Displaying publications 161 - 180 of 288 in total

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  1. Wong JHD, Zin HM, Pawanchek M, Ng KH
    Phys Med, 2019 Nov;67:40-49.
    PMID: 31669669 DOI: 10.1016/j.ejmp.2019.10.019
    OBJECTIVE: Medical physics in Malaysia is still considered a young profession. This workforce survey aims to understand the status, aspirations, motivation and experiences of medical physicists (MPs) in the country. A subsection of this survey also aims to understand the role of women.

    METHOD: A survey was carried out between April 20 and May 30, 2018 by a working group under the Medical Physics Division of the Malaysian Institute of Physics (IFM). The survey form was designed using Google Form and sent to various public and private institutions nationwide that employed MPs registered with IFM.

    RESULTS: A total of 106 responses (28% men and 72% women) were analysed. This represented 30% of the medical physics workforce. Majority of them had postgraduate degrees, but their clinical training is mostly obtained on the job with no certification. The number of low-ranking female MPs was disproportionately high. MPs worked long hours and achieving work-life balance (WLB) was a challenge. Factors that improved their WLB included working close to home, having a supportive manager and flexible working hours. Most MPs aspired to become professional and mentor younger compatriots, besides contributing to patient care and research. Gender discrimination was reportedly low.

    CONCLUSION: Medical physics in Malaysia is growing and has a strong representation of women. In future, they would probably take over the top management from their male counterparts, whose number had stagnated. A united effort was essential to set up a proper clinical training system to train clinically qualified MPs.

  2. Azman RR, Shah MNM, Ng KH
    Korean J Radiol, 2019 03;20(3):399-404.
    PMID: 30799570 DOI: 10.3348/kjr.2018.0416
    The use of computed tomography (CT) in emergency departments has increased over several decades, as physicians increasingly depend on imaging for diagnoses. Patients and medical personnel are put at risk due to frequent exposure to and higher levels of radiation, with very little evidence of improvements in outcomes. Here, we explore why CT imaging has a tendency to be overused in emergency departments and the obstacles that medical personnel face in ensuring patient safety. The solution requires cooperation from all emergency care stakeholders as well as the continuous education of doctors on how CT scans help in particular cases.
  3. Cheah SH, Ng KH, Johgalingam VT, Ragavan M
    J Endocrinol, 1995 Aug;146(2):331-7.
    PMID: 7561646
    The effects of exogenously introduced oestradiol-17 beta (E) and relaxin (RLX) on cervical extensibility and collagen organisation were tested in rats ovariectomised in late pregnancy. When the cervices were stretched in vitro by 1 mm increments, it was found that those from rats given E alone generated significantly higher tensions than those from control rats, while cervices from rats given both E and RLX had tensions similar to controls. Examination of cervical sections under the light microscope and ultra-thin sections under the electron microscope showed that the collagen fibres in the cervices from E-treated rats were highly organised, whereas those from animals given E+RLX and control animals were disorganised and dispersed. It was concluded that E decreased cervical extensibility, while RLX counteracted the effect of E to maintain a soft and easily extensible cervix.
  4. Santos JC, Wong JHD, Pallath V, Ng KH
    Phys Eng Sci Med, 2021 Sep;44(3):833-841.
    PMID: 34283393 DOI: 10.1007/s13246-021-01036-9
