MyMedR

Fulltext Comparison of low-contrast detectability of computed radiography and screen/film mammography systems

Noriah Jamal, Ng, Kwan-Hoong, McLean, Donald

Journal of Nuclear and Related Technologies, 2008;2008(2):1-8.

MyJurnal

The objective of this study is to compare low-contrast detectability of computed radiography (CR) and screen/film (SF) mammography systems. The Nijimegen contrast detail test object (CDMAM type 3.4) was imaged at 28 kV, in automatic exposure control mode separately. Six medical imaging physicists read each CDMAM phantom image. Contrast detail curves were plotted to compare lowcontrast detectability of CR (soft copy and hard copy) and SF mammography systems. Effect of varying exposure parameters, namely kV, object position inside the breast phantom, and entrance surface exposure (ESE) on the contrast detail curve were also investigated using soft copy CR. The significance of the difference in contrast between CR and SF, and for each exposure parameter, was tested using non-parametric Kruskal-Wallis test. The low- contrast detectability of the CR (soft copy and hard copy) system was found to be not significantly different to that of the SF system (p>0.05, Kruskal-Wallis test). For CR soft copy, no significant relationship (p>0.05, Kruskal-Wallis test) was seen for variation of kV, object position inside the breast phantom and ESE. This indicates that CR is comparable with SF for useful detection and visualization of low-contrast objects such as small lowcontrast areas corresponding to breast pathology.

Fulltext Evaluation of conventional and computerised monitoring of cardiac function in the coronary care unit

Ng KH

Med J Malaysia, 1983 Dec;38(4):289-93.

PMID: 6599984

One of the important functions of the Coronary Care Unit (CCU) is the continuous and intensive monitoring of cardiac function. To date, many monitoring techniques have been developed and tested. In this paper, both the conventional and computerised monitoring techniques are reviewed and evaluated. It is shown that a computerised system has several defirute advantages over the conventional system, e.g. lower false alarm rate, accurate and fast data processing, retrospective studies. However one also ought to be aware of the limitations,

Modern renaissance: need for holistic knowledge and polymaths to drive change

Ng KH

Phys Eng Sci Med, 2023 Sep;46(3):955-957.

PMID: 37395928 DOI: 10.1007/s13246-023-01296-7

Vision 20/20: Mammographic breast density and its clinical applications

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.

Fulltext Prejudice in science - Lessons from the coronavirus story

Ng KH, Bezak E

Phys Med, 2020 Jul;75:83-84.

PMID: 32559649 DOI: 10.1016/j.ejmp.2020.06.011

In the current pandemic times, medical physicists may not be aware that there is an interesting story on two significant discoveries related to the coronavirus. One is the invention of the polymerase chain reaction (PCR) and the other is the first electron microscopic observation and identification of the coronavirus. Both of them were disregarded by the reviewers and major journals declined to publish these discoveries. These days, PCR, for example, is a widespread method for analyzing DNA, having a profound effect on healthcare, especially now during the Covid-19 pandemic. Prejudice or perhaps ignorance prevail in every aspect of our society, and there is no exception in scientific research. We need to, however, learn from these two stories and be open-minded about novel discoveries and findings - as they may be just disruptive in the "right" way to lead to an unexpected breakthrough.

Fulltext Understanding and reducing the fear of COVID-19

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).

Fulltext Assessment of surface dose on the art phantom using threedimensional conformal breast radiotherapy

Norhayati Abdullah, Wong, Jeannie Hsiu Ding, Ng, Kwan Hoong, Ung, Ngie Min

Jurnal Sains Nuklear Malaysia, 2015;27(1):21-28.

MyJurnal

The assessment of surface dose is essential in radiotherapy to avoid deterministic effect or to
reduce the severity of side effects from radiation treatment. In this study, the surface dose for breast
cancer radiotherapy was measured using two types of dosimeter; Thermoluminescent Dosimeter
(TLD) and Optically Stimulated Luminescent Dosimeter (OSLD). The study was performed on the
left breast of female Alderson Radiation Therapy (ART) phantom. The treatment planning was
carried out on the ART phantom to determine the homogeneity of dose distribution within the target
organ is complied with the tolerance limits of 95% to 107% as recommended by the International
Commission on Radiation Units and Measurements (ICRU)’s Report No. 50. From the treatment
planning result, the phantom then was irradiated with 267 cGy dose per fraction for two beam
fields; medial tangential and lateral tangential fields using a 6 MV photon beam produced from
three-dimensional (3D) conformal radiotherapy. Result shows that the OSLD provides 25.7% and
23.5% higher surface dose compared to TLD for medial tangential and lateral tangential fields,
respectively. This condition may be due to higher effective point of measurement and angular
dependence of the OSLD compared to TLD. As a conclusion, suitable dosimeter should be selected
to ensure accurate estimation of surface dose could be made thus reduction of skin reaction to
patient could be achieved.

