This paper aims at presenting preliminary results of a survey on physical factors, namely tube
potential (kV), tube current exposure time product (mAs) and compressed breast thickness (CBT)
during voluntary mammography screening using Full-Field Digital Mammography (FFDM) System
in Malaysia. Retrospective data were collected from 1128 FFDM images of 282 women from three
major ethnic groups (Malay, Chinese and Indian) who underwent voluntary screening
mammography at Breast Centre, International Islamic University Malaysia from January to March
2008. Results from the present study were then compared with results from the previous study on
Screen-Film Mammography System (SFM) according to the ethnic group for both Cranio-caudal
(CC) and Mediol-Lateral (MLO) views. We found that the mean kV for CC view for the three ethnic
groups are Malay (28), Chinese (28) and Indian (28), and for MLO view are Malay (29), Chinese
(28) and Indian (29). These values are higher than the kV for SFM which were Malay (26), Chinese
(27) and Indian (26) for CC and Malay (26), Chinese (27) and Indian (26) for CC and MLO views
respectively. The mean mAs for CC and MLO views for FFDM were lower compared to SFM
systems. These values were Malay (104), Chinese (108) and Indian (91) for CC views and Malay
(106), Chinese (105), and Indian (94) for MLO views for the FFDM system. The values for SFM
system are for CC and MLO views were Malay (120), Chinese (106) and Indian (126), and Malay
(166), Chinese (132), Indian (183) respectively. The median CBT for CC and MLO views increased
by 27% and 7% respectively on the FFDM compared to the SFM system. In conclusion, the FFDM
operates with higher kV, lower mAs, and higher CBT when compared with SFM system. Median
CBT on CC and MLO view with FFDM system are 27% and 7% higher respectively compared to
the SFM. We are currently collecting data on mean glandular dose with FFDM systems to assess
how the change in local mammography practice influences this value. This will allow comparison
with related data from other parts of the world.
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.
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.
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.
In this paper, we report the dosimetry methodology used in the IAEA/WHO Thermoluminescent Dosimeter (TLD) Postal Dose Quality Audit Service and the results of 22 Malaysian radiotherapy centres participated in the audit from 2011 to 2015. Each participating centre was provided with a few sets of TLD capsule (two unit of TLD capsules to be irradiated and a control TLD in one set) as requested by the centres. The participating centres were asked to irradiate each TLD capsule at 2 Gy absorbed a dose to water under reference conditions i.e the TLD capsule is positioned at 10 cm depths in water, at central axis with 10 cm x 10 cm field size at 100 cm Source-Surface Distance or 100 cm Source-Axis Distance. In this period, a total of 70 photon beams consist of 43 beams and 27 beams produced by 6 MV and 10 MV photon beams, respectively have been audited. The results demonstrated that all participating centres comply with the acceptance limits of ± 5% as recommended by the International Commission on Radiation Units and Measurements (ICRU) Report 24, except eight photon beams from six centres. However, these centres presented better compliance results after being followed up with a second round of TLD irradiation.
Stevia rebaudiana Bertoni is a perennial herb that belongs to the family of Asteraceae. It is a
natural sweetener plant known as sweet leaf, which is estimated to be 300 times sweeter than cane
sugar. In this study, micropropagation and in vitro mutagenesis of this natural herb was
successfully conducted. It was found that shoot tips on MS medium supplemented with 1 mg/l
Kinetin showed the highest shoot induction and multiplication after 3 weeks of culture
(5.50±1.95a). Radiosensitivity test was conducted to identify the dose that killed 50% of the
irradiated explants (LD50) for in vitro stevia shoots and to select effective doses to be used for the in
vitro mutagenesis. Shoot tips were irradiated with acute and chronic gamma radiation at 0, 10, 20,
30, 40, 60, and 80Gy. At 60 Gy and 80 Gy, all treated shoot tips were not survived. In this study,
LD50 for the stevia was estimated at 29 Gy for acute irradiation and 45 Gy for chronic irradiation.
The effective doses were selected at 10, 20, 30 and 40 Gy. These selected doses were applied for the
in vitro mutagenesis of the stevia shoots
Mixed organic liquid waste generated from health-care and research activities containing tritium, carbon-14, and other radionuclide posed specific challenges in its management. Often, this waste becomes legacy waste in many nuclear facilities and being considered as ‘problematic’ waste. One of the most important recommendations made by IAEA is to perform multistage processes aiming at declassification of the waste. At this moment, approximately 3000 bottles of mixed liquid waste, with estimated volume of 6000 litres are currently stored at the National Radioactive Waste Management Centre, Malaysia and some have been stored for more than 25 years. The aim of this study is to develop a characterization protocol towards reclassification of these wastes. The characterization protocol entails waste identification, waste screening and segregation, and analytical radionuclides profiling using analytical procedures involving gross alpha beta, and gamma spectrometry. The results obtained from the characterization protocol are used to establish criteria for speedy classification of the waste.
