Displaying publications 1 - 20 of 283 in total

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  1. Ng KH, Abdullah BJJ, Rassiah P, Sivalingam S
    Med J Malaysia, 1999 Jun;54(2):185-91.
    PMID: 10972028
    X-ray based radiological procedure statistics and trend in Malaysia for 1990-1994 is reported; this information allows comparisons to be made with the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) Report. Additionally it is essential information for health care planners and providers. Malaysia is categorised as a health care level II country based on the UNSCEAR definition. In 1994, the number of physicians, radiologists, x-ray units and x-ray examinations per 1000 population was 0.45, 0.005, 0.065 and 183 respectively. 3.6 million x-ray examinations were performed in 1994, with chest radiography being the commonest study (63%). Information on x-ray examinations, number of hospitals and x-ray units is reported for the Ministry of Health, private practice and teaching hospitals. Examination frequency increased in computed tomography (161%), cardiac procedures (190%), and mammography (240%); while a decrease in barium studies (-23%), cholecystography (-36%), and intravenous urography (-51%) was noted. There is a potential and need to expand and upgrade radiological services.
  2. Ng KH, Peh WC
    Singapore Med J, 2008 Dec;49(12):967-8; quiz 969.
    PMID: 19122944
    The purpose of the results section is to present the main data collected and the observations made during the research. It provides interpretation of the analysed data and does not contain details on the methods, materials or discussion. The first step in writing the results section is to review the analysed data and determine which results to present. This can be done by deciding which results are relevant to the question(s) presented in the introduction, and may be supplemented by illustrative tables and figures. The results section guides the reader through the questions investigated in the study and sets the stage for the discussion in the next section.
  3. Ng KH, Peh WC
    Singapore Med J, 2008 Nov;49(11):856-8; quiz 859.
    PMID: 19037549
    When writing scientific papers to share their research findings with their peers, it is not enough for researchers to just communicate the results of their study; it is equally important to explain the process by which they arrived at their results, so that the study can be replicated to validate the observations. The materials and methods section is used to describe the experimental design and provide sufficient details so that a competent colleague can repeat the experiment. A good materials and methods section will enable readers to evaluate the research performed and replicate the study, if necessary.
  4. Ng KH, Peh WC
    Singapore Med J, 2009 May;50(5):458-60; quiz 461.
    PMID: 19495512
    The discussion section comprises the last component in the IMRAD system. The purpose of this section is to provide the interpretation of the results obtained, explain the implications of the findings, state study limitations and make suggestions for future research. This is a critical part of the scientific paper, as it places the particular study within the broader context of how the research contributes to improving diagnosis, treatment or patient care.
  5. Ng KH, Peh WC
    Singapore Med J, 2010 Feb;51(2):101-3; quiz 104.
    PMID: 20358146
    A technical note is a short article giving a brief description of a specific development, technique or procedure, or it may describe a modification of an existing technique, procedure or device applicable to medicine. The technique, procedure or device described should have practical value and should contribute to clinical diagnosis or management. It could also present a software tool, or an experimental or computational method. Technical notes are variously referred to as technical innovations or technical developments. The main criteria for publication will be the novelty of concepts involved, the validity of the technique and its potential for clinical applications.
  6. Ng KH, Peh WC
    Singapore Med J, 2010 May;51(5):362-6.
