Isodose mapping of terrestrial gamma radiation in Sarawak-Borneo: Insights from surface-weathered soil analysis.

Presentation of baseline data on terrestrial gamma radiation (TGR) levels is crucial for assessing the annual effective dose received by the public due to natural radiation exposure. Cumulative doses from various sources can become significant, warranting a spatial understanding of TGR distribution. Few countries have comprehensively mapped TGR on a national scale, often facing challenges due to remote or inaccessible regions. This study investigated the influence of weathered soil groups on TGR dose rates in Sarawak-Borneo, Malaysia, to facilitate insights for TGR projection and isodose mapping. A total of 1044 TGR dose rate measurements were collected using NaI (Tl) scintillation detector survey meters, with a mean of 100 nGy h-1 and a range of 8-375 nGy h-1. Non-parametric statistical analyses of variance using Welch's ANOVA, Brown-Forsythe, and Kruskal-Wallis validated (P-sig.=.000) notable dissimilarities among six categories of superficial-weathered soil. Graphical analysis using Sinclair's cumulative plot revealed deviations at intervals of 50, 80, 100, 120, 175, and 205 nGy h-1. These deviations indicate distinct lithological influences. Skeletal soil (entisols) and podzolic soils had high mean dose rates (148 and 113 nGy h-1, respectively) due to limited development, thus preserving abundant uranium (U) and thorium (Th). Meanwhile, gleysols and thionic soils exhibited compatible means (90 and 82 nGy h-1, respectively), while alluvial (or transported soils) and organic soils displayed lower dose rate ranges (mean of 76 and 47 nGy h-1, respectively), reflecting rapid hydrolysis weathering processes. Simple linear regression analysis revealed a strong relationship between TGR dose rate and mean value of weathered soil groups (y = 0.851x + 0.141 nGy h-1), signifying the significance and magnitude of weathered soil groups' impact on TGR dose rates. The obtained R-value is 0.704, indicating a strong linear correlation among soil group variables, and a Durbin-Watson statistic of 1.41, suggesting positive autocorrelation among residuals, thus positive relationships. An isodose map was successfully developed using the Kriging technique, aligning with lithological features of the study area. Semivariogram analysis reveals spatial dependence within a range of 1.47°, supporting the Kriging technique's suitability for spatial inference. In conclusion, this study has successfully revealed the relationship between TGR dose rates and superficial-weathered soil in Sarawak-Borneo. While the linear relationship is applicable to the Sundaland-Borneo tectonic block, it has potential to be used as a valuable tool for spatial inference of TGR dose rates in isodose development with similar lithologial characteristics, aiding in radiation exposure assessment and environmental monitoring.

Vascular Access in Hemodialysis: Peculiarities in a Low-Income Setting, Pattern, Prevalence and Relationship with Intradialysis Events and Dialysis Dose.

OBJECTIVES: Dialysis vascular access has remained a major determinant of intra and inter-dialytic events and the dialysis dose, and this impacts the quality of life, morbidity and mortality of dialysis patients. Assessing the different access types would help minimize peri-dialytic events and improve outcome. METHODS: This was a retrospective, age and sex-matched, comparative study that assessed dialysis sessions with tunneled dialysis catheters (TDCs) with arteriovenous fistula (AVF). RESULTS: Two hundred and four participants with 1062 sessions were involved. The male participants had 66.7% of all sessions, 60.6% of sessions with TDCs and 87.3% of sessions with AVF, P=0.001. The elderly constituted 23.5% of all participants but 37.7% of sessions with AVF, P=0.04. The percentage of the health-insured was more in sessions with AVF compared to the study population, P<0.001. Diabetics were more likely to use the TDCs, P=0.06. Participants using AVF were more likely to receive full dialysis and erythropoietin treatment, P<0.001. Intradialytic hypotension and dialysis termination were commoner with AVF than TDCs, P=0.03 and P=0.04 respectively. The dialysis dose was higher with AVF than TDCs, P=0.02. Predictors of AVF as dialysis access were male gender, advancing age, health insurance and full treatment compliance. CONCLUSION: There is predominance of venous catheters in our dialysis population. The AVF gave better BP control, fluid and solute clearance, and dialysis dose, and was commoner with males, the health insured and older participants. Intradialytic hypotension was commoner with AVF as IDHT was commoner with TDCs.

