Search

The dynamics of the diffraction peak shape during pulsed heat load on mosaic single-crystal tungsten were measured at the `Plasma' scattering station on the eighth beamline of the VEPP-4 synchrotron radiation source at the Budker Institute of Nuclear Physics. The observed evolution of the diffraction peak shape agrees with theoretical predictions based on calculations of deformation caused by pulsed heating. Three clearly distinguishable stages of the diffraction-peak evolution were found, correlating with the evolution of temperature and deformation distributions. The residual plastic deformation increased with subsequent heating pulses.

Theoretical and experimental research results related with the influence of correlation of signals in neighboring elements of digital X-ray receiver-transformer produced on the evaluation of the output ratio noise/signal and, as a consequence, on the evaluation of quantum registration efficiency are described in the paper.

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.

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.

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.

The authors suggest that the coefficient, representing the ratio between the sizes of the small pelvis section and fetal head section, be used for the prediction of labor outcome for the fetus in women with a contracted pelvis. When the coefficient values K1-K4 were lower than 1.32, 1.35, 0.68, and 0.79, more than 90% of the newborns developed signs of cerebral circulation disorders, this prompting the use of cesarean section for this group of pregnant women. Timely correction of the policy of labor management with due consideration for the anatomical features of the pelvis helped reduce the perinatal mortality in multigravidae to 5/1000, mainly at the expense of carrying out planned cesarean section and monitoring in labor.

Performance principles are given for a digital x-ray unit. Radiation doses are compared with a standard diagnostic x-ray unit. It is shown that a digital x-ray unit provides frontal view radiographs with 40 +/- 10 mR radiation dose which is 40 times less than that for the film.

The paper gives account of advantages and disadvantages of ultrasonic and conventional X-ray pelvimetries for diagnosing the contracted pelvis in obstetrics. It also describes a basically new X-ray pelvimetry by using a digital X-ray unit one of whose basic advantages is a low maternal and fetal load (one-twentieth as high as routine X-ray pelvimetry). X-ray pelvimetry with the use of the digital X-ray unit was performed in 366 pregnant and parturient women, of them 188 showed various forms of the anatomically contracted pelvis. Out of them 47% had deliveries by cesarean operation. The potentialities of this unit make it possible to predict both the biomechanism of labor and its outcome.