Displaying publications 361 - 380 of 712 in total

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  1. Effect of inorganic salts and glucose additives on dose-response, melting point and mass density of genipin gel dosimeters
    Al-jarrah AM, Abdul Rahman A, Shahrim I, Razak NN, Ababneh B, Tousi ET
    Phys Med, 2016 Jan;32(1):36-41.
    PMID: 26494156 DOI: 10.1016/j.ejmp.2015.09.003
    Genipin gel dosimeters are hydrogels infused with a radiation-sensitive material which yield dosimetric information in three dimensions (3D). The effect of inorganic salts and glucose on the visible absorption dose-response, melting points and mass density of genipin gel dosimeters has been experimentally evaluated using 6-MV LINAC photons. As a result, the addition of glucose with optimum concentration of 10% (w/w) was found to improve the thermal stability of the genipin gel and increase its melting point (Tm) by 6 °C accompanied by a slight decrease of dose-response. Furthermore, glucose helps to adjust the gel mass density to obtain the desired tissue-equivalent properties. A drop of Tm was observed when salts were used as additives. As the salt concentration increased, gel Tm decreased. The mass density and melting point of the genipin gel could be adjusted using different amounts of glucose that improved the genipin gel suitability for 3D dose measurements without introducing additional toxicity to the final gel.
    Matched MeSH terms: Dose-Response Relationship, Radiation; Radiation Dosage*
  2. Real-time eye lens dose monitoring during cerebral angiography procedures
    Safari MJ, Wong JH, Kadir KA, Thorpe NK, Cutajar DL, Petasecca M, et al.
    Eur Radiol, 2016 Jan;26(1):79-86.
    PMID: 26002131 DOI: 10.1007/s00330-015-3818-9
    OBJECTIVES: To develop a real-time dose-monitoring system to measure the patient's eye lens dose during neuro-interventional procedures.

    METHODS: Radiation dose received at left outer canthus (LOC) and left eyelid (LE) were measured using Metal-Oxide-Semiconductor Field-Effect Transistor dosimeters on 35 patients who underwent diagnostic or cerebral embolization procedures.

    RESULTS: The radiation dose received at the LOC region was significantly higher than the dose received by the LE. The maximum eye lens dose of 1492 mGy was measured at LOC region for an AVM case, followed by 907 mGy for an aneurysm case and 665 mGy for a diagnostic angiography procedure. Strong correlations (shown as R(2)) were observed between kerma-area-product and measured eye doses (LOC: 0.78, LE: 0.68). Lateral and frontal air-kerma showed strong correlations with measured dose at LOC (AKL: 0.93, AKF: 0.78) and a weak correlation with measured dose at LE. A moderate correlation was observed between fluoroscopic time and dose measured at LE and LOC regions.

    CONCLUSIONS: The MOSkin dose-monitoring system represents a new tool enabling real-time monitoring of eye lens dose during neuro-interventional procedures. This system can provide interventionalists with information needed to adjust the clinical procedure to control the patient's dose.

    KEY POINTS: Real-time patient dose monitoring helps interventionalists to monitor doses. Strong correlation was observed between kerma-area-product and measured eye doses. Radiation dose at left outer canthus was higher than at left eyelid.

