Health physics
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Comparative Study
Characterization of the magnetic fields around walk-through and hand-held metal detectors.
Magnetic field strength measurements were made around eight hand-held and 10 walk-through metal detectors. The method was similar to that used in previous research for Electronic Article Surveillance units except a Cartesian rather than cylindrical coordinate system was used. Special magnetic field probes specifically designed for metal detector measurements were used. ⋯ For the hand-held metal detector measurements at the location of the maximum magnetic field strength, measurements by three individuals had a repeatability (percent standard deviation) of 5.9%. Limited repeatability data were collected for on-site measurements of walk-through detectors. One unit showed repeatability of 0.1 to 4.5%; a multi-zone unit showed repeatability of 2.7 to 67.5%.
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Knowledge of dispersion rates and patterns of radioactive aerosols and gases through workrooms is critical for understanding human exposure and for developing strategies for worker protection. The dispersion within rooms can be influenced by complex interactions between numerous variables, but especially ventilation design and room furnishings. For this study, dependence of airflow and aerosol dispersion on workroom geometry (furnishings) and ventilation rate were studied in an experimental room that was designed to approximate a plutonium laboratory. ⋯ Comparisons were made of air velocities, turbulence, and aerosol transport across different ventilation rates and room configurations. A strong influence of ventilation rate on aerosol dispersion rates and air velocity was found, and changes in room geometry had significant effects on aerosol dispersion rates and patterns. These results are important with regards to constant evaluation of placement of air sampling equipment, benchmarking numerical models of room airflow, and design of ventilation and room layouts with consideration of worker safety.
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Lead aprons utilized by personnel performing fluoroscopy are routinely inspected for damage to comply with the requirements of hospital accrediting organizations. Fluoroscopic or radiographic examination of lead aprons may reveal imperfections ranging from small pinholes to large tears. Currently, there are no standards establishing a criteria for acceptance or rejection of lead aprons. ⋯ Often lead aprons are discarded due to small imperfections, a practice that can become costly to these institutions. We have calculated increases in doses to the whole body for varying sizes of holes, including special consideration of the effects on effective dose equivalent when the hole is over the testes and thyroid. ALARA standards for cost per personsievert averted are used to establish a rational basis for criteria of acceptance or rejection of lead aprons.
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This case report describes the medical follow-up of a 46-y-old (at the time of exposure) man who in 1971 accidentally exposed the fingers of his right hand to gamma-ray radiation from an iridium source that was used for nondestructive testing [estimated radiation dose: 26 Gy to 90 Gy (2,600 rad to 9,000 rad)]. No prominent acute injury was detected except for leukocytopenia (800 mm(-3)) and thrombocytopenia (15,000 mm(-3)). ⋯ Radiological examinations prior to and following the operation revealed atrophic change of the finger bones and arterial injuries. Angiographic findings coincided with the region and extent of radiation injury of the fingers, which indicates that arterial damage is involved in the development of this chronic disorder.
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The use of 192Ir brachytherapy for the treatment of in-stent restenosis of the coronary arteries has shown promising clinical results. This paper investigates the radiation exposure of catheterization laboratory staff associated with the performance of this procedure. ⋯ The average radiation dose received by laboratory personnel during a representative 192Ir endocoronary brachytherapy procedure is estimated to be less than 0.1% of the NCRP recommended annual radiation worker's Maximum Permissible Dose (1% of the general public's MPD). This level is justifiable as long as the use of 192Ir benefits patients by producing an improved clinical outcome relative to the use of a less penetrating radionuclide or the application of alternative therapies. Further optimization of the delivery procedure is expected to reduce staff dose.