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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Kenaf (Hibiscus cannabinus L.) is one of the world’s most economically important fiber crops particularly in Asia-Pacific region. Mutation induction is a method to increase genetic divergence associated with selection, recombination, or a combination of these approaches in plant breeding. One of preliminary procedures for an execellent mutation breeding program is the radiosensitivity study to determine the optimal doses for irradiation. A total of 10 different doses of acute gamma rays (0, 100, 200, 400, 800, 1000, 1200, 1500, 1700 and 2000 Gy) from ceasium-137 source were applied to the seeds of V 36 kenaf variety. The irradiated seeds including the control were planted in trough for 30 days. The gamma irradiation effects on several parameters such as seedling survival percentages, plant height, root length, shoot fresh weight, root frest weight, shoot dry weight and root dry weight were analysed. From the radiosensitivity curve, the LD50 and LD25 values were estimated at 810 and 310 Gy, respectively. Two doses (200 Gy and 300 Gy) based on LD25 were chosen for evaluating the effects of gamma irradiation on morphological traits in M1 generation. Irradiated and non-irradiated seeds were planted in the field at Beseri, Perlis. About 10 phenotypic traits of irradiated plants were observed and evaluated against the controls. Cluster analysis on M1 progenies showed that the mutation could be classified into eight genotypic groups. The first two components from principal component analysis explained about 77.99% of variation. Number of seeds per pod, weight of seeds per plant and dry stem biomass play an important role in explaining the variation since they showed positive correlated values for the first component analysis. Morphological changes such as flower shape, flower colour, and leaf shape were also observed in M1 generation. The findings of this study are important in determining the effectiveness of these doses in generating mutations on kenaf plant and subsequent breeding program to develop new kenaf varieties with enhanced quality traits.
The Malaysian’s PUSPATI TRIGA Reactor (RTP) achieved its initial criticality on June 28, 1982. The reactor is designed to effectively implement various fields of basic nuclear research, manpower training, and production of radioisotopes. Several past activities on neutronics modelling development and validation of the RTP were carried out using Monte Carlo Code MCNP. In this work, the developed model was used to characterise in-core and beam-ports irradiation facilities of the reactor. The thermal and fast neutron flux distributions in these facilities were determined using MCNP mesh tally method. It was found that the flux as well as its spectral characteristics depended very much on the position of the irradiation facility in the reactor core or in the beam-ports. The maximum neutron flux was found to be in the Central Thimble facility with 1.98E13 nv of thermal neutron. The thermal-to-total flux ratio varies significantly from 0.41 for the in-core facility, 0.58 in the reflector and up to 0.88 in the beam-ports.
Accumulation kinetic trends of cesium and cadmium in the Penaeus monodon were studied using Cs-134 and Cd-109 as a tracer. The objective of this study was to quantify the uptake and loss/depuration kinetic of these two radionuclides in the Penaeus monodon. Uptake and loss/depuration kinetic of these two radionuclides in the Penaeus monodon were varied widely, displayed a simple double kinetic model of linear and exponential trend with time unless modified by moulting at the stage in the mount cycle. Therefore, the variation of Cs-134 and Cd-109 bio-concentration factor could be concluded considerably influence by moulting cycle, environmental and biological condition as well as physico-chemical that direct effects on their uptake and loss/depuration kinetic.
The particleboards were fabricated using Rhizophora spp. wood particles with particles size less than 74 μm. The corn starch was used as a bio-adhesive in the fabrication of Rhizophora spp. particleboards. The corn starch bonded particleboards were fabricated at 5% and 10% corn starch based on dry mass of Rhizophora spp. wood particles. The measurement of mass attenuation coefficients of the particleboards were made at low and intermediate photon energies. The mass attenuation coefficient at low photon energy was measured using X-ray fluorescent (XRF) configuration based on attenuation of Kα1 X-ray energies between 16.59 and 25.26 keV given by niobium, molybdenum, palladium and tin metal plates. The calculated mass attenuation coefficients of samples were compared to the theoretical values mass attenuation coefficients of water calculated using the photon cross-section database (XCOM). The results showed that mass attenuation coefficients of 10% corn starch added Rhizophora spp. particleboards were in good agreement of water within 7.96 and 4.94% for 5% and 10% corn starch Rhizophora spp. Particleboards, respectively compared to 14.57 and 16.16% in binderless Rhizophora spp. particleboards and raw Rhizophora spp. wood, respectively.
