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 leg. No grid is used. The cassette may be placed longitudinally so that both the knee & ankle joints are within the region x-rayed.
The central ray is perpendicular to the midway between the knee and ankle joints. See cross mark in the image above.
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. Again placed the cassette longitudinally so that both joints are within the area imaged. Centre at mid leg.
Exposure is about 57 kVp and 5 mAs.
FFD is 100 cm.