Effect of I,25-dihydroxycholecalciferol in renal osteodystrophy. (1/22)

A 23-year-old man with medullary cystic disease had been undergoing hemodialysis for 5 years and had become confined to a wheelchair because of renal osteodystrophy. He was treated with 125-dihydroxycholecalciferol, 2.0 mug (later 1.0 mug) three times a week, administered by way of the venous end of the dialysis machine. Within 1 month bone pain lessened and his ability to stand and walk improved. By 3 months he was walking short distances and by 5 months, long distances. Calcium balance was near zero before treatment and was strongly positive during treatment. Bone mineral content in the lower femur, measured by photon absorptiometry, increased at a rate of 32.2% per year. In contrast, 26 other patients on long-term hemodialysis had a mean loss of bone mineral content of 14.0% per year. Radiographs taken during treatment showed a decrease in subperiosteal bone resorption and healing of a pseudofracture. A significant decrease in the mean serum alkaline phosphatase value was noted during treatment, but no significant changes in mean serum calcium or phosphorus values were seen.  (+info)

Thenar muscle blood flow and bone mineral in the forearms of lumberjacks. (2/22)

Forty lumberjacks who had used a chain saw for 0-20 years and who had no general disease affecting the bones were studied by measuring the thenar muscle blood flow of both hands by the 133-Xe local clearance method. Bone mineral in the left forearm in the region of cancellous and cortical bone was assessed by the 241-Am gamma ray attenuation method. Virbration was found to decrease the blood flow in the saw-bearing left hand compared with the right hand of the lumberjacks. The bone mineral density (g/vm-3) was lower in the forearm bones of the lumberjacks than in controls of the same age with healthy bones. Moreover the poorer the thenar muscle blood flow, the greater was the decrease in the mineral density of the distal radius. Measurement of the mineral density of the forearm bones by the gramma ray attenuation method can be used for early detection of bone lesions in traumatic vasospastic disease.  (+info)

Bone mineral content determined by functional imaging. (3/22)

Quantitation of bone mineral by photon absorptiometry is a simple and accurate method for determining changes in bone volume and mineral content in serial studies. An extension of the scintillation camera method for studying such changes in the calcaneous is described. This technique is applicable to large areas of bone, thereby minimizing the effect of repositioning errors. Using a 40-mCi 241Am sheet source, a 2.1% reproducibility in bone phantoms and a 2.4% reproducibility in normal patients was achieved. Several case studies are presented to illustrate sensitivity and clinical application of the method. Although bone mineral determinations are now performed in a limited number of health care facilities, the scintillation camera method described in this report could increase the availability of these determinations significantly.  (+info)

Radiation hazards from 241Am sources used in thyroid studies. (4/22)

The neutron and gamma photon doses corresponding to the neck and eye level from an 241AmO2 source used in thyroid studies have been theoretically estimated. The radiation hazard to the patient is found to be not significant.  (+info)

Worldwide bioassay data resources for plutonium/americium internal dosimetry studies. (5/22)

Biokinetic models are the scientific underpinning of internal dosimetry and depend, ultimately, for their scientific validation on comparisons with human bioassay data. Three significant plutonium/americium bioassay databases, known to the authors, are described: (1) Sellafield, (2) Los Alamos and (3) the United States Transuranium Registry. A case is made for a uniform standard for database format, and the XML standard is discussed.  (+info)

A device for in vitro irradiation with alpha-particles using an alpha-emitting radioactive source. (6/22)

A device to irradiate a monolayer of cultured cells with alpha-particles using an Am-241 alpha-source (33.4 MBq) was designed to investigate RBEs of alpha-particles in cell killing, induction of chromosome aberration, mutagenic changes and transformation. This device can be used conveniently in a common laboratory by a small number of researchers without any limitation of machine time. The device performs as follows: (1) The energy of alpha-particles at the entrance of the cell layer is 3.20 MeV with a standard deviation of 0.25 MeV, (2) the incident angle to the cell layer is 82.8 degrees with a standard deviation of 3.2 degrees, (3) the fluence rate is 4.7 x 10(5) cm-2.min-1, (4) the average LET infinity for a cell layer 5 microns thick is 138 keV/micron, (5) the average dose rate for a cell layer 5 microns thick is 0.10 Gy/min., (6) a temperature and CO2 concentration conducive to cell cultivation are maintained during irradiation.  (+info)

Separation techniques for quantification of radionuclides in environmental samples. (7/22)

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Investigation of activation rate uniformity in a prompt-gamma rays IVNAA facility. (8/22)

The preliminary design studies for developing a prompt-gamma rays in vivo neutron activation analysis facility are in construction at Neutron Activation Research Centre of Ferdowsi University of Mashhad. In this work, activation rate distribution is studied in different bilateral configurations in order to reduce the CV of activation rate distribution throughout the body to less than 10%. It means that the maximum RMS deviation from the mean value of distribution must be smaller than 0.5%. The best case includes two pairs of (241)Am-Be neutron sources. Each pair (with 70 cm distance between two sources) is positioned within up and down 40 x 110 cm(2) area graphite collimators. Also, four moderator/reflector objects are added to transversal body surfaces with 5 cm thick water and 3 cm thick graphite. The proper thickness of polyethylene pre-moderators is chosen 8 mm. The RMS deviation of distribution is 0.3% with the mean activation rate of 1.85 x 10(-6) cm(-3).  (+info)

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