Flow measurement is a critical element for liquid resources monitoring for various applications in many industrial systems. The purposes of the study are to determine the flow rate of liquid system in flow rig using radiotracer techniques and to compare the result with that obtained by the conventional flow meters. The flow rig consists of 58.7m long and 20cm diameter pipeline that can accommodate about 0.296m3 of liquid. Tap water was used as liquid flow in pipeline and conventional flow meters were also installed at the flow rig. Radiotracer was injected as a sharp pulse into the inlet p.peline. The pulse was monitored at the inlet and various points along the outlet pipeline using collimated scintillation detector. The peak to peak and total count methods were applied for radiotracer techniques and showed the comparable results with conventional flow meter.
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.
One of the most prevailing issues in the operation of Nuclear Reactor is the safety of the system. Worldwide publicity on a few nuclear accidents as well as the notorious Hiroshima and Nagasaki bombing have always brought about public fear on anything related to nuclear. Most findings on the nuclear reactor accidents are closely related to the reactor cooling system. Thus, the understanding of the behaviour of reactor cooling system is very important to ensure the development and improvement on safety can be continuously done. Throughout the development of nuclear reactor technology, investigation and analysis on reactor safety have gone through several phases. In the early days, analytical and experimental methods were employed. For the last three decades ID system level codes were widely used. The continuous development of nuclear reactor technology has brought about more complex system and processes of nuclear reactor operation. More detailed dimensional simulation codes are needed to assess these new reactors. This paper discusses the development of 3D CFD usage in nuclear reactor safety analysis worldwide. A brief review on the usage of CFD at Malaysia's Reactor TRIGA PUSPATI is also presented.
Data transmission in field works especially that is related to industry, gas and chemical is paramount importance to ensure data accuracy and delivery time. A development of wireless detector system for remote data acquisition to be applied in conducting fieldwork in industry is described in this paper. A wireless communication which is applied in the project development is a viable and cost-effective method of transmitting data from the detector to the laptop on the site to facilitate data storage and analysis automatically, which can be used in various applications such as column scanning. The project involves hardware design for the detector and electronics parts besides programming for control board and user interface. A prototype of a wireless gamma scintillation detector is developed with capabilities of transmitting data to computer via radio frequency (RF) and recording the data within the 433MHz band at baud rate of 19200.
Anthropogenic airborne depositions of 210Po,
210Pb and 210Po/210Pb in the mosses and surface soils
collected at the vicinity of a coal-fired power plant were studied. The purpose of the study was to
determine activity concentrations of 210Po,
210Pb and 210Po/210Pb for assessing their variation
accumulation in the mosses and surface soils collected at the vicinity of a coal-fired power plant.
Other purposes were to determine their concentration factor (CF) in relation to track the potential
source of those radionuclides and to identify most suitable moss species as a biological indicator
for atmospheric deposition contaminants. In this study, different species of moss Leucobryum
aduncum, Campylopus serratus, Syrrhopodon ciliates and Vesicularia montagnei were collected in
May 2011 at the area around 15 km radius from Tanjung Bin coal-fired power plant located in
Pontian, Johor. The activity concentrations of 210Po,
210Pb and 210Po/210Pb in mosses were in the
range of 76.81 ± 4.94 – 251.33 ± 16.33 Bq/kg dry wt., 54.37 ± 3.38 – 164.63 ± 11.64 Bq/kg dry wt.
