Chien-Yi Chen

Seroprevalence of Helicobacter pylori infection among schoolchildren and teachers in Taiwan.

Background:  Helicobacter pylori are associated with chronic antral gastritis that is related to duodenal ulcer, gastric ulcer, and probably gastric adenocarcinoma. Infection of H. pylori during childhood is considered an important risk factor for gastric carcinoma in adult life.

Optimizing the TLD-100 readout system for various radiotherapy beam doses using the Taguchi methodology

The TLD-100 readout system was optimized for various radiotherapy beam doses using the Taguchi method. The radiotherapy beam was produced by a Varian 21EX linear accelerator (LINAC) at 6MV. The beam doses were 50, 100 and 150cGy, and the measured data in each group were averaged from three TLD-100 chips. A total of nine combinations of four parameters were arranged, in the manner suggested by Taguchi. The four parameters were defined as initial temperature, heating rate, preheat time and maximum set temperature of the readout system during TLD reading. The loss function eta adopted herein was specifically defined to satisfy the requirements of both sharp linearity and good reproducibility of the TLD reading at various radiotherapy beam doses. The optimized values were: (1) 50( composite function)C for initial temperature, (2) 3 (degrees C)/s for heating rate, (3) 5 min for the TLD preheat time and (4) 250 degrees C for the maximum temperature for TLD reading. Additionally, the parameters that dominated the TLD readout were: (1) initial temperature, (2) heating rate and (4) maximum temperature setting for TLD reading; and the minor parameter was (3) TLD preheat time before reading. The interactions among the dominant parameters were also studied: no significant cross interaction occurred between initial temperature and heating rate or between initial temperature and maximum temperature. However, a complex cross-interaction existed between optimal heating rate and maximum temperature.

Trace elements of Taiwanese dioscorea spp. using instrumental neutron activation analysis

Abstract Twenty-two varieties categorized into six distinct species of dioscorea spp. had their concentration of trace elements evaluated by instrumental neutron activation analysis. The various dioscoreas were planted in the same plantation area to effectively suppress the diversity from different planted land, thus, the disagreement between each trace element was concluded from the nature of various species of dioscoreas themselves. Nineteen trace elements were verified and a quantified index, AT, was introduced to help classify the elements. A smaller AT indicated a close consistency of the concentration for specific trace element in various dioscorea . Thus, K, Zn, and Rb were in Group 1, which had the minimum ATs, Cl, Na, Mg, Fe, Mn, Br, and Co were in Group 2, which had the medium ATs, while the remaining of the trace elements, V, As, Sb, Cu, Se, Al, La, Sc, and Sm were all in Group 3, which had the maximum ATs. The different ATs and various species of dioscorea s were also discussed.

Seroepidemiology of hepatitis A virus infection among schoolchildren in Taiwan

Taiwan was a hyperendemic area for hepatitis A virus (HAV) infection before 1980. The aim of this study was to examine the association between seropositivity of antibodies against HAV (anti‐HAV) by a community‐based survey. School children from 10 elementary and 3 junior high schools, as well as staff members who worked at the above schools in central Taiwan were selected at random in this study. Anti‐HAV was tested in sera of 1,954 healthy schoolchildren (aged 7–15 years old) and 254 teachers by enzyme‐linked immunosorbent assay. Schoolchildren had a low prevalence of anti‐HAV (2.3%) in contrast to the high seroprevalence in their teachers (52%). The seropositive rates of HAV antibody among the study subjects were increasing with age. No significant differences of anti‐HAV seroprevalence among the study subjects were observed when they were stratified by gender, geographical area, household members, and parental education. Whereas, the anti‐HAV seroprevalence was significantly higher in schoolchildren who were either aboriginal or living in areas without a supply of drinking tap‐water. The seroprevalence of HAV data among the healthy pediatric population would be helpful to evaluate the need for mass vaccination policies. J. Med. Virol. 83:196–200, 2011.

Bromine and iodine in Chinese medical herbs determined via epithermal neutron activation analysis

Nineteen natural herbs and two prescriptions prepared from mixed herbs were analyzed via epithermal neutron activation analysis (ENAA) to evaluate their bromine and iodine concentration. Traditional medical doctors prescribed the samples presented in this work to most Taiwanese children for strengthening their immune systems. Empirical results indicated a wide diversity of bromine in the samples. Yet, the iodine concentration was only around one to tenth or twentieth of the bromine. The maximum daily intake (MDI) for various medical herbs was also widely diversified from one to tenfold on the basis of various criteria. The minimum detectable concentration (MDC) of bromine and iodine found was 0.42±0.14 ppm and 0.067±0.016 ppm, respectively. Compared to that from conventional thermal neutron activation analysis (NAA) for a similar evaluation, the extremely low MDC obtained here was attributed to the large amount of thermal neutron absorption during sample irradiation.

Distribution of spatial photoneutrons inside a 70 kg water phantom via neutron activation analysis

This study evaluated spatial Phi(th) inside a 70kg water phantom using the NAA method. Fifty indium foils were placed inside the water phantom and exposed under 15MV LINAC for 2.5min to yield the 10Gy X-ray dose. The Phi(th) value at the isocenter of the water was 1.03x10(6)ncm(-2)/Gy-X, and the maximum quantity of Phi(th) appeared at the water surface along the z-axis, 3.99x10(6)ncm(-2)/Gy-X. The thermal neutron dose at isocenter of the water phantom occupied approximately 0.151% of the whole photo and neutron dose.

