A radiation system (50), comprising a patient support platform (3). An X-ray radiation source (2a, 2b, 2c) is positioned beneath the patient support platform and enclosed by fixed radiation shielding. An X-ray radiation detector (22) is positioned above the patient support platform. A detector X-ray radiation shield (1, 11) comprising shield extension (7) is arranged on either side of the patient support platform, which extend from the X-ray radiation 5 detector to the fixed radiation shielding. The shield extensions are able to be moved relative to the source radiation shield to allow access to a patient on the support platform.