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Direct analysis of molybdenum target generated x‐ray spectra with a portable device
Author(s) -
Stumbo S.,
Bottigli U.,
Golosio B.,
Oliva P.,
Tangaro S.
Publication year - 2004
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1785891
Subject(s) - collimator , x ray tube , spectral line , optics , signal (programming language) , ionization , x ray , materials science , sampling (signal processing) , physics , ionization chamber , anode , detector , computer science , electrode , ion , astronomy , programming language , quantum mechanics
In routine applications, information about the photon flux of x‐ray tubes is obtained from exposure measurements and cataloged spectra. This approach relies mainly on the assumption that the real spectrum is correctly approximated by the cataloged one, once the main characteristics of the tube such as voltage, target material, anode angle, and filters are taken account of. In practice, all this information is not always available. Moreover, x‐ray tubes with the same characteristics may have different spectra. We describe an apparatus that should be useful for quality control in hospitals and for characterizing new radiographic systems. The apparatus analyzes the spectrum generated by an x‐ray mammographic unit. It is based on a commercial CZT produced by AMPTEK Inc. and a set of tungsten collimator disks. The electronics of the CZT are modified so as to obtain a faster response. The signal is digitized using an analog to digital converter with a sampling frequency of up to 20 MHz. The whole signal produced by the x‐ray tube is acquired and analyzed off‐line in order to accurately recognize pile‐up events and reconstruct the emitted spectrum. The energy resolution has been determined using a calibrated x‐ray source. Spectra were validated by comparison of the HVL measured using an ionization chamber.