OBJECTIVE To re-evaluate gonad shielding in paediatric pelvic radiography in terms of attainable radiation risk reduction and associated loss of diagnostic information. METHODS A study on patient dose and the quality of gonad shielding was performed retrospectively using 500 pelvic radiographs of children from 0 to 15 years old. In a subsequent study, 195 radiographs without gonad shielding w...

In the present work a three-dimensional model has been developed to study shielding gas flow and heat transfer in a laser welding process using computational fluid dynamics. This investigation was motivated by problems met while using an optical system to track the weld path. The aim of this study was to investigate if the shielding gas flow could disturb the observation area of the optical sys...

In this paper, fabric density influence on the shielding effectiveness of electromagnetic shielding fabric is studied. A series of blended shielding fabrics are tested using a waveguide tube testing method to obtain the shielding effectiveness with different density. Experimental results show that the shielding effectiveness increases with the increase of fabric density, and there are two rapid...

To develop materials for shielding astronauts from the hazards of GCR, natural Martian surface materials are considered for their potential as radiation shielding for manned Mars missions. The modified radiation fluences behind various kinds of Martian rocks and regolith are determined by solving the Boltzmann equation using NASA Langley's HZETRN code along with the 1977 Solar Minimum galactic ...

SUMMARY The paper investigates efficiency of different shielding techniques. The study was performed on the basis of 3-D substation model design where the finite-element method for calculation of magnetic fields (the EMAS software) was used and measurements were performed. The study was designed to meet the following objectives: − to obtain a useful analytical tool for evaluation of magnetic fi...

PURPOSE Ionizing radiation is implicated in nearly 2% of malignancies in the United States; radiation shields prevent unnecessary radiation exposure during medical imaging. Contemporary radiation shield utilization for adult patients in the United States is poorly defined. Therefore, we evaluated the prevalence of protective shielding utilization in adult patients undergoing CT scans in United ...

The relationship between surface transfer impedance and stirred mode chamber shielding effectiveness proposed by Eicher and Boillot has been simplified. This simplified relationship was used to compare the measured stirred mode chamber shielding effectiveness of nine shielding artifacts with the shielding effectiveness of the same samples calculated from transfer impedance measurements made at ...

normal 0 false false false en-us x-none fa introduction: in radiation therapy centers across iran, protection of normal tissues is usually accomplished by either cerrobend or lead block shielding. in this study, the influence of these two shielding methods on central axis dose distribution of photon beam a cobalt unit was investigated in clinical conditions. materials and methods: all measureme...

............................................................................................................. 8 I. Theoretical Background .................................................................... 9 Cognitive Control ............................................................................................................ 10 An Introduction to Cognitive Control.........................

Using 40 ns laser pulses, we probe the real-time dynamics of ultracold ionizing collisions in metastable xenon. We time resolve both shielding and enhancement effects, and observe the production of Xe2 molecular ions through associative ionization. We estimate the rate of molecule formation in excited-state collisions, and directly measure the role of both flux enhancement and excited state sur...