title: Derivation of total filtration thickness for diagnostic x-ray source assembly.
abstract: The method defined by the IEC 60522 for determining the inherent filtration of an x-ray source device is applicable only for a limited range of tube voltage. Because the users cannot legally remove the x-ray movable diaphragm of the x-ray source device, total filtration, which is the sum of the additional filtration diaphragm movable for specific filtration and x-ray, cannot be measured. We develop a method for simply obtaining the total filtration for different tube voltage values. Total filtration can be estimated from a ratio R' of the air kerma [Formula: see text], which is measured with an Al plate with thickness T, and [Formula: see text] measured without an Al plate. The conditions of the target material of the x-ray source device are then entered into the Report 78 Spectrum Processor to calculate the air kerma K x and K x+T for Al thicknesses x and (x  +  T), respectively, to obtain R. The minimum value of x, which is the difference between the R and R', is the total filtration of the x-ray source device. The total filtration calculated using the industrial x-ray source device was within  ±1% in the 40-120 kV range. This method can calculate the total filtration using air kerma measurements with and without the Al plate. Therefore, the load on the x-ray tube can be reduced, and preparation of multiple Al plates is not necessary. Furthermore, for the 40-120 kV tube voltage range, the user can easily measure the total filtration.
authors.affiliation: Medicine and Medical Sciences, University of Tsukuba, 1-1-1, Tennoudai, Tsukuba-city, Ibaraki 305-8575, Japan.
authors.forename: Michiharu
authors.initials: M
authors.lastname: Sekimoto
authors.forename: Yoh
authors.initials: Y
authors.lastname: Katoh
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D005374:Filtration / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D011859:Radiography / Q000295:instrumentation* / Q000379:methods