    PMID: 20593139
    Evidence-based medicine (EBM) aims to combine the best available scientific evidence with clinical experience and individual judgment of patient needs. In the hierarchy of scientific evidence, systematic reviews (along with meta-analyses) occupy the highest levels in terms of the quality of evidence. A systematic review is the process of searching, selecting, appraising, synthesising and reporting clinical evidence on a particular question or topic. It is currently considered the best, least biased and most rational way to organise, gather, evaluate and integrate scientific evidence from the rapidly-changing medical and healthcare literature. Systematic reviews could be used to present current concepts or serve as review articles and replace the traditional expert opinion or narrative review. This article explains the structure and content of a systematic review.
  7. Peh WC, Ng KH
    Singapore Med J, 2010 Jan;51(1):10-3; quiz 14.
    PMID: 20200769
    A case report is a description of a single case with unique features. This includes a previously-unreported clinical condition, previously-unreported observation of a recognised disease, unique use of imaging or diagnostic test to reveal a disease, previously-unreported treatment in a recognised disease, or previously-unreported complication of a procedure. Case reports should be short and focused, with a limited number of figures and references. The structure of a case report usually comprises a short unstructured (or no) abstract, brief (or no) introduction, succinct but comprehensive report of the case, and to-the-point discussion.
  8. Saffor A, bin Ramli AR, Ng KH
    Australas Phys Eng Sci Med, 2003 Jun;26(2):39-44.
    PMID: 12956184
    Wavelet-based image coding algorithms (lossy and lossless) use a fixed perfect reconstruction filter-bank built into the algorithm for coding and decoding of images. However, no systematic study has been performed to evaluate the coding performance of wavelet filters on medical images. We evaluated the best types of filters suitable for medical images in providing low bit rate and low computational complexity. In this study a variety of wavelet filters are used to compress and decompress computed tomography (CT) brain and abdomen images. We applied two-dimensional wavelet decomposition, quantization and reconstruction using several families of filter banks to a set of CT images. Discreet Wavelet Transform (DWT), which provides efficient framework of multi-resolution frequency was used. Compression was accomplished by applying threshold values to the wavelet coefficients. The statistical indices such as mean square error (MSE), maximum absolute error (MAE) and peak signal-to-noise ratio (PSNR) were used to quantify the effect of wavelet compression of selected images. The code was written using the wavelet and image processing toolbox of the MATLAB (version 6.1). This results show that no specific wavelet filter performs uniformly better than others except for the case of Daubechies and bi-orthogonal filters which are the best among all. MAE values achieved by these filters were 5 x 10(-14) to 12 x 10(-14) for both CT brain and abdomen images at different decomposition levels. This indicated that using these filters a very small error (approximately 7 x 10(-14)) can be achieved between original and the filtered image. The PSNR values obtained were higher for the brain than the abdomen images. For both the lossy and lossless compression, the 'most appropriate' wavelet filter should be chosen adaptively depending on the statistical properties of the image being coded to achieve higher compression ratio.
  9. Lau S, Ng KH, Abdul Aziz YF
    Br J Radiol, 2016 Oct;89(1066):20160258.
    PMID: 27452264 DOI: 10.1259/bjr.20160258
    OBJECTIVE: To investigate the sensitivity and robustness of a volumetric breast density (VBD) measurement system to errors in the imaging physics parameters including compressed breast thickness (CBT), tube voltage (kVp), filter thickness, tube current-exposure time product (mAs), detector gain, detector offset and image noise.

