title: Equivalent half-value layers.
authors.affiliation: National Physical Laboratory, Teddington, Middlesex.
authors.forename: J E
authors.initials: JE
authors.lastname: Burns
mesh_terms: D000535:Aluminum; D002138:Calibration; D003300:Copper; D006801:Humans; D011874:Radiometry / Q000592:standards; D011879:Radiotherapy Dosage / Q000592:standards*; D012015:Reference Standards; D014964:X-Ray Therapy / Q000592:standards*
chemical_list: D003300:Copper; D000535:Aluminum