OBJECTIFS: L'accès vasculaire à la dialyse reste un déterminant majeur des événements intra et inter-dialytiques et de la dose de dialyse, ce qui a un impact sur la qualité de vie, la morbidité et lamortalité des dialysés. L'évaluation des différents types d'accès permettrait de minimiser les événements péridialytiques et d'améliorer les résultats. MÉTHODES: Il s'agit d'une étude comparative rétrospective, appariée selon l'âge et le sexe, qui a évalué les séances de dialyse avec des cathéters de dialyse tunnellisés (CDT) et des fistules artérioveineuses (FAV). RÉSULTATS: Deux cent quatre participants ont participé à 1 062 séances. Les hommes représentaient 66,7 % de toutes les séances, 60,6 % des séances avec CDT et 87,3 % des séances avec FAV, P=0,001. Les personnes âgées représentaient 23,5 % de l'ensemble des participants, mais 37,7 % des séances avec FVA, P=0,04. Le pourcentage d'assurés sociaux était plus élevé dans les sessions avec AVF que dans la population étudiée, P<0.001. Les diabétiques étaient plus susceptibles d'utiliser les CDT, P=0,06. Les participants utilisant la FVA étaient plus susceptibles de recevoir une dialyse complète et un traitement à l'érythropoïétine, P<0,001. L'hypotension intradialytique et l'arrêt de la dialyse étaient plus fréquents avec l'AVF qu'avec les CDT, P=0,03 et P=0,04. La dose de dialyse était plus élevée en cas de FVA qu'en cas de CDT, P=0,02. Les facteurs prédictifs de l'utilisation de la FVA comme accès à la dialyse étaient le sexe masculin, l'âge avancé, l'assurance maladie et l'observance totale du traitement. CONCLUSION: Il y a une prédominance des cathéters veineux dans notre population de dialysés. Le FVA permet un meilleur contrôle de la PA, de la clairance des fluides et des solutés et de la dose de dialyse, et il est plus fréquent chez les hommes, les assurés sociaux et les participants plus âgés. L'hypotension intradialytique était plus fréquente avec le FVA que l'IDHT était plus fréquente avec les CDT. Mots-clés: Cathéters veineux centraux, fistule artério-veineuse, veine jugulaire interne tunnellisée.

Tabulation of organ dose conversion factors for terrestrial radioactivity monitoring program.

Terrestrial radioactivity monitoring of 238U and 232Th series, and 40K in soil is an essential practice for radioactivity and radiation measurement of a place. In conventional practice, only basic data can be in-situ measured using a survey instrument, for example radioactivity concentration in soil and ambient dose equivalent rate. For other physical quantities, for example organ absorbed dose and organ equivalent dose, the measurement is impossible to be performed and can only be computed using Monte Carlo radiation transport simulations. In the past, most of the works only focused on calculating air-kerma-to-effective dose conversion factors. However, the information on organ dose conversion factors is scarcely documented and reported. This study was conducted to calculate organ absorbed and tissue-weighted equivalent dose conversion factors as a result of exposure from terrestrial gamma radiation. Series of organ dose conversion factors is produced based on computations from Monte Carlo MCNP5 simulations using modelled gamma irradiation geometry and established adult MIRD phantom. The study found out that most of the radiation exposed organs absorb energy at comparable rates, except for dense and superficial tissues i.e., skeleton and skin, which indicated slightly higher values. The good agreement between this work and previous studies demonstrated that our gamma irradiation geometry and modelling of gamma radiation sources are adequate. Therefore, the proposed organ dose conversion factors from this study are reasonably acceptable for dose estimation in environmental radioactivity monitoring practices.