    METHODS: 3317 raw digital mammograms were processed with Volpara(®) (Matakina Technology Ltd, Wellington, New Zealand) to obtain fibroglandular tissue volume (FGV), breast volume (BV) and VBD. Errors in parameters including CBT, kVp, filter thickness and mAs were simulated by varying them in the Digital Imaging and Communications in Medicine (DICOM) tags of the images up to ±10% of the original values. Errors in detector gain and offset were simulated by varying them in the Volpara configuration file up to ±10% from their default values. For image noise, Gaussian noise was generated and introduced into the original images.

    RESULTS: Errors in filter thickness, mAs, detector gain and offset had limited effects on FGV, BV and VBD. Significant effects in VBD were observed when CBT, kVp, detector offset and image noise were varied (p 

  10. Ng KH, Lau S
    Med Phys, 2015 Dec;42(12):7059-77.
    PMID: 26632060 DOI: 10.1118/1.4935141
    Breast density is a strong predictor of the failure of mammography screening to detect breast cancer and is a strong predictor of the risk of developing breast cancer. The many imaging options that are now available for imaging dense breasts show great promise, but there is still the question of determining which women are "dense" and what imaging modality is suitable for individual women. To date, mammographic breast density has been classified according to the Breast Imaging-Reporting and Data System (BI-RADS) categories from visual assessment, but this is known to be very subjective. Despite many research reports, the authors believe there has been a lack of physics-led and evidence-based arguments about what breast density actually is, how it should be measured, and how it should be used. In this paper, the authors attempt to start correcting this situation by reviewing the history of breast density research and the debates generated by the advocacy movement. The authors review the development of breast density estimation from pattern analysis to area-based analysis, and the current automated volumetric breast density (VBD) analysis. This is followed by a discussion on seeking the ground truth of VBD and mapping volumetric methods to BI-RADS density categories. The authors expect great improvement in VBD measurements that will satisfy the needs of radiologists, epidemiologists, surgeons, and physicists. The authors believe that they are now witnessing a paradigm shift toward personalized breast screening, which is going to see many more cancers being detected early, with the use of automated density measurement tools as an important component.
  11. Lim BC, Kueh YC, Arifin WN, Ng KH
    MyJurnal
    Objective: To determine the factor structure of the Health Promoting Behaviours (HPB) component of Health Promoting Lifestyle Profile-II among undergraduate students in Universiti Sains Malaysia (USM) by confirmatory factor analysis (CFA).
    Methods: A cross sectional study was conducted among undergraduate students. The data was collected in the USM campus using a proportionate cluster sampling method. The HPB questionnaire was handed to students in the lecture hall and collected immediately when the lecture finished. CFA was conducted using robust maximum likelihood estimation due to violation of multivariate normality assumption. A three-factor model was tested for measurement model validity and construct validity.
    Results: A total of 788 students participated in the study. CFA of a 21-item, three-factor model yielded an adequate goodness-of-fit values. The measurement model also showed a good convergent and discriminant validity after model re-specification.
    Conclusion: The health promoting behaviours scale was proven to have a valid measurement model and reliable constructs. It was deemed suitable for use to measure the health promoting behaviours components of a healthy lifestyle among Malaysian undergraduate students. It was recommended to further conduct cross-validation studies in other Malaysian public universities to provide additional empirical evidence to support its use.
  12. Abdul Hadi MFR, Abdullah AN, Hashikin NAA, Ying CK, Yeong CH, Yoon TL, et al.
    Med Phys, 2022 Dec;49(12):7742-7753.
    PMID: 36098271 DOI: 10.1002/mp.15980
    PURPOSE: Monte Carlo (MC) simulation is an important technique that can help design advanced and challenging experimental setups. GATE (Geant4 application for tomographic emission) is a useful simulation toolkit for applications in nuclear medicine. Transarterial radioembolization is a treatment for liver cancer, where microspheres embedded with yttrium-90 (90 Y) are administered intra-arterially to the tumor. Personalized dosimetry for this treatment may provide higher dosimetry accuracy compared to the conventional partition model (PM) calculation. However, incorporation of three-dimensional tomographic input data into MC simulation is an intricate process. In this article, 3D Slicer, free and open-source software, was utilized for the incorporation of patient tomographic images into GATE to demonstrate the feasibility of personalized dosimetry in hepatic radioembolization with 90 Y.

    METHODS: In this article, the steps involved in importing, segmenting, and registering tomographic images using 3D Slicer were thoroughly described, before importing them into GATE for MC simulation. The absorbed doses estimated using GATE were then compared with that of PM. SlicerRT, a 3D Slicer extension, was then used to visualize the isodose from the MC simulation.

    RESULTS: A workflow diagram consisting of all the steps taken in the utilization of 3D Slicer for personalized dosimetry in 90 Y radioembolization has been presented in this article. In comparison to the MC simulation, the absorbed doses to the tumor and normal liver were overestimated by PM by 105.55% and 20.23%, respectively, whereas for lungs, the absorbed dose estimated by PM was underestimated by 25.32%. These values were supported by the isodose distribution obtained via SlicerRT, suggesting the presence of beta particles outside the volumes of interest. These findings demonstrate the importance of personalized dosimetry for a more accurate absorbed dose estimation compared to PM.

