Determining Cassette Side on Lateral Foot X-rays

Primary Radiographic Indicators

On a lateral foot radiograph, the side against the cassette can be determined by identifying which toes appear more inferior, with the medial side against the cassette when the 5th toe is down, and the lateral side against the cassette when the great toe is down, according to Praxis Medical Insights 1
When the great toe is positioned down, the hallux sesamoids are typically better visualized and more clearly separated on the lateral projection, due to the medial structures being farther from the cassette, resulting in less geometric distortion 1

Standard lateral foot radiographs are routinely obtained with the medial side down, which is the most common positioning for routine foot imaging, and is the expected orientation in clinical practice, as recommended by Praxis Medical Insights 1
Consistent positioning is essential for detecting subtle malalignment between serial studies when weight-bearing lateral radiographs are obtained, as inconsistent cassette-side positioning can make comparison difficult 1
The American College of Radiology recommends not confusing laterality markers with cassette-side determination, as these markers indicate which foot is being imaged, not which side is against the cassette, and can be misleading confounding features that don't reflect actual anatomic positioning, according to Radiology 2