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Proceedings Paper

Quality assurance in mammography: a new instrument for operational characteristics and focal-spot-sizes measurements
Author(s): Newton S.M. Curi; Annie France Frere; Homero Schiabel; Henrique J. Q. de Oliveira; Marcio A. Marques
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Paper Abstract

This work is about the development of a computer-based instrument intended to be applied to quality assurance of mammography systems. It was designed in order to obtain information about kVp, mA, exposure time, dosage, waveform and other important operational characteristics of the radiographic equipment by means of few singular exposures. In addition, the measurement of the focal spot sizes is provided, as in the field center, as in any other location. Indeed the system is designed to determine automatically the position of the sensor relative to the field center, independent on the place where it is positioned on the equipment table. Thus, the instrument is composed by a system which determines automatically the position of the test object relative to the field center, and it is based on silicon sensors coupled to an electronic amplifier system, and to a notebook computer. Calculations made by the software, developed specifically for this application, can correct automatically the shifts of positioning of the test objects relative to the field center. By using the field characteristics equations, it is able to determine also the target angulation on the anode, and intensity distributions characteristics due to the Heel effect. The notebook screen can display, thus, information about the operational characteristics of the radiological system, as well as a diagram of the effective focal spot characteristics along the radiation field. In tests performed with a mammography equipment, the instrument was able to determine the operational conditions with an average accuracy of +/- 1% and the average error of the focal spot sizes measurements was as low as 10 micrometer.

Paper Details

Date Published: 24 July 1998
PDF: 12 pages
Proc. SPIE 3336, Medical Imaging 1998: Physics of Medical Imaging, (24 July 1998); doi: 10.1117/12.317067
Show Author Affiliations
Newton S.M. Curi, Univ. of Sao Paulo (Brazil)
Annie France Frere, Univ. of Sao Paulo (Brazil)
Homero Schiabel, Univ. of Sao Paulo (Brazil)
Henrique J. Q. de Oliveira, Univ. of Sao Paulo (Brazil)
Marcio A. Marques, Univ. of Sao Paulo (Brazil)


Published in SPIE Proceedings Vol. 3336:
Medical Imaging 1998: Physics of Medical Imaging
James T. Dobbins; John M. Boone, Editor(s)

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