    CONCLUSION: The methodology provided in this study can assist users (especially students or researchers who are new to MC simulation) in navigating intricate steps required in the importation of tomographic data for MC simulation. These steps can also be utilized for other radiation therapy related applications, not necessarily limited to internal dosimetry.

  13. Bradley DA, Ng KH, Aziz YB
    Int J Rad Appl Instrum A, 1988;39(5):439-40.
    PMID: 2840420
    The utility of a phantom material, based on SMR(L) [Standard Malaysian Rubber] grade natural rubber and a formulation used for the proprietary rubber phantom-material, Temex, has been examined for the 1-MeV photon-Measurement has also been performed with 60-keV photons using the radionuclide 241Am. At photon-therapy energy levels the measured response, when compared with tabulated central-axis percentage depth doses for the defined measuring conditions, produces everywhere (in the range 1-19 cm depth) better than 2% deviation. The favourable measured response characteristics combined with the ease of processing and casting the phantom material provide the basis for useful radiotherapy machine calibration and anthropomorphic dosimetry measurements. The measured mass-attenuation coefficient, at 60keV, of 0.204 cm2 g-1 (+/- 3%) is in close agreement with tabulated values for water (0.2055 cm2 g-1).
  14. Gill MK, Vijayananthan A, Kumar G, Jayarani K, Ng KH, Sun Z
    Quant Imaging Med Surg, 2015 Aug;5(4):524-33.
    PMID: 26435916 DOI: 10.3978/j.issn.2223-4292.2015.04.04
    To determine the effective radiation dose and image quality resulting from 100 versus 120 kilovoltage (kV) protocols among patients referred for computed tomography pulmonary angiography (CTPA).
  15. Siar CH, Ng KH
    J Nihon Univ Sch Dent, 1993 Jun;35(2):134-8.
    PMID: 7692017
    Granular cell ameloblastoma (GCA) is a well recognized variant of follicular ameloblastoma with extensive granular cell change. In contrast, plexiform granular cell odontogenic tumor (PGCOT) is a rare and recently described lesion characterized histologically by a monophasic plexiform pattern of granular cells. In this paper, two cases of an unusual granular cell odontogenic tumor exhibiting combined features of these two entities are described along with their immunohistochemical characteristics. The granular cells of both the GCA and PGCOT areas showed similar patterns of expression for keratin and S-100, which differed from those of typical ameloblastoma. No reactivity for desmin or vimentin was noted. The histomorphologic and immunohistochemical features of these hybrid tumors suggest that the granular cells present have a common origin, most probably the odontogenic epithelium.
  16. Ng KH, Kemp R
    J Zhejiang Univ Sci B, 2020 9 8;21(9):752-754.
    PMID: 32893533 DOI: 10.1631/jzus.B2000228
    The world is now plagued by a pandemic of unprecedented nature caused by a novel, emerging, and still poorly understood infectious disease, coronavirus disease 2019 (COVID-19) (Wu and McGoogan, 2020). In addition to the rapidly growing body of scientific and medical literature that is being published, extensive public reports and stories in both the traditional media and social media have served to generate fear, panic, stigmatization, and instances of xenophobia (Zarocostas, 2020).
  17. Leong SS, Jalalonmuhali M, Md Shah MN, Ng KH, Vijayananthan A, Hisham R, et al.
    Br J Radiol, 2023 Mar 01;96(1144):20220288.
    PMID: 36802861 DOI: 10.1259/bjr.20220288
    OBJECTIVE: Many studies have conflicting findings in using shear wave elastography (SWE) to assess renal fibrosis. This study reviews the use of SWE to evaluate pathological changes in native kidneys and renal allografts. It also tries to elucidate the confounding factors and care taken to ensure the results are consistent and reliable.

    METHODS: The review was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. Literature search was conducted in Pubmed, Web of Science and Scopus database up to 23 October 2021. To evaluate risk and bias applicability, the Cochrane risk-of bias tool and GRADE was used. The review was registered under PROSPERO CRD42021265303.

