Displaying publications 281 - 300 of 712 in total

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  1. Effect of modified calm conditions on nuclear dispersion estimates
    Hu SJ, Katagiri H, Kobayashi H
    Health Phys, 1995 Jan;68(1):67-70.
    PMID: 7989197
    When the definition of calm in atmospheric diffusion analyses is changed from 0.5 m s-1 to 0.1 m s-1, actual and more accurate low wind speeds and wind directions can be used to calculate the average air concentrations due to continuous releases of radionuclides at 10-m stack height more realistically and accurately. However, this modified calm condition has little affect on the calculated adult thyroid exposure for a postulated accident.
    Matched MeSH terms: Thyroid Gland/radiation effects*
  2. Radiation-induced pericardial disease: a case report
    Doi SA, Azman W, Leong KW, Bosco J
    Ann Acad Med Singap, 1995 May;24(3):459-61.
    PMID: 7574433
    A typical case of chronic pericardial effusion resulting in cardiac tamponade is presented. A pericardiocentesis was done for diagnosis and drainage, followed by a pleuro-pericardial window as definitive therapy. The minimal cumulative dose expected to produce pericardial disease is about 4000 rads, and the disease usually manifests within 12 months of such radiation exposure, as in this patient. It is concluded that for symptomatic pericardial effusions, available evidence justifies a subtotal pericardiectomy, a window procedure being reserved to tide over ill patients as in this patient. No strong evidence exists for the efficacy of steroid therapy; such therapy is reserved for asymptomatic mild effusions, which may also resolve spontaneously.
    Matched MeSH terms: Radiation Injuries/etiology*
  3. Letter from Ipoh
    Bertell R, Jayabalan T
    JAMA, 1990 Feb 2;263(5):662.
    PMID: 2296121
    Matched MeSH terms: Abnormalities, Radiation-Induced/etiology
  4. Distribution of radium in oil and gas industry wastes from Malaysia
    Omar M, Ali HM, Abu MP, Kontol KM, Ahmad Z, Ahmad SH, et al.
    Appl Radiat Isot, 2004 May;60(5):779-82.
    PMID: 15082059
    Radium concentrations in 470 samples of the various types of waste from oil and gas industries were analysed using gamma spectrometers. The results showed that the radium concentration varied within a wide range. The highest mean 226Ra and 228Ra concentrations of 114,300 and 130,120 Bq/kg, respectively, were measured in scales. Overall, 75% of the waste, mostly sludge and extraction residue lies within the normal range of radium concentration in soils of Malaysia. However, some platform sludge can have radium concentration up to 560 Bq/kg.
    Matched MeSH terms: Radiation Monitoring/methods
  5. Utilisation of Diffusion Tensor Imaging in Intracranial Radiotherapy and Radiosurgery Planning for White Matter Dose Optimization: A Systematic Review
    Yahya N, Manan HA
    World Neurosurg, 2019 Oct;130:e188-e198.
    PMID: 31326352 DOI: 10.1016/j.wneu.2019.06.027
    BACKGROUND: Diffusion tensor imaging (DTI), which visualizes white matter tracts, can be integrated to optimize intracranial radiation therapy (RT) and radiosurgery (RS) treatment planning. This study aimed to systematically review the integration of DTI for dose optimization in terms of evidence of dose improvement, clinical parameter changes, and clinical outcome in RT/RS treatment planning.

    METHODS: PubMed and Scopus electronic databases were searched based on the guidelines established by PRISMA to obtain studies investigating the integration of DTI in intracranial RT/RS treatment planning. References and citations from Google Scholar were also extracted. Eligible studies were extracted for information on changes in dose distribution, treatment parameters, and outcome after DTI integration.

    RESULTS: Eighteen studies were selected for inclusion with 406 patients (median study size, 19; range: 2-144). Dose distribution, with or without DTI integration, described changes of treatment parameters, and the reported outcome of treatment were compared in 12, 7, and 10 studies, respectively. Dose distributions after DTI integration improved in all studies. Delivery time or monitor unit was higher after integration. In studies with long-term follow-up (median, >12 months), neurologic deficits were significantly fewer in patients with DTI integration.

    CONCLUSIONS: Integrating DTI into RT/RS treatment planning improved dose distribution, with higher treatment delivery time or monitor unit as a potential drawback. Fewer neurologic deficits were found with DTI integration.