    Matched MeSH terms: Lens, Crystalline/radiation effects*; Radiation Dosage
  3. Fulltext Optimisation of the Photonic Efficiency of TiO2 Decorated on MWCNTs for Methylene Blue Photodegradation
    Abdullahi N, Saion E, Shaari AH, Al-Hada NM, Keiteb A
    PLoS One, 2015;10(5):e0125511.
    PMID: 25993127 DOI: 10.1371/journal.pone.0125511
    MWCNTs/TiO2 nanocomposite was prepared by oxidising MWCNT in H2SO4/HNO3 then decorating it with TiO2-p25 nanopowder. The composites were characterised using XRD, TEM, FT-IR PL and UV-vis spectroscopy. The TEM images have shown TiO2 nanoparticles immobilised onto the sidewalls of the MWCNTs. The UV-vis spectrum confirms that the nanocomposites can significantly absorb more light in the visible regions compared with the commercial TiO2 (P25). The catalytic activity of these nanocomposites was determined by photooxidation of MB aqueous solution in the presence of visible light. The MWCNTs/TiO2 (1:3) mass ratio showed maximum degradation efficiency. However, its activity was more favourable in alkaline and a neutral pH than an acidic medium.
    Matched MeSH terms: Methylene Blue/radiation effects*; Titanium/radiation effects*
  4. Characterization of a MOSkin detector for in vivo skin dose measurements during interventional radiology procedures
    Safari MJ, Wong JH, Ng KH, Jong WL, Cutajar DL, Rosenfeld AB
    Med Phys, 2015 May;42(5):2550-8.
    PMID: 25979047 DOI: 10.1118/1.4918576
    The MOSkin is a MOSFET detector designed especially for skin dose measurements. This detector has been characterized for various factors affecting its response for megavoltage photon beams and has been used for patient dose measurements during radiotherapy procedures. However, the characteristics of this detector in kilovoltage photon beams and low dose ranges have not been studied. The purpose of this study was to characterize the MOSkin detector to determine its suitability for in vivo entrance skin dose measurements during interventional radiology procedures.
    Matched MeSH terms: Dose-Response Relationship, Radiation; Skin/radiation effects*
  5. Fulltext Gamma irradiation and red cell haemolysis: a study at the Universiti Kebangsaan Malaysia Medical Centre
    Yousuf R, Mobin MH, Leong CF
    Malays J Pathol, 2015 Aug;37(2):91-4.
    PMID: 26277664 MyJurnal
    Gamma-irradiation of blood components is regarded a safe procedure used for prevention of transfusion associated graft-versus-host disease. However, reports showed that irradiation can cause erythrocyte haemolysis and damage to the RBC membrane. In University Kebangsaan Malaysia Medical Centre (UKMMC), a number of suspected transfusion reactions (TR) featured unusual isolated episodes of red-coloured-urine or haemoglobinuria among paediatric patients without clinical features of acute haemolytic TR. Haemolysis of irradiated red cells was suspected as a cause. This study was conducted to evaluate haemolytic changes of RBC components following irradiation. A prospective, pre- and post- irradiation comparative study was conducted on 36 paired RBC-components in the blood-bank, UKMMC in the year 2013. Samples were tested for plasma-Hb, percent-haemolysis, plasma-potassium (K⁺) and lactate dehydrogenase (LDH) level. Post-irradiation mean plasma-Hb and percent-haemolysis were significantly higher than pre-irradiation values at 0.09 ±0.06g/dl VS 0.10 ± 0.06g/dl and 0.19 ± 0.13% VS 0.22 ± .13% respectively, while plasma-K⁺ and LDH values did not show significant difference. However, the mean percent-haemolysis level was still within recommended acceptable levels for clinical use, supporting that irradiated RBC units were safe and of acceptable quality for transfusion. There was no conclusive reason for isolated haemoglobinuria following transfusion of irradiated red-cell products. Further research is suggested to investigate the other possible causes.
    Matched MeSH terms: Erythrocytes/radiation effects*; Hemolysis/radiation effects*
  6. Prediction of terrestrial gamma dose rate based on geological formations and soil types in the Johor State, Malaysia
    Saleh MA, Ramli AT, bin Hamzah K, Alajerami Y, Moharib M, Saeed I
    J Environ Radioact, 2015 Oct;148:111-22.
    PMID: 26142818 DOI: 10.1016/j.jenvrad.2015.05.019
