New technology for transmission measurements in process pipes.

Transmission measurements of radiation through process pipes provide a non-intrusive method of determining the amount of product present in the pipes. The product could be a liquid, a slurry, or a gas, which is the most challenging because of the low density. Traditionally, these techniques have used a radioactive source that has to be replaced periodically. We have developed a transmission technique based on an X-ray tube instead of a decaying source. A notch filter is used to provide a narrow transmission line, and a thin silicon transmission detector is used to monitor the X-ray tube output. The transmitted X-rays are measured with a high-throughput gamma spectrometer that consists of a NaI(Tl) detector and an MCA with precise dead time correction. This spectrometer provides stable transmission measurements with an accuracy of a fraction of a percent. The shielding and collimator are made of machinable tungsten for thermal mechanical stability, as well low-cost, low-weight tungsten powder in polymer castings. We describe two methods of measuring the pipe wall thickness without evacuating the pipe. Our particular application was for enrichment monitors for UF(6) in process pipes. Enrichment monitors that are independent of the plant data require two measurements: a transmission measurement to determine the total amount of uranium in the pipe and a measurement of the 186-keV gamma-ray line to determine the amount of (235)U present. The ratio of these values gives the enrichment. Previous designs used a decaying radioactive source such as (57)Co (122 keV, T(½)=272 days) or (109)Cd (22 keV, T(½)=1.2 years). A major effort was required to access and periodically replace these sources in operating plants. In this report, we describe the use of an X-ray tube, which eliminated the source problem, and other innovations. Then we present data from an enrichment monitor that incorporates these innovations.

Somatostatin receptor 5 and cannabinoid receptor 1 activation inhibit secretion of glucose-dependent insulinotropic polypeptide from intestinal K cells in rodents.

AIMS/HYPOTHESIS: Glucose-dependent insulinotropic polypeptide (GIP) is an enteroendocrine hormone that promotes storage of glucose and fat. Its secretion from intestinal K cells is triggered by nutrient ingestion and is modulated by intracellular cAMP. In view of the proadipogenic actions of GIP, this study aimed to identify pathways in K cells that lower cAMP levels and GIP secretion. METHODS: Murine K cells purified by flow cytometry were analysed for expression of G(αi)-coupled receptors by transcriptomic microarrays. Somatostatin and cannabinoid receptor expression was confirmed by quantitative RT-PCR. Hormone secretion in vitro was measured in GLUTag and primary murine intestinal cultures. cAMP was monitored in GLUTag cells using the genetically encoded sensor Epac2-camps. In vivo tolerance tests were performed in cannulated rats. RESULTS: Purified murine K cells expressed high mRNA levels for somatostatin receptors (Sstrs) Sstr2, Sstr3 and Sstr5, and cannabinoid receptor type 1 (Cnr1, CB1). Somatostatin inhibited GIP and glucagon-like peptide-1 (GLP-1) secretion from primary small intestinal cultures, in part through SSTR5, and reduced cAMP generation in GLUTag cells. Although the CB1 agonist methanandamide (mAEA) inhibited GIP secretion, no significant effect was observed on GLP-1 secretion from primary cultures. In cannulated rats, treatment with mAEA prior to an oral glucose tolerance test suppressed plasma GIP but not GLP-1 levels, whereas the CB1 antagonist AM251 elevated basal GIP concentrations. CONCLUSIONS/INTERPRETATION: GIP release is inhibited by somatostatin and CB1 agonists. The differential effects of CB1 ligands on GIP and GLP-1 release may provide a new tool to dissociate secretion of these incretin hormones and lower GIP but not GLP-1 levels in vivo.

Amputation neuroma of the great auricular nerve after operations on the parotid gland.

We found an incidence of 6% (5/81) of traumatic neuroma after section of the great auricular nerve during operations on the parotid gland. Excision permits definitive diagnosis, the stump being allowed to retract beneath the belly of the sternomastoid muscle. However, excision is not always indicated, and the diagnosis can be made clinically allowing for a more conservative treatment policy.

Trans rectal ultrasound guided radioactive seed implant: the Sumter experience.