    Matched MeSH terms: Radiation Dosage*
  6. Biological polymeric shielding design for an X-ray laboratory using Monte Carlo codes
    Tajudin SM, Tabbakh F
    Radiol Phys Technol, 2019 Sep;12(3):299-304.
    PMID: 31302871 DOI: 10.1007/s12194-019-00522-w
    Photon irradiation facilities are often shielded using lead despite its toxicity and high cost. In this study, three Monte Carlo codes, EGS5, MCNPX, and Geant4, were utilized to investigate the efficiency of a relatively new polymeric base compound (CnH2n), as a radiation shielding material for photons with energies below 150 keV. The proposed compound with the densities of 6 and 8 g cm-3 were doped with the weight percentages of 8.0 and 15.0% gadolinium. The probabilities of photoelectric effect and Compton scattering were relatively equal at low photon energies, thus the shielding design was optimized using three Monte Carlo codes for the conformity of calculation results. Consequently, 8% Gd-doped polymer with thickness less than 2 cm and density of 6 g cm-3 was adequate for X-ray room shielding to attenuate more than 95% of the 150-keV incident photons. An average dose rate reduction of 88% can be achieved to ensure safety of the radiation area.
    Matched MeSH terms: Radiation Protection/instrumentation*
  7. Fulltext Exposure Level to Caregivers Resulting From the Scattered Radiation During a Radiographic Procedure
    Sayed, I. S., Yusri, N. H.
    Physics and Technology in Medicine, 2020;1(1):22-26.
    MyJurnal
    In radiography, radiation workers are responsible to protect patients and their caregivers from adverse effects of X-rays during diagnostic procedures. The X-ray examination rooms are designated as controlled areas where only authorised persons are allowed to enter. However, sometimes radiographers allow next in-line patients’ and caregivers in X-ray examination room and ask them to stand behind the mobile lead shielding when exposure is on. The objectives of this study were to determine the amount of scatter radiation dose at different heights with respect to the floor in the X-ray examination room and to educate and increase the awareness of radiation workers about the scattered radiation in minimizing the unnecessary radiation dose to patient’s caregivers. Siemens Multix Top X-ray system was used. Kyoto Kagaku PBU-50 whole body phantom was scanned. The phantom (torso) was positioned for anteroposterior (AP) lumbar projection on the examination table. The nanoDot OSLDs were fixed behind the lead shielding at different heights (120, 130, 140, 150, 160 and 170 cm) with respect to the floor 2.5 meters away from the central ray of X-ray beam. The phantom was exposed using different tube voltages 68 kVp, 79 kVp and 90 kVp at a constant tube current of 32 mAs fixing a 100 cm source to image distance (SID). Scatter radiation doses measured at different heights were different for each exposure. The highest scattered radiation dose measured was 6.4 mGy at 130 cm height for 79 kVp exposure. In conclusion the measured scattered radiation doses were within the acceptable annual dose limits as recommended by NCRP 116 and ICRP 103 for patient caregiver. However, a smallest amount of radiation dose may increase the risk of cancer. Thus, the negligence must not be overlooked because it exposes the caregiver to unnecessary radiation.
    Matched MeSH terms: Radiation Dosage; Scattering, Radiation
  8. Photocatalytic performance of TiO2/Clinoptilolite: Comparison study in suspension and hybrid photocatalytic membrane reactor
    Dzinun H, Othman MHD, Ismail AF
    Chemosphere, 2019 Aug;228:241-248.
    PMID: 31035161 DOI: 10.1016/j.chemosphere.2019.04.118
    Comparison studies in suspension and hybrid photocatalytic membrane reactor (HPMR) system was investigated by using Reactive Black 5 (RB5) as target pollutant under UVA light irradiation. To achieve this aim, hybrid TiO2/clinoptilolite (TCP) photocatalyst powder was prepared by solid-state dispersion (SSD) methods and embedded at the outer layer of dual layer hollow fiber (DLHF) membranes fabricated via single step co-spinning process. TiO2 and CP photocatalyst were also used as control samples. The samples were characterized by Scanning Electron Microscopy (SEM), Energy Dispersion of X-ray (EDX), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analyses. The result shows that TCP was actively functioned as photocatalyst in suspension system and 86% of RB5 photocatalytic degradation achieved within 60 min; however the additional step is required to separate the catalyst with treated water. In the HPMR system, even though the RB5 photocatalytic degradation exhibits lower efficiency however the rejection of RB5 was achieved up to 95% under UV irradiation due to the properties of photocatalytic membranes. The well dispersed of TCP at the outer layer of DLHF membrane have improved the surface affinity of DL-TCP membrane towards water, exhibit the highest pure water flux of 41.72 L/m2.h compared to DL-TiO2 membrane. In general, CP can help on improving photocatalytic activity of TiO2 in suspension, increased the RB5 removal and the permeability of DLHF membrane in HPMR system as well.
