Patient lies supine on the table.
For AP, straightened both his legs by pulling both of them down slightly. The foot is in neutral position. Place a suitable size cassette below his knee joint. No grid is used.
The central ray is perpendicular to a point 1/2 inch inferior to the apex of patella.
For lateral view, turn the patient slightly by lifting his opposite buttock. The knee should be in lateral position making an angle of about 120 degrees (not 90 degrees). Again placed the cassette under the knee joint. Centre perpendicular to a point 1 inch (2.5 cm) below and 1 inch (2.5 cm) behind the apex of the patella.
For radiation protection, place a lead apron over the patient's pelvis.
Exposure for AP is about 55 kVp and 5 mAs.
Exposure for lateral is 55 kVp and 4 mAs.
FFD is 100 cm.