John Roderick Cameron (1922-2005): Scientist, teacher, mentor, inventor, and philanthropist extraordinaire

Ng KH, Doi K

Radiol Phys Technol, 2024 Mar;17(1):1-8.

PMID: 38347240 DOI: 10.1007/s12194-023-00775-6

The Fukushima nuclear crisis reemphasizes the need for improved risk communication and better use of social media

Ng KH, Lean ML

Health Phys, 2012 Sep;103(3):307-10.

PMID: 22850236 DOI: 10.1097/HP.0b013e318257cfcb

The potential of social media has expanded far beyond the initial function of social communication among a network of friends. It has become an increasingly important tool in risk communication to allow the dissemination of timely and accurate information to global citizens to make more informed choices regarding a particular crisis. The Fukushima nuclear crisis is an example where the potential of social media was not fully tapped. This caused undue stress and distrust of authorities. While the use of social media in this crisis could have altered significantly the level of trust in authorities and others, two additional points should be considered. One point is the use of plain language versus scientific language in order to reach a wider audience. The other is an urgent need to improve public information especially in the event of a nuclear emergency and to enhance educational efforts and action by improving radiological protection communication from regulatory bodies and international agencies. These are points that also play a large role in the use of social media.

Diagnostic radiology in the tropics: technical considerations

Ng KH, McLean ID

Semin Musculoskelet Radiol, 2011 Nov;15(5):441-5.

PMID: 22081279 DOI: 10.1055/s-0031-1293490

An estimated two thirds of the world's population is currently without access to diagnostic radiology services, and most of them live in resource-limited tropical regions with harsh environments. Most patients are diagnosed and treated in poorly equipped government-funded hospitals and clinics that have insufficiently trained staff and are barely operational. Any available imaging equipment is likely to be functioning suboptimally and be poorly maintained. The root of the problem is usually a lack of know-how and a quality culture, combined with insufficient basic equipment and infrastructure. Radiological imaging is an essential aspect of primary care and used in the critical diagnosis and management of trauma, tuberculosis, pneumonia, acquired immunodeficiency syndrome, cancer, and other respiratory and abdominal diseases. Considerations such as quality management and infrastructure, personnel, equipment, and radiation protection and safety are important to ensure the proper functioning and rational use of a diagnostic radiology facility in the tropics.

Fulltext A model for online interactive remote education for medical physics using the Internet

Woo MK, Ng KH

J Med Internet Res, 2003 Jan-Mar;5(1):e3.

PMID: 12746208

Medical physics is a relatively small community but it spans great geographical distances, usually with a scarcity of experts whose expertise could greatly benefit students entering into the field. In addition there are many software systems for which an interactive education method would be most advantageous.

Fulltext Intercomparison programme of absorbed dose for megavoltage X-ray teletherapy units in Malaysia

Norhayati Abdullah, Ng, Kwan Hoong, Wong, Jeannie Hsiu Ding, Ngie Min Ung, Taiman Kadni, Siti Sara Deraman

Jurnal Sains Nuklear Malaysia, 2016;28(2):11-19.

MyJurnal

The objective of this study is to perform a thermoluminescent dosimetry (TLD) postal dose quality audit for megavoltage X-ray teletherapy units in Malaysia. This audit is essential to be carried out to ensure adequate precision in the dosimetry of clinical beams before being delivered to the patients. Through this work, participating centres were requested to irradiate three capsules of TLD-100 powder with an absorbed dose to water of 2 Gy for 6MV and10MV photon beams. The International Atomic Energy Agency (IAEA)’s Technical Report Series No. 398 is used as a reference standard for TLD irradiation. Atotal of 22photon beamsfrom ten radiotherapy centres comprising onegovernment hospital and nineprivate medical centres were evaluated. The percentage deviation of user’s measured absorbed dose relative to Secondary Standard Dosimetry Laboratory (SSDL) mean absorbed dose was calculated. The results showed that all photon beams are within the IAEA’s acceptance limit of ± 5% except six photon beams. These centres were followed up with a second round of TLD irradiation which resulted in a better compliance.As a conclusion, regular audits should be performed to ensure consistency of radiotherapy treatment unit performances thus maintaining the accuracy of dose delivered to patients inall radiotherapy centres in Malaysia.

A clarion call to introduce artificial intelligence (AI) in postgraduate medical physics curriculum

Ng KH, Wong JHD

Phys Eng Sci Med, 2022 Jan 10.

PMID: 35006576 DOI: 10.1007/s13246-022-01099-2

Fulltext It is Time to Incorporate Artificial Intelligence in Radiology Residency Programs

Ng KH, Tan CH

Korean J Radiol, 2023 Mar;24(3):177-179.

PMID: 36788774 DOI: 10.3348/kjr.2022.1023

Fulltext AsiaSafe: Cultivating a Safety Culture for Radiation in Diagnosis, Intervention, Therapy, and Beyond

Ho ELM, Ng KH

Korean J Radiol, 2024 Jan;25(1):8-10.