    Matched MeSH terms: Naphthalenesulfonates/radiation effects
  9. Personalized administration of contrast medium with high delivery rate in low tube voltage coronary computed tomography angiography
    Tan SK, Ng KH, Yeong CH, Raja Aman RRA, Mohamed Sani F, Abdul Aziz YF, et al.
    Quant Imaging Med Surg, 2019 Apr;9(4):552-564.
    PMID: 31143647 DOI: 10.21037/qims.2019.03.13
    Background: High delivery rate is an important factor in optimizing contrast medium administration in coronary computed tomography angiography (CCTA). A personalized contrast volume calculation algorithm incorporating high iodine delivery rate (IDR) can reduce total iodine dose (TID) and produce optimal vessel contrast enhancement (VCE) in low tube voltage CCTA. In this study, we developed and validated an algorithm for calculating the volume of contrast medium delivered at a high rate for patients undergoing retrospectively ECG-gated CCTA with low tube voltage protocol.

    Methods: The algorithm for an IDR of 2.22 gI·s-1 was developed based on the relationship between VCE and contrast volume in 141 patients; test bolus parameters and characteristics in 75 patients; and, tube voltage in a phantom study. The algorithm was retrospectively tested in 45 patients who underwent retrospectively ECG-gated CCTA with a 100 kVp protocol. Image quality, TID and radiation dose exposure were compared with those produced using the 120 kVp and routine contrast protocols.

    Results: Age, sex, body surface area (BSA) and peak contrast enhancement (PCE) were significant predictors for VCE (P<0.05). A strong linear correlation was observed between VCE and contrast volume (r=0.97, P<0.05). The 100-to-120 kVp contrast enhancement conversion factor (Ec) was calculated at 0.81. Optimal VCE (250 to 450 HU) and diagnostic image quality were obtained with significant reductions in TID (32.1%) and radiation dose (38.5%) when using 100 kVp and personalized contrast volume calculation algorithm compared with 120 kVp and routine contrast protocols (P<0.05).

    Conclusions: The proposed algorithm could significantly reduce TID and radiation exposure while maintaining optimal VCE and image quality in CCTA with 100 kVp protocol.

    Matched MeSH terms: Radiation Exposure; Radiation Dosage
  10. Health Risk Implication and Spatial Distribution of Radon in Groundwater Along the Lithological Contact in South India
    Adithya VSP, Chidambaram S, Prasanna MV, Venkatramanan S, Tirumalesh K, Thivya C, et al.
    Arch Environ Contam Toxicol, 2021 Jan;80(1):308-318.
    PMID: 33398396 DOI: 10.1007/s00244-020-00798-9
    The presence of radioactive elements in groundwater results in high health risks on surrounding populations. Hence, a study was conducted in central Tamil Nadu, South India, to measure the radon levels in groundwater and determine the associated health risk. The study was conducted along the lithological contact of hard rock and sedimentary formation. The concentrations of uranium (U) varied from 0.28 to 84.65 µg/L, and the radioactivity of radon (Rn) varied from 258 to 7072 Bq/m3 in the collected groundwater samples. The spatial distribution of Rn in the study area showed that higher values were identified along the central and northern regions of the study area. The data also indicate that granitic and gneissic rocks are the major contributors to Rn in groundwater through U-enriched lithological zones. The radon levels in all samples were below the maximum concentration level, prescribed by Environmental Protection Agency. The effective dose levels for ingestion and inhalation were calculated according to parameters introduced by UNSCEAR and were found to be lesser (0.235-6.453 μSvy-1) than the recommended limit. Hence, the regional groundwater in the study area does not pose any health risks to consumers. The spatial distribution of Rn's effective dose level indicates the higher values were mainly in the central and northern portion of the study area consist of gneissic, quarzitic, and granitic rocks. The present study showed that Rn concentrations in groundwater depend on the lithology, structural attributes, the existence of uranium minerals in rocks, and the redox conditions. The results of this study provide information on the spatial distribution of Rn in the groundwater and its potential health risk in central Tamil Nadu, India. It is anticipated that these data will help policymakers to develop plans for management of drinking water resources in the region.
