PubMed · 10111160
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J Charry. 1991. Tech-tips/techni-trucs.. https://pubmed.ncbi.nlm.nih.gov/10111160/
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A prototype miniature neutron source reactor (MNSR) with a thermal neutron flux of 3.0 x 10(11) n cm(-2) s(-1) has been used to determine the concentrations of some nutrient elements leading to short-lived activation products in commercial tea leaf samples from Nigeria. A total of eight elements Al, Ca, Cl, Cu, K, Mg, Mn and Na, that can be routinely used for quality control purposes, were analyzed in this study. Two biological reference materials, tomato leaves (NIST-1573) and citrus leaves (NIST-1572) were used as the standard and quality control materials, respectively. The analytical results show that the average concentrations of Al, Ca, Cl, Cu, K, Mg, Mn and Na in Nigerian tea are slightly higher when compared with a Chinese herbal tea analyzed in this study. The concentration ratios of K/Ca were found to be high in all the samples analyzed suggesting cultivation in potash-rich soils.
OBJECTIVE: The purpose of this study was to investigate if an octadecyl (18C) minicolumn could be applied successfully for quality control of 99mTc exametazime (HMPAO). METHODS: The 18C column system using saline eluent was validated against the Whatman 17 method in calculating the percent radiochemical purity of 99mTc-HMPAO. The behavior of 99mTc-pertechnetate (99mTc04-) and hydrolyzed-reduced 99mTc (99mTc02) on the column was examined, as well as method reproducibility. RESULTS: The column method is reproducible and yields results that are highly comparable to the Whatman 17 method. Technetium-99m-pertechnetate is associated with the eluent, and some 99mTc02 is retained by the column but this level is insignificant to the final patient dose. CONCLUSION: The minicolumn system is safe, simple, rapid and reliable for the quality control analysis of routine 99mTCHMPAO preparations.
Linac-based radiosurgery has many advantages over the gamma knife, including low initial cost and no need of source replacement. On the other hand, most of the medical linacs currently in use were not originally designed to be applied for radiosurgery, and, therefore, careful quality assurance programs are required. In the gantry-head of a linac, a small CCD video camera is mounted in a position optically identical to that of the x-ray source. The video signal from the camera was digitalized to be evaluated for geometrical errors. A metal ball fixed to the stereotactic base frame via XYZ-sliding rods was used as a simulated target. Displacements of the target from the isocenter were measured during rotation of the gantry. Displacements in the gantry-rotation plane were satisfactorily small, while those perpendicular to it were maximal at gantry position angles of 0 degree and 180 degrees. This error night be caused by gravitational vending of the heavy gantry head. Although other major errors of the linac were within one millimeter, the center of coach rotation around the isocenter did not coincide with the center of gantry rotation, probably owing to gravitational vending. Special care should be taken when very small collimators are employed.