    This study aims to predict and estimate unmeasured terrestrial gamma dose rate (TGDR) using statistical analysis methods to derive a model from the actual measurement based on geological formation and soil type. The measurements of TGDR were conducted in the state of Johor with a total of 3873 measured points which covered all geological formations, soil types and districts. The measurements were taken 1 m above the soil surface using NaI [Ti] detector. The measured gamma dose rates ranged from 9 nGy h(-1) to 1237 nGy h(-1) with a mean value of 151 nGy h(-1). The data have been normalized to fit a normal distribution. Tests of significance were conducted among all geological formations and soil types, using the unbalanced one way ANOVA. The results indicated strong significant differences due to the different geological formations and soil types present in Johor State. Pearson Correlation was used to measure the relations between gamma dose rate based on geological formation and soil type (D(G,S)) with the gamma dose rate based on geological formation (D(G)) or soil type (D(s)). A very good correlation was found between D(G,S) and D(G) or D(G,S) and D(s). A total of 118 pairs of geological formations and soil types were used to derive the statistical contribution of geological formations and soil types to gamma dose rates. The contribution of the gamma dose rate from geological formation and soil type were found to be 0.594 and 0.399, respectively. The null hypotheses were accepted for 83% of examined data, therefore, the model could be used to predict gamma dose rates based on geological formation and soil type information.
    Matched MeSH terms: Radiation Dosage; Radiation Monitoring/methods*
  7. A simplified approach for exit dose in vivo measurements in radiotherapy and its clinical application
    Banjade DP, Shrestha SL, Shukri A, Tajuddin AA, Bhat M
    Australas Phys Eng Sci Med, 2002 Sep;25(3):110-8.
    PMID: 12416587
    This is a study using LiF:Mg;Ti thermoluminescent dosimeter (TLD) rods in phantoms to investigate the effect of lack of backscatter on exit dose. Comparing the measured dose with anticipated dose calculated using tissue maximum ratio (TMR) or percentage depth dose (PDD) gives rise to a correction factor. This correction factor may be applied to in-vivo dosimetry results to derive true dose to a point within the patient. Measurements in a specially designed humanoid breast phantom as well as patients undergoing radiotherapy treatment were also been done. TLDs with reproducibility of within +/- 3% (1 SD) are irradiated in a series of measurements for 6 and 10 MV photon beams from a medical linear accelerator. The measured exit doses for the different phantom thickness for 6 MV beams are found to be lowered by 10.9 to 14.0% compared to the dose derived from theoretical estimation (normalized dose at dmax). The same measurements for 10 MV beams are lowered by 9.0 to 13.5%. The variations of measured exit dose for different field sizes are found to be within 2.5%. The exit doses with added backscatter material from 2 mm up to 15 cm, shows gradual increase and the saturated values agreed within 1.5% with the expected results for both beams. The measured exit doses in humanoid breast phantom as well as in the clinical trial on patients undergoing radiotherapy also agreed with the predicted results based on phantom measurements. The authors' viewpoint is that this technique provides sufficient information to design exit surface bolus to restore build down effect in cases where part of the exit surface is being considered as a target volume. It indicates that the technique could be translated for in vivo dose measurements, which may be a conspicuous step of quality assurance in clinical practice.
    Matched MeSH terms: Breast/radiation effects*; Scattering, Radiation
  8. A study of mean glandular dose during diagnostic mammography in Malaysia and some of the factors affecting it
    Jamal N, Ng KH, McLean D
    Br J Radiol, 2003 Apr;76(904):238-45.
    PMID: 12711643
    The primary objective of this study was to determine the mean glandular dose (MGD) during diagnostic mammography in Malaysia. The secondary objective was to evaluate some of the factors affecting MGD. A survey of standard MGD was performed, based upon quality control records for the period October 1999 to August 2001. This covered 30 mammography units from 9 manufacturers. MGD was also measured for a series of patients attending mammography examinations at three other mammography units. MGD per film was estimated from recorded radiographic factors, the compressed breast thickness (CBT) and X-ray unit calibration data. MGD per woman was calculated by summing the MGDs for all films, and averaging it over both breasts. 300 women drawn equally from three major ethnic groups, namely Malay, Chinese and Indian, took part in the study. The difference of MGD per woman between ethnic groups was tested for significance using non-parametric Kruskal-Wallis and median tests. The factors affecting MGD per woman were tested for significance using a multivariate analysis of variance. The MGD for the phantom was 1.23 mGy (range 0.22-2.39 mGy) while the mean patient based MGD per film was 1.54 mGy and 1.82 mGy for the craniocaudal and mediolateral oblique views, respectively. The mean MGD per woman was 3.37 mGy. It was also found that there is no significant difference in MGD per woman among the ethnic groups (p>0.05, Kruskal-Wallis test). However, on the multivariate test two factors, namely half value layer of the X-ray beam and (CBT), had a significant effect on MGD per woman (p<0.05). No significant relationships were seen between MGD per woman with respect to ethnicity, body mass index or age.
