title: Half-value-layer increase owing to tungsten buildup in the x-ray tube: fact or fiction.
abstract: The half-value layer (HVL) of an x-ray beam is generally believed to increase with x-ray tube use. This increase in HVL has previously been attributed to the hardening of the x-ray beam as a result of a buildup of tungsten on the x-ray tube glass window. Radiographs and HVL measurements were obtained to determine the effect of tungsten deposited on the x-ray tube windows. This work, along with the HVL data from approximately 200 functioning x-ray tubes used for all applications that were monitored for more than 8 years, indicated there is no significant increase in HVL with diagnostic x-ray tube use.
mesh_terms: D005898:Glass; D011786:Quality Control; D011859:Radiography / Q000295:instrumentation*; D013679:Technology, Radiologic; D014414:Tungsten
chemical_list: D014414:Tungsten