This process is called differential diagnosis. It is system of narrowing down, through the process of elimination, a working diagnosis of your condition. There are literally hundreds of medcial tests available to your doctor, from blood panels to exploratory surgery. Don't be shy about asking the doctor why a specific test was ordered and what is likely to be learned from such a test. X-rays are not favored for showing subtle detail often required in determining a disk bulge or herniation.
Most physicians believe the risk of radiation is low compared to the benefits.
MRI Also referred to as magnetic resonance imaging. The MRI is considered the most powerful diagnostic tool for actually seeing detailed images of the human body. The MRI can show the exact location and shape of a disk bulge or herniation, it can show detailed images of lesions, soft tissue and spinal cord abnormalities to name a few. One complete scan can take about an hour to perform. It is noninvasive, painless, and there are no documented side effects.