MyMedR

Displaying publications 1 - 20 of 182 in total

Abstract:

Sort:

The quantification of PET-CT radiotracers to determine minimal scan time using quadratic formulation

Said MA, Musarudin M, Zulkaffli NF

Ann Nucl Med, 2020 Dec;34(12):884-891.
PMID: 33141408 DOI: 10.1007/s12149-020-01543-x

OBJECTIVE: 18F is the most extensively used radioisotope in current clinical practices of PET imaging. This selection is based on the several criteria of pure PET radioisotopes with an optimum half-life, and low positron energy that contributes to a smaller positron range. In addition to 18F, other radioisotopes such as 68Ga and 124I are currently gained much attention with the increase in interest in new PET tracers entering the clinical trials. This study aims to determine the minimal scan time per bed position (Tmin) for the 124I and 68Ga based on the quantitative differences in PET imaging of 68Ga and 124I relative to 18F.
METHODS: The European Association of Nuclear Medicine (EANM) procedure guidelines version 2.0 for FDG-PET tumor imaging has adhered for this purpose. A NEMA2012/IEC2008 phantom was filled with tumor to background ratio of 10:1 with the activity concentration of 30 kBq/ml ± 10 and 3 kBq/ml ± 10% for each radioisotope. The phantom was scanned using different acquisition times per bed position (1, 5, 7, 10 and 15 min) to determine the Tmin. The definition of Tmin was performed using an image coefficient of variations (COV) of 15%.
RESULTS: Tmin obtained for 18F, 68Ga and 124I were 3.08, 3.24 and 32.93 min, respectively. Quantitative analyses among 18F, 68Ga and 124I images were performed. Signal-to-noise ratio (SNR), contrast recovery coefficients (CRC), and visibility (VH) are the image quality parameters analysed in this study. Generally, 68Ga and 18F gave better image quality as compared to 124I for all the parameters studied.
CONCLUSION: We have defined Tmin for 18F, 68Ga and 124I SPECT CT imaging based on NEMA2012/IEC2008 phantom imaging. Despite the long scanning time suggested by Tmin, improvement in the image quality is acquired especially for 124I. In clinical practice, the long acquisition time, nevertheless, may cause patient discomfort and motion artifact.

Matched MeSH terms: Radiation Dosage
Fulltext Radiation exposure to the surgeon during femoral interlocking nailing under fluoroscopic imaging

Muzaffar TST, Imran Y, Iskandar MA, Zakaria A

Med J Malaysia, 2005 Jul;60 Suppl C:26-9.
PMID: 16381279

Femoral interlocking nailing requires fluoroscopic assistance for insertion of the nail and distal screws. In this study, scattered radiation to the eye and hand of the operating surgeon was measured during the procedure. Thermo-luminescent dosimeter (TLD) was used to quantify the dose received by the surgeon. The mean radiation exposure time during the procedure was 3.89 minutes. The mean scattered radiation doses to the hand and eye were 0.27 mSv and 0.09 mSv per procedure respectively. These very low doses have made a surgeon very unlikely to receive more than the recommended annual dose limit set by the National Council on Radiological Protection.

Matched MeSH terms: Radiation Dosage*
Fulltext Preparation and characterization of hydrogels from grafting of vinyl pyrrolidone onto carboxymethyl cellulose

Ahmad, M.B., Hashim, K.B., Mohd Yazid, N., Zainuddin, N.

Pertanika Journal of Science & Technology, 2012;20(2):425-433.
MyJurnal

In this work, hydrogels were prepared from carboxymethyl cellulose (CMC) and 1-vinyl-2-pyrrolidone(VP) by Electron Beam irradiation in the presence of N,N'-methylenebisacrylamide (BIS) as a crosslinkingagent. The parameters studied include stirring time and percentage of crosslinking agent. Hydrogels werecharacterized using Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy(SEM). VP and BIS were found be effective as reinforcement materials to improve the properties ofCMC. Meanwhile, the optimum conditions were 5% BIS and 3 hours of stirring time. The gel fractionincreased when irradiation dose was increased. FTIR confirmed the crosslinking reaction between CMCand VP after the irradiation process by using BIS as the crosslinking agent. TGA thermograms showedchanges in the thermal properties of CMC-VP hydrogels in the presence of different amounts of BIS.

