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Fulltext Perception towards teaching and learning of clinical education among physiotherapy students during clinical placements. [Persepsi terhadap pengajaran dan pembelajaran pendidikan klinikal di kalangan pelajar fisioterapi semasa penempatan klinikal]

Ramli A, Ramli NI, Kamarudin K, Bahari SE, Azmi NA

Jurnal Sains Kesihatan Malaysia, 2012;10(2):1-7.
MyJurnal

This study aims to identify the perception of third year physiotherapy students on the teaching and learning during clinical placements. A sample of 154 third year undergraduate and diploma students from the Universiti Kebangsaan Malaysia, the Universiti Teknologi Mara and the Kolej Sains Kesihatan Bersekutu completed the questionnaire. High internal reliability of teaching and learning activities scale in the questionnaire was determined using Cronbach alpha (α = 0.94). Findings showed significant differences (p < 0.05) of perception among students in the clinical block between different levels of education, the ideal number of students in a group during clinical teaching session, and in the activity of ‘patient-centered activities,’ as well as 'feedback to the student.’ These findings demonstrated that the level of education does influence the students’ perceptions on their teaching and learning during clinical placements. In conclusion, the level of education is a contributory factor that influences the students’ rate of learning in clinical education.
Keywords: Clinical education, physiotherapy students, perception, undergraduate, diploma
Fulltext Physio-Chemical Analysis of Amide and Amine Poly(dimethylsiloxane)-Modified Defoamer for Efficient Oil-Water Separation

Hassan A, Jumbri K, Ramli A, Borhan N

ACS Omega, 2021 Jun 15;6(23):14806-14818.
PMID: 34151062 DOI: 10.1021/acsomega.1c00350

The formation of foam due to the injection of surfactant foam in FAWAG causes significant problems in the oil well production and separation facilities. The excessive foam can lead to the reduction of the separator capacity as well as its efficiency. A defoamer is needed to break and destroy the foam in the separator. There are many commercially available defoamer agents in the market, but not all defoamers are suitable for every application. For this reason, four modified silicone-based defoamers were successfully synthesized and characterized based on the data obtained from the screening process using various commercial defoamers. The performance of modified defoamers was evaluated using TECLIS FoamScan that imitate real conditions of treatment. The results show that all four of the modified silicone-based defoamers, especially amide-terminated-modified defoamers (S2) showed excellent performance as a defoaming agent to mitigate foam in specific conditions. The best-case condition for the modified defoamer to perform was at a high temperature (60 °C), gas flow rate of 1.0 L/min, and low ration concentration of the surfactant to brine (30:70). The study on the bubble count and distribution using a KRÜSS Dynamic Foam Analyzer revealed that S2 excellently contributes to the formation of unstable foam that can fasten foam destruction in the foaming system.
Fulltext Pleuritic chest pain and fever: An unusual presentation of aortic dissection

Mohamed-Yassin MS, Baharudin N, Ramli AS, Hashim H

Malays Fam Physician, 2019;14(1):47-52.
PMID: 31289633

It remains a challenge to diagnose aortic dissection in primary care, as classic clinical features are not always present. This case describes an atypical presentation of aortic dissection, in which the patient walked in with pleuritic central chest pain associated with a fever and elevated C-reactive protein. Classic features of tearing pain, pulse differentials, and a widened mediastinum on chest X-ray were absent. This unusual presentation highlights the need for a heightened level of clinical suspicion for aortic dissection in the absence of classic features. The case is discussed with reference to the literature on the sensitivity and specificity of the classic signs and symptoms of aortic dissection. A combination of the aortic dissection detection risk score (ADD-RS) and D-dimer test is helpful in ruling out this frequently lethal condition.
Fulltext Point Set Denoising Using Bootstrap-Based Radial Basis Function

Liew KJ, Ramli A, Abd Majid A

PLoS One, 2016;11(6):e0156724.
PMID: 27315105 DOI: 10.1371/journal.pone.0156724

This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study.
Predicting terrestrial gamma dose rate based on geological and soil information: case study of Perak state, Malaysia