    Matched MeSH terms: Radiation Monitoring/methods*
  11. Micronucleated erythrocytes as an assay to assess actions by physical and chemical genotoxic agents in Clarias gariepinus
    Bahari IB, Noor FM, Daud NM
    Mutat Res, 1994 Aug;313(1):1-5.
    PMID: 7519306
    An in vivo study on the effects of both physical (gamma-radiation) and chemical (mitomycin C) genotoxic agents was carried out with the catfish species, Clarias gariepinus. The fish were either exposed to gamma-radiation at doses of 0-9 Gy or injected intraperitoneally with mitomycin C at concentrations of 0-2 mg/kg. Micronucleated erythrocytes were sampled from 0 to 60 days post treatment. Data obtained showed a time-dependent response of the induction of micronucleated erythrocytes with both genotoxic agents. A linear dose-dependent increase was observed 2-4 days after treatment. These data show the importance of sampling time in the micronucleus assay with Clarias gariepinus.
    Matched MeSH terms: Erythrocytes/radiation effects*
  12. Recent developments of zinc oxide based photocatalyst in water treatment technology: A review
    Lee KM, Lai CW, Ngai KS, Juan JC
    Water Res, 2016 Jan 01;88:428-448.
    PMID: 26519627 DOI: 10.1016/j.watres.2015.09.045
    Today, a major issue about water pollution is the residual dyes from different sources (e.g., textile industries, paper and pulp industries, dye and dye intermediates industries, pharmaceutical industries, tannery and craft bleaching industries, etc.), and a wide variety of persistent organic pollutants have been introduced into our natural water resources or wastewater treatment systems. In fact, it is highly toxic and hazardous to the living organism; thus, the removal of these organic contaminants prior to discharge into the environment is essential. Varieties of techniques have been employed to degrade those organic contaminants and advanced heterogeneous photocatalysis involving zinc oxide (ZnO) photocatalyst appears to be one of the most promising technology. In recent years, ZnO photocatalyst have attracted much attention due to their extraordinary characteristics. The high efficiency of ZnO photocatalyst in heterogeneous photocatalysis reaction requires a suitable architecture that minimizes electron loss during excitation state and maximizes photon absorption. In order to further improve the immigration of photo-induced charge carriers during excitation state, considerable effort has to be exerted to further improve the heterogeneous photocatalysis under UV/visible/solar illumination. Lately, interesting and unique features of metal doping or binary oxide photocatalyst system have gained much attention and became favourite research matter among various groups of scientists. It was noted that the properties of this metal doping or binary oxide photocatalyst system primarily depend on the nature of the preparation method and the role of optimum dopants content incorporated into the ZnO photocatalyst. Therefore, this paper presents a critical review of recent achievements in the modification of ZnO photocatalyst for organic contaminants degradation.
    Matched MeSH terms: Water Pollutants, Chemical/radiation effects*
  13. Staff and ambient radiation dose resulting from therapeutic nuclear medicine procedures
    Alkhorayef M, Sulieman A, Mohamed-Ahmed M, Al-Mohammed HI, Alkhomashi N, Sam AK, et al.
    Appl Radiat Isot, 2018 Nov;141:270-274.
    PMID: 30145016 DOI: 10.1016/j.apradiso.2018.07.014
    With associated cure rates in excess of 90%, targeted 131I radioactive iodine therapy has clearly improved thyroid cancer survival. Thus said, potential radiation risks to staff represent a particular concern, current study seeking to determine the radiation exposure of staff from 131I patients during hospitalization, also estimating accumulated dose and related risk to staff during preparation of the radioactive iodine. In present study made over the three-month period 1st February to 1st May 2017, a total of 69 patient treatments were investigated (comprising a cohort of 46 females and 23 males), this being a patient treatment load typically reflective of the workload at the particular centre for such treatments. The patients were administered sodium iodide 131I, retained in capsules containing activities ranging from 370 to 5550 MBq at the time of calibration, radioiodine activity depends on many factors such as gender, clinical indication, body mass index and age. The staff radiation dose arising from each patient treatment was measured on three consecutive days subsequent to capsule administration. In units of µSv, the mean and dose-rates range at distances from the patients of 5 cm, 1 m and 2 m were 209 ± 73 (165-294), 6.8 ± 2 (5.3-9.5) and 0.9 ± 0.3 (0.7-1.2). The annual dose (also measured in units of µSv), based on annual records of doses, for medical physicists, technologists and nurses were 604, 680 and 1000 µSv respectively. In regard to current practice and workload, staff exposures were all found to be below the annual dose limit for radiation workers.
