Which is not correct in lumbar anteroposterior photography?

Straighten your hips and knees. The incorrect anteroposterior photography of the lumbar spine is that the hips and knees are straight. Lumbar anteroposterior position refers to the routine shooting method of lumbar examination in radiological examination. The main purpose is to check the overall morphological structure of the lumbar vertebral body, as well as the positional relationship between the lumbar segments, and to check whether there are abnormal structures on the lumbar vertebral body.