"Compression paddle gallstone": artifact of standard radiographic accessory.
D002765:Cholecystography / Q000295:instrumentation*; D002769:Cholelithiasis / Q000000981:diagnostic imaging*; D006801:Humans; D011856:Radiographic Image Enhancement / Q000295:instrumentation; D013679:Technology, Radiologic / Q000295:instrumentation*; D014986:Xeroradiography / Q000295:instrumentation*