The fermentation of Pleurotus pulmonarius (non-irradiated) and Pleurotus pulmonarius (irradiated) were carried out in Erlenmeyer flask 500 mL (working volume 250 mL) and screened for the presence of β-glucan (1, 3:1, 6). The biomass obtained was extracted using Modified Mizuno Method to get the endopolysaccharide. The endopolysaccharides of Pleurotus pulmonarius (irradiated) contained higher content of β-glucan (1, 3:1, 6) with 16.7 g/100g crude polysaccharide compared to the non-irradiated strain. The irradiated strain was chosen for further investigation. Fractionation of endopolysaccharide Pleurotus pulmonarius (irradiated) using column chromatograph yielded 7 fractions. The first fraction (F1) contained high molecular weight fraction ~ 105 Da which potential immunomodulation characteristics. The Pleurotus pulmonarius (irradiated) was produced in a 5 L air-lift bioreactor. The highest biomass was obtained at air flowrate of 2 L/min, yielding productivity of 2.56 g/L.d.
The objective of this study was to measure indoor radon concentrations in the expected high risk area around Ipoh in Kinta Valley, Perak. The area was chosen based on its own special characteristics. The measurements were carried out by means of long term exposure (3 months) using CR-39 solid state nuclear track detector. The mean indoor radon concentration in Ipoh was 45 Bq/m3 which is equivalent to effective dose of 1.1 mSv/y. This value was higher compared to low or normal area in Bangi, Selangor but comparable to the world average value reported by UNSCEAR. The maximum value of indoor radon concentration measured was 87 Bq/m3.
In this paper a study on the relationship between axial speed va, radial shock speed vs, piston speed
vp and pinch temperature with the variation of pressure P0 was carried out. The Lee’s 5 phase
model code was used in this study by configuring the India Bhabha Atomic Research Center
(BARC) plasma focus machine to operate in the pressure (P0) range from 1 Torr to 14 Torr. The
relationships between these parameters were obtained as follows:
Va ≈ 9Po-0.37, Vs ≈ 45P0-0.48, Vp ≈ 30P0-0.47 and Tpinch(max) ≈ 11P0-1
This study evaluates the ImageJ software as dosimetric tools for analyzing the film dosimeter in high energy photons and electrons. The percentage depth dose of photons of 6 and 10 MV and electrons of 6 and 9 MeV were measured using the Gafchromic EBT2 film dosimeter. The films were scanned and analyzed using the Verisoft software and ImageJ. The beam profiles at nominal photon and electron beam parameters were also evaluated using the two methods. The PDD measured in ImageJ at high energy photons were in good agreement within 1% percentage of discrepancy at all depths in comparison to the Verisoft software. The PDD measured in ImageJ at high energy electrons also showed good agreement to Verisoft software within 8% percentage of discrepancy at all depths. The measured flatness of beam profiles at Dmax, R50, R80 and R90 in ImageJ were also in good agreement to Verisoft software with flatness value between 4 and 8%. The results indicated the suitability of ImageJ software as dosimetric tool for analyzing EBT2 film dosimeter at high energy photon and electrons.
This study was conducted to evaluatethe nitrogen use efficiency and 13C isotope discrimination of rice mutant lines viz.NMR151 and NMR152. Both cultivars are developed under rice radiation mutagenesis programme for adaptability to aerobic conditions. In the present study, NMR151 and NMR152 were grown under conditions of varying water potentials and nitrogen levels in a shade house. The rice mutant lines were planted on sandy loam soil. Three watering regimes and three nitrogen levels in a completely randomized design with three replications were carried out. The rice mutants were grown for 110 days under three water potentials, (i) Field capacity from 0 to 40 DAS and saturated from 41 to 110 DAS [ST], (ii) Field capacity from 0 to 110 DAS [FC], and (iii) Field capacity from 0 to 40 DAS and 70% of field capacity from 41 to 110 DAS [SS]. Direct 15N isotopic tracer method was used in this study, whereby the 15N labelled urea fertilizer 5.20% atom excess (a.e) was utilized as a tracer for nitroge nuse efficiency study (NUE)by the test crops. 15Nisotope presence in the samples was determined using emission spectrometry and percentage of total nitrogen was determined by the Kjeldahl method. 15N a.e values of the samples were used in the determination of the efficiency of N used by the mutant varieties. The 13C isotope discrimination (Δ13C) technique was used as a tool to identify drought resistance rice species with improves water use efficiency (WUE). WUE is the ratio of the biomass produced by the water consumed. For 13C discrimination analysis, a sample of rice leaf was analyzed for 13C content by using Isotope Ratio Mass Spectrometer (IRMS).The parameter, viz. plant height, number of tillers, grain yield, 1000 grain weight, NUE, Δ13Cand WUE were recorded. Results from this study showed nitrogen rates imparted significant effects on plant height, number of tillers, grain yield, 1000 grain weight and WUE, while water potentials had significant effects on plant height, grain yield, 1000 grain weight, NUE, Δ13Cand WUE. Δ13C has a low but significantly negative relationship with WUE. Rice mutants NMR151 and NMR152 were found to be not significantly different except for their NUE.