Ramli AT, Apriantoro NH, Heryansyah A, Basri NA, Sanusi MS, Abu Hanifah NZ

J Radiol Prot, 2016 Mar;36(1):20-36.
PMID: 26583298 DOI: 10.1088/0952-4746/36/1/20

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

Sanusi MSM, Ramli AT, Hashim S, Lee MH

Ecotoxicol Environ Saf, 2021 Jan 15;208:111727.
PMID: 33396058 DOI: 10.1016/j.ecoenv.2020.111727

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

Ariffin F, Ramli AS, Naim N, Selamat MI, Syed-Jamal SJ

Med J Malaysia, 2014 Oct;69(5):210-5.
PMID: 25638233

Dengue is life-threatening and the paediatric population is highly susceptible to complications. Deterioration can occur rapidly and ability to recognise early warning signs is crucial. This study aims to determine the knowledge and awareness of parents and carers and to predict their ability in recognising life-threatening symptoms and signs of dengue in children and to assess their health-seeking behaviour in dengue emergency. Methods This is a crosssectional study involving parents and carers of children ≤ 12 years old in schools and kindergartens in the Gombak district. Demographic details, knowledge on life-threatening symptoms and signs of dengue and health-seeking behaviour were collected using a self-administered questionnaire and knowledge scoring was done. The questionnaire was pilot tested with a Cronbach alpha of 0.82. The results were analysed using SPSS version 20.0. Results Total respondents were 866 with 44.8% men and 55.2% women. The mean age was 40.3 years (SD ± 5.7). Knowledge score of dengue life threatening features among respondents were good (30.0%) to average (56.8%). Respondents were able to recognise fever (98.5%), petechial rash (97.1%) and bleeding (65.2%) but were less able to recognise abdominal pain (22.3%) and passing less urine (28.2%) as life threatening dengue features. However, the ability to recognise fever is a poor predictor in recognising life threatening dengue in children compared to all other symptoms which were good predictors. A respondent that recognise stomach pain or neck stiffness were five times more likely to recognise life-threatening dengue. Respondents preferred to bring their children to the clinic (50.8%) or hospital (37.8%) themselves Instead of calling for ambulance. Worryingly, some would give antipyretics (3.6%) or wait for improvements (7.8%). Conclusion Concerted efforts by the schools, healthcare professionals and health authorities are required to educate parents and carers to identify life-threatening features of dengue and to improve their health seeking-behaviour.
Regulatory requirements for nuclear power plant site selection in Malaysia-a review

Basri NA, Hashim S, Ramli AT, Bradley DA, Hamzah K

J Radiol Prot, 2016 Dec;36(4):R96-R111.
PMID: 27631675

Malaysia has initiated a range of pre-project activities in preparation for its planned nuclear power programme. Clearly one of the first steps is the selection of sites that are deemed suitable for the construction and operation of a nuclear power plant. Here we outline the Malaysian regulatory requirements for nuclear power plant site selection, emphasizing details of the selection procedures and site characteristics needed, with a clear focus on radiation safety and radiation protection in respect of the site surroundings. The Malaysia Atomic Energy Licensing Board (AELB) site selection guidelines are in accord with those provided in International Atomic Energy Agency (IAEA) and United Stated Nuclear Regulatory Commission (USNRC) documents. To enhance the suitability criteria during selection, as well as to assist in the final decision making process, possible assessments using the site selection characteristics and information are proposed.
Fulltext Review of functional markers for improving cooking, eating, and the nutritional qualities of rice