Matched MeSH terms: Radiation Dosage
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
The absorbed dose in femur exposed to diagnostic radiography

Salehi Z, Yusoff AL

Radiat Prot Dosimetry, 2013;154(3):396-9.
PMID: 23012482 DOI: 10.1093/rpd/ncs239

A femur phantom made of wax and a real human bone was used to study the dose during radiographical procedures. The depth dose inside the phantom was determined using DOSXYZnrc, a Monte Carlo simulation software. The results were verified with measurements using TLD-100H. It was found that for 2.5 mm aluminium filtered 84-kVp X-rays, the radiation dose in the bone reached 57 % higher than the surface dose, i.e. 3.23 mGy as opposed to 2.06 mGy at the surface. The use of real bone introduces variations in the bone density in the DOSXYZnrc model, resulting in a lower attenuation effect than expected from solid bone tissues.

Matched MeSH terms: Radiation Dosage*
X-ray spectra and quality parameters from Monte Carlo simulation and analytical filters

Salehi Z, Ya Ali NK, Yusoff AL

Appl Radiat Isot, 2012 Nov;70(11):2586-9.
PMID: 22940409 DOI: 10.1016/j.apradiso.2011.12.007

BEAMnrc was used to derive the X-ray spectra, from which HVL and homogeneity coefficient were determined, for different kVp and filtration settings. Except for the peak at 61 keV, the spectra are in good agreement with the IPEM report 78 data for the case of filtered beams, whereas the unfiltered beams exhibit softer spectra. Although the current attenuation data deviates from the IPEM 78 data by ~±0.5%, this has negligible effects on the calculated HVL values.

Matched MeSH terms: Radiation Dosage*
Coronary CT angiography with single-source and dual-source CT: comparison of image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated protocols

Sabarudin A, Sun Z, Yusof AK

Int J Cardiol, 2013 Sep 30;168(2):746-53.
PMID: 23098849 DOI: 10.1016/j.ijcard.2012.09.217

This study is conducted to investigate and compare image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated coronary CT angiography (CCTA) with the use of single-source CT (SSCT) and dual-source CT (DSCT).

Matched MeSH terms: Radiation Dosage*
Fulltext Morphological and biochemical responses of Oryza sativa L. (cultivar MR219) to ion beam irradiation

Ling AP, Ung YC, Hussein S, Harun AR, Tanaka A, Yoshihiro H

J Zhejiang Univ Sci B, 2013 Dec;14(12):1132-43.
PMID: 24302713 DOI: 10.1631/jzus.B1200126

Heavy ion beam, which has emerged as a new mutagen in the mutation breeding of crops and ornamental plants, is expected to result in the induction of novel mutations. This study investigates the morphological and biochemical responses of Oryza sativa toward different doses of carbon ion beam irradiation.

Matched MeSH terms: Radiation Dosage
Fulltext Measurement of radioactivity in soils of Karamjal and Harbaria mangrove forest of Sundarbans for establishment of radiological database

Siraz MMM, A M J, Alam MS, Rashid MB, Hossain Z, Khandaker MU, et al.

PLoS One, 2023;18(10):e0289113.
PMID: 37856554 DOI: 10.1371/journal.pone.0289113

This work presents the first in-depth study of soil radioactivity in the mangrove forest of Bangladesh part of the Sundarbans. It used HPGe gamma-ray spectrometry to measure the amount of natural radioactivity in soil samples from Karamjal and Harbaria sites of the world's largest mangrove forest. The activity concentrations of most of the 226Ra (14±2 Bqkg-1 to 35±4 Bqkg-1) and 232Th (30±5 Bqkg-1 to 50±9 Bqkg-1) lie within the world average values, but the 40K concentration (370± 44 Bqkg-1 to 660±72 Bqkg-1) was found to have exceeded the world average value. The evaluation of radiological hazard parameters revealed that the outdoor absorbed dose rate (maximum 73.25 nGyh-1) and outdoor annual effective dose (maximum 0.09 mSvy-1) for most samples exceeded the corresponding world average values. The elevated concentration of 40K is mainly due to the salinity intrusion, usage of fertilizers and agricultural runoff, and migration of waste effluents along the riverbanks. Being the pioneering comprehensive research on the Bangladesh side of the Sundarbans, this study forms a baseline radioactivity for the Sundarbans before the commissioning of the Rooppur Nuclear Power Plant in Bangladesh.

