Displaying publications 61 - 80 of 110 in total

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  1. Fulltext Towards 5G: A Photonic Based Millimeter Wave Signal Generation for Applying in 5G Access Fronthaul
    Alavi SE, Soltanian MR, Amiri IS, Khalily M, Supa'at AS, Ahmad H
    Sci Rep, 2016 Jan 27;6:19891.
    PMID: 26814621 DOI: 10.1038/srep19891
    5G communications require a multi Gb/s data transmission in its small cells. For this purpose millimeter wave (mm-wave) RF signals are the best solutions to be utilized for high speed data transmission. Generation of these high frequency RF signals is challenging in electrical domain therefore photonic generation of these signals is more studied. In this work, a photonic based simple and robust method for generating millimeter waves applicable in 5G access fronthaul is presented. Besides generating of the mm-wave signal in the 60 GHz frequency band the radio over fiber (RoF) system for transmission of orthogonal frequency division multiplexing (OFDM) with 5 GHz bandwidth is presented. For the purpose of wireless transmission for 5G application the required antenna is designed and developed. The total system performance in one small cell was studied and the error vector magnitude (EVM) of the system was evaluated.
  2. Fulltext Increment of Access Points in Integrated System of Wavelength Division Multiplexed Passive Optical Network Radio over Fiber
    Amiri IS, Alavi SE, Soltanian MR, Fisal N, Supa'at AS, Ahmad H
    Sci Rep, 2015;5:11897.
    PMID: 26153536 DOI: 10.1038/srep11897
    This paper describes a novel technique to increase the numbers of access points (APs) in a wavelength division multiplexed-passive optical network (WDM-PON) integrated in a 100 GHz radio-over-fiber (RoF). Eight multi-carriers separated by 25 GHz intervals were generated in the range of 193.025 to 193.200 THz using a microring resonator (MRR) system incorporating an add-drop filter system. All optically generated multi-carriers were utilized in an integrated system of WDM-PON-RoF for transmission of four 43.6 Gb/sec orthogonal frequency division multiplexing (OFDM) signals. Results showed that an acceptable BER variation for different path lengths up to 25 km was achievable for all four access points and thus the transmission of four OFDM channels is feasible for a 25 km standard single mode fiber (SSMF) path length.
  3. Effect of an extract of Erioglossum edule on the central nervous system
    Sattar MA, Gan EK, Loke SE, Mah KF, Wong WH
    J Ethnopharmacol, 1989 Apr;25(2):217-20.
    PMID: 2747256
  4. Plasmodium falciparum: gene structure and hydropathy profile of the major merozoite surface antigen (gp195) of the Uganda-Palo Alto isolate
    Chang SP, Kramer KJ, Yamaga KM, Kato A, Case SE, Siddiqui WA
    Exp Parasitol, 1988 Oct;67(1):1-11.
    PMID: 3049134
    The gene encoding the 195,000-Da major merozoite surface antigen (gp195) of the FUP (Uganda-Palo Alto) isolate of Plasmodium falciparum, a strain widely used for monkey vaccination experiments, has been cloned and sequenced. The translated amino acid sequence of the FUP gp195 protein is closely related to the sequences of corresponding proteins of the CAMP (Malaysia) and MAD-20 (Papua New Guinea) isolates and more distantly related to those of the Wellcome (West Africa) and K1 (Thailand) isolates, supporting the proposed allelic dimorphism of gp195 within the parasite population. The prevalence of dimorphic sequences within the gp195 protein suggests that many gp195 epitopes would be group-specific. Despite the extensive differences in amino acid sequence between gp195 proteins of these two groups, the hydropathy profiles of proteins representative of both groups are very similar. The conservation of overall secondary structure shown by the hydropathy profile comparison indicates that gp195 proteins of the various P. falciparum isolates are functionally equivalent. This information on the primary structure of the FUP gp195 protein will enable us to evaluate the possible roles of conserved, group-specific and variable epitopes in immunity to the blood stage of the malaria parasite.
  5. Development and validation of a new vision screening test algorithm for public use mobile application- A pilot study
    Siti Nor Aishah AR, Mutalib A, Asma H, Baig AA, Naing NN, Hashim SE, et al.
    Med J Malaysia, 2020 11;75(6):685-690.
    PMID: 33219178
    OBJECTIVES: To design and develop a simple vision test algorithm for mobile application and perform a pilot study to determine its validity and reliability as a tool for vision test in the community.