Radiological hazard associated with amang processing industry in Peninsular Malaysia and its environmental impacts.

Continuous depletion in tin productions has led to a newly emerging industry that is a tin by-product (amang) processing industry to harness mega tons of tin by-products produced in the past. Amang composed of profitable multi-heavy minerals and rare-earth elements. With poorly established safety and health practices in operating plant, amang poses extremely high radioactivity problem associated with high occupational ionizing radiation exposures to workers and continuously impacting the local environment with radioactive contamination from industrial effluent and solid waste into lithosphere and water bodies. The radioactivity level of 238U and 232Th series in the mineral varies from few hundreds up to ~200,000 and ~400,000 Bq kg-1 respectively and are potential to yield more than ~ 30,000 nGy h-1 of gamma (γ) radiation exposure to plant workers. The study found out that for 8 h of work time, a worker is estimated to receive an average effective dose of 0.1 mSv per day from external γ radiation source with a maximum up to 2 mSv per day for extreme exposure situation. Interferences of different exposure routes for examples inhalation of equivalent equilibrium concentration (ECC) of 222Rn and 220Rn progenies and airborne long-lived α particles from the dusty working environment could pose a higher total effective dose as much as 5 mSv per day and 115 mSv per year. The value is 5 times higher than the annual dose limit for designated radiation worker (20 mSv) in Peninsular Malaysia. The study found that 41% of the total received an effective dose received by a worker is contributed by 222Rn, 32% of airborne particulates and dust, 23% from external γ exposure and 4% from 220Rn. Based on radioecological risk assessment, the study found out that the aquatic environment is the highly exposed group to ionizing radiation from industrial effluent discharge and sand residues. With the impotent establishment of radiation protection in the industry, plus the country newly introduced long-term plan to revive tin mining as well as its accessory amang mineral, it is necessary for the government to harmonize current regulation to improve the worker safety and health as well as sustaining local environment.

Assessment of impact of urbanisation on background radiation exposure and human health risk estimation in Kuala Lumpur, Malaysia.

Kuala Lumpur has been undergoing rapid urbanisation process, mainly in infrastructure development. The opening of new township and residential in former tin mining areas, particularly in the heavy mineral- or tin-bearing alluvial soil in Kuala Lumpur, is a contentious subject in land-use regulation. Construction practices, i.e. reclamation and dredging in these areas are potential to enhance the radioactivity levels of soil and subsequently, increase the existing background gamma radiation levels. This situation is worsened with the utilisation of tin tailings as construction materials apart from unavoidable soil pollutions due to naturally occurring radioactive materials in construction materials, e.g. granitic aggregate, cement and red clay brick. This study was conducted to assess the urbanisation impacts on background gamma radiation in Kuala Lumpur. The study found that the mean value of measured dose rate was 251±6nGyh-1 (156-392nGyh-1) and 4 times higher than the world average value. High radioactivity levels of 238U (95±12Bqkg-1), 232Th (191±23Bqkg-1,) and 40K (727±130Bqkg-1) in soil were identified as the major source of high radiation exposure. Based on statistical ANOVA, t-test, and analyses of cumulative probability distribution, this study has statistically verified the dose enhancements in the background radiation. The effective dose was estimated to be 0.31±0.01mSvy-1 per man. The recommended ICRP reference level (1-20mSvy-1) is applicable to the involved existing exposure situation in this study. The estimated effective dose in this study is lower than the ICRP reference level and too low to cause deterministic radiation effects. Nevertheless based on estimations of lifetime radiation exposure risks, this study found that there was small probability for individual in Kuala Lumpur being diagnosed with cancer and dying of cancer.

Video-assisted thoracic surgery in a Nigerian teaching hospital: Experience and challenges.