PMID: 38184764 DOI: 10.3348/kjr.2023.0945

Surveying trends in radiation oncology medical physics in the Asia Pacific Region

Kron T, Healy B, Ng KH

Phys Med, 2016 Jul;32(7):883-8.

PMID: 27320695 DOI: 10.1016/j.ejmp.2016.06.001

OBJECTIVE: Our study aims to assess and track work load, working conditions and professional recognition of radiation oncology medical physicists (ROMPs) in the Asia Pacific Region over time.

METHODS: A structured questionnaire was mailed in 2008, 2011 and 2014 to senior medical physicists representing 23 countries. The questionnaire covers 7 themes: education and training including certification; staffing; typical tasks; professional organisations; resources; research and teaching; job satisfaction.

RESULTS: Across all surveys the response rate was >85% with the replies representing practice affecting more than half of the world's population. The expectation of ROMP qualifications (MSc and between 1 and 3years of clinical experience) has not changed much over the years. However, compared to 2008, the number of medical physicists in many countries has doubled. Formal professional certification is only available in a small number of countries. The number of experienced ROMPs is small in particular in low and middle income countries. The increase in staff numbers from 2008 to 2014 is matched by a similar increase in the number of treatment units which is accompanied by an increase in treatment complexity. Many ROMPs are required to work overtime and not many find time for research. Resource availability has only improved marginally and ROMPs still feel generally overworked, but professional recognition, while varying widely, appears to be improving slowly.

CONCLUSION: While number of physicists and complexity of treatment techniques and technologies have increased significantly, ROMP practice remains essentially unchanged over the last 6years in the Asia Pacific Region.

Fulltext Therapeutic radionuclides in nuclear medicine: current and future prospects

Yeong CH, Cheng MH, Ng KH

J Zhejiang Univ Sci B, 2014 Oct;15(10):845-63.

PMID: 25294374 DOI: 10.1631/jzus.B1400131

The potential use of radionuclides in therapy has been recognized for many decades. A number of radionuclides, such as iodine-131 ((131)I), phosphorous-32 ((32)P), strontium-90 ((90)Sr), and yttrium-90 ((90)Y), have been used successfully for the treatment of many benign and malignant disorders. Recently, the rapid growth of this branch of nuclear medicine has been stimulated by the introduction of a number of new radionuclides and radiopharmaceuticals for the treatment of metastatic bone pain and neuroendocrine and other malignant or non-malignant tumours. Today, the field of radionuclide therapy is enjoying an exciting phase and is poised for greater growth and development in the coming years. For example, in Asia, the high prevalence of thyroid and liver diseases has prompted many novel developments and clinical trials using targeted radionuclide therapy. This paper reviews the characteristics and clinical applications of the commonly available therapeutic radionuclides, as well as the problems and issues involved in translating novel radionuclides into clinical therapies.

Radiation dose in coronary CT angiography associated with prospective ECG-triggering technique: comparisons with different CT generations

Sabarudin A, Sun Z, Ng KH

Radiat Prot Dosimetry, 2013;154(3):301-7.

PMID: 22972797 DOI: 10.1093/rpd/ncs243

A retrospective analysis was performed in patients undergoing prospective ECG-triggered coronary computed tomography (CT) angiography (CCTA) with the single-source 64-slice CT (SSCT), dual-source 64-slice CT (DSCT), dual-source 128-slice CT and 320-slice CT with the aim of comparing the radiation dose associated with different CT generations. A total of 164 patients undergoing prospective ECG-triggered CCTA with different types of CT scanners were studied with the mean effective doses estimated at 6.8 ± 3.2, 4.2 ± 1.9, 4.1±0.6 and 3.8 ± 1.4 mSv corresponding to the 128-slice DSCT, 64-slice DSCT, 64-slice SSCT and 320-slice CT scanners. In this study a positive relationship was found between the effective dose and the body mass index (BMI). A low radiation dose is achieved in prospective ECG-triggered CCTA, regardless of the CT scanner generation. BMI is identified as the major factor that has a direct impact on the effective dose associated with prospective ECG-triggered CCTA.

Global quality control perspective for the physical and technical aspects of screen-film mammography--image quality and radiation dose

Ng KH, Jamal N, DeWerd L

Radiat Prot Dosimetry, 2006;121(4):445-51.

PMID: 16709704

The systematic monitoring of image quality and radiation dose is an ultimate solution to ensuring the continuously high quality of mammography examination. At present several protocols exist around the world, and different test objects are used for quality control (QC) of the physical and technical aspects of screen-film mammography. This situation may lead to differences in radiation image quality and dose reported. This article reviews the global QC perspective for the physical and technical aspects of screen-film mammography with regard to image quality and radiation dose. It points out issues that must be resolved in terms of radiation dose and that also affect the comparison.

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.

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