Formulae were investigated for predicting the effective dose to children, per unit administered activity of various pediatric radiopharmaceuticals, based only on the weight of the patient. Their influence on the uniformity of effective dose from total administered activity was also examined. Methods: The formulae were obtained from calculations of effective dose per unit administered activity (mSv.MBq(-1)) for five anthropomorphic mathematical phantoms applicable for newborn, 1-yr-, 5-yr-, 10-yr- and 15-yr-old children, having body weights of 3.4, 9.8, 19, 32 and 57 kg, respectively, using published biokinetic models. Results: In general, there was good linear correlation between effective dose per unit administered activity and inverse weight but, for some radiopharmaceuticals, logarithmic regression on weight provided a better fit to the data, An administered activity schedule based on body surface area, used with these formulae, resulted in reasonable uniformity of effective dose for children of all ages, with varying degrees of uniformity for different radiopharmaceuticals (coefficient of variation (COV) up to 20%). Individual activity schedules for separate radiopharmaceuticals gave best uniformity (COV < 7%) while a single general schedule, based on the mean results of the present study, yielded acceptable uniformity (COV less than or equal to 10%) over the pediatric range. Conclusion: Effective dose per unit administered activity (mSv.MBq(-1)) of pediatric radiopharmaceuticals can be predicted from body weight alone by using simple formulae, acid appropriately choosing the administered activity schedule leads to similar values of effective dose for children of all ages from a given radiopharmaceutical procedure.

UNLABELLED After intravenous administration of 99mTc-DMSA, biokinetic data were collected from studies on 24 children aged from 5 wk to 14.8 yr (15 normal and 9 with renal pathology). METHODS Patients were imaged with a gamma camera up to 30 hr postinjection and the absolute activities in the kidneys, liver, spleen, bladder, knees and whole body were estimated using an attenuation-corrected conjugate counting technique. Renal uptake and elimination rates and urinary excretion of radioactivity were also measured. RESULTS In children with normal renal function, maximal kidney uptake was 42.4% +/- 5.4% and was taken up with a half-time of 1.0 +/- 0.2 hr. Renal excretion amounted to 18.0% +/- 4.4% at 24 hr and was lowest in children aged less than 1 yr. In children with abnormal renal function, apart from the expected reduction in renal uptake there was evidence of wider variations in uptake rate and increased urinary excretion. Mean uptakes in liver and spleen were approximately 5% and 2%, respectively, in all patients and uptake in knees, assumed to reside in the metaphyseal growth complexes, was 1.4%. CONCLUSION In children with normal renal function, there was little evidence of age-dependent biokinetic factors other than reduced urinary excretion and lower uptake in knees in children aged less than 1 yr. The results therefore suggest that a single biokinetic model may suffice for radiation dosimetry purposes in normal children irrespective of age.

UNLABELLED:Radiation dosimetry was performed on 24 children (aged 5 wk to 14.8 yr) who were undergoing routine diagnostic investigation of renal impairment with 99mTc-DMSA.METHODS:Organ doses were calculated using MIRDOSE 3 with biokinetic data obtained in previously described studies, and effective doses and effective dose equivalents were estimated. Interpolation by inverse weight between pediatric anthropomorphic phantoms was compared with age-matching to discrete phantoms. Administered activities were scaled by body surface area from the adult activity of 100 MBq and the resulting radiation doses in normal children were compared with those that would have resulted from a schedule based on body weight.RESULTS:The effective doses estimated by interpolation differed by up to 46% from those based on discrete phantoms and showed less variation. In children with normal bilateral renal function, the mean effective dose per administered activity was 0.91 +/- 0.08 mSv or 0.98 +/- 0.29 mSv by the two methods, respectively. Renal pathology reduced the effective dose, on average, by 15% of the value for normal patients.CONCLUSION:Over the pediatric age range, the uniformity of effective dose values was improved by scaling the administered activity according to body surface area rather than to body weight.

