A system and method of producing a reference graph for use in selecting the proper radiation levels for use during radiation therapy. Using the radiation treatment plan, a physician can then create a dose volume histogram. The dose volume histogram is used to create a risk map for selected tissue. Data from one or more databases is then accessed and overlaid onto the risk map to create a reference graph. The data from the selected databases contains historical data of past radiation levels used during prior radiation therapies. Furthermore, the historical data can contain instances of adverse reactions due to high radiation levels. The physician can view the reference graph to determine if the radiation being used on a patient is either overly aggressive or overly safe in all areas of affected tissue.