    Artificial intelligence (AI) is an innovative tool with the potential to impact medical physicists' clinical practices, research, and the profession. The relevance of AI and its impact on the clinical practice and routine of professionals in medical physics were evaluated by medical physicists and researchers in this field. An online survey questionnaire was designed for distribution to professionals and students in medical physics around the world. In addition to demographics questions, we surveyed opinions on the role of AI in medical physicists' practices, the possibility of AI threatening/disrupting the medical physicists' practices and career, the need for medical physicists to acquire knowledge on AI, and the need for teaching AI in postgraduate medical physics programmes. The level of knowledge of medical physicists on AI was also consulted. A total of 1019 respondents from 94 countries participated. More than 85% of the respondents agreed that AI would play an essential role in medical physicists' practices. AI should be taught in the postgraduate medical physics programmes, and that more applications such as quality control (QC), treatment planning would be performed by AI. Half of the respondents thought AI would not threaten/disrupt the medical physicists' practices. AI knowledge was mainly acquired through self-taught and work-related activities. Nonetheless, many (40%) reported that they have no skill in AI. The general perception of medical physicists was that AI is here to stay, influencing our practices. Medical physicists should be prepared with education and training for this new reality.
  5. Tan LK, Wong JH, Ng KH
    AJR Am J Roentgenol, 2006 Mar;186(3):898-901.
    PMID: 16498128
    The purpose of this article was to develop a low-cost method for high-quality remote capturing and recording of multimedia presentations.
  6. Jamal N, Ng KH, McLean D, Looi LM, Moosa F
    AJR Am J Roentgenol, 2004 Mar;182(3):713-7.
    PMID: 14975974
    This study was undertaken to estimate mammographic breast glandularity in Malaysian women from radiographic data.
  7. Ng KH, Lai SY, Jamaludin NFM, Mohamed AR
    J Hazard Mater, 2022 Feb 05;423(Pt A):127061.
    PMID: 34788939 DOI: 10.1016/j.jhazmat.2021.127061
    While sulphur dioxide (SO2) is known for its toxicity, numerous effective countermeasures were innovated to alleviate its hazards towards the environment. In particular, catalytic reduction is favoured for its potential in converting SO2 into harmless, yet marketable product, such as elemental sulphur. Therefore, current review summarises the critical findings in catalytic SO2 reduction, emphasising on both dry- and wet-based technology. As for the dry-based technology, knowledge related to SO2 reduction over metal-, rare earth- and carbon-based catalysts are summarised. Significantly, both the reduction mechanisms and important criteria for efficient SO2 reduction are elucidated too. Meanwhile, the wet-based SO2 reduction are typically conducted in reactive liquid medium, such as metal complexes, ionic liquids and organic solvents. Therefore, the applications of the aforesaid liquid mediums are discussed thoroughly in the similar manner to dry-technology. Additionally, the pros and cons of each type of catalyst are also presented to provide valuable insights to the pertinent researchers. Finally, some overlooked aspects in both dry- and wet-based SO2 reduction are identified, with potential solutions given too. With these insights, current review is anticipated to contribute towards practicality improvement of catalytic SO2 reduction, which in turn, protects the environment from SO2 pollution.
  8. Siar CH, Nakano K, Ng KH, Tomida M, Nagatsuka H, Kawakami T
    Eur J Med Res, 2010 Apr 08;15(4):180-4.
    PMID: 20554499
    BACKGROUND: Squamous odontogenic tumor (SOT) is a rare benign odontogenic epithelial neoplasm. A slow-growing painless expansive swelling is the common presenting symptom. Histopathologically, SOT can be easily misdiagnosed as an acanthomatous ameloblastoma. Although Notch receptors and ligands have been shown to play a role in cell fate decisions in ameloblastomas, the role of these cell signaling molecules in SOT is unknown.