Lau WC, Rafii MY, Ismail MR, Puteh A, Latif MA, Ramli A

Front Plant Sci, 2015;6:832.
PMID: 26528304 DOI: 10.3389/fpls.2015.00832

After yield, quality is one of the most important aspects of rice breeding. Preference for rice quality varies among cultures and regions; therefore, rice breeders have to tailor the quality according to the preferences of local consumers. Rice quality assessment requires routine chemical analysis procedures. The advancement of molecular marker technology has revolutionized the strategy in breeding programs. The availability of rice genome sequences and the use of forward and reverse genetics approaches facilitate gene discovery and the deciphering of gene functions. A well-characterized gene is the basis for the development of functional markers, which play an important role in plant genotyping and, in particular, marker-assisted breeding. In addition, functional markers offer advantages that counteract the limitations of random DNA markers. Some functional markers have been applied in marker-assisted breeding programs and have successfully improved rice quality to meet local consumers' preferences. Although functional markers offer a plethora of advantages over random genetic markers, the development and application of functional markers should be conducted with care. The decreasing cost of sequencing will enable more functional markers for rice quality improvement to be developed, and application of these markers in rice quality breeding programs is highly anticipated.
Fulltext Risk of serious adverse events after the BNT162b2, CoronaVac, and ChAdOx1 vaccines in Malaysia: A self-controlled case series study

Ab Rahman N, Lim MT, Lee FY, Lee SC, Ramli A, Saharudin SN, et al.

Vaccine, 2022 Jul 30;40(32):4394-4402.
PMID: 35667917 DOI: 10.1016/j.vaccine.2022.05.075

BACKGROUND: Rapid deployment of COVID-19 vaccines is challenging for safety surveillance, especially on adverse events of special interest (AESIs) that were not identified during the pre-licensure studies. This study evaluated the risk of hospitalisations for predefined diagnoses among the vaccinated population in Malaysia.
METHODS: Hospital admissions for selected diagnoses between 1 February 2021 and 30 September 2021 were linked to the national COVID-19 immunisation register. We conducted self-controlled case-series study by identifying individuals who received COVID-19 vaccine and diagnosis of thrombocytopenia, venous thromboembolism, myocardial infarction, myocarditis/pericarditis, arrhythmia, stroke, Bell's Palsy, and convulsion/seizure. The incidence of events was assessed in risk period of 21 days postvaccination relative to the control period. We used conditional Poisson regression to calculate the incidence rate ratio (IRR) and 95% confidence interval (CI) with adjustment for calendar period.
RESULTS: There was no increase in the risk for myocarditis/pericarditis, Bell's Palsy, stroke, and myocardial infarction in the 21 days following either dose of BNT162b2, CoronaVac, and ChAdOx1 vaccines. A small increased risk of venous thromboembolism (IRR 1.24; 95% CI 1.02, 1.49), arrhythmia (IRR 1.16, 95% CI 1.07, 1.26), and convulsion/seizure (IRR 1.26; 95% CI 1.07, 1.48) was observed among BNT162b2 recipients. No association between CoronaVac vaccine was found with all events except arrhythmia (IRR 1.15; 95% CI 1.01, 1.30). ChAdOx1 vaccine was associated with an increased risk of thrombocytopenia (IRR 2.67; 95% CI 1.21, 5.89) and venous thromboembolism (IRR 2.22; 95% CI 1.17, 4.21).
CONCLUSION: This study shows acceptable safety profiles of COVID-19 vaccines among recipients of BNT162b2, CoronaVac, and ChAdOx1 vaccines. This information can be used together with effectiveness data for risk-benefit analysis of the vaccination program. Further surveillance with more data is required to assess AESIs following COVID-19 vaccination in short- and long-term.
Fulltext Serology surveillance of SARS-CoV-2 antibodies among healthcare workers in COVID-19 designated facilities in Malaysia

Woon YL, Lee YL, Chong YM, Ayub NA, Krishnabahawan SL, Lau JFW, et al.

