Radiographic Positioning and Procedural Technique
Core vocabulary
Describe projections, not views. Know AP, PA, lateral (state the side nearest the image receptor), oblique, axial and tangential. Body positions include supine, prone, decubitus (named by the side down), Trendelenburg, reverse Trendelenburg, Fowler's and lithotomy. The central ray may be angled cephalad or caudad and is centred to a landmark; SID and OID drive magnification.
Technique discipline
Identify the patient, explain the procedure, remove artefact-producing items, position with stable body contact, collimate, shield where appropriate, expose, then evaluate against criteria and repeat only when diagnostically necessary. Standard chest: PA erect at 180 cm, scapulae rotated clear of lung fields, adequate inspiration shown by nine to ten posterior ribs above the diaphragm. An AP mobile chest magnifies the heart and is a documented compromise.
Trauma and special groups
Trauma: immobilise, image in the position of least movement, take two orthogonal projections, and clear movement of lines with the trauma team. Children need distraction, short exposures and warm rooms. Bariatric patients need weight-rated equipment, larger receptors and extra staff.
Traps
Naming a decubitus by the side that is up; assuming AP and PA chest projections are interchangeable; forgetting that the aim is a diagnostic image, not a textbook-perfect one.
Worked example
A patient who cannot stand: take an AP semi-erect chest on the trolley at 100 cm SID, shield the abdomen, and document that cardiac size is magnified and not assessable. Do not exceed the grid's focusing distance to compensate.