    METHODS: A simple visual acuity test algorithm in the form of a single letter E display was designed as the optotype for development of a mobile application. The standardised optotype is presented at random to test visual acuity for corresponding level of 3/60, 6/60, 6/18, and 6/12. The final result is auto-generated based on the classification of the WHO for visual impairment and blindness. The Snellen chart was used as the gold standard to determine its validity while five different users were involved to determine its inter-rater reliability. A pilot study was performed between April till November 2019, in the Universiti Sultan Zainal Abidin Medical Centre (UMC) at Kuala Nerus and Mooris Optometrist Centre at Marang, Terengganu. A total of 279 participants aged four years old and above were involved in this study.

    RESULTS: The highest sensitivity was found at the vision level cut-off point of 6/12 with the percentage of 92.7% and 86.8% for the right and left eye, respectively. The specificity was more than 89% for all vision levels in both eyes. The Krippendorff's alpha value for the inter-rater reliability was 0.87 and 0.83.

    CONCLUSION: The relatively high level of validity and reliability obtained indicate the feasibility of using the designed optotype to develop a valid and reliable mobile app for vision test. The app can be used to screen vision by nonmedical persons, at anytime and anywhere to help improve public awareness and capability to correctly determine their visual status.

  6. Paediatric cataract surgery in Hospital Kuala Lumpur - A 5-year review of visual outcomes
    Chew FLM, Qurut SE, Hassan I, Lim ST, Ramasamy S, Rahmat J
    Med J Malaysia, 2019 02;74(1):15-19.
    PMID: 30846656
    INTRODUCTION: Paediatric cataract surgery is challenging with reported post-operative visual acuity (VA) of 0.3LogMar or better varying between 33% to 68% of patients.

    OBJECTIVE: The aim is to document the post-operative refraction, VA and complications of non-traumatic pediatric cataract surgery performed in a tertiary referral center in Malaysia.

    METHODOLOGY: This retrospective study reviewed case notes of all consecutive patients aged 12 years and below who underwent cataract surgery from January 2010 to December 2015. Patients were recruited if they had a minimum of six months post-operative follow-up. Exclusion criteria included traumatic cataract, central nervous system abnormalities, incomplete medical records or pre-existing ocular pathology. Subjects were divided into two groups based on refraction at one month. Subjects with refraction within 1- dioptre of the targeted spherical equivalent were in the success group and the rest were in the failure group.

    RESULTS: A total of 111 subjects were recruited (65 subjects in success group and 46 subjects in the failure group). Mean age at surgery was 33.14 (SD: 33.47) months. The success group had significantly longer axial length (p:0.0045, CI: 0.566-0.994, OR: 0.750). At final review, 44.1%(49/111) subjects had visual acuity of 0.3LogMar or better. The success group had better final mean VA in comparison to the failure group (p:0.034, CI:1.079-7.224, OR: 2.791).

    CONCLUSION: The outcome of non-traumatic paediatric cataract surgery was acceptable with 58.6% achieved targeted refractive correction at 1-month post-operative period. Longer axial length was associated with better refractive outcome. Capsule related complications was the most common intra-operative complication.

