CT examination can better show whether there is any narrowing of the spinal canal and the cause of narrowing, such as osteophytes, disc herniation, hypertrophy of the ligamentum flavum, tumors and so on. The lumbar spine has five sections, each section is the vertebral body in front and the canal in the back, and the five sections are connected together as the lumbar spinal canal. And in the lumbar spinal canal there is the spinal cord, the spinal cord sends out nerves from the spinal cord above, one section at a time, and from the two intervertebral foramina through. If the narrowing of the spinal canal compresses the spinal cord and nerves, the patient will experience symptoms such as pain, dyskinesia sensory abnormalities. The spinal canal is normally 15-25mm, which is the normal anterior and posterior diameter of the spinal canal. Once there is ligamentum flavum osteophyte can cause stenosis symptoms. If the degree of stenosis is large and the compression on the nerves or spinal cord is severe enough to require surgery, CT can provide accurate clinical guidance to clarify where the lesion is and where to operate.