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

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The image should include the distal end of the radius and ulna and the proximal end of the metacarpals. The pisiform should be seen clearly in profile situated anterior to the triquetral. The long axis of the scaphoid should be seen perpendicular to the image receptor. The image receptor and beam are often centred too low, thereby excluding the upper thoracic vertebrae from the image. The lower vertebrae are also often not included. L1 can be identified easily by the fact that it usually will not have a rib attached to it.

Fracture of the waist of the scaphoid may not be clearly visible, if at all, at presentation. It carries a high risk of delayed avascular necrosis of the distal pole, which can cause severe disability. If suspected clinically, the patient may be re-examined after 10 days of immobilization, otherwise a technetium bone scan or magnetic resonance imaging (MRI) may offer immediate diagnosis.The petrous ridges must appear below the floors of the maxillary sinuses. There should be no rotation. The central ray is angled 30 degrees cranially at an angle of 60 degrees to the image receptor and is centred 5 cm inferior to the angle of the mandible remote from the image receptor. Collimate to include the whole of the mandible and temporomandibular joint (include the external auditory meatus within the collimation field). Both the elbow and the wrist joint must be demonstrated on the radiograph. Both joints should be seen in the true antero-posterior position, with the radial and ulnar styloid processes and the epicondyles of the humerus equidistant from 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. The image should include the distal phalanges and calcaneum. The ankle joint and soft tissue margins of the plantar aspect of the foot should be included. The longitudinal arches of the feet should be clearly demonstrated.

Give clear instructions Explain what you are doing Explain why you are doing it Invite and answer any questions The patient lies on the side to be examined, with the knee flexed at 45 or 90 degrees. The other limb is brought forward in front of the one being examined and supported on a sandbag. A sandbag is placed under the ankle of the affected side to bring the long axis of the tibia parallel to the image receptor. The position of the limb is now adjusted to ensure that the femoral condyles are superimposed vertically. The centre of the image receptor is placed level with the medial tibial condyle. The heart is moved further from the image receptor, thus increasing magnification and reducing accuracy of assessment of heart size (cardiothoracic ratio (CRT)). The vertical central ray is directed to the centre of the imaging receptor. Using a short exposure time, the exposure is made on arrested respiration. Scleroderma (one cause of Raynaud’s disease) causes wasting and calcification of the soft tissue of the finger pulp. Chip fracture of the base of the dorsal aspect of the distal phalanx is associated with avulsion of the insertion of the extensor digitorum tendon, leading to the mallet finger deformity. In cases of severe trauma, when the fingers cannot be flexed, it may be necessary to take a lateral projection of all the fingers superimposed, as for the lateral projection of the hand, but centring over the proximal interphalangeal joint of the index finger.

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The central ray is directed perpendicular to the image receptor and centred in the midline at the levels of the angles of the mandible. A true lateral will have been achieved if the lateral portions of the floors of the anterior cranial fossa are superimposed. Always prepare the X-ray room for the procedure prior to the patient entering the room. Follow departmental protocols for the examination, e.g. the focus receptor distance (FRD), normally 110 cm unless otherwise stated. If using computed radiography: 1 do not take multiple projections on one receptor/plate as this will confuse image processing algorithms; 2 use the smallest receptor size consistent with size of the body part to maximize resolution. Always collimate to the area of interest as excessive field sizes reduce image quality and increase patient dose. It is best practice to apply anatomical side markers at the time of the examination and not to use electronic markers when post processing the image.