Maine doctors will have access to patient X-rays, mammograms and other medical images regardless of their location as part of a new electronic archive described as a nationwide first.The archive is expected to free health care providers from the hassle and cost of copying scans to CDs when a doctor wants to review patient medical images taken by another provider. Piloted by HealthInfoNet, the state's health information exchange, the archive is being tested by three health care organizations. The pilot kicks off formally on Thursday at MaineGeneral Medical Center in Augusta and Waterville, followed by Eastern Maine Medical Center in Bangor and Cary Medical Center in Caribou later this month.