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  1. An international survey of imaging practices in radiotherapy
    Martin CJ, Kron T, Vassileva J, Wood TJ, Joyce C, Ung NM, et al.
    Phys Med, 2021 Oct;90:53-65.
    PMID: 34562809 DOI: 10.1016/j.ejmp.2021.09.004
    Improvements in delivery of radiation dose to target tissues in radiotherapy have increased the need for better image quality and led to a higher frequency of imaging patients. Imaging for treatment planning extends to function and motion assessment and devices are incorporated into medical linear accelerators (linacs) so that regions of tissue can be imaged at time of treatment delivery to ensure dose distributions are delivered as accurately as possible. A survey of imaging in 97 radiotherapy centres in nine countries on six continents has been undertaken with an on-line questionnaire administered through the International Commission on Radiological Protection mentorship programme to provide a snapshot of imaging practices. Responses show that all centres use CT for planning treatments and many utilise additional information from magnetic resonance imaging and positron emission tomography scans. Most centres have kV cone beam CT attached to at least some linacs and use this for the majority of treatment fractions. The imaging options available declined with the human development index (HDI) of the country, and the frequency of imaging during treatment depended more on country than treatment site with countries having lower HDIs imaging less frequently. The country with the lowest HDI had few kV imaging facilities and relied on MV planar imaging intermittently during treatment. Imaging protocols supplied by vendors are used in most centres and under half adapt exposure conditions to individual patients. Recording of patient doses, a knowledge of which is important in optimisation of imaging protocols, was limited primarily to European countries.
  2. Photon irradiation response of photonic crystal fibres and flat fibres at radiation therapy doses
    Hashim S, Ibrahim SA, Che Omar SS, Alajerami YS, Saripan MI, Noor NM, et al.
    Appl Radiat Isot, 2014 Aug;90:258-60.
    PMID: 24858954 DOI: 10.1016/j.apradiso.2014.04.016
    Radiation effects of photon irradiation in pure Photonic Crystal Fibres (PCF) and Flat fibres (FF) are still much less investigated in thermoluminescense dosimetry (TLD). We have reported the TL response of PCF and FF subjected to 6 MV photon irradiation. The proposed dosimeter shows good linearity at doses ranging from 1 to 4 Gy. The small size of these detectors points to its use as a dosimeter at megavoltage energies, where better tissue-equivalence and the Bragg-Gray cavity theory prevails.
  3. Fulltext Sensitive Fibre-Based Thermoluminescence Detectors for High Resolution In-Vivo Dosimetry
    Ghomeishi M, Mahdiraji GA, Adikan FR, Ung NM, Bradley DA
    Sci Rep, 2015;5:13309.
    PMID: 26314683 DOI: 10.1038/srep13309
    With interest in the potential of optical fibres as the basis of next-generation thermoluminescence dosimeters (TLDs), the development of suitable forms of material and their fabrication has become a fast-growing endeavour. Present study focuses on three types of Ge-doped optical fibres with different structural arrangements and/or shapes, namely conventional cylindrical fibre, capillary fibre, and flat fibre, all fabricated using the same optical fibre preform. For doses from 0.5 to 8 Gy, obtained at electron and photon energies, standard thermoluminescence (TL) characteristics of the optical fibres have been the subject of detailed investigation. The results show that in collapsing the capillary fibre into a flat shape, the TL yield is increased by a factor of 5.5, the yield being also some 3.2 times greater than that of the conventional cylindrical fibre fabricated from the same perform. This suggests a means of production of suitably sensitive TLD for in-vivo dosimeter applications. Addressing the associated defects generating luminescence from each of the optical fibres, the study encompasses analysis of the TL glow curves, with computerized glow curve deconvolution (CGCD) and 2(nd) order kinetics.
  4. Evaluation of Ge-doped silica fibre TLDs for in vivo dosimetry during intraoperative radiotherapy
    Moradi F, Ung NM, Mahdiraji GA, Khandaker MU, See MH, Taib NA, et al.
    Phys Med Biol, 2019 04 12;64(8):08NT04.
    PMID: 30840946 DOI: 10.1088/1361-6560/ab0d4e
    Ge-doped silica fibre (GDSF) thermoluminescence dosimeters (TLD) are non-hygroscopic spatially high-resolution radiation sensors with demonstrated potential for radiotherapy dosimetry applications. The INTRABEAM® system with spherical applicators, one of a number of recent electronic brachytherapy sources designed for intraoperative radiotherapy (IORT), presents a representative challenging dosimetry situation, with a low keV photon beam and a desired rapid dose-rate fall-off close-up to the applicator surface. In this study, using the INTRABEAM® system, investigations were made into the potential application of GDSF TLDs for in vivo IORT dosimetry. The GDSFs were calibrated over the respective dose- and depth-range 1 to 20 Gy and 3 to 45 mm from the x-ray probe. The effect of different sizes of spherical applicator on TL response of the fibres was also investigated. The results show the GDSF TLDs to be applicable for IORT dose assessment, with the important incorporated correction for beam quality effects using different spherical applicator sizes. The total uncertainty in use of this type of GDSF for dosimetry has been found to range between 9.5% to 12.4%. Subsequent in vivo measurement of skin dose for three breast patients undergoing IORT were performed, the measured doses being below the tolerance level for acute radiation toxicity.
  5. Monte Carlo skin dose simulation in intraoperative radiotherapy of breast cancer using spherical applicators
    Moradi F, Ung NM, Khandaker MU, Mahdiraji GA, Saad M, Abdul Malik R, et al.
    Phys Med Biol, 2017 Jul 28;62(16):6550-6566.
    PMID: 28708603 DOI: 10.1088/1361-6560/aa7fe6
    The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators.

