title: A special ionisation chamber for quality control of diagnostic and mammography X ray equipment.
abstract: A quality control program for X ray equipment used for conventional radiography and mammography requires the constancy check of the beam qualities in terms of the half-value layers. In this work, a special double-faced parallel-plate ionisation chamber was developed with inner electrodes of different materials, in a tandem system. Its application will be in quality control programs of diagnostic and mammography X ray equipment for confirmation of half-value layers previously determined by the conventional method. Moreover, the chamber also may be utilised for measurements of air kerma values (and air kerma rates) in X radiation fields used for conventional radiography and mammography. The chamber was studied in relation to the characteristics of saturation, ion collection efficiency, polarity effects, leakage current, and short-term stability. The energy dependence in response of each of the two faces of the chamber was determined over the conventional radiography and mammography X ray ranges (unattenuated beams). The different energy response of the two faces of the chamber allowed the formation of a tandem system useful for the constancy check of beam qualities.
authors.affiliation: Instituto de Pesquisas Energéticas e Nucleares Comissão Nacional de Energia Nuclear PO Box 11049, 05422-970, São Paulo, SP, Brazil. amcosta@ipen.br
authors.forename: A M
authors.initials: AM
authors.lastname: Costa
authors.forename: L V E
authors.initials: LV
authors.lastname: Caldas
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D008327:Mammography / Q000295:instrumentation* / Q000379:methods; D011785:Quality Assurance, Health Care / Q000379:methods*; D011786:Quality Control; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation* / Q000379:methods; D011859:Radiography / Q000295:instrumentation* / Q000379:methods; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers