The ultimate check of the actual dose delivered to a patient in radiotherapy can be achieved by using dosimetric measurements. The aims of this study were to develop and evaluate a custom handmade head and neck phantom for evaluation of Three-Dimensional Conformal Radiation Therapy (3D-CRT) dose planning and delivery. A phantom of head and neck region of a medium built male patient with nasopharyngeal cancer was constructed from Perspex material. Primary and secondary Planning Target Volume (PTV) and twelve Organs at Risk (OAR) were delineated using Treatment Planning System (TPS) guided by computed tomography printout transverse images. One hundred and seven (107) holes distributed among the organs were loaded with Rod-shaped Thermoluminescent dosimeters (LiF:Mg,Ti TLDs) after common and individual calibration. Head and neck phantom was imaged, planned and irradiated conformally (3D-CRT) by linear accelerator (LINAC Siemens Artiste). The planned predicted doses by TPS at PTV and OAR regions were obtained and compared with the TLD measured doses using the phantom. Repeated TLD measurements were reproducible with a percent standard deviation of < 3.5%. Moreover, the average of dose discrepancies between TLDs reading and TPS predicted doses were found to be < 5.3%. The phantom’s preliminary results have proved to be a valuable tool for 3D-CRT treatment dose verification.
Detection and analysis of resin is particularly significant since the commercial value of agarwood is related to the quantity of resins that are present. This article explores the potential of a scanning electron microscope in combination with new non-destructive 3D visualization technique, X-ray micro-computed tomography, as imaging tools to visualize micro-structure resin in agarwood. These techniques were used to compare two samples of agarwood chips: high grade and low grade. From the results, it can be concluded that a wood cell filled with resin deposit have a higher attenuation. It can be shown that the combination of scanning electron microscopy and micro-CT can offer high resolution images concerning the localization and structure of resin inside Agarwood. While the second allows the 3D investigation of internal structure of agarwood, the first technique can provide details 2D morphological information. These imaging techniques, although sophisticated can be used for standard development especially in grading of agarwoodlbr commercial activities.
An improved laboratory technique for measurement of polonium-210(
210Po) in environmental
samples has been developed in Radiochemistry and Environmental Laboratory (RAS), Malaysian
Nuclear Agency. To further improve this technique, a study with the objectives to determine the
optimum conditions for
210Po deposition and; evaluate the accuracy and precision results for
the determination of 2 1 0 P o in environmental samples was carried-out. Polonium-210 which
is an alpha emitter obtained in acidic solution through total digestion and dissolution of samples
has been efficiently plated onto one side of the silver disc in the spontaneous plating process for
measurement of its alpha activity. The optimum conditions for deposition of 210Po were achieved
using hydrochloric acid (HCl) media at acidity of 0.5 M with the presence of 1.0 gram hydroxyl
ammonium chloride and the plating temperature at 90
oC. The plating was carried out in 80 mL
HCl solution (0.5 M) for 4 hours. The recorded recoveries obtained using 2 0 9 P o tracers in
the CRM IAEA-385 and environmental samples were 85% – 98% whereby the efficiency of the
new technique is a distinct advantage over the existing techniques. Therefore, optimization of
deposition parameters is a prime importance to achieve accuracy and precision results as well as
economy and time saving
The most commonly used techniques of alpha and gamma spectrometry were performed to measure
210Pb activity in marine sediment core as a comparison. Alpha analytical technique measured the
activity of 210Pb from it’s in-grow grand-daughter 210Po after a chemical separation, assuming
radioactive equilibrium between the two radionuclides. Meanwhile, gamma analysis technique
allows direct measurement, non-destructive and no preliminary chemical separation. Through the
comparison, it is found that both alpha and gamma analysis techniques were slightly difference.
Overall, the results from alpha analytical technique were basically higher than those from the
gamma analytical techniques. Some logical argument had been discussed to explain this situation.
In routine analysis, the analytical technique used should be chosen carefully based on advantages
and disadvantages of the each technique and analysis requirements. Therefore, it is recommended to
determine exactly the needs and purpose of analysis and to know the sample history before decide
the appropriate analytical technique
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
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.
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.
Chrysanthemum morfolium is an important temperate cut flower and potted plant for Malaysian local market and exporter. Considering chrysanthemum as a popular vegetatively propagated ornamental plant, induce mutations for breeding purposes are more beneficial. Several of physical mutagens have been used in mutation breeding including x-rays, gamma rays and ion beams. Gamma rays and ion beams are from two different linear energy transfer (LET) which are low and high, respectively. The objective of this study was to compare the effectiveness of acute gamma and ion beam irradiation in generating flower colour mutations on nodal explants of Chrysanthemum morifblium cv. Reagan Red'. The nodal explants were irradiated with acute gamma (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110 and 120 Gy) and ion beam (0, 0.5, 1.0, 2.0, 3.0, 5.0, 8.0, 10, 15, 20 and 30 Gy). The optimal dose for in vitro shoot regeneration using acute gamma was in the range of 10 to .15.0Gy and for ion beam was between 3.5 to 4.OGv. Relative biological effectiveness for ion beam was found 3.75 higher than the acute gamma. The regenerated plantlets were planted in the greenhouse at MARDI, Cameron Highland for morphological screening. The highest frequency of flower colour mutation for acute gamma was 77.8% whilst for ion beam were between 42.3 to 58.3%.
Development of biofertilizer seed treatments for okra seeds were carried out by mixing phosphate
solubilising bacteria (AP 3) and plant growth promoter (AP 2) with adhesives. The seeds were
coated with inoculums and four types of adhesives namely, Gum Arabic; Polyethylene Glycol
(PEG); Sodium Alginate and Methycellulose respectively. From eight seed treatments, all seed
treatments significantly increased seed germinations except treatment T4 (Gum Arabic and AP3).
In general, maximum germination rates and log of viable cells were observed when treated with
polyethylene glycol 4000 (PEG) mixed with AP2 (T7) and AP3 (T8). These results show that using
PEG as adhesive enhanced the germination rates and log of viable cells of AP2 and AP3. Thus,
PEG could be a good adhesive for seed treatment. In greenhouse experiment, okra seeds treatment
with AP2 and PEG (T1) showed the highest dry weight compared to other treatments. Seeds
treatment with AP3 and PEG (T2) showed higher contribution of N compare to seeds treatment
(T1). There were no significant different within seed treatments and urea treatment in okra yield.
All treatments significantly increased yields compared with control
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.
The thermoluminescence kinetic parameters of Ge-doped flat fibre have been investigated comprehensively using the computerized glow curve deconvolution analysis. The Ge-doped flat fibre was irradiated to 6 MV and 10 MV photon beam with dose ranging from 100 cGy to 300 cGy. Analysis was done using WinGCF software on the dependence of the glow curve intensity on dose delivered and the determination of the trap parameters. Ge-doped flat fibre was found to be linear over the entire dose range explored for both 6 MV and 10 MV irradiations with r2 value of 0.9955 and 0.9933 respectively. The glow curve consists of five individual glow peaks. The peak height increases with increasing irradiation dose. The first peak (P1) is a dominant individual peak for low temperature peak (LTP) with the maximum temperature ranging from 167.4°C to 179.0°C for both beams studied. Meanwhile, peak (P4) is a dominant individual glow curve for high temperature peak (HTP) with maximum temperature for 6 MV and 10 MV and is observed between 264.5°C to 279.4°C. Peak 1 has the lowest activation energy which is less than 0.72 eV while peak 2 shows the highest activation energy (1.3 eV < Ea < 2.1 eV) which indicates the deepest electrons trap. The results showed that the peak integral will increases as the dose increases. The Ge-doped flat fibre demonstrated the second-order kinetic peak behavior by exhibiting the symmetric shape of the glow curve with high temperature half of the curve slightly broader than the low temperature half, which suggests the possibility of electron retrapping.
Prompt gamma-ray analysis (PGA) and instrumental neutron activation analysis (INAA) are essential for the study of rare samples such as meteorites because of non-destructivity and relatively being free from contaminations. The objective of this research is to utilize PGA and INAA techniques for comparative study and apply them to meteorite analyses. In this study, 11 meteorite samples received from the Meteorite Working Group of NASA were analyzed. The Allende meteorite powder was included as quality control material. Results from PGA and INAA for Allende showed in good agreement with literature values, signifying the reliabilities of these two methods. Elements Al, Ca, Mg, Mn, Na and Ti were determined by both methods and their results are compared. Comparison of PGA and INAA data using linear regression analysis showed correlations coefficients r2 > 0.90 for Al, Ca, Mn and Ti, 0.85 for Mg, and 0.38 for Na. The PGA results for Na using 472 keV were less accurate due to the interference from the broad B peak. Therefore, Na results from INAA method are preferred. For other elements (Al, Ca, Mg, Mn and Ti), PGA and INAA results can be used as cross-reference for consistency. The PGA and INAA techniques have been applied to meteorite samples and results are comparable to literature values compiled from previously analyzed meteorites. In summary, both PGA and INAA methods give reasonably good agreement and are indispensable in the study of meteorites.
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.
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.
Sludge and scales produced during oil and gas production contain enhanced naturally occurring
radioactive material (NORM). Sludge and scales are under the jurisdiction of Department of
Environment (DOE) and also Atomic Energy Licensing Board (AELB). AELB has issued a
guideline regarding the disposal of sludge and scales as in its guideline (LEM/TEK/30 SEM.2,
1996). In this guideline, Radiological Impact Assessment (RIA) should be carried out on all
proposed disposals and has to demonstrate that no member of public will be exposed to more than
1 mSv/y. This paper presented RIA analysis using RESRAD computer code for the disposal of
treated sludge. RESRAD (RESidual RADioactive) developed by Argonne National Laboratory is to
estimate radiation doses and risks from residual radioactive materials. The dose received by the
member of public is found to be well below the stipulated limit.
The indoor and outdoor radon concentrations in Cameron Highlands (Peninsular Malaysia) and Ranau (East Malaysia) were measured. The measurements were carried out using passive method based on CR-39 solid state nuclear track detector (SSNTD) (for indoor measurements in Cameron Highlands) and active method using continuous radon/thoron progeny monitor (for indoor and outdoor measurements in Ranau and outdoor measurements in Cameron Highlands). The mean indoor radon concentrations in Cameron Highlands and Ranau were 50 Bqm-3 and 1.5 Bqm-3, respectively. The mean indoor radon concentration in Cameron Highlands was slightly higher compare to the world average. The maximum value recorded was 97 Bqm-3 which is almost similar to WHO reference level. The mean outdoor radon concentrations in Cameron Highlands and Ranau were 7.4 Bqm-3and 1.7 Bqm-3, respectively. The outdoor concentrations were low and comparable to world outdoor average.
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
The combination of irradiation and biological technique was chosen to study COD, BOD5 and colour removal from textiles effluent in the presence of food industry wastewater. Two biological treatments, the first consisting a mix of non irradiated textile and food industry wastewater and the second a mix of irradiated textiles wastewater and food industry wastewater were operated in parallel. Reduction percentage of COD in textiles wastewater increased from 29.4% after radiation to 62.4% after further undergoing biological treatment. After irradiation, the BOD5 of textiles wastewater was reduced by 22.1%, but reverted to the original value of 36mg/1 after undergoing biological treatment. Colour had decreased from 899.5 ADMI to 379.3 ADM1 after irradiation and continued to decrease to 109.3 ADMI after passing through biological treatment.
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.
In industrial plants such as electricity generating, petroleum, chemical and petrochemical plants, pipelines are used extensively to transport liquid from one location to another. In radiation vulcanization of natural rubber latex (RVNRL) plants, pipelines are also used to transport latex to storage tank. During one of its maintenance activities, a pipeline intelligent gauge (PIG) that was used to monitor pipe integrity jammed inside the pipe causing interruption to its operation or loading activities. Sealed source technology was utilized to determine the location of jammed PIG in the pipeline. Fast neutrons from a 50 mCi Americium Beryllium (AmBe241), with energy range between 0.5 to11 MeV, were used for the study. Helium 3 (He3) detector was used to detect slow neutrons having a range of energy of 30 eV- 0.5 MeV. The investigation was carried out using neutron backscatter technique scanner. By adopting back-scattered technique, the location of jammed PIG in the pipeline has been successfully determined.