Displaying publications 1 - 20 of 95 in total

  1. Mei-Wo Yii, Zal U'yun Wan Mahmood
    Natural radioactivityin thesurface soil from thevicinity of Lynas Rare-earth plantin Kuantan, Pahanghad been studied with aim of evaluating environmental radioacitivityof thatarea. The radioactivities of the samples have been measured usinga low-background HPGe gamma detector. The concentration of 226Ra ranged found to be between 8.7 –76.9 Bq/kg (mean 33.7 Bq/kg); activity of 238U from 8.7 to 80.5 Bq/kg (mean 36.9 Bq/kg); as for 232Th, it ranged from 6.2 to 121.5 Bq/kg(mean 58.2 Bq/kg)and that of 40K,the values was from 19.1 to 778.9 Bq/kg (mean of 221.3 Bq/kg). Activity standard deviation for226Ra, 238U, 232Th and 40K were 14.2 Bq/kg, 14.7 Bq/kg, 26.1 Bq/kg and 185.6 Bq/kg, respectively. To evaluate the risk of radiation hazard to human, several parameters, i.e. the radium equivalent activity, External hazard index, Representative level index and dose rate in air from the terrestrial natural gamma radiation were calculatedwith the mean valuesfound to be136.7 Bq/kg, 0.4, 1.0, 65 nGy/h, respectively. The data were discussed and compared with those obtained from the previous studies given in the literatures. Thisstudy found that themean dose equivalent received by an individual at the vicinity area (outdoor) of Lynas plant was estimated to be 82.0 Sv/yr, whichis far below the annual dose limitof1,000 Sv/yrfor general public as stipulated in the national act.
  2. Noriah Jamal, Humairah Samad Cheung
    The objective of this study was to examine the mammographic breast density of women with breast cancer detected on voluntary mammographic screening at two selected screening centersin Malaysia.This was a retrospective study of Full-Field Digital Mammography(FFDM) images of150 Malaysian women with biopsy-proven breast cancer. The study population comprised 73 Malays(37.7%), 59 Chinese (39.3%) and 18 Indians (12.0%). The Tabár breast density Patterns(I -V) wereused to evaluate mammographic breast density. Data were analyzed using descriptive statistics. The results were compared with findings from a similar study on a group of 668 women who did not have breast cancer.The results showed that 44.7% of the study populationhad dense breasts (Patterns IV and V), 14.7% had predominantly fatty breasts (Patterns II and III) while 40.7% had Pattern I. The proportion of study populationwith dense breasts decreased with age. In conclusion, the proportion of women with dense breasts decreased with age. Majority of the women with cancer (44.7%) had dense breasts of Tabár Patterns IV and V, which has been associated with increased risk of breast cancer detected by voluntary mammographic screening. The results support the notion that increased breast density is a risk factor of breast cancer.
  3. Zal U’yun Wan Mahmood, Mei, Wo Yii, Abdul Kadir Ishak
    This study was performed to observe the variation in the distribution of 210Po,210Pb and 210Po/210Pb activity ratio throughtheir vertical profile of the sediment cores takenat surrounding Sungai Linggi estuary. Five sediment cores were takenin February 2011 and were cutto an intervalof 2 cm layer. Activity concentrations of 210Po and 210Pb were determined using alpha radiochemical analysis and gamma direct measurement, respectively. Generally, the measured activity of 210Po, 210Pb and 210Po/210Pbwere in the ranges of 22.73 –139.06 Bqkg-1dw., 37.88 –176.24 Bqkg-1dw.and 0.23 –1.34, respectively. The variation in the distribution profile for the radionuclides are believed to be influencedby human activities such as agriculture, fertilizer, vehicles, burned fuel fossil and forest, industrialand others via river input from land-base.Other factor is due to organic mattercontent played importantrole as the geochemical carrier to transportthose radionuclides at study area. It was provedthat hasa strong correlation between the radionuclide distribution and the sedimentcomposition of organic matter.Furthermore, in those rangesreflectedthat 210Pb activities were higher than210Po with an activity ratio average of 0.79. This is probably due to dramatic increase of excess 210Pb supplied from atmospheric deposition, in situ decay of 226Ra and as a result of diagenetic remolibilazationof 210Pbin deeper layesof the sediment column. Thus, thosefactors are majorcontributions on thevariation of 210Po and 210Pb in the sediment core at surrounding Sungai Linggi estuary.
