title: Roentgenographic bone density changes in astronauts during representative Apollo space flight.
mesh_terms: D015502:Absorptiometry, Photon; D001132:Arm / Q000000981:diagnostic imaging; D001826:Body Fluids; D001861:Bone Regeneration; D001842:Bone and Bones / Q000000981:diagnostic imaging*; D002113:Calcification, Physiologic; D002118:Calcium / Q000378:metabolism / Q000652:urine; D004032:Diet; D005528:Foot / Q000000981:diagnostic imaging; D006225:Hand / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D005082:Physical Exertion; D011859:Radiography / Q000295:instrumentation; D013026:Space Flight; D013628:Talus / Q000000981:diagnostic imaging; D013997:Time Factors; D014953:Wrist / Q000000981:diagnostic imaging
chemical_list: D002118:Calcium