Evaluation of effective dose for a patient under Ga-67 nuclear examination using TLD, water phantom and a simplified model

This study evaluated the effective dose of Ga-67 for a patient undergoing Ga-67 citrate nuclear examination by applying thermoluminescent dosimeter (TLD) technique and an indigenous water phantom. The Ga-67 radionuclide remaining in the body inevitably generated a measurable internal dose even though gamma camera scanning took only minutes to complete the clinical examination. For effective simulation of the cumulated effective dose for a patient undergoing examination, 150 TLDs were placed inside the water phantom for 6 days to monitor the gamma ray dose from the distributed Ga-67 citrate solution. The inserted TLDs represented internal organs, and the effective dose was calculated according to data in the ICRP-60 report. The water phantom was designed to model the body of a healthy human weighing 70 kg, and the water that was mixed with Ga-67 citrate solution was slowly replaced with fresh feed water to yield the required biological half life of the phantom. After continuously feeding in fresh water throughout the 6 days of TLD exposure, the TLDs were analyzed to determine the effective doses from the various biological half lives of the phantom. The derived effective dose of 185 MBq Ga-67 citrate solution for male/female (M/F) was 10.7/12.2, 10.7/12.0, 8.7/9.9 and 6.0/6.8 mSv, of biological half lives of 6.0, 4.5, 3.0 and 1.5 days, respectively. Although these experimental results correlated well with earlier empirical studies, they were lower than most calculated values. The cumulated uncertainty in the effective dose was 12.5–19.4%, which was acceptable in terms of both TLD counting statistic and reproducibility.

Pediatric Reference Intervals for Several Biochemical Analytes in School Children in Central Taiwan

BACKGROUND/PURPOSE Reference intervals of biochemical tests for screening for diabetes mellitus and liver and renal function among school children in Central Taiwan have never been documented. Therefore, this study aimed to establish the reference intervals for the above mentioned biochemical tests for pediatric populations. METHODS A total of 4326 subjects, including 2029 kindergarten children, 1624 elementary-school children, 325 junior-high-school children, and 348 teachers were selected randomly in Central Taiwan. All serum alanine aminotransferase (ALT), blood urea nitrogen (BUN), creatinine (Cr) and glucose levels were determined using a Beckman Synchron CX5 analyzer. The reference intervals reflected estimates of the 2.5th-97.5th percentiles of non-parametric distributions. RESULTS Adults had significantly higher biochemical analyte values [except for BUN/creatinine (B/C) ratio] than children had. Multiple logistic regression analysis showed that biochemical analyte values were significantly higher in male than in female subjects. The concentrations of glucose and Cr increased with age. On the contrary, the B/C ratio decreased with age. CONCLUSION Our study provides new pediatric reference intervals (2.5th-97.5th percentiles) of 60-99 mg/dL for serum glucose concentrations, 8-38 IU/L for ALT, 0.4-1.1 mg/L for Cr, 8.7-18.0 mg/L for BUN, and 10-34 for B/C ratio. The B/C ratio in children was higher than those of adults, possibly due to that children had a higher intake of protein.

Biodistribution and Dosimetry of 131I in Thyroidectomy Patients Using Semiquantitative γ-Camera Imaging

The aim of this study was to determine the biodistribution, effective retention half-time (T(eff)), and internal organ dosimetry of (131)I administered to patients with papillary thyroid cancer after a total or near total thyroidectomy, and whole-body and organ activity was measured by gamma-camera imaging at 16 time points over 5 days following the administration of 1.1 GBq of (131)I in 5 patients. Whole-body scanning was performed by using a Siemens E-CAM() gamma-camera at a fixed distance of 5 cm from the patient. (131)I activity in regions of interest (ROIs) corresponding to the bladder, heart wall, kidneys, liver, lower gastrointestinal tract, lung, stomach, and thyroid remnants were measured, with measurements in the thigh used as the background. Most activity was localized to the lower gastrointestinal tract and thyroid remnants on day 1. The longest T(eff) was in the lung and the shortest was in the bladder (34.0 and 16.8 hours, respectively). The three organs with the highest absorbed doses per unit of administered activity were the lower gastrointestinal tract (2.03 mSv/MBq), the stomach (1.32 mSv/MBq), and the heart wall (1.24 mSv/MBq). T(eff) for thyroid remnants and the whole body were also estimated. We evaluated these organ doses to determine the normal tissues most likely at risk for stochastic and deterministic effects associated with (131)I therapy for thyroid cancer and benign disease. Our results represent preliminary findings, and the study will continue to accrue a greater number of study participants.

Optimal conditions for identifying 80Br and 128I in health food Angelica keiskei using rapid epithermal neutron activation analysis.

This study presents an optimal rapid epithermal neutron activation analysis (ENAA) technique, using a 1mm Cd filter in reactor neutron flux, to analyze 80Br and 128I in the roots, stems, and leaves of health food Angelica keiskei (AK). Various sample weights of lichen (IAEA-336) for each portion of AK, under various periods of irradiation and counting, were used to optimize the elemental analysis. Selecting the analytical conditions depends on the minimum detectable concentration (MDC), required sensitivities and the quantitative accuracy of Br and I elements. These findings imply that the MDCs of Br and I, measured under 10min activation and 5min counting followed by 10min decaying, using 350mg of lichen are ideal for elemental analysis. Moreover, each portions of AK were analyzed under optimal conditions. The elemental concentrations of Br, Cl, I, Mg, Mn and Na and their implications are discussed.