    Matched MeSH terms: Breast/radiation effects*; Radiation Dosage
  9. Medically important solar ultraviolet A. Radiation measurements
    Ilyas M, Abdul Aziz D, Tajuddin MR
    Int J Dermatol, 1988 Jun;27(5):315-8.
    PMID: 3391727
    Results from a 6-year study of solar ultraviolet A (UVA) radiation measurements at the equatorial location of Penang (5 degrees N) are presented. On clear days, the diurnal flux reaches a very high dosage of about 3.0 x 10(-2) KWHM-2 around midday. The average daily total flux is in the range of 1.6 x 10(-1) KWHM-2 and does not change much seasonally. The high 83% cloud cover only reduces the incoming flux to about half. The radiation flux represents a lower limit of the incident UVA radiation applicable to much of the equatorial/tropical region.
    Matched MeSH terms: Circadian Rhythm/radiation effects; Skin/radiation effects
  10. The 808 nm and 980 nm infrared laser irradiation affects spore germination and stored calcium homeostasis: A comparative study using delivery hand-pieces with standard (Gaussian) or flat-top profile
    Ferrando S, Agas D, Mirata S, Signore A, De Angelis N, Ravera S, et al.
    J. Photochem. Photobiol. B, Biol., 2019 Oct;199:111627.
    PMID: 31536925 DOI: 10.1016/j.jphotobiol.2019.111627
    Photobiomodulation relies on the transfer of energy from incident photons to a cell photoacceptor. For many years the concept of photobiomodulation and its outcome has been based upon a belief that the sole receptor within the cell was the mitochondrion. Recently, it has become apparent that there are other photoacceptors operating in different regions of the electromagnetic spectrum. Alternative photoacceptors would appear to be water and mechanisms regulating calcium homeostasis, despite a direct effect of laser photonic energy on intracellular calcium concentration outwith mitochondrial activity or influence, have not been clearly demonstrated. Therefore, to increase the knowledge of intracellular‑calcium and laser photon interaction, as well as to demonstrate differences in irradiation profiles with modern hand-pieces, we tested and compared the photobiomodulatory effect of 808 nm and 980 nm diode laser light by low- and higher-energy (60s, 100 mW/cm2, 100 mW/cm2, 500 mW/cm2, 1000 mW/cm2, 1500 mW/cm2, 2000 mW/cm2) irradiated with a "standard" (Gaussian fluence distribution) hand-piece or with a "flat-top" (uniform fluence) hand-piece. For this purpose, we used the eukaryote unicellular-model Dictyostelium discoideum. The 808 nm and 980 nm infrared laser light, at the energy tested directly affect the stored Ca2+ homeostasis, independent of the mitochondrial respiratory chain activities. From an organism perspective, the effect on Ca2+-dependent signal transduction as the regulator of spore germination in Dictyostelium, demonstrates how a cell can respond quickly to the correct laser photonic stimulus through a different cellular pathway than the known light-chromophore(mitochondria) interaction. Additionally, both hand-piece designs tested were able to photobiomodulate the D. discoideum cell; however, the hand-piece with a flat-top profile, through uniform fluence levels allows more effective and reproducible effects.
    Matched MeSH terms: Homeostasis/radiation effects*; Germination/radiation effects*
  11. Fulltext Digital healthcare and shifting equipoise in radiation oncology: The butterfly effect of the COVID-19 pandemic
    Boon IS, Lim JS, Au Yong TPT, Boon CS
    J Med Imaging Radiat Sci, 2021 03;52(1):11-13.
    PMID: 33097437 DOI: 10.1016/j.jmir.2020.10.002
    Matched MeSH terms: Radiation Oncology/education; Radiation Oncology/organization & administration*
  12. A fully coupled multiphase model for infrared-convective drying of sweet potato
    Onwude DI, Hashim N, Chen G, Putranto A, Udoenoh NR
    J Sci Food Agric, 2021 Jan 30;101(2):398-413.
    PMID: 32627847 DOI: 10.1002/jsfa.10649
    BACKGROUND: Combined infrared (CIR) and convective drying is a promising technology in dehydrating heat-sensitive foods, such as fruits and vegetables. This novel thermal drying method, which involves the application of infrared energy and hot air during a drying process, can drastically enhance energy efficiency and improve overall product quality at the end of the process. Understanding the dynamics of what goes on inside the product during drying is important for further development, optimization, and upscaling of the drying method. In this study, a multiphase porous media model considering liquid water, gases, and solid matrix was developed for the CIR and hot-air drying (HAD) of sweet potato slices in order to capture the relevant physics and obtain an in-depth insight on the drying process. The model was simulated using Matlab with user-friendly graphical user interface for easy coupling and faster computational time.

