Basic Patient Position
The patient stands ERECT facing the cassette, the cassette is raised so the top is 3cm above the skin margins above the apices, the patient's chin is rested on the top of the cassette holder, the patient is asked to place the backs of the hands on the waist at the sides. The shoulders and arms are rolled forward to bring the scapulae towards the side of the chest. Exposure is made on deep suspended inspiration.
The patient should wear lead apron which should be placed posteriorly.
Avoid irradiation of the eyes and thyroid.
The beam is centred midline at the level of T4 - Horizontal ray. Beam collimated superoinferiorly and laterally to the chest only. Ensure apices and costo-phrenic angles are not
The actual exposure factors are variable i.e depending on the machine specification, type and condition of film processor, use of bucky, screen-film combination, screen speed etc. These have to be determined by experience and trial and error.