    CASE REPORT: This paper describes a case of SOT affecting the anterior mandible of a 10-year-old Indian female. The patient was treated by local surgical excision and there has been no follow-up clinical record of recurrence 5 years after primary treatment. Histo?pathological examination revealed a solid, locally-infiltrative neoplasm composed of bland-looking squamatoid islands scattered in a mature fibrous connective tissue stroma and the diagnosis was SOT. Immunohistochemical evaluation showed positive reactivity of varying intensity in the neoplastic epithelial cells for Notch1, Notch3, Notch4, and their ligands Jagged1 and Delta1. Expression patterns showed considerable overlap. No immunoreactivity was detected for Notch2 and Jagged2.

    CONCLUSIONS: Present findings suggest that Notch receptors and their ligands play differential roles in the cytodifferentiation of SOT.

  9. Siar CH, Nakano K, Chelvanayagam PI, Ng KH, Nagatsuka H, Kawakami T
    Eur J Med Res, 2010 Mar 30;15(3):135-8.
    PMID: 20452900
    The purpose of this report is to document a case of unsuspected ameloblastoma involving the right man dibular subpontic region in a 38-year-old Cambodian female patient. This lesion was purportedly preceded by multiple radiolucencies which were diagnosed as radicular cysts and treated a few times in the past years by enucleation followed by endodontic therapy of the affected teeth. Bridgework restoration of the partially edentulous area was performed. This case report demonstrates radiographic changes that occurred in the periods before and after the diagnosis of ameloblastoma. The case may represent an example of radicular cysts and ameloblastoma occurring as a collision phenomenon, or the ameloblastoma may have arisen as a result of neoplastic transformation of the lining epithelium in an inflammatory odontogenic epithelial cyst.
  10. Siar CH, Ng KH, Chia TY, Kulkarni MG
    Singapore Med J, 1988 Feb;29(1):83-5.
    PMID: 3406779
    The aetiology, clinical and histological features of neurilemmomas of the oral and paraoral regions are briefly outlined. Two cases of atypical neurilemmomas of the tongue are described with an intent to document the partial encapsulation and multilobular distribution of the neurogenic tissue noted in these two lesions.
  11. Hariyanto AP, Budiarti NT, Suprijanto, Ng KH, Haryanto F, Endarko
    Phys Eng Sci Med, 2023 Sep;46(3):1175-1185.
    PMID: 37253939 DOI: 10.1007/s13246-023-01283-y
    TMP is gradually becoming a fundamental element for quality assurance and control in ionizing and non-ionizing radiation imaging modalities as well as in the development of different techniques. This study aimed to evaluate and obtain polyvinyl chloride tissue mimicking material for dual-modality breast phantoms in mammography and ultrasound. Breast tissue equivalence was evaluated based on X-ray attenuation properties, speed of sound, attenuation, and acoustic impedance. There are six samples of PVC-plasticizer material with variations of PVC concentration and additives. The evaluation of X-ray attenuation was carried out using mammography from 23 to 35 kV, while the acoustic properties were assessed with mode A ultrasound and a transducer frequency of 5 MHz. A breast phantom was created from TMP material with tissue equivalence and was then evaluated using mammography as well as ultrasound to analyze its image quality. The results showed that samples A (PVC 5%, DOP 95%), B (PVC 7%, DOP 93%), C (PVC 10%, DOP 90%), E (PVC 7%, DOP 90%, graphite 3%), and F (PVC 7%, DOP 90%, silicone oil 3%) have the closest equivalent to the ACR breast phantom material with a different range of 0.01-1.39 in the 23-35 kV range. Based on the evaluation of the acoustic properties of ultrasound, A had high similarity to fat tissue with a difference of 0.03 (dB cm- 1 MHz- 1) and 0.07 (106 kg m- 2 s- 1), while B was close to the glandular tissue with a difference of 9.2 m s- 1. Multilayer breast phantom images' results showed gray levels in mammography and ultrasound modalities. Therefore, this study succeeded in establishing TMP material for mammography and ultrasound. It can also be used for simple quality assurance and control programs.
  12. Md Shah MN, Azman RR, Chan WY, Ng KH
    Can Assoc Radiol J, 2024 Feb;75(1):92-97.
    PMID: 37075322 DOI: 10.1177/08465371231171700
    The past two decades have seen a significant increase in the use of CT, with a corresponding rise in the mean population radiation dose. This rise in CT use has caused improved diagnostic certainty in conditions that were not previously routinely evaluated using CT, such as headaches, back pain, and chest pain. Unused data, unrelated to the primary diagnosis, embedded within these scans have the potential to provide organ-specific measurements that can be used to prognosticate or risk-profile patients for a wide variety of conditions. The recent increased availability of computing power, expertise and software for automated segmentation and measurements, assisted by artificial intelligence, provides a conducive environment for the deployment of these analyses into routine use. Data gathering from CT has the potential to add value to examinations and help offset the public perception of harm from radiation exposure. We review the potential for the collection of these data and propose the incorporation of this strategy into routine clinical practice.
  13. Ng KH, Wong JHD, Leong SS
    Phys Eng Sci Med, 2024 Mar;47(1):17-29.
    PMID: 38078996 DOI: 10.1007/s13246-023-01358-w
    Chronic kidney disease is a leading public health problem worldwide. The global prevalence of chronic kidney disease is nearly five hundred million people, with almost one million deaths worldwide. Estimated glomerular filtration rate, imaging such as conventional ultrasound, and histopathological findings are necessary as each technique provides specific information which, when taken together, may help to detect and arrest the development of chronic kidney disease, besides managing its adverse outcomes. However, estimated glomerular filtration rate measurements are hampered by substantial error margins while conventional ultrasound involves subjective assessment. Although histopathological assessment is the best tool for evaluating the severity of the renal pathology, it may lead to renal insufficiency and haemorrhage if complications occurred. Ultrasound shear wave elastography, an emerging imaging that quantifies tissue stiffness non-invasively has gained interest recently. This method applies acoustic force pulses to generate shear wave within the tissue that propagate perpendicular to the main ultrasound beam. By measuring the speed of shear wave propagation, the tissue stiffness is estimated. This paper reviews the literature and presents our combined experience and knowledge in renal shear wave elastography research. It discusses and highlights the confounding factors on shear wave elastography, current and future possibilities in ultrasound renal imaging and is not limited to new sophisticated techniques.
