MyMedR

Maternal mortality in University Hospital Kuala Lumpur, Malaysia

Kong H, Sinnathuray TA, Ng KH

Med J Malaysia, 1974 Jun;28(4):226-8.

A comparison of trimethoprim-sulphamethoxazole and penicillin-streptomycin in the treatment of gynaecological infections

Wong WP, Ng KH, Chai KH

Med J Malaysia, 1973 Dec;28(2):125-7.

PMID: 4276230

Survey of postgraduate medical physics programmes in the Asia-Oceania region

Wong JHD, Ng KH, Sarasanandarajah S

Phys Med, 2019 Oct;66:21-28.

PMID: 31546154 DOI: 10.1016/j.ejmp.2019.09.079

The increased use of medical imaging and radiation therapies has resulted in a high demand for medical physicists. Although medical physics programmes are well established in advanced countries, the same cannot be said for many low- and medium-income countries. In some countries, there may be huge variations in the graduates' skill and quality, which pose a problem in ensuring patient safety, providing quality assurance in treatments, optimisation of protocols and standardisation of quality. It also makes any yet-to-be-established regional peer recognition efforts problematic. In order to understand the depth of this problem, a survey was carried out as part of the home-based assignment under the RAS 6088 IAEA programme. A large diversity in terms of course content, duration, clinical training and student profile could be observed across the Asia-Oceania universities surveyed. Out of 25 programmes, only six received recognition from professional bodies, and they were mostly in Australia and New Zealand. Hence, to ensure quality education, a regional curriculum model needs to be developed to harmonise standards. And there is still a long way to go towards standardizing medical physics education and clinical training in the region.

Volumetric breast density measurement: sensitivity analysis of a relative physics approach

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

Fulltext Mammographic compression in Asian women

Lau S, Abdul Aziz YF, Ng KH

PLoS One, 2017;12(4):e0175781.

PMID: 28419125 DOI: 10.1371/journal.pone.0175781

OBJECTIVES: To investigate: (1) the variability of mammographic compression parameters amongst Asian women; and (2) the effects of reducing compression force on image quality and mean glandular dose (MGD) in Asian women based on phantom study.

METHODS: We retrospectively collected 15818 raw digital mammograms from 3772 Asian women aged 35-80 years who underwent screening or diagnostic mammography between Jan 2012 and Dec 2014 at our center. The mammograms were processed using a volumetric breast density (VBD) measurement software (Volpara) to assess compression force, compression pressure, compressed breast thickness (CBT), breast volume, VBD and MGD against breast contact area. The effects of reducing compression force on image quality and MGD were also evaluated based on measurement obtained from 105 Asian women, as well as using the RMI156 Mammographic Accreditation Phantom and polymethyl methacrylate (PMMA) slabs.

RESULTS: Compression force, compression pressure, CBT, breast volume, VBD and MGD correlated significantly with breast contact area (p<0.0001). Compression parameters including compression force, compression pressure, CBT and breast contact area were widely variable between [relative standard deviation (RSD)≥21.0%] and within (p<0.0001) Asian women. The median compression force should be about 8.1 daN compared to the current 12.0 daN. Decreasing compression force from 12.0 daN to 9.0 daN increased CBT by 3.3±1.4 mm, MGD by 6.2-11.0%, and caused no significant effects on image quality (p>0.05).

CONCLUSIONS: Force-standardized protocol led to widely variable compression parameters in Asian women. Based on phantom study, it is feasible to reduce compression force up to 32.5% with minimal effects on image quality and MGD.

Ante-partum localisation of the placenta with radioactive isotope Indium ( 113m IN)

Ng KH, Sinnathuray TA, Lau KS

Med J Malaya, 1972 Mar;26(3):159-63.

PMID: 5031010

Use of a modified natural-rubber phantom for radiotherapy dosimetry measurements

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).

Risk Communication Strategies for Possible Health Risks From Radio-Frequency Electromagnetic Fields (RF-EMF) Emission by Telecommunication Structures

Fernandez PR, Ng KH, Kaur S

Health Phys, 2019 06;116(6):835-839.

