Traditionally, when preparing 99mTc-labeled radiopharmaceuticals, 99mTcpertechnetate is added to the entire contents of a vial of reagent kit, and patient doses are subsequently withdrawn from the ...vial. This technique of compounding can be potentially wasteful for two reasons: (1) once reconstituted with 99mTc, most reagent kits have a relatively short shelf-life, and thus the entire contents may not be used before expiration and (2) due to a need to conserve radioactivity in many hospitals, enough 99mTcpertechnetate is added to the reagent kit in order to retrieve only 1-2 patient doses, even though adequate chemicals (ligand, reducing agent, etc.) are present in the reagent kit to supply as many as 5-10 doses. Hence, a method for optimizing the efficient use of reagent kits would be desirable. The purpose of this study was to determine the feasibility of unit-dosing non-radioactive reagent kits and storing these cold unit doses (CUDs) for eventual labeling with 99mTc. To evaluate this concept, unit doses were prepared from reagent kits of medronate (MDP) and pentetate (DTPA). The specific variables studied in this research were the effects of storage time, storage temperature and reconstitution volume (dilution) on the unit doses. These effects were monitored by measuring the radiochemical and biodistribution properties of the unit doses following their final reconstitution with 99mTcpertechnetate. The labeling efficiency was determined using instant thin layer chromatograph (ITLC), and the biodistribution patterns of these radiolabeled CUDs were studied in mice. The results showed the MDP- and DTPA-CUDs stored at -18 degrees C retained the properties which resulted in acceptable radiochemical purity and biodistribution in mice for as long as 30 days. On the other hand, the radiochemical purity of MDP and DTPA unit doses stored at 25 degrees C deteriorated rapidly. Mean radiochemical purities as low as 0.58-19.4% were observed on day 30. Altered biodistributions were observed in a manner consistent with the decreased labeling efficiencies. The CUDs of lower dilution (3 mL) appeared to be more stable than the CUDs of higher dilution (10 mL). However, the effect of reconstitution volume was much less significant than the temperature effect on the CUDs. In conclusion, the concept of unit-dosing non-radioactive reagent kits appears to provide an efficient and cost-saving method for preparing infrequent and emergency radiopharmaceutical doses. The study also showed that the storage temperature of these unit doses is critical to the success of the procedure. The volume of reconstitution has a minimal impact on the stability of CUDs if stored at the appropriate temperature.
It is commonly recognized that multiple chip module (MCM) packaging offers great advantages in system performance by virtue of the elimination of an entire level of interconnection. Multilayer ...thin-film module technologies for high-performance multiple chip packaging were developed and integrated. The technologies, which feature four copper layers, polyimide dielectric, controlled-impedance transmission lines, and solder bump assembly, were demonstrated on a variety of vehicles including, recently, a 4-kbyte RAM module operating at above 100-MHz clock frequency. The generic MCM substrate technology is described. The process can be designed to be compatible with a number of substrate materials as required for specific applications.< >
A new procedure has been developed for fabricating small-area silicon avalanche diodes directly on a plated copper heat sink. The process incorporates multilayer vapor-phase epitaxially grown silicon ...and a preferential electrochemical etching technique to fabricate thin uniform silicon films; 6 µ thick films on 2-cm diameter wafers have been obtained reproducibly with little difficulty. Inverted mesa diodes 30-40 µ in diameter have been formed by etching through the unmasked area of the thinned silicon wafer. Implementation of this technology has resulted in single drift region p + -n-n + diodes that generate over ¼ W CW power with 6-percent efficiency at 60 GHz.