    Matched MeSH terms: Radiation Exposure; Radiation Dosage
  14. Reduction of Delayed Homologous Recombination by Induction of Radioadaptive Response in RaDR-GFP Mice (Yonezawa Effect): An Old Player With a New Role
    Liu C, Hirakawa H, Tanaka K, Mohd Saaya F, Nenoi M, Fujimori A, et al.
    Dose Response, 2019 03 04;17(1):1559325819833840.
    PMID: 30858771 DOI: 10.1177/1559325819833840
    Radiotherapy (RT) treats cancer effectively with high doses of ionizing radiation (IR) to killing cancer cells and shrinking tumors while bearing the risk of developing different side effects, including secondary cancer, which is most concerning for long-term health consequences. Genomic instability (GI) is a characteristic of most cancer cells, and IR-induced GI can manifest as delayed homologous recombination (HR). Radioadaptive response (RAR) is capable of reducing genotoxicity, cell transformation, mutation, and carcinogenesis, but the rational evidence describing its contributions to the reduction of radiation risk, in particular, carcinogenesis, remains fragmented. In this work, to investigate the impact of RAR on high-dose, IR-induced GI measured as delayed HR, the frequency of recombinant cells was comparatively studied under RAR-inducible and -uninducible conditions in the nucleated cells in hematopoietic tissues (bone marrow and spleen) using the Rosa26 Direct Repeat-green fluorescent protein (RaDR-GFP) homozygote mice. Results demonstrated that the frequency of recombinant cells was significantly lower in hematopoietic tissues under RAR-inducible condition. These findings suggest that reduction in delayed HR may be at least a part of the mechanisms underlying decreased carcinogenesis by RAR, and application of RAR would contribute to a more rigorous and scientifically grounded system of radiation protection in RT.
    Matched MeSH terms: Radiation Protection; Radiation, Ionizing
  15. Fulltext Radiation Safety in Emergency Medicine: Balancing the Benefits and Risks
    Azman RR, Shah MNM, Ng KH
    Korean J Radiol, 2019 03;20(3):399-404.
    PMID: 30799570 DOI: 10.3348/kjr.2018.0416
    The use of computed tomography (CT) in emergency departments has increased over several decades, as physicians increasingly depend on imaging for diagnoses. Patients and medical personnel are put at risk due to frequent exposure to and higher levels of radiation, with very little evidence of improvements in outcomes. Here, we explore why CT imaging has a tendency to be overused in emergency departments and the obstacles that medical personnel face in ensuring patient safety. The solution requires cooperation from all emergency care stakeholders as well as the continuous education of doctors on how CT scans help in particular cases.
    Matched MeSH terms: Radiation Dosage; Radiation, Ionizing
  16. Fulltext Kinetics Study of Microwave-Assisted Brine Extraction of Lipid from the Microalgae Nannochloropsis sp
    Zghaibi N, Omar R, Kamal SMM, Biak DRA, Harun R
    Molecules, 2020 Feb 12;25(4).
    PMID: 32059440 DOI: 10.3390/molecules25040784
    The kinetics of lipid extraction utilizing microwave-assisted extraction (MAE) from Nannochloropsis sp. microalgae were studied using a low cost and green solvent, namely brine (NaCl) solution. The kinetic modelling of the lipid extraction was performed to evaluate the mechanism of the lipid mass transfer using different extraction models, including Fick's Law, First and Second-order Rate Law and the Patricelli mathematical model. The Patricelli mathematical model described the kinetics of lipid extraction well, with the highest average values of determination coefficient (R2 ≥ 0.952) and the lowest average values of mean relative percentage deviation (MRPD ≤ 8.666%). The lipid analysis indicated a positive influence of the microwave temperature and time on the quantity and quality of extracted lipids. SEM analysis of spent microalgae clearly shows an increase in the distorted cell with increase microwave temperature and time, which could be directly correlated to the mechanism of the MAE-brine technique.
    Matched MeSH terms: Lipids/radiation effects
  17. ASSESSMENT OF PATIENT'S RADIATION EXPOSURES RESULTED FROM PET/CT 18F-FCH AND 68GA-PSMA PROCEDURES
    Salah H, Al-Mohammed HI, Mayhoub FH, Sulieman A, Alkhorayef M, Abolaban FA, et al.