    HIGHLIGHTS: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin safety.

  6. Borosilicate glass 60Co high dose rate brachytherapy thermoluminescence dosimetry
    Nazeri AAZA, Sani SFA, Ung NM, Almugren KS, Alkallas FH, Bradley DA
    Appl Radiat Isot, 2021 Oct;176:109814.
    PMID: 34175543 DOI: 10.1016/j.apradiso.2021.109814
    Brachytherapy is commonly used in treatment of cervical, prostate, breast and skin cancers, also for oral cancers, typically via the application of sealed radioactive sources that are inserted within or alongside the area to be treated. A particular aim of the various brachytherapy techniques is to accurately transfer to the targeted tumour the largest possible dose, at the same time minimizing dose to the surrounding normal tissue, including organs at risk. The dose fall-off with distance from the sources is steep, the dose gradient representing a prime factor in determining the dose distribution, also representing a challenge to the conduct of measurements around sources. Amorphous borosilicate glass (B2O3) in the form of microscope cover slips is recognized to offer a practicable system for such thermoluminescence dosimetry (TLD), providing for high-spatial resolution (down to 
  7. Fulltext Tailored Ge-doped fibres for passive electron radiotherapy dosimetry
    Mat Nawi SN, Abdul Sani SF, Khandaker MU, Ung NM, Almugren KS, Alkallas FH, et al.
    PLoS One, 2020;15(7):e0235053.
    PMID: 32673337 DOI: 10.1371/journal.pone.0235053
    Study has been made of the thermoluminescence yield of various novel tailor-made silica fibres, 6 and 8 mol % Ge-doped, with four differing outer dimensions, comprised of flat and cylindrical shapes, subjected to electron irradiation. Main thermoluminescence dosimetric characteristics have been investigated, including the glow curve, dose response, energy dependence, minimum detectable dose, effective atomic number, linearity of index and sensitivity of the fibres. The studies have also established the uncertainties involved as well as the stability of response in terms of fading effect, reproducibility and annealing. In addition, dose-rate dependence was accounted for as this has the potential to be a significant factor in radiotherapy applications. The 6 and 8 mol % fibres have been found to provide highly linear dose response within the range 1 to 4 Gy, the smallest size flat fibre, 6 mol% Ge-doped, showing the greatest response by a factor of 1.1 with respect to the highly popular LiF phosphor-based medium TLD100. All of the fibres also showed excellent reproducibility with a standard deviation of < 2% and < 4% for 6 and 8 mol % Ge-doped fibres respectively. For fading evaluation, the smallest 6 mol% Ge-doped dimension flat fibre, i.e., 85 × 270 μm displayed the lowest signal loss within 120 days post-irradiation, at around 26.9% also showing a response superior to that of all of the other fibres. Moreover, all the fibres and TLD-100 chips showed independence with respect to electron irradiation energy and dose-rate. Compared with the 8 mol% Ge-doped optical fibres, the 6 mol% Ge-doped flat optical fibres have been demonstrated to possess more desirable performance features for passive dosimetry, serving as a suitable alternative to TLD-100 for medical irradiation treatment applications.
  8. In vivo skin dose measurement using MOSkin detectors in tangential breast radiotherapy
    Jong WL, Ung NM, Wong JH, Ng KH, Wan Ishak WZ, Abdul Malik R, et al.
    Phys Med, 2016 Nov;32(11):1466-1474.
    PMID: 27842982 DOI: 10.1016/j.ejmp.2016.10.022