Lancet Reg Health West Pac, 2021 Apr;9:100123.
PMID: 33778796 DOI: 10.1016/j.lanwpc.2021.100123

Background: Asymptomatic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections are well documented. Healthcare workers (HCW) are at increased risk of infection due to occupational exposure to infected patients. We aim to determine the prevalence of SARS-CoV-2 antibodies among HCW who did not come to medical attention.
Methods: We prospectively recruited 400 HCW from the National Public Health Laboratory and two COVID-19 designated public hospitals in Klang Valley, Malaysia between 13/4/2020 and 12/5/2020. Quota sampling was used to ensure representativeness of HCW involved in direct and indirect patient care. All participants answered a self-administered questionnaire and blood samples were taken to test for SARS-CoV-2 antibodies by surrogate virus neutralization test.
Findings: The study population comprised 154 (38.5%) nurses, 103 (25.8%) medical doctors, 47 (11.8%) laboratory technologists and others (23.9%). A majority (68.9%) reported exposure to SARS-CoV-2 in the past month within their respective workplaces. Adherence to personal protection equipment (PPE) guidelines and hand hygiene were good, ranging from 91-100% compliance. None (95% CI: 0, 0.0095) of the participants had SARS-CoV-2 antibodies detected, despite 182 (45.5%) reporting some symptoms one month prior to study recruitment. One hundred and fifteen (29%) of participants claimed to have had contact with known COVID-19 persons outside of their workplace.
Interpretation: Zero seroprevalence among HCW suggests a low incidence of undiagnosed COVID-19 infection in our healthcare setting during the first local wave of SARS-CoV-2 infection. The occupational risk of SARS-CoV-2 transmission within healthcare facilities can be prevented by adherence to infection control measures and appropriate use of PPE.
Fulltext Study on physiochemical properties and the halalness of commercially marketed vinegar in Malaysia

Jamaludin, M.A., Amin, A., Fadzlillah, N. A., Kartika, B., Othman, R., Sani, S., et al.

International Food Research Journal, 2017;24(101):0-0.
MyJurnal

Vinegar is very popular as traditional ingredient for cooking, pickling, and preservation. It is made from sugar or starch by an alcoholic and acetous fermentation and produces ethanol as a by-product. Alcohol is prohibited to be consumed for Muslim or used as ingredient if it is exceeding the allowable limit as stated by Islamic Council in Malaysia. According to Fatwa Committee National Council of Islamic Religious Affairs Malaysia, natural occurrences of ethanol in food products are acceptable if the ethanol contents are less than 1% in beverages and 0.5% for flavoring or coloring substances for the purpose of stabilization. On the other hand, for specific vinegar product, as stated by Malaysian Food Act and Regulation, acetic acid content must be at least 4%. According to FAO/WHO, a product is to be labelled as vinegar if the acetic acid content is 6% and with a maximum residual alcohol content of 0.5%v/v for wine vinegar and 1%v/v for other vinegars. This study investigated the physiochemical properties of the vinegar from different sources of raw materials. Total solubility (TA) by using Brix method, pH, and alcohol and acetic acid content by GC-TOF/MS of 12 commercial vinegars from Malaysia and abroad were studied. The result shown that for pH value of commercial vinegar are ranged from 2.51-3.14°Brix from 2.10-40.73°Brix, acetic acid is ranged from 0.0253-0.1276% and ethanol content from 0-0.5911%. Thus, this study will come out with the clear observation on ethanol content in fermented product which is vinegar in order to categories the halalness of the product that available in Malaysia market especially the ones that are produced internationally. Lastly, as shown by the profiling study, vinegar that are imported internationally may contain some amount of alcohol in contrast with the one that locally produced in Malaysia and has Halal certification.
Tabulation of organ dose conversion factors for terrestrial radioactivity monitoring program

Sanusi MSM, Hassan WMSW, Hashim S, Ramli AT

Appl Radiat Isot, 2021 Aug;174:109791.
PMID: 34062400 DOI: 10.1016/j.apradiso.2021.109791