  4. Nazaratul Ashifa Abdullah Salim, Roslanzairi Mostapha, Zainon Othman, Nor Afiqah Harun, Mohd Suhaimi Hamzah, Shamsiah Abdul Rahman, et al.
    Stable isotope analysis has widely been used to trace the origin of organic materials in various fields, such as geochemistry, biochemistry, archeology and petroleum. In past a decade, it has also become an important tool for food traceability study. The globalisation of food markets and the relative ease which food commodities are transported through and between countries and continentsmeans that consumers are increasingly concerned about the origin of the foods they eat. The natural abundance of stable isotope variation such as carbon, nitrogen, hydrogen and oxygen are usedas geographic tracersor marker to determine the geographic origin of fruits, crop, vegetables and food products from animal. The isotopic compositions of plant materials reflect various factors such as isotopic compositions of source materials and their assimilation processes as well as growth environments. This paper will discuss on stable carbon and nitrogen isotopic compositions inricethat been determined by Isotope Ratio Mass Spectromety, advantages, limitations and potential of other analysis applicationsthat can be incorporated in food traceability system.
  5. Rokiah Mohd Sabri, Abd Halim Baijan, Siti A’iasah Hashim, Mohd Rizal Md Chulan, Leo, Kwee Wah, Mukhlis Mokhtar, et al.
    A 3.375 kJ plasma focus is designed to operate at 13.5 kV for studying X-ray source in Argon discharge. X-rays are detected by a film from the mammography radiographic plate using radiography technique. The feasibility of plasma focus as a high intensity flash X-ray radiation for a good contrast in radiography image is presented.
  6. Muhammad Fakhrurazi Ahmad Fadzil, Siti Selina Abdul Hamid, Siti Najila Mohd Janib, Azahari Kasbollah, Syed Asraf Fahlawi Wafa
    Medical radioisotope is a small quantity of radioactive substance used for the purpose of diagnostic and therapy of various diseases. In Malaysia, the emerging of new nuclear medicine centers or institutions in both government and private sectors rose abruptly for the past few years. Currently, there are no data available on the usage and demand of these medical radioisotope or radiopharmaceuticals. The aim of this study is to assess current medical radioisotopes and radiopharmaceuticals usage and also to provide data on current medical radioisotope and radiopharmaceuticals demand for both private and government hospitals or institutions in Malaysia. A survey for a period of 3 months was conducted across Malaysia. The survey was divided into five (5) main parts and it was distributed among healthcare professionalsinvolved working with medical radioisotope and radiopharmaceuticals in private, government and university based hospitals or institutions and was distributed manually either by hand, mail ore-mail.Data is presented in either pie chart or bar chart. Survey results found out that the highest demand and the highest usage among all radioisotopes are Technetium-99m and radioiodine isotopes such as the iodine-131, iodine-131 MIBG, iodine-123 and iodine-123 MIBG. Technetium-99m is the backbone of nuclear medicine whereby more than 80% of Nuclear Medicine services utilize this radioisotope. Technetium-99m supply chain is unstable globally and in coming future, two main reactors that produce 60% of world Molybdenum-99 will shut down and the supply of molybdenum-99 will be disrupted. In radioiodine services, currently, Iodine-123 can’t be obtained in Malaysia and neighboring countries due to its short half-life. Iodine-123 is useful in diagnostic of thyroid related diseases. As for PET services, the highest demands are F-18 FDG and gallium-68 Generator. It is important for Malaysia to self-produced medical radioisotope and radiopharmaceuticals to meet the local market demand.
  7. Norhayati Abdullah, Ng, Kwan Hoong, Wong, Jeannie Hsiu Ding, Ngie Min Ung, Taiman Kadni, Siti Sara Deraman
    The objective of this study is to perform a thermoluminescent dosimetry (TLD) postal dose quality audit for megavoltage X-ray teletherapy units in Malaysia. This audit is essential to be carried out to ensure adequate precision in the dosimetry of clinical beams before being delivered to the patients. Through this work, participating centres were requested to irradiate three capsules of TLD-100 powder with an absorbed dose to water of 2 Gy for 6MV and10MV photon beams. The International Atomic Energy Agency (IAEA)’s Technical Report Series No. 398 is used as a reference standard for TLD irradiation. Atotal of 22photon beamsfrom ten radiotherapy centres comprising onegovernment hospital and nineprivate medical centres were evaluated. The percentage deviation of user’s measured absorbed dose relative to Secondary Standard Dosimetry Laboratory (SSDL) mean absorbed dose was calculated. The results showed that all photon beams are within the IAEA’s acceptance limit of ± 5% except six photon beams. These centres were followed up with a second round of TLD irradiation which resulted in a better compliance.As a conclusion, regular audits should be performed to ensure consistency of radiotherapy treatment unit performances thus maintaining the accuracy of dose delivered to patients inall radiotherapy centres in Malaysia.