  7. Evaluating the performance of MM/PBSA for binding affinity prediction using class A GPCR crystal structures
    Yau MQ, Emtage AL, Chan NJY, Doughty SW, Loo JSE
    J Comput Aided Mol Des, 2019 05;33(5):487-496.
    PMID: 30989574 DOI: 10.1007/s10822-019-00201-3
    The recent expansion of GPCR crystal structures provides the opportunity to assess the performance of structure-based drug design methods for the GPCR superfamily. Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA)-based methods are commonly used for binding affinity prediction, as they provide an intermediate compromise of speed and accuracy between the empirical scoring functions used in docking and more robust free energy perturbation methods. In this study, we systematically assessed the performance of MM/PBSA in predicting experimental binding free energies using twenty Class A GPCR crystal structures and 934 known ligands. Correlations between predicted and experimental binding free energies varied significantly between individual targets, ranging from r = - 0.334 in the inactive-state CB1 cannabinoid receptor to r = 0.781 in the active-state CB1 cannabinoid receptor, while average correlation across all twenty targets was relatively poor (r = 0.183). MM/PBSA provided better predictions of binding free energies compared to docking scores in eight out of the twenty GPCR targets while performing worse for four targets. MM/PBSA binding affinity predictions calculated using a single, energy minimized structure provided comparable predictions to sampling from molecular dynamics simulations and may be more efficient when computational cost becomes restrictive. Additionally, we observed that restricting MM/PBSA calculations to ligands with a high degree of structural similarity to the crystal structure ligands improved performance in several cases. In conclusion, while MM/PBSA remains a valuable tool for GPCR structure-based drug design, its performance in predicting the binding free energies of GPCR ligands remains highly system-specific as demonstrated in a subset of twenty Class A GPCRs, and validation of MM/PBSA-based methods for each individual case is recommended before prospective use.
  8. Fulltext Author Correction: Towards 5G: A Photonic Based Millimeter Wave Signal Generation for Applying in 5G Access Fronthaul
    Alavi SE, Soltanian MRK, Amiri IS, Khalily M, Supa'at ASM, Ahmad H
    Sci Rep, 2020 Jul 22;10(1):12147.
    PMID: 32699388 DOI: 10.1038/s41598-020-69377-1
    An amendment to this paper has been published and can be accessed via a link at the top of the paper.
  9. Assessing GPCR homology models constructed from templates of various transmembrane sequence identities: Binding mode prediction and docking enrichment
    Loo JSE, Emtage AL, Ng KW, Yong ASJ, Doughty SW
    J Mol Graph Model, 2017 Dec 29;80:38-47.
    PMID: 29306746 DOI: 10.1016/j.jmgm.2017.12.017
    GPCR crystal structures have become more readily accessible in recent years. However, homology models of GPCRs continue to play an important role as many GPCR structures remain unsolved. The new crystal structures now available provide not only additional templates for homology modelling but also the opportunity to assess the performance of homology models against their respective crystal structures and gain insight into the performance of such models. In this study we have constructed homology models from templates of various transmembrane sequence identities for eight GPCR targets to better understand the relationship between transmembrane sequence identity and model quality. Model quality was assessed relative to the crystal structure in terms of structural accuracy as well as performance in two typical structure-based drug design applications: ligand binding pose prediction and docking enrichment in virtual screening. Crystal structures significantly outperformed homology models in both assessments. Accurate ligand binding pose prediction was possible but difficult to achieve using homology models, even with the use of induced fit docking. In virtual screening using homology models still conferred significant enrichment compared to random selection, with a clear benefit also observed in using models optimized through induced fit docking. Our results indicate that while homology models that are reasonably accurate structurally can be constructed, without significant refinement homology models will be outperformed by crystal structures in ligand binding pose prediction and docking enrichment regardless of the template used, primarily due to the extremely high level of structural accuracy needed for such applications.
  10. Fulltext A survey on burnout and depression risk among anaesthetists during COVID-19: the tip of an iceberg?
    Tsan SEH, Kamalanathan A, Lee CK, Zakaria SA, Wang CY
    Anaesthesia, 2021 03;76 Suppl 3:8-10.
    PMID: 32776524 DOI: 10.1111/anae.15231
  11. Fulltext Sharps injury in Hospital Universiti Kebangsaan Malaysia (HUKM): experiences of health care workers and students
    Santhna LP, Samsiah M, Raja Lexshimi RG, Roshdinom R, Ho SE, Hamidah H
    Medicine & Health, 2007;2(1):86-92.
    MyJurnal
    Sharps injury among health care workers in HUKM has received serious attention lately due to the possible transmission of diseases like HIV, Hepatits B and Hepatitis C, which can cause serious consequences for the victim. The aim of the study was to gain a deeper understanding of the emotional problems experienced by health care workers who had incurred a sharps injury and the coping strategies adopted by them to overcome the problem. A 28 item semi-structured questionnaire was designed by the supervisors and the researcher as there was no existing questionnaire to be adopted, as no research had been carried out in this area prior to this. The target group consisted of 64 health care workers of different categories working in HUKM. Data was collected over a period of five months from November 2000 to March 2001. The results of the study revealed that the most frequently injured were the staff nurses, nearly 90% of whom were emotionally upset and were worried that they might contract a disease. There was no significant difference in the emotional stress experienced by the different categories of the health care workers, all were equally upset about the injury but each category of staff adopted different methods to overcome the tragedy. Open comments and opinions about prevention and the management of the sharps injury in HUKM as given by the respondents here are taken into account. Several views given by the participants were explored and discussed. Finally, several implications for nursing and recommendations have been presented.
    Study site: Wards and the general operating theatres in Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
  12. Is arthroscopic assisted percutaneous screw fixation as good as open reduction and internal fixation for the treatment of displaced intra-articular calcaneal fractures?
    Yeap EJ, Rao J, Pan CH, Soelar SA, Younger ASE
    Foot Ankle Surg, 2016 Sep;22(3):164-169.
    PMID: 27502224 DOI: 10.1016/j.fas.2015.06.008
    BACKGROUND: This study compares the outcomes of calcaneal fracture surgery after open reduction internal fixation and plating (ORIF) versus arthroscopic assisted percutaneous screw fixation (APSF).