    RESULTS: The gas pressure for CIR-HAD was higher centrally and decreased gradually towards the surface of the product. This implies that drying force is stronger at the product core than at the product surface. A phase change from liquid water to vapour occurs almost immediately after the start of the drying process for CIR-HAD. The evaporation rate, as expected, was observed to increase with increased drying time. Evaporation during CIR-HAD increased with increasing distance from the centreline of the sample surface. The simulation results of water and vapour flux revealed that moisture transport around the surfaces and sides of the sample is as a result of capillary diffusion, binary diffusion, and gas pressure in both the vertical and horizontal directions. The nonuniform dominant infrared heating caused the heterogeneous distribution of product temperature. These results suggest that CIR-HAD of food occurs in a non-uniform manner with high vapour and water concentration gradient between the product core and the surface.

    CONCLUSIONS: This study provides in-depth insight into the physics and phase changes of food during CIR-HAD. The multiphase model has the advantage that phase change and impact of CIR-HAD operating parameters can be swiftly quantified. Such a modelling approach is thereby significant for further development and process optimization of CIR-HAD towards industrial upscaling. © 2020 Society of Chemical Industry.

    Matched MeSH terms: Ipomoea batatas/radiation effects; Plant Tubers/radiation effects
  13. TERRESTRIAL RADIONUCLIDES IN SURFACE (DAM) WATER AND CONCOMITANT DOSE IN METROPOLITAN KUALA LUMPUR
    Khandaker MU, Uwatse OB, Bin Shamsul Khairi KA, Faruque MRI, Bradley DA
    Radiat Prot Dosimetry, 2019 Dec 31;185(3):343-350.
    PMID: 30806465 DOI: 10.1093/rpd/ncz018
    Batu Dam is of considerable importance to the metropolis of Kuala Lumpur, its existence and the quality assessment of its waters being essential in helping to maintain the lives of a large sector of the Malaysian population. Concerning the level of naturally occurring radioactivity contained within its waters, a well characterised HPGe γ-ray technique has been used in making measurements of the concentrations of primordial radionuclides in samples of surface water from the Dam. Based on the mean individual daily consumption of dam water, estimation has been made of the concomitant radiation dose. Activity concentrations, in units of Bq l-1, have been found to be in the range 2.4-3.2 for 226Ra, 1.1-1.3 for 232Th and 22.7-40.7 for 40K, in line with literature data for surface waters. The total annual ingestion dose for infants (<1 y) and adolescents (12-17 y) are found to be significant and greater than the World Health Organization recommended maximum dose of 0.1 mSv y-1 from the imbibing of drinking water. However, the Dam water does not pose a threat to public health, the Dam water not being used as the sole source of drinking water. Noting that this is the only known study of water from Batu Dam, the reported levels allow for evaluation of future changes in the natural radioactivity profile.
    Matched MeSH terms: Radiation Dosage; Radiation Monitoring/methods*
  14. MRI-based brain structural changes following radiotherapy of Nasopharyngeal Carcinoma: A systematic review
    Voon NS, Lau FN, Zakaria R, Md Rani SA, Ismail F, Manan HA, et al.
    Cancer Radiother, 2021 Feb;25(1):62-71.
    PMID: 33414057 DOI: 10.1016/j.canrad.2020.07.008
    PURPOSE: Nasopharyngeal carcinoma (NPC) radiotherapy (RT) irradiates parts of the brain which may cause cerebral tissue changes. This study aimed to systematically review the brain microstructure changes using MRI-based measures, diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI) and voxel-based morphometry (VBM) and the impact of dose and latency following RT.

    METHODS: PubMed and Scopus databases were searched based on PRISMA guideline to determine studies focusing on changes following NPC RT.

    RESULTS: Eleven studies fulfilled the inclusion criteria. Microstructural changes occur most consistently in the temporal region. The changes were correlated with latency in seven studies; fractional anisotropy (FA) and gray matter (GM) volume remained low even after a longer period following RT and areas beyond irradiation site with reduced FA and GM measures. For dosage, only one study showed correlation, thus requiring further investigations.

    CONCLUSION: DTI, DKI and VBM may be used as a surveillance tool in detecting brain microstructural changes of NPC patients which correlates to latency and brain areas following RT.