108 patients were treated between 1/06/97 and 7/19/99. Ages ranged from 53 years to 82 years. Pretreatment PSA ranged from 4.0 to 34.6 and post treatment PSA from 0 to 7.3. Given the fact that carcinoma of the prostate is a relatively slow growing tumor and that long survival times are not uncommon even in the face of relatively advanced disease, our treatment team believes that the preferred method of treatment in otherwise healthy patients who have a 20 year life expectancy is radical surgery. We do believe that brachytherapy has a role in the treatment of organ-confined disease and may possibly be proven to be as effective as surgery; however, until there is at least 15-year data, it cannot be considered as the primary treatment of choice in young men. The senior author has stressed the term "treatment team" in this paper for a reason. We sincerely believe that the best results for our patients are obtained when we approach the treatment of the patient as a unified team that makes use of our individual talents and training for the good of the patient as a whole. Each member of the team performs the procedures that he is best trained to do, and we are consistent in our approach and advice to our patients regardless of our disciplines.

Lingual access for third molar surgery: a 20-year retrospective audit.

We describe a technique for obtaining lingual access for the insertion of a wide metal retractor to protect the lingual nerve from accidental damage during third molar surgery. We also report an audit of a single practice over a 20-year period using the technique described. The approach involves raising soft tissues on the lingual side of the lower third molar tooth to allow insertion of a broad Hovell's lingual retractor. We conclude that raising lingual tissues to form a wide tension-free flap and inserting a specifically designed retractor does not increase the incidence of lingual nerve morbidity. Indeed, the overall incidence of lingual nerve damage was particularly low compared with those in other published series.

Safety recommendations for laser pointers.

The use of laser diode pointers that operate in the visible radiation region (400-760 nm) is becoming widespread. These pointers are intended for use by educators while presenting talks in the classroom or at conventions and meetings. They are also useful in any situation where one needs to point out special items during any instructive situation. The pointers can be purchased in novelty stores, mail-order magazines, office supply stores, common electronic stores, and over the internet. The power omitted by these laser pointers ranges from 1 to 5 mW. The potential for hazard with laser pointers is generally considered to be limited to the unprotected eyes of individuals who might be exposed by a direct beam (intrabeam viewing). No skin hazard usually exists. There are, however, even more powerful laser pointers now appearing. The units are imported into the U.S. often without proper manufacturer certification or labeling. The potential for hazards with these devices is not well understood by the general public and workers, and numerous exposure incidents have been recorded by the authors. Users of these products need to be alerted to the potential hazards and be encouraged to follow appropriate safety recommendations. These factors are discussed and safety recommendations for laser pointers are presented.

Induced radioactivity of LDEF materials and structural components.

We present an overview of the Long Duration Exposure Facility (LDEF) induced activation measurements. The LDEF, which was gravity-gradient stabilized, was exposed to the low Earth orbit (LEO) radiation environment over a 5.8 year period. Retrieved activation samples and structural components from the spacecraft were analyzed with low and ultra-low background HPGe gamma spectrometry at several national facilities. This allowed a very sensitive measurement of long-lived radionuclides produced by proton- and neutron-induced reactions in the time-dependent, non-isotropic LEO environment. A summary of major findings from this study is given that consists of directionally dependent activation, depth profiles, thermal neutron activation, and surface beryllium-7 deposition from the upper atmosphere. We also describe a database of these measurements that has been prepared for use in testing radiation environmental models and spacecraft design.

Waldenstrom's macroglobulinemia: search for occupational exposure.

Two cases of Waldenstrom's macroglobulinemia (WM) that occurred in employees from one university academic department were investigated using approaches for both cluster and single case investigation. Common personal characteristics and potential past hazardous exposures were evaluated. The patients shared a young age at diagnosis, worked in the same building, and had similar duration of time between first entering the building and diagnosis of WM. No evidence was found to support the original hypothesis that exposure to radioactive material could be related to the occurrence of WM. Although this investigation did not identify a common causal agent among two cases of a rare disease, investigations of disease clusters may be useful for developing etiologic hypotheses even when a full-scale epidemiologic study is not undertaken. Detailed descriptions of case characteristics can help generate ideas for further research.

Foot currents and ankle SARs induced by dielectric heaters.

Data are presented on ankle-specific SARs and foot currents as a function of strengths of radio-frequency electromagnetic fields encountered by operators of dielectric heaters. The determination of foot currents was based on near-field exposures in which reactive coupling dominates, and which can result in substantial SARs in exposed workers. The operators were located less than one wavelength from--usually within one meter of--the dielectric heaters, which generated fields at frequencies from 6.5 to 65 MHz. At distances normally assumed by workers, maximal strengths of electric fields ranged from 10(4) to 2.4 x 10(6) V2/m2; maximal strengths of magnetic fields ranged from 5.0 x 10(-3) to 33.3 A2/m2. Currents through both feet to ground were measured while operators stood where they normally worked. Maximal currents ranged from 3 to 617 mA, rms. Nearly 27 percent of the dielectric heaters induced foot currents that exceeded the 200-mA limit that has been proposed for a new ANSI C95.1 standard. Twenty percent of the heaters induced foot currents that exceeded 350 mA. SARs in ankles were calculated from foot currents, and they approximated 5 W/kg at 100 mA, 29 W/kg at 250 mA, and 57 W/kg at 350 mA. The maximal SAR in the ankle was approximately 176 W/kg at 617 mA.