    The purpose of this study is to measure patient skin dose in tangential breast radiotherapy. Treatment planning dose calculation algorithm such as Pencil Beam Convolution (PBC) and in vivo dosimetry techniques such as radiochromic film can be used to accurately monitor radiation doses at tissue depths, but they are inaccurate for skin dose measurement. A MOSFET-based (MOSkin) detector was used to measure skin dose in this study. Tangential breast radiotherapies ("bolus" and "no bolus") were simulated on an anthropomorphic phantom and the skin doses were measured. Skin doses were also measured in 13 patients undergoing each of the techniques. In the patient study, the EBT2 measurements and PBC calculation tended to over-estimate the skin dose compared with the MOSkin detector (p<0.05) in the "no bolus radiotherapy". No significant differences were observed in the "bolus radiotherapy" (p>0.05). The results from patients were similar to that of the phantom study. This shows that the EBT2 measurement and PBC calculation, while able to predict accurate doses at tissue depths, are inaccurate in predicting doses at build-up regions. The clinical application of the MOSkin detectors showed that the average total skin doses received by patients were 1662±129cGy (medial) and 1893±199cGy (lateral) during "no bolus radiotherapy". The average total skin doses were 4030±72cGy (medial) and 4004±91cGy (lateral) for "bolus radiotherapy". In some cases, patient skin doses were shown to exceed the dose toxicity level for skin erythema. Hence, a suitable device for in vivo dosimetry is necessary to accurately determine skin dose.
  9. Fulltext Assessment of demineralized tooth lesions using optical coherence tomography and other state-of-the-art technologies: a review
    Mohamad Saberi FN, Sukumaran P, Ung NM, Liew YM
    Biomed Eng Online, 2022 Dec 03;21(1):83.
    PMID: 36463182 DOI: 10.1186/s12938-022-01055-x
    Tooth demineralization is one of the most common intraoral diseases, encompassing (1) caries caused by acid-producing bacteria and (2) erosion induced by acid of non-bacterial origin from intrinsic sources (e.g. stomach acid reflux) and extrinsic sources (e.g. carbonated drinks). Current clinical assessment based on visual-tactile examination and standardized scoring systems is insufficient for early detection. A combination of clinical examination and technology is therefore increasingly adapted. This paper reviews various procedures and technologies that have been invented to diagnose and assess the severity of tooth demineralization, with focus on optical coherence tomography (OCT). As a micron-resolution non-invasive 3D imaging modality, variants of OCT are now available, offering many advantages under different working principles for detailed analytical assessment of tooth demineralization. The roles, capabilities and impact of OCT against other state-of-the-art technologies in both clinical and research settings are described. (139 words).
  10. Remodeling in Aortic Stenosis With Reduced and Preserved Ejection Fraction: Insight on Motion Abnormality Via 3D + Time Personalized LV Modeling in Cardiac MRI
    Chuah SH, Tan LK, Md Sari NA, Chan BT, Hasikin K, Lim E, et al.
    J Magn Reson Imaging, 2023 Jul 15.
    PMID: 37452574 DOI: 10.1002/jmri.28915
    BACKGROUND: Increased afterload in aortic stenosis (AS) induces left ventricle (LV) remodeling to preserve a normal ejection fraction. This compensatory response can become maladaptive and manifest with motion abnormality. It is a clinical challenge to identify contractile and relaxation dysfunction during early subclinical stage to prevent irreversible deterioration.

    PURPOSE: To evaluate the changes of regional wall dynamics in 3D + time domain as remodeling progresses in AS.