    Radiat Prot Dosimetry, 2021 Oct 12;195(3-4):349-354.
    PMID: 34144608 DOI: 10.1093/rpd/ncab077
    This study has sought to evaluate patient exposures during the course of particular diagnostic positron emission tomography and computed tomography (PET/CT) techniques. A total of 73 patients were examined using two types of radiopharmaceutical: 18F-fluorocholine (FCH, 48 patients) and 68Ga-prostate-specific membrane antigen (PSMA, 25 patients). The mean and range of administered activity (AA) in MBq, and effective dose (mSv) for FCH were 314.4 ± 61.6 (462.5-216.8) and 5.9 ± 1.2 (8.8-4.11), respectively. Quoted in the same set of units, the mean and range of AA and effective dose for 68Ga-PSMA were 179.3 ± 92.3 (603.1-115.1) and 17.9 ± 9.2 (60.3-11.5). Patient effective doses from 18F-FCH being a factor of two greater than the dose resulting from 68Ga-PSMA PET/CT procedures. CT accounts for some 84 and 23% for 18F-FCH and 68Ga-PSMA procedures, accordingly CT acquisition parameter optimization is recommended. Patient doses have been found to be slightly greater than previous studies.
    Matched MeSH terms: Radiation Exposure*
  18. 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.
    Matched MeSH terms: Radiation Oncology*
  19. Fulltext Raman and photoluminescence spectroscopy analysis of gamma irradiated human hair
    Lam SE, Mat Nawi SN, Abdul Sani SF, Khandaker MU, Bradley DA
    Sci Rep, 2021 04 12;11(1):7939.
    PMID: 33846448 DOI: 10.1038/s41598-021-86942-4
    Preliminary study has been made of black human hair, carbon concentration of some 53%, a model in examining the potential of hair of the human head in retrospective and emergency biodosimetry applications, also offering effective atomic number near to that of water. The hair samples were exposed to [Formula: see text]Co gamma rays, delivering doses from 0 to 200 Gy. Structural alterations were observed, use being made of Raman and photoluminescence (PL) spectroscopy. Most prominent among the features observed in the first-order Raman spectra are the D and G peaks, appearing at 1370 [Formula: see text] and 1589 [Formula: see text] respectively, the intensity ratio [Formula: see text] indicating dose-dependent defects generation and annealing of structural alterations. The wavelengths of the PL absorption and emission peaks are found to be centred at [Formula: see text] nm and [Formula: see text] nm, respectively. The hair samples mean band gap energy ([Formula: see text]) post-irradiation was found to be [Formula: see text] eV, of the order of a semiconductor and approximately two times the [Formula: see text] of other carbon-rich materials reported via the same methodology.
    Matched MeSH terms: Hair/radiation effects*
  20. Tabulation of organ dose conversion factors for terrestrial radioactivity monitoring program
    Sanusi MSM, Hassan WMSW, Hashim S, Ramli AT
    Appl Radiat Isot, 2021 Aug;174:109791.
    PMID: 34062400 DOI: 10.1016/j.apradiso.2021.109791
    Terrestrial radioactivity monitoring of 238U and 232Th series, and 40K in soil is an essential practice for radioactivity and radiation measurement of a place. In conventional practice, only basic data can be in-situ measured using a survey instrument, for example radioactivity concentration in soil and ambient dose equivalent rate. For other physical quantities, for example organ absorbed dose and organ equivalent dose, the measurement is impossible to be performed and can only be computed using Monte Carlo radiation transport simulations. In the past, most of the works only focused on calculating air-kerma-to-effective dose conversion factors. However, the information on organ dose conversion factors is scarcely documented and reported. This study was conducted to calculate organ absorbed and tissue-weighted equivalent dose conversion factors as a result of exposure from terrestrial gamma radiation. Series of organ dose conversion factors is produced based on computations from Monte Carlo MCNP5 simulations using modelled gamma irradiation geometry and established adult MIRD phantom. The study found out that most of the radiation exposed organs absorb energy at comparable rates, except for dense and superficial tissues i.e., skeleton and skin, which indicated slightly higher values. The good agreement between this work and previous studies demonstrated that our gamma irradiation geometry and modelling of gamma radiation sources are adequate. Therefore, the proposed organ dose conversion factors from this study are reasonably acceptable for dose estimation in environmental radioactivity monitoring practices.
    Matched MeSH terms: Radiation Monitoring/methods*
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