title: A simple method for evaluation of half-value layer variation in CT equipment.
abstract: Tandem systems, each formed by a pencil ionization chamber with and without a specific covering, were developed and tested in standard radiation beams. These systems were designed to be used in computed tomography radiation beams, where the half-value layer (HVL) determination is not an easy task. The behaviour of the tandem systems in diagnostic radiology showed the possibility of their use to confirm HVL values previously determined by the conventional HVL measurement method in quality control programmes. These systems also have other advantages: low cost, easy application and quick measurement procedure.
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares, Comissão Nacional de Energia Nuclear, Av. Prof. Lineu Prestes, 2242, CEP 05422-970 São Paulo, Brazil. afmaia@ipen.br
authors.forename: Ana F
authors.initials: AF
authors.lastname: Maia
authors.forename: Linda V E
authors.initials: LV
authors.lastname: Caldas
mesh_terms: D000535:Aluminum / Q000737:chemistry; D002138:Calibration; D003300:Copper / Q000737:chemistry; D006801:Humans; D019904:Polymethyl Methacrylate / Q000737:chemistry; D011786:Quality Control; D011829:Radiation Dosage; D011874:Radiometry; D015203:Reproducibility of Results; D013679:Technology, Radiologic; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014965:X-Rays
chemical_list: D003300:Copper; D019904:Polymethyl Methacrylate; D000535:Aluminum