  14. Velayutham P, Govindasamy GK, Raman R, Prepageran N, Ng KH
    Indian J Otolaryngol Head Neck Surg, 2014 Jan;66(Suppl 1):169-72.
    PMID: 24533378 DOI: 10.1007/s12070-011-0406-4
    The objective of this study is to assess high frequency hearing (above 8 kHz) loss among prolonged mobile phone users is a tertiary Referral Center. Prospective single blinded study. This is the first study that used high-frequency audiometry. The wide usage of mobile phone is so profound that we were unable to find enough non-users as a control group. Therefore we compared the non-dominant ear to the dominant ear using audiometric measurements. The study was a blinded study wherein the audiologist did not know which was the dominant ear. A total of 100 subjects were studied. Of the subjects studied 53% were males and 47% females. Mean age was 27. The left ear was dominant in 63%, 22% were dominant in the right ear and 15% did not have a preference. This study showed that there is significant loss in the dominant ear compared to the non-dominant ear (P 
  15. Cheow YH, Ng KH, Phang C, Ng KH
    Heliyon, 2024 Aug 15;10(15):e35379.
    PMID: 39170258 DOI: 10.1016/j.heliyon.2024.e35379
    This paper establishes a fractional-order economic growth model to model the gross domestic product (GDP). The fractional-order model consists of a differential equation of integer and fractional orders, where the GDP is a function of several exploratory variables. An empirical application is adopted using Malaysia's GDP data from 1956 to 2018, incorporating exploratory variables such as total population, crude death rate, production of logs, gross fixed capital formation, exports of goods and services, general government final consumption expenditure, private final consumption expenditure, and the impact of investment. Extensive comparisons were carried out to evaluate the modelling performance of the full and reduced fractional-order multiple linear regression models with the benchmark models, namely full and reduced integer-order multiple linear regression models. Results indicate that the reduced fractional-order model with six exploratory variables, excluding the crude death rate and production of logs, predominates other models for the in-sample model fitting based on the Akaike information criterion, coefficient of determination and other criteria. Furthermore, the fractional-order model offers the best-of-sample forecasts evaluated based on the root mean square forecast error and mean absolute forecast error. The application of the Diebold-Mariano test also serves to confirm the superior performance of the suggested fractional-order model, revealing a significant difference in forecasting ability between the fractional-order and integer-order models.
  16. Lim BC, Kueh YC, Arifin WN, Ng KH
    Malays J Med Sci, 2016 Jul;23(4):33-45.
    PMID: 27660543 MyJurnal DOI: 10.21315/mjms2016.23.4.5
    Heart disease knowledge is an important concept for health education, yet there is lack of evidence on proper validated instruments used to measure levels of heart disease knowledge in the Malaysian context.
  17. Siar CH, Tsujigiwa H, Ishak I, Hussin NM, Nagatsuka H, Ng KH
    PMID: 25446507 DOI: 10.1016/j.oooo.2014.09.017
    To determine the distribution patterns of bone resorption regulators, receptor activator of nuclear factor κ-B (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG) in recurrent ameloblastoma (RAs) and to clarify their impact on the biologic behavior of these neoplasms.
  18. Yeong CH, Ng KH, Abdullah BJJ, Chung LY, Goh KL, Perkins AC
    Appl Radiat Isot, 2014 Dec;94:216-220.
    PMID: 25222875 DOI: 10.1016/j.apradiso.2014.08.009
    Radionuclide imaging using (111)In, (99m)Tc and (153)Sm is commonly undertaken for the clinical investigation of gastric emptying, intestinal motility and whole gut transit. However the documented evidence concerning internal radiation dosimetry for such studies is not readily available. This communication documents the internal radiation dosimetry for whole gastrointestinal transit studies using (111)In, (99m)Tc and (153)Sm labeled formulations. The findings were compared to the diagnostic reference levels recommended by the United Kingdom Administration of Radioactive Substances Advisory Committee, for gastrointestinal transit studies.
  19. Zourmand A, Mirhassani SM, Ting HN, Bux SI, Ng KH, Bilgen M, et al.
    Biomed Eng Online, 2014;13:103.
    PMID: 25060583 DOI: 10.1186/1475-925X-13-103
    The phonetic properties of six Malay vowels are investigated using magnetic resonance imaging (MRI) to visualize the vocal tract in order to obtain dynamic articulatory parameters during speech production. To resolve image blurring due to the tongue movement during the scanning process, a method based on active contour extraction is used to track tongue contours. The proposed method efficiently tracks tongue contours despite the partial blurring of MRI images. Consequently, the articulatory parameters that are effectively measured as tongue movement is observed, and the specific shape of the tongue and its position for all six uttered Malay vowels are determined.Speech rehabilitation procedure demands some kind of visual perceivable prototype of speech articulation. To investigate the validity of the measured articulatory parameters based on acoustic theory of speech production, an acoustic analysis based on the uttered vowels by subjects has been performed. As the acoustic speech and articulatory parameters of uttered speech were examined, a correlation between formant frequencies and articulatory parameters was observed. The experiments reported a positive correlation between the constriction location of the tongue body and the first formant frequency, as well as a negative correlation between the constriction location of the tongue tip and the second formant frequency. The results demonstrate that the proposed method is an effective tool for the dynamic study of speech production.
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