    Matched MeSH terms: Brain/radiation effects*; Temporal Lobe/radiation effects
  15. Enhanced DNA double-strand break repair of microbeam targeted A549 lung carcinoma cells by adjacent WI38 normal lung fibroblast cells via bi-directional signaling
    Kobayashi A, Tengku Ahmad TAF, Autsavapromporn N, Oikawa M, Homma-Takeda S, Furusawa Y, et al.
    Mutat Res, 2017 10;803-805:1-8.
    PMID: 28689138 DOI: 10.1016/j.mrfmmm.2017.06.006
    Understanding the mechanisms underlying the radiation-induced bystander effect (RIBE) and bi-directional signaling between irradiated carcinoma cells and their surrounding non-irradiated normal cells is relevant to cancer radiotherapy. The present study investigated propagation of RIBE signals between human lung carcinoma A549 cells and normal lung fibroblast WI38 cells in bystander cells, either directly or indirectly contacting irradiated A549 cells. We prepared A549-GFP/WI38 co-cultures and A549-GFP/A549 co-cultures, in which A549-GFP cells stably expressing H2BGFP were co-cultured with either A549 cells or WI38 cells, respectively. Using the SPICE-NIRS microbeam, only the A549-GFP cells were irradiated with 500 protons per cell. The level of γ-H2AX, a marker for DNA double-strand breaks (DSB), was subsequently measured for up to 24h post-irradiation in three categories of cells: (1) "targeted"/irradiated A549-GFP cells; (2) "neighboring"/non-irradiated cells directly contacting the "targeted" cells; and (3) "distant"/non-irradiated cells, which were not in direct contact with the "targeted" cells. We found that DSB repair in targeted A549-GFP cells was enhanced by co-cultured WI38 cells. The bystander response in A549-GFP/A549 cell co-cultures, as marked by γ-H2AX levels at 8h post-irradiation, showed a decrease to non-irradiated control level when approaching 24h, while the neighboring/distant bystander WI38 cells in A549-GFP/WI38 co-cultures was maintained at a similar level until 24h post-irradiation. Surprisingly, distant A549-GFP cells in A549-GFP/WI38 co-cultures showed time dependency similar to bystander WI38 cells, but not to distant cells in A549-GFP/A549 co-cultures. These observations indicate that γ-H2AX was induced in WI38 cells as a result of RIBE. WI38 cells were not only involved in rescue of targeted A549, but also in the modification of RIBE against distant A549-GFP cells. The present results demonstrate that radiation-induced bi-directional signaling had extended a profound influence on cellular sensitivity to radiation as well as the sensitivity to RIBE.
    Matched MeSH terms: Fibroblasts/radiation effects*; Bystander Effect/radiation effects*
  16. Fulltext Quantification and Radiological Risk Estimation Due to the Presence of Natural Radionuclides in Maiganga Coal, Nigeria
    Kolo MT, Khandaker MU, Amin YM, Abdullah WH
    PLoS One, 2016;11(6):e0158100.
    PMID: 27348624 DOI: 10.1371/journal.pone.0158100
    Following the increasing demand of coal for power generation, activity concentrations of primordial radionuclides were determined in Nigerian coal using the gamma spectrometric technique with the aim of evaluating the radiological implications of coal utilization and exploitation in the country. Mean activity concentrations of 226Ra, 232Th, and 40K were 8.18±0.3, 6.97±0.3, and 27.38±0.8 Bq kg-1, respectively. These values were compared with those of similar studies reported in literature. The mean estimated radium equivalent activity was 20.26 Bq kg-1 with corresponding average external hazard index of 0.05. Internal hazard index and representative gamma index recorded mean values of 0.08 and 0.14, respectively. These values were lower than their respective precautionary limits set by UNSCEAR. Average excess lifetime cancer risk was calculated to be 0.04×10-3, which was insignificant compared with 0.05 prescribed by ICRP for low level radiation. Pearson correlation matrix showed significant positive relationship between 226Ra and 232Th, and with other estimated hazard parameters. Cumulative mean occupational dose received by coal workers via the three exposure routes was 7.69 ×10-3 mSv y-1, with inhalation pathway accounting for about 98%. All radiological hazard indices evaluated showed values within limits of safety. There is, therefore, no likelihood of any immediate radiological health hazards to coal workers, final users, and the environment from the exploitation and utilization of Maiganga coal.
    Matched MeSH terms: Background Radiation/adverse effects; Radiation Dosage