    STUDY TYPE: Retrospective.

    POPULATION: A total of 31 AS patients with reduced and preserved ejection fraction (14 AS_rEF: 7 male, 66.5 [7.8] years old; 17 AS_pEF: 12 male, 67.0 [6.0] years old) and 15 healthy (6 male, 61.0 [7.0] years old).

    FIELD STRENGTH/SEQUENCE: 1.5 T Magnetic resonance imaging/steady state free precession and late-gadolinium enhancement sequences.

    ASSESSMENT: Individual LV models were reconstructed in 3D + time domain and motion metrics including wall thickening (TI), dyssynchrony index (DI), contraction rate (CR), and relaxation rate (RR) were automatically extracted and associated with the presence of scarring and remodeling.

    STATISTICAL TESTS: Shapiro-Wilk: data normality; Kruskal-Wallis: significant difference (P 

  11. Regional assessment of LV wall in infarcted heart using tagged MRI and cardiac modelling
    Jahanzad Z, Liew YM, Bilgen M, McLaughlin RA, Leong CO, Chee KH, et al.
    Phys Med Biol, 2015 May 21;60(10):4015-31.
    PMID: 25919317 DOI: 10.1088/0031-9155/60/10/4015
    A segmental two-parameter empirical deformable model is proposed for evaluating regional motion abnormality of the left ventricle. Short-axis tagged MRI scans were acquired from 10 healthy subjects and 10 postinfarct patients. Two motion parameters, contraction and rotation, were quantified for each cardiac segment by fitting the proposed model using a non-rigid registration algorithm. The accuracy in motion estimation was compared to a global model approach. Motion parameters extracted from patients were correlated to infarct transmurality assessed with delayed-contrast-enhanced MRI. The proposed segmental model allows markedly improved accuracy in regional motion analysis as compared to the global model for both subject groups (1.22-1.40 mm versus 2.31-2.55 mm error). By end-systole, all healthy segments experienced radial displacement by ~25-35% of the epicardial radius, whereas the 3 short-axis planes rotated differently (basal: 3.3°; mid:  -1° and apical:  -4.6°) to create a twisting motion. While systolic contraction showed clear correspondence to infarct transmurality, rotation was nonspecific to either infarct location or transmurality but could indicate the presence of functional abnormality. Regional contraction and rotation derived using this model could potentially aid in the assessment of severity of regional dysfunction of infarcted myocardium.
  12. Motion corrected LV quantification based on 3D modelling for improved functional assessment in cardiac MRI
    Liew YM, McLaughlin RA, Chan BT, Abdul Aziz YF, Chee KH, Ung NM, et al.
    Phys Med Biol, 2015 Apr 7;60(7):2715-33.
    PMID: 25768708 DOI: 10.1088/0031-9155/60/7/2715
    Cine MRI is a clinical reference standard for the quantitative assessment of cardiac function, but reproducibility is confounded by motion artefacts. We explore the feasibility of a motion corrected 3D left ventricle (LV) quantification method, incorporating multislice image registration into the 3D model reconstruction, to improve reproducibility of 3D LV functional quantification. Multi-breath-hold short-axis and radial long-axis images were acquired from 10 patients and 10 healthy subjects. The proposed framework reduced misalignment between slices to subpixel accuracy (2.88 to 1.21 mm), and improved interstudy reproducibility for 5 important clinical functional measures, i.e. end-diastolic volume, end-systolic volume, ejection fraction, myocardial mass and 3D-sphericity index, as reflected in a reduction in the sample size required to detect statistically significant cardiac changes: a reduction of 21-66%. Our investigation on the optimum registration parameters, including both cardiac time frames and number of long-axis (LA) slices, suggested that a single time frame is adequate for motion correction whereas integrating more LA slices can improve registration and model reconstruction accuracy for improved functional quantification especially on datasets with severe motion artefacts.
  13. Fulltext Thermoluminescence Response of Ge-Doped Cylindrical-, Flat- and Photonic Crystal Silica-Fibres to Electron and Photon Radiation
    Entezam A, Khandaker MU, Amin YM, Ung NM, Bradley DA, Maah J, et al.
    PLoS One, 2016;11(5):e0153913.
    PMID: 27149115 DOI: 10.1371/journal.pone.0153913
    Study has been made of the thermoluminescence (TL) response of silica-based Ge-doped cylindrical, flat and photonic crystal fibres (referred to herein as PCF-collapsed) to electron (6, 12 and 20 MeV) and photon (6, 10 MV) irradiation and 1.25 MeV γ-rays, for doses from 0.1 Gy to 100 Gy. The electron and photon irradiations were delivered through use of a Varian Model 2100C linear accelerator located at the University of Malaya Medical Centre and γ-rays delivered from a 60Co irradiator located at the Secondary Standard Dosimetry Laboratory (SSDL), Malaysian Nuclear Agency. Tailor-made to be of various dimensions and dopant concentrations (6-10% Ge), the fibres were observed to provide TL yield linear with radiation dose, reproducibility being within 1-5%, with insensitivity to energy and angular variation. The sensitivity dependency of both detectors with respect to field size follows the dependency of the output factors. For flat fibres exposed to 6 MV X-rays, the 6% Ge-doped fibre provided the greatest TL yield while PCF-collapsed showed a response 2.4 times greater than that of the 6% Ge-doped flat fibres. The response of cylindrical fibres increased with core size. The fibres offer uniform response, high spatial resolution and sensitivity, providing the basis of promising TL systems for radiotherapy applications.
  14. Neck node bolus technique in the treatment of Nasopharyngeal Carcinoma with Intensity-modulated radiotherapy
    Phua CE, Ung NM, Tan BS, Tan AL, Eng KY, Ng BS
    Asian Pac J Cancer Prev, 2012;13(12):6133-7.
    PMID: 23464418
    PURPOSE: To study the effect of bolus versus no bolus in the coverage of the nodal tumour volume with intensity-modulated radiotherapy (IMRT) for the treatment of nasopharyngeal carcinoma (NPC).