  8. Zal U'yun Wan Mahmood, Nita Salina Abu Bakar, Mohamad Noh Sawon, Khairul Nizam Razali, Mohd Tarmizi Ishak, Norfaizal Mohamed, et al.
    Results ofthe bioaccumulation study anddose assessmentof Th-232 in whole-body Anabas testudineus are presented. The objective of this study was to evaluate the effect of Th-232 concentration activity on the laboratory bioaccumulation and total dose rate in Anabas testudineus. Anabas testudineus adults were exposed to different waterborne Th-232 levels: 0 Bq/L (control), 50 Bq/L and 100 Bq/L for 30 day (uptake phase). Whole-body uptakesof Th-232 in Anabas testudineuswere calculated and total dose ratesusing ERICA Assessment Tool were also estimated. The results showed the increase of waterborne Th-232 concentration corresponded to a progressive increase of Th-232accumulation and total dose rate (internal and external) in whole-body Anabas testudineus.Considering the ERICA dose rate screening value of 10 μGy/h, the findings can be concluded the estimated of total dose rate (0.38 –1.29μGy/h) in Anabas testudineuswasin orderof small magnitude. Nevertheless, these results showed that the Anabas testudineushas a potential to accumulate thorium.
  9. Noraishah Othman, Nor Pa’iza Mohamad Hasan, Nazrul Hizam Yusoff, Mohd Amirul Syafiq Mohd Yunos, Engku Mohd Fahmi Engku Chik
    Radiotracer technology is a technique of radioactive injection into the systemand the detection is done using radiationdetector.It is alsoa tool for investigating and solving plant process problems namely process malfunctions andmechanical damages. Radiotracer is the most preferred stimulus response techniques in the industries due to its non-invasive application and on line monitoring capabilities, which avoid shut down of the plant. Radiotracer techniques have many advantages, such as high detection sensitivity, in-situ detection, availability of a wide range of compatible radiotracers for different phases, rapid response and high reliability and accuracy of the results. The residence time distribution (RTD) is one of the important parameters that can provide information on the characteristics or hydrodynamics of the nuclear reactor. In this paper, the overall review is presented in brief regarding radiotracer technology in plant operation.
  10. Phua Choo Kwai Hoe, Halimi Mohd Saud, Khairuddin Abdul Rahim
    Gamma irradiation is widely used in sterilizationand mutagenesis,especially for plant breeding and crop protection. Microbial mutagenesisthrough gamma irradiation is mainly applied in fermentation industry. In agriculture, gamma irradiation is mostlyapplied in cropimprovement. Microbial mutagenesis is mainly applied against fungus and spore-forming bacteria,which are resistant to gamma irradiation.Response of microbes to gamma irradiation varies and depends on various factors. Reviewof previous works on gamma irradiation for microbial mutagenesis in agriculture may provide some information for the use of this method. Thegeneral view ongamma irradiation, its application,and mutagenesis are discussedin this paper. Further investigation onmicrobial mutagenesis should consider molecular changes,information on which is lacking in previous works.Moreover, studies on microbial mutagenesis are still lacking in Malaysiadespite having severalgamma irradiation facilities.Therefore, further studies on microbial mutagenesis should be conducted.
  11. Muhamat Omar, Zalina Laili, Abd Khalik Wood, Julia Abdul Karim, Zarina Masood, Mohd Fazli Zakaria, et al.
    A systematic study to assess the concentration of radionuclides in primary coolant and associated water samples from the operation of a TRIGA Mark II reactor has been carried out. The samples were transferred into appropriate counting container and were counted by efficiency-calibrated gamma spectrometer systems for several hours to obtain statistically adequate data for qualitative and quantitative evaluation of the radioactive materials presence. The primary coolant was found to contain various gamma emitting radionuclides including 24Na, 41Ar, 42K, 51Cr, , 54Mn, 56Mn, 60Co, 99mTc, 122Sb, 124Sb and 187W. Most of the detected radionuclides were inferred to be originated from activation products of (n,) nuclear reactions of elements of reactor components such as stainless steel and aluminium alloy used in the reactor system. The study confirms the integrity of the reactor system with no apparent release of any fission products radionuclide into the coolant water system.