and 1.10 – 2.00, respectively. Meanwhile the ranges for those radionuclides in the surface soil
were 33.53 ± 2.10 – 179.67 ± 12.15 Bq/kg dry wt., 20.55 ± 1.33 – 106.62 ± 6.64 Bq/kg dry wt. and
1.61 – 2.44, respectively. Corresponding high ability of Leucobryum aduncum to accumulate more
210Po and 210Pb, wide geographical distribution, most abundant and high CF, therefore, the
findings can be concluded this species was the most suitable as a biological indicator for
atmospheric deposition contaminants such as 210Po and 210Pb. Furthermore, it is clear the
accumulation of 210Po and 210Pb in mosses might be supplied from various sources of atmospheric
deposition such as coal-fired power plant operation, industrial, agriculture and fertilizer activities,
burned fuel fossil and forest; and other potential sources. Meanwhile, the
Carbon-11 labeled radiotracers, such as 11C-acetate and
11C-palmitate are widely used in positron
emission tomography (PET) for noninvasive evaluation of myocardial metabolism under varied
physiological conditions.These tracers are attractive probes of tissue physiology, because they are
simply radiolabled versions of the native biochemical substrates. One of the major metabolites
generated by these tracers upon the administration is 11CO2 produced via the citric acid cycle. In
quantitative modeling of
11C-acetate and
11C-palmitate PET data, the fraction of blood
11C
radioactivity present as
11CO2 needs to be measured to obtain a correct radiotracer arterial
input function. Accordingly, the literature describes a method whereby the total blood
11C-activity
is counted in blood samples treated with base solution, while the fraction of
1 1CO2 is measured
after the blood is treated with acid followed by a 10 minutes gas-purge. However, a detailed
description of the experimental validation of this method was not provided. The goal of this study
was to test the reliability of a 10 minute gas purging method used to assay
11CO2 radioactivity in
blood
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.
For addressing the issue of adulteration and counterfeiting of the sources of origin for the edible bird’s nests (EBNs), a preliminary study of elemental characterization for their geochemical markers was performed. This study aims to characterize the elemental profiles as geochemical markers and evaluate the relationships between these markers which could be used for the verification of the geographical origin of EBN in Malaysia. EBN samples from house and cave nests that represent a range of geographical and environmental characteristics were analysed using Neutron Activation Analysis (NAA) technique. The method was validated by analysing the Standard Reference Material SRM-1515 (Apple Leaves) and SRM-1573a (Tomato Leaves) of NIST. A total of 18 elements were determined. The results showed a statistical analysis of one way ANOVA has proven that there have a significant different elemental profiles in both EBN, clearly V, As, Ba, Sc, Sm and Th were not detectable in the house EBNs. Therefore, initial finding could be concluded that those elements can be identified as the key elements for geochemical marker to differentiate the type of EBN. Furthermore the differnces probably due to natural presence of those elements as well as regional or location and seasonal variation factors affecting the dietry habits of the swiftlets.
Changes in molecular structure configuration during strain induced crystallisation of an amorphous Poly(Lactic Acid) (PLA 4032D) polymer was monitored in-situ by simultaneously recording the wide angle x-ray scattering (WAXS) and small angle x-ray scattering (SAXS) patterns together with polymer deformation images and force data. The amorphous chain orientation from the beginning of deformation until the onset of crystallisation was studied from the WAXS patterns. The true mechanical behaviour described by the true stress-true strain curve related to an amorphous chain orientation exhibited a linear behaviour. Approaching critical amorphous orientation, the true stress-true strain curve deviated from linear into non-linear behaviour. After the onset of crystallization, when the deformed polymer became a semicrystalline state, the true mechanical behaviour exhibited true strain hardening which greatly affected by the formation of the morphology. The gradual true strain hardening was associated with the formation of micro-fibrillar structure containing thin crystallite morphology whilst sharp increased in true strain hardening was associated with the formation of stacked lamellar morphology in the form of macro-lattice structure. The study was accomplished by the application of high brilliance synchrotron radiation at beamline ID2 of ESRF, Grenoble in France and the usage of the high contrast resolution of WAXS and SAXS charge-couple device (CCD) camera as well as 40 milliseconds temporal resolution of data acquisition system.
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.
A study to assess the concentration of radionuclides in spent resins of the PUSPATI TRIGA Mark II reactor coolant purification system has been carried out. Fresh spent resins collected and analysed in May 2010, after the changing of leaked heat exchanger in Sept. 2009 was found to contain 24Na, 122Sb, 51Cr, 124Sb, 58Co, 65Zn, 54Mn and 60Co. Old spent resins removed in 2001 and 2002 but analysed in 2010 indicated the presence of 60Co and 152Eu as radionuclides with half-lives of < 1 year might have already been decayed out. These results can be used to establish radionuclide inventory of the spent resins as part of radiation protection programme.
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.
Qualitative and quantitative analysis of samples require good judgment from the analysts. These two aspects in gamma spectrometric analysis of Proficiency Test and solid radioactive waste samples for the determination of radionuclides are discussed. It is vital to judge and decide what energy peaks belong to which radionuclides prior to the creation of customized radionuclide library for the analysis of specific samples. Corrections due to radionuclide decay and growth, and the half-life assigned to a particular radionuclide in the uranium and thorium series are also discussed. Discussion on judgment to confirm the presence of thorium in food samples based on gamma spectrometry and neutron activation analysis is also provided.