Solid state detector energy response in W/Al mammography radiation quality series

Ionization chambers and solid state detectors incorporated into multimeters are often used for quality control in different modalities of medical imaging and diagnostic radiology. The equipment to be used in the routine QC procedures needs to be calibrated under well-known radiation conditions (known as radiation qualities) defined by the international standards. International standards IEC 61267:2005 [IEC 62167, IEC 2005] and IAEA TRS 457:2007 [IAEA TRS 457, IAEA 2007] cover general radiography and fluoroscopy radiation qualities (abbreviated as RQR and RQA series, in the voltage range from 40 kV to 150 kV), and computerized tomography radiation qualities (abbreviated as RQT series, in the voltage range from 100 kV to 150 kV), among other. In the field of mammography reference radiation fields are defined for molybdenum anode/filtration combination (Mo/Mo, abbreviated as RQR-M series, in the voltage range from 25 kV to 35 kV). Since Mo/Mo mammography units are widespread and available at hospitals they have been included in the standard [IEC 62167, IEC 2005]. Even so, Secondary Standard Dosimetry Laboratories (SSDLs) that are performing calibrations of QC dosimeters for end-users, rarely have availability of such anode/filtration combination under reference laboratory conditions. SSDLs most often employ X-ray generators with W/Al combinations. Additionally, nowadays many different combinations of anode/filtration are present in mammography units of different manufacturers that are commonly used in the hospitals. Multimeters are often sensitive to spectral changes caused by different anode/filter combination, so it is doubtful that the traceability established for one anode/filter combination can be used to measure doses for another combination. Measurements with different solid state detectors were performed under laboratory conditions with W/Al radiation qualities established in the SSDL. In the future, research will be expanded to clinical conditions in radiation fields produced by mammography units which ...