  12. Md Fakarudin Ab Rahman, M. Iqbal Saripan, Nor Pa’iza Mohamad Hasan, Ismail Mustapha
    The total mass attenuation coefficients (μ/ρ) of stainless steel (SS316L) and carbon steel (A516) that are widely used as petrochemical plant components, such as distillation column, heat exchanger, boiler and storage tank were measured at 662, 1073 and 1332 keV of photon energies. Measurements of radiation intensity for various thicknesses of steel were made by using transmission method. The γ-ray intensity were counted by using a Gamma spectrometer that contains a Hyper-pure Germanium (HPGe) detector connected with Multi Channel Analyzer (MCA). The effective numbers of atomic (Zeff) and electron (Neff) obtained experimentally were compared by those obtained through theoretical calculation. Both experimental and calculated values of Zeff and Neff were in good agreement.
  13. Zaidi Embong
    This review briefly describes some of the techniques available for analysing surfaces and illustrates their usefulness with a few examples such as a metal and alloy. In particular, Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and laser Raman spectroscopy are all described as advanced surface analytical techniques. In analysing a surface, AES and XPS would normally be considered first, with AES being applied where high spatial resolution is required and XPS where chemical state information is needed. Laser Raman spectroscopy is useful for determining molecular bonding. A combination of XPS, AES and Laser Raman spectroscopy can give quantitative analysis from the top few atomic layers with a lateral spatial resolution of
  14. Mohd Amirul Syafiq Mohd Yunos, Zainal Abidin Talib, Wan Mahmood Mat Yunus, Liew, Josephine Ying Chyi, Paulus, Wilfred Sylvester
    Semiconductor thin films Copper Tin Selenide, Cu2SnSe3, a potential compound for solar cell applications or semiconductor radiation detector were prepared by thermal evaporation method onto well-cleaned glass substrates. The as-deposited films were annealed in flowing purified nitrogen N2, for 2 hours in a temperature range from 100˚C to 500˚C. The structure of as-deposited and annealed films has been studied by X-ray diffraction technique. The semi-quantitative analysis indicated from Reitveld refinement show that the samples composed of Cu2SnSe3 and SnSe. These studies revealed that the films were structured in mixed phase between cubic space group F-43m (no. 216) and orthorhombic space group P n m a (no. 62). The crystallite size and lattice strain were determined from Scherrer calculation method. The results show that increasing in annealing temperature resulted in direct increase in crystallite size and decrease in lattice strain.
  15. Rosli Darmawan
    The study on the possibility of using DMU Kinematics module in CAE tools for dose exposure work planning was carried out. A case scenario was created using 3D CAD software and transferred to DMU Kinematics module in a CAE software. The work plan created using DMU Kinematics module was animated to simulate a real time scenario. Data on the phantom position against the radioactive source was collected by activating positioning sensors in the module. The data collected was used to calculate the estimated dose rate exposure for the phantom. The results can be used to plan the safest and optimum procedures in carrying out the radiation related task.
  16. Nur Humaira’ Lau Abdullah, Zal U’yun Wan Mahmood, Norfaizal Mohamed @ Muhamad, Nazaratul Ashifa Abdullah Salim, Ahmad Nazrul Abd Wahid, Nor Dalila Desa, et al.
    A glasshouse experiment was performed to evaluate the uptake of grasses viz. Napier and Vetiver
    in radiophytoremediation of caesium-contaminated soil. The radiophytoremediation experiment
    was designed according to the Randomized Complete Block Design (RCBD). The grasses were
    grown in troughs filled with soil mixed with a known specific activity of 134Cs. Initial Cs activity and
    activity after different cultivation time intervals of 1, 3, 6 and 9 months were analyzed using gamma
    spectrometer direct measurement. The results showed the uptake of caesium by Napier and Vetiver
    after 9 months with the transfer factors (TF) were 4.70 and 6.25, respectively. The remediation of
    caesium from the contaminated soil during the study period was 98.08% for Napier and 98.21% for
    Vetiver. Both grasses have been found to accumulate caesium, with Vetiver accumulating higher
    than Napier. Thus, the present study suggests that Vetiver could be used as a potential plant for
    radiophytoremediation of caesium.