Visible-light system for detecting doxorubicin contamination on skin and surfaces.

A portable system that uses fluorescence stimulated by visible light to identify doxorubicin contamination on skin and surfaces was studied. When activated by violet-blue light in the 465-nm range, doxorubicin fluoresces, emitting orange-red light in the 580-nm range. The light source to stimulate fluorescence was a slide projector with a filter to selectively pass short-wave (blue) visible light. Fluorescence was both observed visually with viewing spectacles and photographed. Solutions of doxorubicin in sterile 0.9% sodium chloride injection were prepared in nine standard concentrations ranging from 2 to 0.001 mg/mL. Droplets of each admixture were placed on stainless steel, laboratory coat cloth, pieces of latex examination glove, bench-top absorbent padding, and other materials on which antineoplastics might spill or leak. These materials then were stored for up to eight weeks and photographed weekly. The relative ability of water, household bleach, hydrogen peroxide solution, and soap solution to deactivate doxorubicin was also measured. Finally, this system was used to inspect the antineoplastic-drug preparation and administration areas of three outpatient cancer clinics for doxorubicin contamination. Doxorubicin fluorescence was easily detectable with viewing spectacles when a slide projector was used as the light source. The photographic method was sensitive for doxorubicin concentrations from 2.0 to 0.001 mg/mL. Immersion of study materials in bleach for one minute eliminated detectable fluorescence. Doxorubicin contamination is detectable for at least eight weeks in the ambient environment. Probable doxorubicin contamination was detected in two of the three clinics surveyed. A safe, portable system that uses fluorescence stimulated by visible light is a sensitive method for detecting doxorubicin on skin and surfaces.

Optical radiation hazards of laser welding processes. Part II: CO2 laser.

There has been an extensive growth within the last five years in the use of high-powered lasers in various metalworking processes. The two types of lasers used most frequently for laser welding/cutting processes are the Neodymium-yttrium-aluminum-garnet (Nd:YAG) and the carbon dioxide (CO2) systems. When such lasers are operated in an open beam configuration, they are designated as a Class IV laser system. Class IV lasers are high-powered lasers that may present an eye and skin hazard under most common exposure conditions, either directly or when the beam has been diffusely scattered. Significant control measures are required for unenclosed (open beam), Class IV laser systems since workers may be exposed to scattered or reflected beams during the operation, maintenance, and service of these lasers. In addition to ocular and/or skin exposure hazards, such lasers also may present a multitude of nonlaser beam occupational concerns. Radiant energy measurements are reported for both the scattered laser radiation and the plasma-related plume radiations released during typical high-powered CO2 laser-target interactions. In addition, the application of the nominal hazard zone (NHZ) and other control measures also are discussed with special emphasis on Class IV industrial CO2 laser systems.

Evaluation of a smoke evacuator used for laser surgery.

A preliminary study was conducted to determine the effectiveness of a smoke evacuation system used in laser surgery. A 30 W medical CO2 continuous wave (CW) laser was used to make cuts in a pork chop to simulate smoke production during laser surgery. A commercially available smoke evacuation system was used to control the smoke from the simulated surgery. The smoke concentration was measured at 6 in and at 3 and 4 ft from site of laser interaction. The nozzle of the smoke evacuator was located at distances of 2, 6, and 12 in from the surgical site to measure the relative effectiveness of the control. Complete control of smoke was achieved when the nozzle was located at 2 in, but significant amounts of smoke escaped when the nozzle was located at 6 and 12 in. Suggestions for the use of the smoke evacuation system and areas for further study are given.

Hazard zones and eye protection requirements for a frosted surgical probe used with an Nd:YAG laser.

Detailed radiometric analyses are reported on selected frosted-style laser surgical probes that are in use in laser surgical procedures. These measurements were performed in order to determine their nominal hazard zone (NHZ) and the requirement for protective eyewear. All measurements were conducted under worst-case conditions using a 30-W Nd:YAG laser. The results show that for the style of probe tested, the NHZ can be considered a spherical volume of 1.3 m and will require eye protection devices having a maximum optical density rating of 4.3 at 1.06 microns for all personnel who may come within that range.