title: Estimation of the life expectancy of a filament of the conventional X-ray unit: a technical case study.
abstract: Conventional diagnostic X-ray units are used for radiographic imaging in several countries. As a part of our quality control procedures, we recorded entrance surface air kerma, tube voltage, and half-value layer measurements for four diagnostic X-ray tubes over a 108 week course. The entrance surface air kerma for one of the X-ray tubes suddenly declined in the 107th week, and the filament burned out 1 week later. We retrospectively reviewed these data and observed that the entrance surface air kerma of the failing tube had increased as a function of elapsed time. The slopes for these four X-ray units were calculated, and we observed that the slope of the failing tube was higher than that of the other three tubes (P < 0.001). Monitoring of the fluctuation in the entrance surface air kerma would be valuable for predicting the residual life expectancy of X-ray tubes.
authors.affiliation: Department of Radiology, Shiga Medical Center for Children, 5-7-30, Moriyama, Moriyama, Shiga, 524-0022, Japan, ntoki@blue.plala.or.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fukuda
authors.forename: Kosuke
authors.initials: K
authors.lastname: Matsubara
authors.forename: Tosiaki
authors.initials: T
authors.lastname: Miyati
mesh_terms: D000388:Air; D006801:Humans; D011829:Radiation Dosage; D011859:Radiography / Q000295:instrumentation*; D012189:Retrospective Studies; D014965:X-Rays