Terrestrial radioactivity monitoring of 238U and 232Th series, and 40K in soil is an essential practice for radioactivity and radiation measurement of a place. In conventional practice, only basic data can be in-situ measured using a survey instrument, for example radioactivity concentration in soil and ambient dose equivalent rate. For other physical quantities, for example organ absorbed dose and organ equivalent dose, the measurement is impossible to be performed and can only be computed using Monte Carlo radiation transport simulations. In the past, most of the works only focused on calculating air-kerma-to-effective dose conversion factors. However, the information on organ dose conversion factors is scarcely documented and reported. This study was conducted to calculate organ absorbed and tissue-weighted equivalent dose conversion factors as a result of exposure from terrestrial gamma radiation. Series of organ dose conversion factors is produced based on computations from Monte Carlo MCNP5 simulations using modelled gamma irradiation geometry and established adult MIRD phantom. The study found out that most of the radiation exposed organs absorb energy at comparable rates, except for dense and superficial tissues i.e., skeleton and skin, which indicated slightly higher values. The good agreement between this work and previous studies demonstrated that our gamma irradiation geometry and modelling of gamma radiation sources are adequate. Therefore, the proposed organ dose conversion factors from this study are reasonably acceptable for dose estimation in environmental radioactivity monitoring practices.
Fulltext Tailoring the surface area and the acid-base properties of ZrO2 for biodiesel production from Nannochloropsis sp

Rahman NJA, Ramli A, Jumbri K, Uemura Y

Sci Rep, 2019 11 07;9(1):16223.
PMID: 31700157 DOI: 10.1038/s41598-019-52771-9

Bifunctional heterogeneous catalysts have a great potential to overcome the shortcomings of homogeneous and enzymatic catalysts and simplify the biodiesel production processes using low-grade, high-free-fatty-acid feedstock. In this study, we developed ZrO2-based bifunctional heterogeneous catalysts for simultaneous esterification and transesterification of microalgae to biodiesel. To avoid the disadvantage of the low surface area of ZrO2, the catalysts were prepared via a surfactant-assisted sol-gel method, followed by hydrothermal treatments. The response surface methodology central composite design was employed to investigate various factors, like the surfactant/Zr molar ratio, pH, aging time, and temperature on the ZrO2 surface area. The data were statistically analyzed to predict the optimal combination of factors, and further experiments were conducted for verification. Bi2O3 was supported on ZrO2 via the incipient wetness impregnation method. The catalysts were characterized by a variety of techniques, which disclosed that the surfactant-assisted ZrO2 nanoparticles possess higher surface area, better acid-base properties, and well-formed pore structures than bare ZrO2. The highest yield of fatty acid methyl esters (73.21%) was achieved using Bi2O3/ZrO2(CTAB), and the catalytic activity of the developed catalysts was linearly correlated with the total densities of the acidic and basic sites. The mechanism of the simultaneous reactions was also discussed.
Fulltext The level of physical activities amongst elderly in a community

Ramli A

JUMMEC, 2007;10(1):29-33.
MyJurnal

Little is known of Malaysian older people’s participation in physical activities, and the purpose of this pilot study is to explore their participation and the barriers. A self-administered questionnaire was given to 80 eligible respondents at the Kuala Lumpur Health Clinic of which 70 responded. Thirty-six (51.4%) were males and 34 (48.6%) were females. There were 26 (37.1%) Malays, 20 (28.6%) Chinese, 18 (25.7%) Indians and 6 (8.6%) of other ethnic groups. Forty (57.1%) took part in some form of physical activities and the remaining 30 (42.9%) reported no participation at all. The Chinese participated actively in physical activities (90%), followed by Indians (66.7%) and Malays (30.8%). The five common activities were walking (60%), tai chi (20%), gardening (12.5%), stretching (2.5%) and cycling (5.0%). Identified barriers to physical activities were lack of time (26.7%), having health problems (26.7%), was already fit (26.7%), no companion to exercise with (13.3%) and no exercise knowledge (6.7%). These findings indicated that emphasis should be given to the females and the Malay ethnic group when planning physical activity education for the older people as they were identified to be the least active groups.
Study site: Klinik Kesihatan Kuala Lumpur, Wilayah Persekutuan, Malaysia
Fulltext The problems and impacts of orofacial pain among a group of Malaysian aborigines