BACKGROUND: Video-assisted thoracic surgery (VATS) is well established. Its application in Nigeria has however been limited and not been reported. The aim of this study was to describe our institutional experience and challenges with VATS. MATERIALS AND METHODS: This was a retrospective cross-sectional study of all patients that underwent VATS in our institution between March 2008 and June 2013. Data were extracted from a prospectively maintained database. RESULTS: Two hundred and sixty-one patients were assessed as potential VATS cases. VATS was initiated in 26 patients, but completed in 25 patients (9.6%) as there was one case of conversion of a planned VATS bullectomy due to the failure of one lung ventilation. There were 12 males and 13 females. Mean age was 40.7 ± 13.9 years. The indication was interstitial lung disease in 9 patients (36%), malignant pleural effusion in 6 patients (24%), spontaneous pneumothorax in 5 patients (20%), indeterminate pulmonary nodule in 2 patients (8%), pleural endometriosis in 2 patients (8%) and bronchogenic cyst in one patient (4%). Procedures performed were lung biopsy in 13 patients (52%), pleural biopsy and pleurodesis in 6 patients (24%), bullectomy and pleurodesis in 5 patients (20%) and excision of bronchogenic cyst in one patient (4%). Mean hospital stay was 4 ± 0.7 days. There were no complications and no mortalities. CONCLUSION: VATS is being performed in our institution with successful outcomes. The use of VATS in Nigeria is encouraged. The relatively high cost of VATS is, however, a major limitation to more widespread use.

Predicting terrestrial gamma dose rate based on geological and soil information: case study of Perak state, Malaysia.

An extensive terrestrial gamma radiation dose (TGRD) rate survey has been conducted in Perak State, Peninsular Malaysia. The survey has been carried out taking into account geological and soil information, involving 2930 in situ surveys. Based on geological and soil information collected during TGRD rate measurements, TGRD rates have been predicted in Perak State using a statistical regression analysis which would be helpful to focus surveys in areas that are difficult to access. An equation was formulated according to a linear relationship between TGRD rates, geological contexts and soil types. The comparison of in situ measurements and predicted TGRD dose rates was tabulated and showed good agreement with the linear regression equation. The TGRD rates in the study area ranged from 38 nGy h(-1) to 1039 nGy h(-1) with a mean value of 224 ± 138 nGy h(-1). This value is higher than the world average as reported in UNSCEAR 2000. The TGRD rates contribute an average dose rate of 1.37 mSv per year. An isodose map for the study area was developed using a Kriging method based on predicted and in situ TGRD rate values.

One lung ventilation using double-lumen tubes: Initial experience from Lagos, Nigeria.

BACKGROUND: One lung ventilation (OLV) is a technique routinely used in thoracic anesthesia to facilitate thoracic surgery. Double-lumen tubes (DLT) remain the most popular and reliable choice for one lung ventilation especially in adult patients though use in Nigeria is limited. This study aimed to describe the experience in our institution with the use of double-lumen tubes for one lung ventilation. MATERIALS AND METHODS: This was a retrospective cross-sectional study conducted on all patients who had double-lumen tube intubations for one lung ventilation between March 2008 and Feb 2013. RESULTS: A total of 55 patients (27 males and 28 females, with a mean age of 39.6 ± 15.7 years) had left double-lumen tube intubations during the period. There were 30 left-sided (54.5%) and 25 right-sided (45.5%) surgical procedures performed. Tube position was verified by flexible bronchoscopy in 50 patients (91.9%) and by chest auscultation in 5 patients (9.1%) with satisfactory collapse in all but one of the procedures. The major surgical indications for one lung ventilation were Video-assisted Thoracic Surgery (VATS) in 22 patients (40%) and Heller's cardiomyotomy in 17 (30.9%). There were no mortalities and all patients had a complete recovery with no sequelae attributable to double-lumen tube use or one lung ventilation. CONCLUSIONS: One lung ventilation is an integral component of modern anesthetic practice. It can be safely practiced in Nigeria with appropriate equipment and expertise. The use of DLT for OLV to enhance thoracic anesthetic practice should be encouraged in other Nigerian institutions.