The accelerator code Xorbit has an interface to the Experimental Physics and Industrial Control System (EPICS). This means that machine data such as magnet settings can be sent to Xorbit via EPICS, and the resulting orbit parameters such as beta functions, etc., can be calculated. In addition, Xorbit can be made to simulate the real machine, whether the latter is running or not. To accomplish this for the APS, there is a database of process variables in an IOC corresponding to each APS ring and beamline. These process variables are very similar to the real process variables that read and set power supplies and read monitors, except that when a setting is changed, Xorbit is notified via a callback, calculates a new orbit, and outputs the appropriate readbacks to the database. By attaching the string ``Xorbit:`` to a control name the control system will respond to the simulation rather than the real system. This allows the testing of control algorithms, orbit diagnostics, and many other components of the control system (as well as EPICS itself). It is fast enough to be visually similar to accessing the real system.

Following esophagectomy, restoration of swallowing by gastric tube interposition with cervical esophagogastric anastomosis reduces morbidity and mortality associated with intrathoracic anastomoses at the expense of an increased incidence of both anastomotic leak and stricture formation. A retrospective study of 165 patients with either squamous cell carcinoma or adenocarcinoma of the distal esophagus or gastric cardia undergoing esophagogastrectomy with gastric tube interposition and cervical anastomosis at Vancouver, British Columbia, or London, Ontario, was undertaken. Forced-entry multiple logistic regression analysis of factors believed to influence anastomotic outcome was performed. Anastomotic leak occurred in 17% of patients; statistically significant correlation with low preoperative serum albumin (p = 0.005), running suture technique (p = 0.029), high intraoperative blood loss (p = 0.038), and the occurrence of postoperative delayed gastric emptying (p = 0.045) was found. Anastomotic strictures occurred in 31% of patients; a statistically significant correlation was found with preceding anastomotic leak (p = 0.001) and intraoperative blood loss (p = 0.042). Factors including preoperative radiotherapy and diabetes mellitus were not found to be significant.

The ARIES research program is a multi-institutional effort to develop several visions of tokamak reactors with enhanced economic, safety, and environmental features. Three ARIES visions are currently planned for the ARIES program. The ARIES-I design is a DT-burning reactor based on modest extrapolation from the present tokamak physics data base; ARIES-II is a DT-burning reactor which will employ potential advances in physics; and ARIES-III is a conceptual D-3He reactor. The first design to be completed is ARIES-I, a 1000 MWe power reactor. The key features of ARIES-I are: (1) a passively safe and low environmental impact design because of choice of low activation material throughout the fusion power core, (2) an acceptable cost of electricity, (3) a plasma with performance as close as possible to present-day experimental achievements, (4) a high performance, low activation, SiC composite blanket cooled by He, and (5) an advanced Rankine power cycle as planned for near term coal-fired plants. The ARIES-I research has also identified key physics and technology areas with the highest leverage for achieving attractive fusion power system.

Dynamic renal scintigraphy using technetium-99m mercaptoacetylglycylglycylglycine (MAG3) has been described in adults, and clearance values have been established using multiple plasma samples. This study of renal clearance has compared two fundamentally different gamma camera techniques (both of which require a single blood sample) with the multiple blood sampling technique in children (n = 30). Results show that a 40-min dynamic 99mTc-MAG3 renal scintigram coupled with a single plasma sample will allow analysis of the data so that clearance values, which are similar to those from multiple plasma samples, may be calculated. The curve generated from the cardiac region of interest (ROI) provided clearances values that had a high correlation coefficient (0.939-0.951) compared to the multiple-plasma sample technique immaterial of the timing of the blood sample. The renal uptake method of clearance had a lower correlation coefficient (0.89-0.92), which varied with the timing of the blood sample compared to the multiple-plasma sampling technique. This study has demonstrated that an extended gamma camera acquisition coupled with a single-plasma sample may be used for quantitative renal function studies using 99mTc-MAG3.