  17. Ros Anita Ahmad Ramli, Ahmad Zainuri Mohd Dzomir, Zainon Othman, Wan Saffiey Wan Abdullah, Muhamad Samudi Yasir
    The exposure of food to ionizing radiation is being progressively used in many countries to
    inactivate food pathogens, to eradicate pests and to extend shelf-life of food. To ensure free
    consumer choice, irradiated food will be labeled. The availability of a reliable method to detect
    irradiated food is important to enforce legal controls on labeling requirements, ensure proper
    distribution and increase consumer confidence. This paper reports on the preliminary application
    of photostimulated luminescence technique (PSL) as a potential method to detect irradiated food
    and perhaps be used for monitoring irradiated food on sale locally in the near future. Thus this
    study will be beneficial and relevant for application of food irradiation towards improving food
    safety and security in Malaysia.
  18. Norhayati Abdullah, Wong, Jeannie Hsiu Ding, Ng, Kwan Hoong, Ung, Ngie Min
    The assessment of surface dose is essential in radiotherapy to avoid deterministic effect or to
    reduce the severity of side effects from radiation treatment. In this study, the surface dose for breast
    cancer radiotherapy was measured using two types of dosimeter; Thermoluminescent Dosimeter
    (TLD) and Optically Stimulated Luminescent Dosimeter (OSLD). The study was performed on the
    left breast of female Alderson Radiation Therapy (ART) phantom. The treatment planning was
    carried out on the ART phantom to determine the homogeneity of dose distribution within the target
    organ is complied with the tolerance limits of 95% to 107% as recommended by the International
    Commission on Radiation Units and Measurements (ICRU)’s Report No. 50. From the treatment
    planning result, the phantom then was irradiated with 267 cGy dose per fraction for two beam
    fields; medial tangential and lateral tangential fields using a 6 MV photon beam produced from
    three-dimensional (3D) conformal radiotherapy. Result shows that the OSLD provides 25.7% and
    23.5% higher surface dose compared to TLD for medial tangential and lateral tangential fields,
    respectively. This condition may be due to higher effective point of measurement and angular
    dependence of the OSLD compared to TLD. As a conclusion, suitable dosimeter should be selected
    to ensure accurate estimation of surface dose could be made thus reduction of skin reaction to
    patient could be achieved.
  19. Selambakkan, Sarala, Khomsaton Abu Bakar, Jamaliah Shariff, Suhairi Alimon
    This paper studies about water obtained from fish pond of fisheries research centre. Usual water
    quality parameters such as pH, COD, Turbidity and Ammonia content were analyzed before and
    after irradiation. Electron beam irradiation was used to irradiate the water with the dose 100 kGy,
    200 kGy and 300 kGy. Only high dose was applied on this water as only a limited amount of
    samples was supplied. All the parameters indicated a slight increase after irradiation except for the
    ammonia content, which showed a gradual decrease as irradiation dose increases. Sample
    condition was changed before irradiation in order to obtain more effective results in the following
    batch. The water sample from fisheries was diluted with distilled water to the ratio of 1:1.This was
    followed with irradiation at 100 kGy, 200 kGy and 300 kGy. The results still showed an increase in
    all parameters after irradiation except for ammonia content. For the following irradiation batch,
    the pH of the sample was adjusted to pH 4 and pH 8 before irradiation. For this sample the
    irradiation dose selected was only 100 kGy. A higher value of ammonia was observed for the
    sample with pH 4 after irradiation. Other parameters were almost the same as the first two batches
  20. Husaini Salleh, Supian Samat, Mohd Khalid Matori, Muhammad Jamal Md Isa, Mohd Ramli Arshad, Shahrul Azlan Azizan, et al.
    Heel Effect is the well known phenomena in x-ray production. It contributes the effect to image
    formation and as well as scattered radiation. But there is paucity in the study related to heel effect.
    This study is for mapping and profiling the dose on the surface of water phantom by using mobile
    C-arm unit Toshiba SXT-1000A. Based on the result the dose profile is increasing up to at least
    about 57% from anode to cathode bound of the irradiated area. This result and information can be
    used as a guide to manipulate this phenomenon for better image quality and radiation safety for
    this specific and dedicated fluoroscopy unit.
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