good for screening but poor for diagnosis. When a condition is suspected based on chest radiography, additional imaging of the chest can be obtained to definitively diagnose the condition or to provide evidence in favor of the diagnosis suggested by initial chest radiography. Unless a fractured rib is suspected of being displaced, and therefore likely to cause damage to the lungs and other tissue structures, x-ray of the chest is not necessary as it will not alter patient management. Abdomen In children, abdominal radiography is indicated in the acute setting in suspected bowel obstruction, gastrointestinal perforation, foreign body in the alimentary tract, suspected abdominal mass and intussusception (latter as part of the differential diagnosis). Yet, CT scan is the best alternative for diagnosing intra-abdominal injury in children. For acute abdominal pain in adults, an abdominal x-ray has a low sensitivity and accuracy in general. Computed tomography provides an overall better surgical strategy planning, and possibly less unnecessary laparotomies. Abdominal x-ray is therefore not recommended for adults presenting in the emergency department with acute abdominal pain. The standard abdominal X-ray protocol is usually a single anteroposterior projection in supine position. A Kidneys, Ureters, and Bladder projection (KUB) is an anteroposterior abdominal projection that covers the levels of the urinary system, but does not necessarily include the diaphragm. Axial skeleton Head Cerebral angiography allows visualization of blood vessels in and around the brain. A contrast agent is injected prior to the radiographs of the head, Orbital radiography, imaging both left and right eye sockets, generally including the frontal and maxillary sinuses. Dental radiography uses a small radiation dose with high penetration to view teeth, which are relatively dense. A dentist may examine a painful tooth and gum using X-ray equipment. The machines used are typically single-phase pulsating DC, the oldest and simplest sort. Dental technicians or the dentist may run these machines; radiographers are not required by law to be present. A derivative technique from projectional radiography used in dental radiography is orthopantomography. This is a panoramic imaging technique of the upper and lower jaw using focal plane tomography, where the X-ray generator and X-ray detector are simultaneously moved so as to keep a consistent exposure of only the plane of interest during image acquisition. Sinus - The standard protocol in the UK is OM with open mouth. Facial Bones - The standard protocol in the UK is OM and OM 30°.