The Advanced Reactor Innovation and Evaluation Study (ARIES) is a community effort to develop several visions of the tokamak as a fusion power reactor. The aims are to determine its potential economics, safety, and environmental features and to identify physics and technology areas with the highest leverage for achieving the best tokamak reactor. The authors focus on the ARIES-1 design. Parametric systems studies show that the optimum first stability tokamak has relatively low plasma current ( approximately 12 MA), high plasma aspect ratio ( approximately 4-6), and high magnetic field ( approximately 24 T at the coil). ARIES-I is a 1000-MWe (net) reactor with a plasma major radius of 6.5 m, a minor radius of 1.4 m, a neutron wall loading of about 2.8 MW/m/sup 2/, and a mass power density of about 90 kWe/tonne. The ARIES-I reactor operates at steady state using ICRF (ion-cyclotron range of frequency) fast waves to drive current in the plasma core and lower-hybrid waves for edge-plasma current drive. The ARIES-I blanket is cooled by He and consists of SiC-composite structural material, Li/sub 4/SiO/sub 4/ solid breeder, and Be neutron multiplier, all chosen for their low-activation and low-decay after-heat in order to enhance the safety and environmental features of the design. The ARIES-I design has a competitive cost of electricity and superior safety and environmental features.<>

The requirements of (1) an external poloidal-field coil (PFC) system with minimum stored energy, (2) double-null divertor plasmas with elongated D shape, (3) adequate passive stabilization of plasma vertical displacement by a vacuum vessel located behind the blanket zone, and (4) an enhanced plasma beta limit in the first stability regime are incorporated in the Advanced Reactor Innovation and Evaluation Study-I (ARIES-I) concept for a high-field tokamak reactor with high aspect ratio (A=4.5). The plasma current and pressure profiles are also made consistent with enhanced bootstrap current and reduced current drive power by means of ion cyclotron wave or neutral beam injection. These lead to plasmas characterized by an elongation of 1.8 to the divertor X-point, a triangularity of 0.7, a safety factor of ~1.5, a safety factor at the edge >4, a plasma beta of ~2%, and a poloidal beta of ~0.5. With a plasma current of 11 MA, a toroidal field of 13 T at the major radius of 6.5 m, and over 3.5 m of clearance between the PFCs and the plasma edge, the stored energy in the PFC system ranges from 20 GJ during plasma operation at low beta, to 12 GJ during plasma operation at high beta

Critical factors determining the renal handling of 99mTc-dimercaptosuccinic acid (DMSA) are protein binding in plasma and the renal 99mTc-DMSA extraction efficiency. Comparison of the count rate over soft tissue with that over the cardiac blood pool about 1 h after injection demonstrated that 99mTc-DMSA is not exclusively an intravascular label. 99mTc-DMSA was 76% protein bound in plasma as demonstrated by HPLC and gel filtration. Assuming that the 24% that is not protein bound is filtered at the glomerulus, the renal extraction efficiency of 99mTc-DMSA by glomerular filtration is about 5%. Since the total renal extraction efficiency was also found to be about 5%, the majority of the activity that becomes fixed in the renal cortex arrives there as a result of filtration followed by tubular reabsorption rather than by direct extraction from peritubular blood. However, discordant changes in DMSA and DTPA uptake induced by captopril in renovascular hypertension (RVH) suggested that a minority of uptake was by direct peritubular extraction.

MIBG is generating considerable interest for the treatment of neuroblastoma. This study has investigated the biological variation in handling of the compound in children with neuroblastoma. The biodistribution of the compound has been characterised in children undergoing tracer administrations of 123I and 131I-mIBG. Estimates of hepatic and whole body radiation dose delivery have been made. The results indicate substantial interpatient variation in hepatic dose delivery. This organ may be critical in some patients undergoing targeted radiotherapy with mIBG.

