RESUMO
For objective measurement of digital detectors, the authors show it necessary to be limited to the quantum efficiency of recording for assessing the accuracy of measuring the value of a signal and to the frequency-contrast characteristics for estimating spatial accuracy. Since a computer is an integral part of the digital detector, this cannot be a basic obstacle to the application of the proposed procedure.
Assuntos
Intensificação de Imagem Radiográfica , Radiografia/instrumentação , Conversão Análogo-Digital , Humanos , Modelos Teóricos , Teoria QuânticaRESUMO
One- and two-coordinate detectors with proportional chambers developed at the Budker Institute of Nuclear Physics (BINP) are presented. The parallax-free 10 MHz one-coordinate OD-3.1 and OD-3.2 detectors are used in synchrotron radiation powder diffraction and SAXS experiments. The two-coordinate DED-3 detector with a multiwire proportional chamber (MWPC) is used in Laue diffraction. The latest modification of this detector, DED-5, with a working area of 384 x 384 mm, is briefly described. The micro-strip detector prototype MSGC-100 has passed test synchrotron radiation experiments and the next modification (MSGC-500), with 500 channels for high energy, is under construction. The one-coordinate MWPC OD-160 detector, with an angle aperture of 160 degrees and a count rate of 3.3 GHz, is under construction. It will be used for high-resolution powder diffraction. Two types of gas chamber will be used: L for low energies (5-30 keV) and H for high energies (30-70 keV). A 16 degrees section with an H-chamber has been produced and tested on the synchrotron radiation beamline.
RESUMO
The paper outlines a digital radiographic device which records radiation by scanning with a one-dimensional multiwire proportional chamber connected on-line to a computer. The device drastically reduces a dosage load on patients, improves the diagnostic potentialities of projectional radiography, yields quantitative diagnostic information, creates special diagnostic programmes, has fast-access and fire-safe archives. The device may be used for general-purpose radiographic examinations and it has advantages when used instead of conventional fluorographs.