    METHODS AND MATERIALS: This retrospective study used data from 5 consecutive patients with NPC who were treated with bolus for large neck nodes using IMRT from November 2011-January 2012 in our institute. All these patients were treated radically with IMRT according to our institution's protocol. Re-planning with IMRT without bolus for these patients with exactly the same target volumes were done for comparison. Comparison of the plans was done by comparing the V70 of PTV70-N, V66.5 of PTV70-N, V65.1 of PTV70-N and the surface dose of the PTV70-N.

    RESULTS: The mean size of the largest diameter of the enlarged lymph nodes for the 5 patients was 3.9 cm. The mean distance of the GTV-N to the skin surface was 0.6 cm. The mean V70 of PTV70-N for the 5 patients showed an absolute advantage of 10.8% (92.4% vs. 81.6%) for the plan with bolus while the V66.5 of PTV70-N had an advantage of 8.1% (97.0% vs. 88.9%). The mean V65.1 also had an advantage of 7.1% (97.6% vs. 90.5%). The mean surface dose for the PTV70-N was also much higher at 61.1 Gy for the plans with bolus compared to only 23.5 Gy for the plans without bolus.

    CONCLUSION: Neck node bolus technique should be strongly considered in the treatment of NPC with enlarged lymph nodes treated with IMRT. It yields a superior dosimetry compared to non-bolus plans with acceptable skin toxicity.