    METHODS: Group I (N=12) underwent ORIF. Group II (N=15) underwent APSF. Anthropometric data, pre and post-operative stay, complications and duration off work were recorded in this retrospective case cohort study. Radiographs were analyzed for Bohler's, Gissane's angle and Sanders' classification. AOFAS Hindfoot and SF 36 scores were collected at final follow-up.

    RESULTS: Anthropometric data, Bohler's and Gissane's angles, AOFAS and SF 36 scores were not significantly different. Pre-operative duration was 12.3 days in ORIF and 6.9 days in APSF. Post-operative duration was 7.3 days vs 3.8 days. Duration off work was 6.2 months vs 2.9 months.

    CONCLUSION: The APSF group was able to have surgery earlier, go home faster, and return to work earlier. This study was not powered to demonstrate a difference in wound complication rates.

  13. Fulltext A study on anxiety and depression level among high risk inpatient pregnant women in an obstetric ward
    Raja Lexshimi RG, Ho SE, Hamidah H, Rohani M, Syed Zulkifli SZ
    Medicine & Health, 2007;2(1):34-41.
    MyJurnal
    Pregnancy is perceived by many pregnant mothers as a period of happiness in anticipation of motherhood. Not all pregnant mothers experience cheerfulness as some may experience a high anxiety and depression level for unknown reasons. The purpose of this study was to determine the level of anxiety and depression among high risk pregnant women and the factors that contribute to their level of anxiety and depression. A descriptive cross-sectional study was conducted on 38 high risk mothers whose stay in hospital exceeded more than three days in the obstetric ward of Hospital Universiti Kebangsaan Malaysia. A self assessment questionnaire “Hospital Anxiety Depression scale” was used to measure the level of anxiety and depression among high risk pregnant women. Of the 38 participants, 16 (42.1%) women experienced a mild level of anxiety and 22 (57.9%) experienced a severe level of anxiety. Seventeen (44.7%) women was classified as having mild depression and 21 (55.3%) severe depression. The factors contributing to the level of anxiety and depression, include those related with “lack of information on disease”, “family matters” and “finance”. High risk pregnant women in this study experienced a significant level of anxiety and depression during their stay in hospital. It is therefore important for nurses and doctors to be aware and sensitive to the influencing factors that cause anxiety and depression as to enable high risk pregnant mothers to enjoy their pregnancy and childbirth.
    Study site: Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
  14. Fulltext Real-time ultrasound-guided paramedian spinal anaesthesia: evaluation of the efficacy and the success rate of single needle pass
    Chong SE, Mohd Nikman A, Saedah A, Wan Mohd Nazaruddin WH, Kueh YC, Lim JA, et al.
    Br J Anaesth, 2017 05 01;118(5):799-801.
    PMID: 28510752 DOI: 10.1093/bja/aex108
  15. Associations of pre-pregnancy body mass index, middle-upper arm circumference, and gestational weight gain
    Ng CM, Badon SE, Dhivyalosini M, Hamid JJM, Rohana AJ, Teoh AN, et al.
    Sex Reprod Healthc, 2019 Jun;20:60-65.
    PMID: 31084820 DOI: 10.1016/j.srhc.2019.03.002
    OBJECTIVES: An optimal gestational weight gain is essential for maternal health and to reduce adverse birth outcomes. Current guidelines to monitor gestational weight gain are based on pre-pregnancy body mass index (BMI). However, middle-upper arm circumference (MUAC) is increasingly used as an alternative nutritional status measure for pregnant women. Hence, this study aimed to determine associations of MUAC and pre-pregnancy BMI with gestational weight gain rate among Malaysian pregnant women.

    STUDY DESIGN: A cross-sectional study was conducted among 444 pregnant women (≥20 weeks gestation).

    MAIN OUTCOMES MEASURES: Women completed questionnaires on sociodemographic data, maternal characteristics and pre-pregnancy weight. Height, current weight and MUAC were measured at study visit (from 1st February 2016 to 31st January 2017).