Yusof ZYM, Mohamed NH, Radzi Z, Yahya NA, Ramli AS, Abdul Kadir R

Ann Dent, 2007;14(1):31-38.
MyJurnal

Background: The high prevalence and impacts of orofacial pain (OFP) have caused major sufferings to individuals and society. The purpose of the study was to investigate the problems and impacts of OFP among a group of Malaysian aborigines. The objectives were to determine (i) the prevalence, aetiology, duration, severity, types and persistence of OFP during the past 3 months preceding the study; (ii) its associated impact on daily performance; and (iii) the measures taken for pain relief.
Methods: This is a cross sectional study carried out in Kuala Lipis, Pahang involving 6 villages of Orang Asli Bateq and Semai. Study sample was chosen using convenient sampling including adults aged 16 years and above. Participants were invited for an interview using structured questionnaire followed by clinical examination. Data analysis was carried out using SPSS ver12.
Results: Response rate was low at 20% (n = 140). Over one-quarter (26.4%) of the sample experienced OFP in the previous 3 months. Toothache was found to be the main aetiology (83.3%) followed by gingival pain (18.9%), temporomandibular joint (10.8%) and facial pain (8.1%). Mean duration of pain was 9.8 days for toothache, 162.4 days for gingival pain, 7.3 days for TMJ and 5.7 days for facial pain. Of those who had OFP, over half rated the pain as moderate (37.8%) and severe (29.7%) and most of the pain was ‘intermittent’ in nature (81.1%). Over half (62.2%) admitted the pain had disappeared during the interview. In terms of pain relief, 56.8% of the sample used traditional medicine. The pain had impacted on the chewing ability (70.3%, p=0.01), ability to sleep at night (73.0%, p<0.001), levels of anxiety (70.3%), ability to perform daily chores (33.3%) and social life (35.1%) of the Orang Asli sample.
Conclusion: This study suggests the prevalence of OFP was high among the Orang Asli sample, which imposed considerable physical and psychological impacts on daily life.
Key words: orofacial pain; impacts; quality of life; Malaysian aborigines
The thermoluminescence response of doped SiO2 optical fibres subjected to fast neutrons

Hashim S, Bradley DA, Saripan MI, Ramli AT, Wagiran H

Appl Radiat Isot, 2010 Apr-May;68(4-5):700-3.
PMID: 19892557 DOI: 10.1016/j.apradiso.2009.10.027

This paper describes a preliminary study of the thermoluminescence (TL) response of doped SiO(2) optical fibres subjected to (241)AmBe neutron irradiation. The TL materials, which comprise Al- and Ge-doped silica fibres, were exposed in close contact with the (241)AmBe source to obtain fast neutron interactions through use of measurements obtained with and without a Cd filter (the filter being made to entirely enclose the fibres). The neutron irradiations were performed for exposure times of 1-, 2-, 3-, 5- and 7-days in a neutron tank filled with water. In this study, use was also made of the Monte Carlo N-particle (MCNP) code version 5 (V5) to simulate the neutron irradiations experiment. It was found that the commercially available Ge-doped and Al-doped optical fibres show a linear dose response subjected to fast neutrons from (241)AmBe source up to seven days of irradiations. The simulation performed using MCNP5 also exhibits a similar pattern, albeit differing in sensitivity. The TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre, the total absorption cross section for Ge in both the fast and thermal neutrons region being some ten times greater than that of Al.
The thermoluminescence response of doped SiO2 optical fibres subjected to photon and electron irradiations

Hashim S, Al-Ahbabi S, Bradley DA, Webb M, Jeynes C, Ramli AT, et al.