PMID: 30844902 DOI: 10.1097/HP.0000000000001037

There is widespread anxiety and speculation about RF-EMF emissions by telecommunication base stations and structures, as it is perceived by some to be unsafe and a threat to public health. Scientists, medical experts, politicians, journalists, and mobile telecommunication company specialists are involved in an active debate on whether people are immune to RF or if we are gambling with our future. Interviews with 31 individuals from 7 stakeholder groups in Malaysia reveal that the residents' main concerns are that the telecommunication companies do not follow guidelines and as a result the telecommunication structures are constructed close to their homes, which they perceive as a threat to public health. Some residents also do not want these structures because of cultural reasons, while some are jealous over rental income received by the landlords. Meanwhile, the authorities entrusted with safe-guarding public health are involved in a blame game as there is no agency that is clearly in charge. The interviews also highlight that the current risk communication initiatives are more reactive rather than proactive, and that the authorities do not speak in one voice. Based on the outcome of the interviews, eleven recommendations are formulated to improve risk communication initiatives in Malaysia. The recommendations stress on repairing, building, and strengthening trust, because trust in agencies, along with credibility, determines risk communication initiatives' effectiveness. These strategies can also be effectively replicated across regions to deal with contestations over RF-EMF emissions and the impact on health.

Ante-partum localisation of the placenta with radioactive isotope Indium (113mIN)

Ng KH, Sinnathuray TA, Lau KS

Med J Malaysia, 1972 Mar;26(3):159-163.

PMID: 35158513

No abstract available.

Fulltext Dr Sun Yat-sen (1866-1925): medical doctor and China's founding president

Lee KH, Wong DT, Ng KH

Singapore Med J, 2013 Jun;54(6):356-8.

PMID: 23820548

Fulltext Adenomatoid odontogenic tumour: gross and histogical examination of 45 cases

Siar CH, Ng KH, Murugasu P

Singapore Med J, 1987 Apr;28(2):180-9.

PMID: 3629275

This paper represents a reappraisal of the gross and histological features of 45 cases of adenomatoid odontogenic tumours as observed under conventional light and fluorescence microscopy. The findings conformed largely to those of previous studies. Usage of the term adenomatoid odontogenic tumour in preference to its old name 'adenoameloblastoma' is emphasized. The differential diagnosis of this entity from the ameloblastoma and salivary gland tumours is discussed.

Overcoming the Fukushima Wastewater Crisis: What the Japanese Authorities Could Do to Address Opposing Views

Ng KH, Yoong D, Gong J

Health Phys, 2022 Jun 01;122(6):696-704.

PMID: 35486926 DOI: 10.1097/HP.0000000000001548

In April 2021, the Japanese authorities' announcement of their decision to release processed wastewater from the damaged Fukushima Daiichi nuclear power plant into the Pacific Ocean over 30 y, beginning in 2023, triggered strong domestic and international opposition. Failure to handle this situation tactfully can lead to public disorder, civil disobedience, loss of trust in the authorities, and even diplomatic sanctions. In this article, we explain the underlying reasons behind this resistance, and we offer some strategic methods that the Japanese authorities can deploy to address opposing views and overcome the Fukushima wastewater crisis.

Fulltext A comparison between low-dose and standard-dose non-contrasted multidetector CT scanning of the paranasal sinuses

Lam S, Bux S, Kumar G, Ng Kh, Hussain A

Biomed Imaging Interv J, 2009 Jul;5(3):e13.

PMID: 21611051 MyJurnal DOI: 10.2349/biij.5.3.e13

To compare the image quality of the low-dose to the standard-dose protocol of MDCT scanning of the paranasal sinuses, based on subjective assessment and determine the radiation doses to the eyes and thyroid gland and dose reduction between these two protocols.

Comparative assessment of the interfacial soft and hard tissues investing implants and natural teeth in the macaque mandible

Siar CH, Toh CG, Romanos GE, Ng KH

Clin Oral Investig, 2015 Jul;19(6):1353-62.

PMID: 25411082 DOI: 10.1007/s00784-014-1362-7

The aim of this study was to conduct a comparative qualitative and quantitative assessment of the interfacial soft and hard tissues investing implants and natural teeth.

Pain experience and satisfaction with postoperative pain control among surgical patients

Subramanian P, Ramasamy S, Ng KH, Chinna K, Rosli R

Int J Nurs Pract, 2016 Jun;22(3):232-8.