    RESULTS: About a third (34.24%) of pregnant women were overweight or obese prior to pregnancy. MUAC was inversely associated with an inadequate rate of gestational weight gain (OR = 0.77; 95% CI: 0.68, 0.87) as compared to normal gestational weight gain. In contrast, a higher MUAC was associated with a higher odds ratio (OR = 1.28; 95% CI: 1.11, 1.49) of having excessive rate of gestational weight. No associations were found for pre-pregnancy BMI categories for gestational weight gain rate.

    CONCLUSION: Our findings revealed that women with low MUAC were more likely to have an inadequate gestational weight gain rate during pregnancy whereas higher MUAC was associated with an excessive gestational weight gain rate. MUAC may be a useful indicator of nutritional status associated with GWG. Routine measurement of MUAC in pregnant women may help health professionals, particularly in middle-income countries, to counsel women about gestational weight gain.

  16. Therapeutic effect of Moringa oleifera and Thymus vulgaris oils against hepatic coccidiosis in experimentally infected rabbits
    Abu El Ezz NMT, Aboelsoued D, Hassan SE, Abdel Megeed KN, El-Metenawy TM
    Trop Biomed, 2020 Dec 01;37(4):1018-1028.
    PMID: 33612754 DOI: 10.47665/tb.37.4.1018
    The present study was conducted to detect the therapeutic effect of Moringa oleifera and Thymus vulgaris oils on hepatic coccidiosis in experimentally infected rabbits. Also, immunomodulatory effect of the two oils was detected. Twenty-four Newzealand rabbits were used in this study and divided into 4 groups; healthy rabbits, experimentally infected rabbits with Eimeria stiedae oocysts, and two infected treated groups (one with moringa (200 mg/kg) and the other with thyme (500 mg/kg) oils). The results showed highly significant reduction in oocysts shedding (P<0.001 and P<0.05) in the two infected and treated rabbits than the infected non-treated rabbits in almost all days post infection (PI). Thyme oil was more potent and stopped oocysts shedding earlier at the day 34 PI compared to moringa oil at the day 41 PI. Microscopically, there was a damage in the oocysts shed by treated rabbits. Macroscopically, the livers of thyme oil treated rabbits showed more enhancement with protection percentage 75% than those treated with moringa oil in which protection percentage was 55%. The highest titer of antibodies was detected in moringa oil treated rabbits. It was concluded that both moringa and thyme oils had an anti-coccidial effect with thyme oil superiority. So, thyme oil could be useful as an alternative product for the control of rabbit coccidiosis.
  17. Small-field output ratio determination using 6 mol% Ge-doped silica fibre dosimeters
    Lam SE, Noor NM, Bradley DA, Mahmud R, Pawanchek M, Abdul Rashid HA
    Biomed Phys Eng Express, 2020 Nov 05;6(6).
    PMID: 35042836 DOI: 10.1088/2057-1976/abc2a4
    This work investigates the suitability of locally fabricated 6 mol% Ge-doped optical fibres as dosimeters for small-field output ratio measurements. Two fabrications of fibre, cylindrical (CF) and flat (FF) fibres, were used to measure doses in small photon fields, from 4 to 15 mm. The findings were compared to those of commercial Ge-doped fibre (COMM), EBT3 film and an IBA CC01 ionization chamber. Irradiations were carried out using a 6 MV SRS photon beam operating at a dose rate of 1000 cGy min-1, delivering a dose of 16 Gy. To minimise the possibility of the fibres failing to be exposed to the intended dose in small fields, the fibres were accommodated in a custom-made Perspex phantom. For the 4 mm cone the CF and FF measured output ratios were found to be smaller than obtained with EBT3 film by 32% and 13% respectively. Conversely, while for the 6 to 15 mm cone fields the FF output ratios were consistently greater than those obtained using EBT3 film, the CF output ratios differed from those of EBT3 film by at most 3.2%, at 6 mm, otherwise essentially agreeing with EBT3 values at the other field sizes. For the 4 to 7.5 mm cones, all output ratios obtained from Ge-doped optical fibre measurements were greater than those of IBA CC01 ionization chamber. The measured FF and CF output ratios for the 7.5 to 15 mm cones agreed with published MC estimates to within 15% and 13%, respectively. Down to 6 mm cone field, present measurements point to the potential of CF as a small-field dosimeter, its use recommended to be complemented by the use of EBT3 film for small-field dosimetry.
  18. The patellar tendon bar! Is it a necessary feature?
    Abu Osman NA, Spence WD, Solomonidis SE, Paul JP, Weir AM
    Med Eng Phys, 2010 Sep;32(7):760-5.
    PMID: 20678997 DOI: 10.1016/j.medengphy.2010.04.020