Appl Radiat Isot, 2009 Mar;67(3):423-7.
PMID: 18693024 DOI: 10.1016/j.apradiso.2008.06.030

Modern linear accelerators, the predominant teletherapy machine in major radiotherapy centres worldwide, provide multiple electron and photon beam energies. To obtain reasonable treatment times, intense electron beam currents are achievable. In association with this capability, there is considerable demand to validate patient dose using systems of dosimetry offering characteristics that include good spatial resolution, high precision and accuracy. Present interest is in the thermoluminescence response and dosimetric utility of commercially available doped optical fibres. The important parameter for obtaining the highest TL yield during this study is to know the dopant concentration of the SiO2 fibre because during the production of the optical fibres, the dopants tend to diffuse. To achieve this aim, proton-induced X-ray emission (PIXE), which has no depth resolution but can unambiguously identify elements and analyse for trace elements with detection limits approaching microg/g, was used. For Al-doped fibres, the dopant concentration in the range 0.98-2.93 mol% have been estimated, with equivalent range for Ge-doped fibres being 0.53-0.71 mol%. In making central-axis irradiation measurements a solid water phantom was used. For 6-MV photons and electron energies in the range 6, 9 and 12 MeV, a source to surface distance of 100 cm was used, with a dose rate of 400 cGy/min for photons and electrons. The TL measurements show a linear dose-response over the delivered range of absorbed dose from 1 to 4 Gy. Fading was found to be minimal, less than 10% over five days subsequent to irradiation. The minimum detectable dose for 6-MV photons was found to be 4, 30 and 900 microGy for TLD-100 chips, Ge- and Al-doped fibres, respectively. For 6-, 9- and 12-MeV electron energies, the minimum detectable dose were in the range 3-5, 30-50 and 800-1400 microGy for TLD-100 chip, Ge-doped and Al-doped fibres, respectively.
Thermoluminescence dosimetry properties and kinetic parameters of lithium potassium borate glass co-doped with titanium and magnesium oxides

Hashim S, Alajerami YS, Ramli AT, Ghoshal SK, Saleh MA, Abdul Kadir AB, et al.

Appl Radiat Isot, 2014 Sep;91:126-30.
PMID: 24929526 DOI: 10.1016/j.apradiso.2014.05.023

Lithium potassium borate (LKB) glasses co-doped with TiO2 and MgO were prepared using the melt quenching technique. The glasses were cut into transparent chips and exposed to gamma rays of (60)Co to study their thermoluminescence (TL) properties. The TL glow curve of the Ti-doped material featured a single prominent peak at 230 °C. Additional incorporation of MgO as a co-activator enhanced the TL intensity threefold. LKB:Ti,Mg is a low-Z material (Z(eff)=8.89) with slow signal fading. Its radiation sensitivity is 12 times lower that the sensitivity of TLD-100. The dose response is linear at doses up to 10(3) Gy. The trap parameters, such as the kinetics order, activation energy, and frequency factor, which are related to the glow peak, were determined using TolAnal software.
Thermoluminescence responses of photon- and electron-irradiated lithium potassium borate co-doped with Cu+Mg or Ti+Mg

Alajerami YS, Hashim S, Ramli AT, Saleh MA, Saripan MI, Alzimami K, et al.

Appl Radiat Isot, 2013 Aug;78:21-5.
PMID: 23644162 DOI: 10.1016/j.apradiso.2013.03.095

New glasses Li2CO3-K2CO3-H3BO3 (LKB) co-doped with CuO and MgO, or with TiO2 and MgO, were synthesized by the chemical quenching technique. The thermoluminescence (TL) responses of LKB:Cu,Mg and LKB:Ti,Mg irradiated with 6 MV photons or 6 MeV electrons were compared in the dose range 0.5-4.0 Gy. The standard commercial dosimeter LiF:Mg,Ti (TLD-100) was used to calibrate the TL reader and as a reference in comparison of the TL properties of the new materials. The dependence of the responses of the new materials on (60)Co dose is linear in the range of 1-1000 Gy. The TL yields of both of the co-doped glasses and TLD-100 are greater for electron irradiation than for photon irradiation. The TL sensitivity of LKB:Ti,Mg is 1.3 times higher than the sensitivity of LKB:Cu,Mg and 12 times less than the sensitivity of TLD-100. The new TL dosimetric materials have low effective atomic numbers, good linearity of the dose responses, excellent signal reproducibility, and a simple glow curve structure. This combination of properties makes them suitable for radiation dosimetry.

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