    RESULTS: A total of 2921 articles were identified. 104 full texts were examined and 26 studies included in systematic review. 11 studies performed on native kidneys and 15 studies on transplanted kidney. A wide range of impact factors was found that affect the accuracy of SWE of renal fibrosis in adult patients.

    CONCLUSIONS: Compared to point SWE, two-dimensional SWE with elastogram could enable better selection of the region of interest in kidneys, leading to reproducible results. Tracking waves were attenuated as the depth from skin to region of interest increased, therefore, SWE is not recommended for overweight or obese patients. Variable transducer forces might also affect SWE reproducibility, thus, training of operators to ensure consistent operator-dependent transducer forces may be helpful.

    ADVANCES IN KNOWLEDGE: This review provides a holistic insight on the efficiency of using SWE in evaluating pathological changes in native and transplanted kidneys, thereby contributing to the knowledge of its utilisation in clinical practice.

  18. Low WY, Ng KH, Kabir MA, Koh AP, Sinnasamy J
    Scientometrics, 2014;98:1521-1533.
    PMID: 24465065
    Research collaboration is the way forward in order to improve quality and impact of its research findings. International research collaboration has resulted in international co-authorship in scientific communications and publications. This study highlights the collaborating research and authorship trend in clinical medicine in Malaysia from 2001 to 2010. Malaysian-based author affiliation in the Web of Science (Science Citation Index Expanded) and clinical medicine journals (n = 999) and articles (n = 3951) as of 30th Oct 2011 were downloaded. Types of document analyzed were articles and reviews, and impact factors (IF) in the 2010 Journal Citation Report Science Edition were taken to access the quality of the articles. The number of publications in clinical medicine increased from 4.5 % (n = 178) in 2001 to 23.9 % (n = 944) in 2010. The top three contributors in the subject categories are Pharmacology and Pharmacy (13.9 %), General and Internal Medicine (13.6 %) and Tropical Medicine (7.3 %). By journal tier system: Tier 1 (18.7 %, n = 738), Tier 2 (22.5 %, n = 888), Tier 3 (29.6 %, n = 1170), Tier 4 (27.2 %, n = 1074), and journals without IF (2.1 %, n = 81). University of Malaya was the most productive. Local collaborators accounted for 60.3 % and international collaborations 39.7 %. Articles with international collaborations appeared in journals with higher journal IFs than those without international collaboration. They were also cited more significantly than articles without international collaborations. Citations, impact factor and journal tiers were significantly associated with international collaboration in Malaysia's clinical medicine publications. Malaysia has achieved a significant number of ISI publications in clinical medicine participation in international collaboration.
  19. Acharya UR, Hagiwara Y, Sudarshan VK, Chan WY, Ng KH
    J Zhejiang Univ Sci B, 2018 1 9;19(1):6-24.
    PMID: 29308604 DOI: 10.1631/jzus.B1700260
    Radiology (imaging) and imaging-guided interventions, which provide multi-parametric morphologic and functional information, are playing an increasingly significant role in precision medicine. Radiologists are trained to understand the imaging phenotypes, transcribe those observations (phenotypes) to correlate with underlying diseases and to characterize the images. However, in order to understand and characterize the molecular phenotype (to obtain genomic information) of solid heterogeneous tumours, the advanced sequencing of those tissues using biopsy is required. Thus, radiologists image the tissues from various views and angles in order to have the complete image phenotypes, thereby acquiring a huge amount of data. Deriving meaningful details from all these radiological data becomes challenging and raises the big data issues. Therefore, interest in the application of radiomics has been growing in recent years as it has the potential to provide significant interpretive and predictive information for decision support. Radiomics is a combination of conventional computer-aided diagnosis, deep learning methods, and human skills, and thus can be used for quantitative characterization of tumour phenotypes. This paper discusses the overview of radiomics workflow, the results of various radiomics-based studies conducted using various radiological images such as computed tomography (CT), magnetic resonance imaging (MRI), and positron-emission tomography (PET), the challenges we are facing, and the potential contribution of radiomics towards precision medicine.
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