Isodose mapping of terrestrial gamma radiation dose rate of Selangor state, Kuala Lumpur and Putrajaya, Malaysia.

A terrestrial gamma radiation survey for the state of Selangor, Kuala Lumpur and Putrajaya was conducted to obtain baseline data for environmental radiological health practices. Based on soil type, geological background and information from airborne survey maps, 95 survey points statistically representing the study area were determined. The measured doses varied according to geological background and soil types. They ranged from 17 nGy h(-1) to 500 nGy h(-1). The mean terrestrial gamma dose rate in air above the ground was 182 ± 81 nGy h(-1). This is two times higher than the average dose rate of terrestrial gamma radiation in Malaysia which is 92 nGy h(-1) (UNSCEAR 2000). An isodose map was produced to represent exposure rate from natural sources of terrestrial gamma radiation.

Catenin-dependent cadherin function drives divisional segregation of spinal motor neurons.

Motor neurons that control limb movements are organized as a neuronal nucleus in the developing ventral horn of the spinal cord called the lateral motor column. Neuronal migration segregates motor neurons into distinct lateral and medial divisions within the lateral motor column that project axons to dorsal or ventral limb targets, respectively. This migratory phase is followed by an aggregation phase whereby motor neurons within a division that project to the same muscle cluster together. These later phases of motor neuron organization depend on limb-regulated differential cadherin expression within motor neurons. Initially, all motor neurons display the same cadherin expression profile, which coincides with the migratory phase of motor neuron segregation. Here, we show that this early, pan-motor neuron cadherin function drives the divisional segregation of spinal motor neurons in the chicken embryo by controlling motor neuron migration. We manipulated pan-motor neuron cadherin function through dissociation of cadherin binding to their intracellular partners. We found that of the major intracellular transducers of cadherin signaling, γ-catenin and α-catenin predominate in the lateral motor column. In vivo manipulations that uncouple cadherin-catenin binding disrupt divisional segregation via deficits in motor neuron migration. Additionally, reduction of the expression of cadherin-7, a cadherin predominantly expressed in motor neurons only during their migration, also perturbs divisional segregation. Our results show that γ-catenin-dependent cadherin function is required for spinal motor neuron migration and divisional segregation and suggest a prolonged role for cadherin expression in all phases of motor neuron organization.

Penetrating chest wounds: 24 years experience.

Thoracic and thoracoabdominal penetrating wounds are frequently encountered in urban medical centers in the United States. This study was undertaken to determine the clinical characteristics and in hospital outcome of these injuries. This was a longitudinal, nonblinded study using the established standard of care of patients with penetrating chest trauma. It consists of an analysis of a consecutive series of 3049 patients treated at one trauma center between April 1972 and March 1996. There were 1347 stab wounds and 1702 gunshot wounds. Antibiotic prophylaxis was administered to patients who underwent laparotomy or thoracotomy or who had lung contusion with hemoptysis (41.6%, 1296/3049). Of 3049 patients, 196 had cardiac injuries. All of them underwent thoracotomy, and the mortality was 21.9%. In contrast, among 2853 patients without cardiac injuries, only 257 (9%) required thoracotomy; the mortality in this group was 1.5%. Patients with thoracoabdominal injuries (899/3049) had a mortality of 4.3% compared to 2.1% among those who had isolated chest injuries. The overall mortality was 2.8%. Of 1702 patients with gunshot wounds, 85 (5%) sustained transaxial injuries, with an overall mortality of 36.5%. The complication rate among the survivors was 6% with only 2.5% being infectious. We conclude that the mortality for noncardiac penetrating injuries of the chest is low. The presence of associated abdominal injuries increases the mortality twofold. More than one-third of the patients with transaxial wounds die. Gunshot wounds of the heart result in higher mortality than stab wounds to the heart. The infection rate is low.