  17. Quantifying the ultrastructure changes of air-dried and irradiated human amniotic membrane using atomic force microscopy: a preliminary study
    Mohd S, Ghazali MI, Yusof N, Sulaiman S, Ramalingam S, Kamarul T, et al.
    Cell Tissue Bank, 2018 Dec;19(4):613-622.
    PMID: 30056604 DOI: 10.1007/s10561-018-9711-4
    Air-dried and sterilized amnion has been widely used as a dressing to treat burn and partial thickness wounds. Sterilisation at the standard dose of 25 kGy was reported to cause changes in the morphological structure as observed under the scanning electron microscope. This study aimed to quantify the changes in the ultrastructure of the air-dried amnion after gamma-irradiated at several doses by using atomic force microscope. Human placentae were retrieved from mothers who had undergone cesarean elective surgery. Amnion separated from chorion was processed and air-dried for 16 h. It was cut into 10 × 10 mm, individually packed and exposed to gamma irradiation at 5, 15, 25 and 35 kGy. Changes in the ultrastructural images of the amnion were quantified in term of diameter of the epithelial cells, size of the intercellular gap and membrane surface roughness. The longest diameter of the amnion cells reduced significantly after radiation (p 
    Matched MeSH terms: Amnion/radiation effects*; Dose-Response Relationship, Radiation
  18. 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.
    Matched MeSH terms: Skin/radiation effects*; Organs at Risk/radiation effects
  19. CHARACTERISATION AND EVALUATION OF AL2O3:C-BASED OPTICALLY STIMULATED LUMINESCENT DOSEMETER SYSTEM FOR DIAGNOSTIC X-RAYS: PERSONAL AND IN VIVO DOSIMETRY
    Wong JHD, Bakhsh M, Cheah YY, Jong WL, Khor JS, Ng KH
    Radiat Prot Dosimetry, 2019 Dec 31;187(4):451-460.
    PMID: 31650160 DOI: 10.1093/rpd/ncz186
    This study characterises and evaluates an Al2O3:C-based optically stimulated luminescent dosemeter (OSLD) system, commercially known as the nanoDot™ dosemeter and the InLight® microStar reader, for personal and in vivo dose measurements in diagnostic radiology. The system characteristics, such as dose linearity, reader accuracy, reproducibility, batch homogeneity, energy dependence and signal stability, were explored. The suitability of the nanoDot™ dosemeters was evaluated by measuring the depth dose curve, in vivo dose measurement and image perturbation. The nanoDot™ dosemeters were observed to produce a linear dose with ±2.8% coefficient variation. Significant batch inhomogeneity (8.3%) was observed. A slight energy dependence (±6.1%) was observed between 60 and 140 kVp. The InLight® microStar reader demonstrated good accuracy and a reproducibility of ±2%. The depth dose curve measured using nanoDot™ dosemeters showed slightly lower responses than Monte Carlo simulation results. The total uncertainty for a single dose measurement using this system was 11%, but it could be reduced to 9.2% when energy dependence correction was applied.
    Matched MeSH terms: Radiation Dosage; Radiation Dosimeters/standards*
  20. The effects of mis-centering on radiation dose during CT head examination: A phantom study
    Isa INC, Rahmat SMS, Dom SM, Kayun Z, Karim MKA
    J Xray Sci Technol, 2019;27(4):631-639.
    PMID: 31205011 DOI: 10.3233/XST-190491
    There are several factors that may contribute to the increase in radiation dose of CT including the use of unoptimized protocols and improper scanning technique. In this study, we aim to determine significant impact on radiation dose as a result of mis-centering during CT head examination. The scanning was performed by using Toshiba Aquilion 64 slices multi-detector CT (MDCT) scanner and dose were measured by using calibrated ionization chamber. Two scanning protocols of routine CT head; 120 kVp/ 180 mAs and 100 kVp/ 142 mAs were used represent standard and low dose, respectively. As reference measurement, the dose was first measured on standard cylindrical polymethyl methacrylate (PMMA) phantom that positioned at 104 cm from the floor (reference isocenter). The positions then were varied to simulate mis-centering by 5 cm from isocenter, superiorly and inferiorly at 109 cm, 114 cm, 119 cm, 124 cm and 99 cm, 94 cm, 89 cm, 84 cm, respectively. Scanning parameter and dose information from the console were recorded for the radiation effective dose (E) measurement. The highest mean CTDIvol value for MCS and MCI were 105.06 mGy (at +10 cm) and 105.51 mGy (at - 10 cm), respectively which differed significantly (p 
    Matched MeSH terms: Radiation Dosage*; Radiation Dosimeters
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