Critical factors determining the renal handling of 99mTc-dimercaptosuccinic acid (DMSA) are protein binding in plasma and the renal 99mTc-DMSA extraction efficiency. Comparison of the count rate over soft tissue with that over the cardiac blood pool about 1 h after injection demonstrated that 99mTc-DMSA is not exclusively an intravascular label. 99mTc-DMSA was 76% protein bound in plasma as demonstrated by HPLC and gel filtration. Assuming that the 24% that is not protein bound is filtered at the glomerulus, the renal extraction efficiency of 99mTc-DMSA by glomerular filtration is about 5%. Since the total renal extraction efficiency was also found to be about 5%, the majority of the activity that becomes fixed in the renal cortex arrives there as a result of filtration followed by tubular reabsorption rather than by direct extraction from peritubular blood. However, discordant changes in DMSA and DTPA uptake induced by captopril in renovascular hypertension (RVH) suggested that a minority of uptake was by direct peritubular extraction.

A review of the most important reactions of atomic and molecular hydrogen with the fusion edge plasma electrons and ions is presented. An appropriate characterization of the considered collisions processes useful in plasma edge studies (evaluated cross sections, reaction rates, energy gain/loss per collision, etc.) has been performed. While a complete survey of atomic physics of fusion edge plasmas will be given shortly elsewhere, we demonstrate here the relevance of the atomic collision processes for describing the physical state of edge plasmas and understanding the energy balance in cool divertor plasmas. It is found that the excited neutral species play an important role in the low-temperature, high-density plasmas.

This paper presents the results of Monte Carlo simulations of the neutral particle transport inside the pumped limiters installed on the ISX Tokamak. An overview is given of both the experiment and the computer code, DEGAS, used for the calculations. Two configurations of the limiters are treated in both the pumped and the unpumped modes. A variety of scrape-off densities and temperatures typical of those observed experimentally are considered. A number of quantities of interest are calculated including the fate of the neutralized particles, the particle confinement time in the chamber, and the recycling at the neutralizer plate as well as the neutral densities, temperatures and pressures. The calculated pressures are found to be somewhat larger than those measured. The discrepancy is most probably due to uncertainty in the current of ions to the neutralizer plate. The calculations are limited by the inability to include the changes in the plasma parameters due to the neutral processes and by the 2D nature of the code compared with the definitely 3D nature of the limiters. The results and their significance in the understanding of the limiter behavior are discussed.

A lower hybrid heating system has been designed for heating a tokamak reactor to ignition and for sustaining steady-state operation by driving the toroidal plasma current. The power spectrum from an active/passive waveguide grill is computed, and the resulting equilibrium current density profile is computed from a full electromagnetic WKB analysis of wave propagation in a cylinder. The corresponding toroidal current profile is a low-current equilibrium which is stable to various ideal modes at an economically acceptable beta. The electronic circuitry is designed to minimize the electric power required for current drive, and the resulting design appears to provide reliable operation in a reactor environment. The same system can drive current during reactor startup if some of the waveguides are modified slightly. A typical sequence of startup equilibria is calculated.

STARFIRE is a design for a conceptual commercial tokamak electrical power plant based on the deuterium/tritium/lithium fuel cycle. In addition to the goal of being technologically credible, the design incorporates safety and environmental considerations. STARFIRE is considered to be the tenth in a series of commercial fusion power plants.

The anatomical changes in barley (Hordeum vulgare L.) cv. Esmeralda roots caused by C. galinsogae, collected at 10, 20, and 40 days after plant emergence at Singuilucan, Hidalgo are described. It is a recently described pathogen, whose lessions induced on the host plant are unknown. The histological exam showed the 10-day-old juveniles (J2, J3) in the cortical tissue, breaking of neighbouring cells being observed. At 20 d, the juveniles (J3, J4) were found close to the vascular cylinder. Furthermore, the induction of lateral primordia near the nematode was observed. The feeding sites, small and irregular, covered less than 50% of the vascular cylinder and the cortical tissue, with dissolution of internal, and thickening of external cell walls and with disorganization, displacement, and breaking of xylem and phloem. At 40 d, in the cross sections, syncytia were larger, covering 50 to 60% of the vascular cylinder. At cell level, the changes were similar to those observed at 20 d, besides starch being present in abundance. Mature females were observed in the cortex, surrounded by a layer of cork cambium, and the males appeared bent in the same tissue.