PMID: 25355297 DOI: 10.1111/ijn.12363

Alleviating acute pain and providing pain relief are central to caring for surgical patients as pain can lead to many adverse medical consequences. This study aimed to explore patients' experience of pain and satisfaction with postoperative pain control. A cross-sectional survey was carried out among 107 respondents who had undergone abdominal surgery in the surgical ward of an urban hospital using the Revised American Pain Society's Patient Outcome and Satisfaction Survey Questionnaires (APS-POQ-R). Data were analysed using descriptive statistics and chi-square test. Chi-square test showed significant association between race (P = 0.038), education level (P ≤ 0.001), previous operation status (P = 0.032) and operation status (P ≤ 0.001). Further analysis on nominal regression, association between dissatisfaction with factors of operation status (46.09 (95% CI 7.456, 284.947)) and previous operation status (13.38 (95% CI 1.39, 128.74)) was found to be significant. Moderate to high levels of pain intensity in the last 24 h after surgery, as well as moderate to high rates of pain-related interference with care activities were most reported. Pain still remains an issue among surgical patients, and effective pain management and health education are needed to manage pain more effectively after surgery.

Standardisation of clinical breast-density measurement

Ng KH, Yip CH, Taib NA

Lancet Oncol, 2012 Apr;13(4):334-6.

PMID: 22469115 DOI: 10.1016/S1470-2045(12)70093-1

Fulltext Optimising the scan delay for arterial phase imaging of the liver using the bolus tracking technique

Chan R, Kumar G, Abdullah B, Ng Kh, Vijayananthan A, Mohd Nor H, et al.

Biomed Imaging Interv J, 2011 Apr;7(2):e12.

PMID: 22287986 MyJurnal DOI: 10.2349/biij.7.2.e12

To optimize the delay time before the initiation of arterial phase scan in the detection of focal liver lesions in contrast enhanced 5 phase liver CT using the bolus tracking technique.

Subcutaneous reactions and degradation characteristics of collagenous and noncollagenous membranes in a macaque model

Siar CH, Toh CG, Romanos G, Ng KH

Clin Oral Implants Res, 2011 Jan;22(1):113-20.

PMID: 20678135 DOI: 10.1111/j.1600-0501.2010.01970.x

collagenous and noncollagenous membranes have been investigated in many animal systems but their effects in the macaque model are unknown.

Fulltext A survey of radiation dose to patients and operators during radiofrequency ablation using computed tomography

Saidatul A, Azlan C, Megat Amin M, Abdullah B, Ng Kh

Biomed Imaging Interv J, 2010 Jan-Mar;6(1):e1.

PMID: 21611060 MyJurnal DOI: 10.2349/biij.6.1.e2

Computed tomography (CT) fluoroscopy is able to give real time images to a physician undertaking minimally invasive procedures such as biopsies, percutaneous drainage, and radio frequency ablation (RFA). Both operators executing the procedure and patients too, are thus at risk of radiation exposure during a CT fluoroscopy.This study focuses on the radiation exposure present during a series of radio frequency ablation (RFA) procedures, and used Gafchromic film (Type XR-QA; International Specialty Products, USA) and thermoluminescent dosimeters (TLD-100H; Bicron, USA) to measure the radiation received by patients undergoing treatment, and also operators subject to scatter radiation.The voltage was held constant at 120 kVp and the current 70mA, with 5mm thickness. The duration of irradiation was between 150-638 seconds.Ultimately, from a sample of 30 liver that have undergone RFA, the study revealed that the operator received the highest dose at the hands, which was followed by the eyes and thyroid, while secondary staff dosage was moderately uniform across all parts of the body that were measured.

A low-cost phantom for simple routine testing of single photon emission computed tomography (SPECT) cameras

Ng AH, Ng KH, Dharmendra H, Perkins AC

Appl Radiat Isot, 2009 Oct;67(10):1864-8.

PMID: 19049851 DOI: 10.1016/j.apradiso.2008.10.010

A simple sphere test phantom has been developed for routine performance testing of SPECT systems in situations where expensive commercial phantoms may not be available. The phantom was based on a design with six universal syringe hubs set in the frame to support a circular array of six glass blown spheres of different sizes. The frame was then placed into a water-filled CT abdomen phantom and scanned with a triple head camera system (Philips IRIX, USA). Comparison was made with a commercially available phantom (Deluxe Jaszczak phantom). Whereas the commercial phantom demonstrates cold spot resolution, an important advantage of the sphere test phantom was that hot spot resolution could be easily measured using almost half (370MBq) of the activity recommended for use in the commercial phantom. Results showed that the contrast increased non-linearly with sphere volume and radionuclide concentration. The phantom was found to be suitable as an inexpensive option for daily performance tests.

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