    The purpose of this investigation was to vary the load on the patellar tendon bar and to study the subsequent effect this has on the pattern of the pressure distribution at the stump-socket interface. Ten male subjects from the Southern General Hospital in Glasgow, UK participated in this study. Measuring systems utilising strain gauge and electrohydraulic technologies were designed, developed and constructed to enable pressure measurements to be conducted. One transducer, the patellar tendon (PT) transducer, was attached to the patellar tendon bar of the socket such that the patellar tendon bar was capable of being translated by +/-10 mm towards or away from the tendon. The results of this study showed that the position of the patellar tendon bar had no significant effect on the pressure distribution around the socket indicating that it is an unnecessary feature, which, we propose, may be eliminated during manufacture of a trans-tibial socket.
  19. First molecular detection of porcine circovirus type 4 (PCV4) in Malaysia
    Tan CY, Thanawongnuwech R, Arshad SS, Hassan L, Lee CY, Low SE, et al.
    Trop Biomed, 2023 Sep 01;40(3):301-306.
    PMID: 37897162 DOI: 10.47665/tb.40.3.005
    Porcine circovirus type 4 (PCV4) is the newest member in the porcine circovirus family, first reported in 2020. To date, the presence of PCV4 has only been reported in China, South Korea and most recently in Thailand. Detection of PCV4 have been reported in various production stages of pigs from piglets, finishers to sows; associated with a myriad of clinical manifestations including porcine dermatitis and nephropathy syndrome (PDNS), postweaning multisystemic wasting syndrome (PMWS), respiratory, enteric and neurological diseases. While successful virus isolation and culture has yet to be reported, pathogenicity of PCV4 has been demonstrated through infectious clone studies. The objective of this study is to investigate the presence of PCV4 in Malaysian porcine population to update the epidemiology of porcine circoviruses in Malaysia. A total of 49 samples from commercial intensive pig farms, abattoir and wild boar population were subjected to conventional polymerase chain reaction assay to detect PCV4 capsid (cap) genome. Resulting cap nucleotide sequences were analyzed for maximum likelihood phylogeny relationship. Results revealed that PCV4 is present in Peninsular Malaysia at a molecular prevalence of 4.08% (2 / 49 samples). Both PCV4 positive samples originated from clinically healthy finishers. Malaysian PCV4 strains were classified as genotype PCV4b, and were found to be phylogenetically distinct from the China, South Korea and Thailand strains. With this latest update of the novel PCV4 in Malaysia, it is clear that more attention needs to be given to the investigation of novel porcine circoviruses (PCV) and management of PCV diseases.
  20. Carbon rich media for luminescence-based surface dosimetry and study of associated surface defects
    Lam SE, Bradley DA, Mat Nawi SN, Khandaker MU, Abdul Sani SF
    Appl Radiat Isot, 2023 Sep;199:110920.
    PMID: 37419002 DOI: 10.1016/j.apradiso.2023.110920
    The present study continues research into the utilisation of carbonaceous media for medical radiation dosimetry, focusing on the effects of surface area-to-volume ratio and carbon content on structural interaction alterations and dosimetric properties in sheet- and bead-type graphitic materials (with the respective carbon content of ∼98 wt% and ∼90 wt%). Using 60Co gamma-rays and doses from 0.5 Gy to 20 Gy, the study has been made of the response of commercially available graphite in the form of 0.1 mm, 0.2 mm, 0.3 mm and 0.5 mm thick sheets, also of activated carbon beads. Confocal Raman and photoluminescence spectroscopy have been employed, examining radiation-induced structural interaction alterations. Dose-dependent variation in the Raman intensity ratio ID/IG relates to the varying dominance of defect generation and dose-driven defect annealing. Of the various thickness graphite sheets, the 0.1 mm thick medium possesses the greatest surface area-to-volume ratio. Perhaps unsurprisingly, it also exhibits the greatest thermoluminescence (TL) yield compared to that of the other carbonaceous sheet foils used herein. Moreover, the second greatest mass-normalised TL yield has been observed to be that of the porous beads, reflected in the greater defect density (ID/IG > 2) when compared to the other media, due in part to their inherent feature of large internal surface area. Considering the challenge posed in matching skin thickness with skin dose, the near tissue equivalent graphite sheets show particular promise as a skin dosimeter, sensitive as a function of depth.
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