  15. Comparison of planned and measured rectal dose in-vivo during high dose rate Cobalt-60 brachytherapy of cervical cancer
    Zaman ZK, Ung NM, Malik RA, Ho GF, Phua VC, Jamalludin Z, et al.
    Phys Med, 2014 Dec;30(8):980-4.
    PMID: 25086486 DOI: 10.1016/j.ejmp.2014.07.002
    Cobalt-60 (Co-60) is a relatively new source for the application of high-dose rate (HDR) brachytherapy. Radiation dose to the rectum is often a limiting factor in achieving the full prescribed dose to the target during brachytherapy of cervical cancer. The aim of this study was to measure radiation doses to the rectum in-vivo during HDR Co-60 brachytherapy. A total of eleven HDR brachytherapy treatments of cervical cancer were recruited in this study. A series of diodes incorporated in a rectal probe was inserted into the patient's rectum during each brachytherapy procedure. Real-time measured rectal doses were compared to calculated doses by the treatment planning system (TPS). The differences between calculated and measured dose ranged from 8.5% to 41.2%. This corresponds to absolute dose differences ranging from 0.3 Gy to 1.5 Gy. A linear relationship was observed between calculated and measured doses with linear regression R(2) value of 0.88, indicating close association between the measured and calculated doses. In general, absorbed doses for the rectum as calculated by TPS were observed to be higher than the doses measured using the diode probe. In-vivo dosimetry is an important quality assurance method for HDR brachytherapy of cervical cancer. It provides information that can contribute to the reduction of errors and discrepancies in dose delivery. Our study has shown that in-vivo dosimetry is feasible and can be performed to estimate the dose to the rectum during HDR brachytherapy using Co-60.
  16. The characteristics of Fuji IP Cassette Type PII and application for radiation oncology quality assurance tests and portal imaging
    Soh HS, Ung NM, Ng KH
    Australas Phys Eng Sci Med, 2008 Jun;31(2):146-50.
    PMID: 18697706
    The advancement of digital imaging has prompted more medical institutions to go filmless. The computed radiography (CR) system is becoming an important tool not only in diagnostic imaging, but also in radiation oncology. A new CR system that was specially designed for the use in radiation oncology, Fuji IP cassette type PII has been introduced to the market in the middle of year 2006. This project aimed to study some basic physical characteristics of this new type of cassette and explore its application for performing quality assurance (QA) tests and portal imaging in radiotherapy. All the images were read by FCR 5000 Plus reader. The image was found to reach its saturation value of 1023 (due to the image was stored in 10 bits data) by depending on the sensitivity value being adjusted. The uniformity test gave the result of 0.12%. The cassette was used to perform the QA tests which were previously performed using film. All the results met the specification as stated in AAPM Task Group 40. The comparison for the portal images of PortalVision contrast-detail phantom showed that the spatial resolution of the images obtained by CR system (Fujifilm Co., Ltd., Tokyo, Japan) were better than the EPID (Varian Medical Systems, Inc., Palo Alto, USA) and film system (Eastman Kodak Co., New York, USA). The IP cassette type PII was found to be suitable as an alternative QA test tool and portal imaging in radiotherapy.
  17. Medical physics aspects of cancer care in the Asia Pacific region: 2014 survey results
    Kron T, Azhari HA, Voon EO, Cheung KY, Ravindran P, Soejoko D, et al.
    Australas Phys Eng Sci Med, 2015 Sep;38(3):493-501.
    PMID: 26346030 DOI: 10.1007/s13246-015-0373-2
    It was the aim of this work to assess and track the workload, working conditions and professional recognition of radiation oncology medical physicists (ROMPs) in the Asia Pacific region over time. In this third survey since 2008, a structured questionnaire was mailed in 2014 to 22 senior medical physicists representing 23 countries. As in previous surveys the questionnaire covered seven themes: 1 education, training and professional certification, 2 staffing, 3 typical tasks, 4 professional organisations, 5 resources, 6 research and teaching, and 7 job satisfaction. The response rate of 100% is a result of performing a survey through a network, which allows easy follow-up. The replies cover 4841 ROMPs in 23 countries. Compared to 2008, the number of medical physicists in many countries has doubled. However, the number of experienced ROMPs compared to the overall workforce is still small, especially in low and middle income countries. The increase in staff is matched by a similar increase in the number of treatment units over the years. Furthermore, the number of countries using complex techniques (IMRT, IGRT) or installing high end equipment (tomotherapy, robotic linear accelerators) is increasing. Overall, ROMPs still feel generally overworked and the professional recognition, while varying widely, appears to be improving only slightly. Radiation oncology medical physics practice has not changed significantly over the last 6 years in the Asia Pacific Region even if the number of physicists and the number and complexity of treatment techniques and technologies have increased dramatically.
  18. Fulltext On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy
    Yusof FH, Ung NM, Wong JH, Jong WL, Ath V, Phua VC, et al.
    PLoS One, 2015;10(6):e0128544.
    PMID: 26052690 DOI: 10.1371/journal.pone.0128544
    This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements. The effect of incident beam angles on surface dose was also studied. The OSLD was subsequently used to measure surface dose during tangential breast radiotherapy treatments in a phantom study and in the clinical measurement of 10 patients. Surface dose to the treated breast or chest wall, and on the contralateral breast were measured. The WED of the OSLD was found to be at 0.4 mm. For surface dose measurement on a solid water phantom, the Markus ionization chamber measured 15.95% for 6 MV photon beam and 12.64% for 10 MV photon beam followed by EBT3 film (23.79% and 17.14%) and OSLD (37.77% and 25.38%). Surface dose increased with the increase of the incident beam angle. For phantom and patient breast surface dose measurement, the response of the OSLD was higher than EBT3 film. The in-vivo measurements were also compared with the treatment planning system predicted dose. The OSLD measured higher dose values compared to dose at the surface (Hp(0.0)) by a factor of 2.37 for 6 MV and 2.01 for 10 MV photon beams, respectively. The measurement of absorbed dose at the skin depth of 0.4 mm by the OSLD can still be a useful tool to assess radiation effects on the skin dermis layer. This knowledge can be used to prevent and manage potential acute skin reaction and late skin toxicity from radiotherapy treatments.
  19. Fulltext Teaching and learning of postgraduate medical physics using Internet-based e-learning during the COVID-19 pandemic - A case study from Malaysia
    Azlan CA, Wong JHD, Tan LK, A D Huri MSN, Ung NM, Pallath V, et al.
    Phys Med, 2020 Dec;80:10-16.
    PMID: 33070007 DOI: 10.1016/j.ejmp.2020.10.002
    PURPOSE: We present the implementation of e-learning in the Master of Medical Physics programme at the University of Malaya during a partial lockdown from March to June 2020 due to the COVID-19 pandemic.

