TDCR HDCR FETC Radiology Advisor, UK Radiology Advisory Services Ltd, Preston, UK Direct the central ray at right-angles to the image receptor and towards a point 2.5 cm below the sternal angle. Collimate tightly to the spine. Centre to the middle of the image receptor, with the central ray at right-angles to the long axis of the tibia and parallel to an imaginary line joining the malleo

Contents

The normal joint is variable (3–8 mm) in width. The normal difference between the sides should be less than 2–3 mm.1 The inferior surfaces of the acromion and clavicle should normally be in a straight line. Chest – Mobile/Trolley (Antero-posterior) Clavicle – Postero-anterior Clavicle – Infero-superior Coccyx – Lateral Elbow – Antero-posterior Elbow – Antero-posterior Alternate Projections for Trauma Elbow – Lateral Facial Bones – Occipitomental Facial Bones – Occipitomental 30º↓ Femur – Antero-posterior Femur – Lateral Fingers – Dorsi-palmar Fingers – Lateral Index and Middle Fingers Fingers – Lateral Ring and Little Fingers Foot – Dorsi-plantar Foot – Dorsi-plantar Oblique Foot – Lateral Erect Forearm – Antero-posterior Forearm – Lateral Hand – Dorsi-palmar Hand – Dorsi-palmar Oblique Centre to the middle of the image receptor, with the vertical central ray at 90 degrees to an imaginary line joining both femoral condyles. Beam Angulation Radiographic projections are often modified by directing the central ray at some angle to a transverse plane, i.e. either caudally (angled towards the feet) or cranially/cephalic angulation (angled towards the head). The projection is then described as, for example, a lateral 20-degree caudad or a lateral 15-degree cephalad. 10 The area of interest should include the fifth lumbar vertebra and the first sacral segment. A clear joint space should be demonstrated.

Centre in the midline at the level of the posterior superior iliac spines. The central ray is angled 5–15 degrees caudally from the vertical, depending on the sex of the patient. The female requires greater caudal angulation of the beam. The primary beam is collimated to the area of interest. Ankle – Lateral Calcaneum – Axial Cervical Spine – Antero-posterior C3–C7 Cervical Spine – Lateral Erect Cervical Spine – Antero-posterior C1–C2 ‘Open Mouth’ Cervical Spine – Lateral ‘Swimmer’s’ Cervical Spine – Lateral Supine Cervical Spine – Posterior Oblique Cervical Spine – Flexion and Extension Chest – Postero-anterior Chest – Antero-posterior (Erect) Chest – Lateral Chest – Supine (Antero-posterior) Chest – Mobile/Trolley (Antero-posterior) Clavicle – Postero-anterior Clavicle – Infero-superior Coccyx – Lateral Elbow – Antero-posterior Elbow – Antero-posterior Alternate Projections for Trauma Elbow – Lateral Facial Bones – Occipito-mental Facial Bones – Occipito-mental 30º↓ CHEST – SUPINE (ANTERO-POSTERIOR) This projection is usually only utilized when the patient is unable to sit up on a bed or trolley.

These projections demonstrate the pars interarticularis and the apophyseal joints on the side nearest the image receptor. Both sides are taken for comparison. The heart is moved further from the image receptor, thus increasing magnification and reducing accuracy of assessment of heart size (cardiothoracic ratio (CRT)). Commonly only the 90-degree angulation is used. Take care when flexing the knee if a fracture is suspected.