    METHODS: Teaching and Learning (T&L) activities were conducted virtually on e-learning platforms. The students' experience and feedback were evaluated after 15 weeks.

    RESULTS: We found that while students preferred face-to-face, physical teaching, they were able to adapt to the new norm of e-learning. More than 60% of the students agreed that pre-recorded lectures and viewing videos of practical sessions, plus answering short questions, were beneficial. Certain aspects, such as hands-on practical and clinical experience, could never be replaced. The e-learning and study-from-home environment accorded a lot of flexibility. However, students also found it challenging to focus because of distractions, lack of engagement and mental stress. Technical problems, such as poor Internet connectivity and limited data plans, also compounded the problem.

    CONCLUSION: We expect e-learning to prevail in future. Hybrid learning strategies, which includes face-to-face classes and e-learning, will become common, at least in the medical physics programme of the University of Malaya even after the pandemic.

  20. Medical physics aspects of Intensity-Modulated Radiotherapy practice in Malaysia
    Hizam NDA, Ung NM, Jong WL, Zin HM, Rahman ATA, Loh JPY, et al.
    Phys Med, 2019 Nov;67:34-39.
    PMID: 31655398 DOI: 10.1016/j.ejmp.2019.10.023
    PURPOSE: Intensity Modulated Radiotherapy (IMRT) has changed the practice of radiotherapy since its implementation in the 1990s. The purpose of this study is to review current practice of IMRT in Malaysia.

    METHODS: A survey on medical physics aspects of IMRT is conducted on radiotherapy departments across Malaysia to assess the usage, experience and QA in IMRT, which is done for the first time in this country. A set of questionnaires was designed and sent to the physicist in charge for their responses. The questionnaire consisted of four sections; (i) Experience and qualification of medical physicists, (ii) CT simulation techniques (iii) Treatment planning and treatment unit, (iv) IMRT process, delivery and QA procedure.

    RESULTS: A total of 26 responses were collected, representing 26 departments out of 33 radiotherapy departments in operation across Malaysia (79% response rate). Results showed that the medical physics aspects of IMRT practice in Malaysia are homogenous, with some variations in certain areas of practices. Thirteen centres (52%) performed measurement-based QA using 2D array detector and analysed using gamma index criteria of 3%, 3 mm with variation confidence range. In relation to the IMRT delivery, 44% of Malaysia's physicist takes more than 8 h to plan a head and neck case compared to the UK study possibly due to the lack of professional training.

    CONCLUSIONS: This survey provides a picture of medical physics aspects of IMRT in Malaysia where the results/data can be used by radiotherapy departments to benchmark their local policies and practice.

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