Matched MeSH terms: Radiation Dosage
Investigation of the dependence of inactivation coefficient on pertinent physical quality parameters to low doses ionizing radiation

Yousif AA, Bin Bahari I, Yasir MS

Curr Radiopharm, 2012 Jan;5(1):34-7.
PMID: 21864247

Inactivation constant for V79 cells has been extracted from radiobiology experiments that utilize charged particles to irradiate mammal cells in vitro. Physical parameters such as effective charge, radiation mean free path and linear ionization which characterized protons and heluim-4 particles are determined using of standard values. The relationship between inactivation constant α and physical quality parameters have been determined, in this research, for protons and heluim-4 particles. This approach allows getting the characteristic biological response of inactivation of V79 cells in terms of each selected physical quality parameter. The best regression models are formulated for each obtained relationship.

Matched MeSH terms: Radiation Dosage
RADIATION DOSE TO MALDIVIANS VIA THE CONSUMPTION OF TUNA FISH CAUGHT FROM THE COASTAL WATERS OF INDIAN OCEAN

Nadhiya A, Khandaker MU, Mahmud S, Yarima MH

Radiat Prot Dosimetry, 2019 Oct 01;184(3-4):302-306.
PMID: 31034553 DOI: 10.1093/rpd/ncz085

Recognising the consumption of tuna fish as a major foodstuff in Maldivian diet, the presence of naturally occurring radionuclides in Yellowfin and Skipjack tuna are determined by using HPGe gamma-ray spectrometry to evaluate the health hazards to Maldivians. The samples were collected from different atolls of Maldives adjacent to the coastal waters of Indian Ocean. The activity concentrations (Bq kg-1) in Yellowfin tuna for 226Ra, 232Th and 40K are in the ranges of 4.2 ± 1.8-10.5 ± 1.1, 1.3 ± 0.3-3.2 ± 0.7 and 589 ± 29-697 ± 34, respectively while in Skipjack tuna the respective ranges are 3.9 ± 0.5-13.2 ± 1.1, 1.3 ± 0.3-2.7 ± 0.6 and 511 ± 28-681 ± 35. The committed effective dose (mean 263 μSv y-1) received by an individual due to the dietary intake of Yellowfin tuna falling below the UNSCEAR referenced global internal dose limit of 290 μSv y-1; while for Skipjack tuna, the estimated dose (mean 365 μSv y-1) exceeds the world average limiting value. The carcinogenic risk was found to be well below the ICRP referenced acceptable limit of 2.5 × 10-3. The present study indicates that the radiation dose to Maldivian via the consumption of Yellowfin tuna poses an insignificant threat to the public health. However, prolonged consumption of Skipjack tuna fish from the studied areas may pose a cumulative risk to the public health.

Matched MeSH terms: Radiation Dosage
Radiation dose assessment at amang processing plants in Malaysia

Omar M, Sulaiman I, Hassan A, Wood AK

Radiat Prot Dosimetry, 2007;124(4):400-6.
PMID: 17510205

Measurements of external radiation level, radon/thoron daughters concentrations in air and uranium/thorium concentrations in airborne mineral dust at 16 amang plants in Malaysia were carried out for three consecutive months to assess radiation dose to workers. Estimated occupational dose was within the range of 1.7-10.9 mSv y(-1). The mean total dose at the amang plants was 4.1 mSv y(-1). Overall, it was found that the major dose contribution of 80% came from external radiation. Radon/thoron daughters and airborne mineral dust contributed to only 11 and 9% of the total dose, respectively.

Matched MeSH terms: Radiation Dosage*
Fulltext Radiation-induced osteosarcoma of the maxilla

Kasthoori JJ, Wastie ML

Singapore Med J, 2006 Oct;47(10):907-9.
PMID: 16990970

Radiation-induced sarcomas are well-known though uncommon potential late sequelae of radiation therapy. We report irradiation-induced osteosarcoma involving the maxilla following treatment of nasopharyngeal carcinoma in a 44-year-old man who presented with painful cheek swelling. Radiographs and computed tomography showed a large destructive lesion of the left maxilla. Diagnosis of osteosarcoma was confirmed by excision biopsy.

Matched MeSH terms: Radiation Dosage
Tensile properties of vulcanized field natural rubber latex by electron beam

Chai CK, Md. Soot Ahmad, Wan Manshol W. Zin

Sains Malaysiana, 2008;37.

Electron beam vulcanization of natural rubber latex has been developed as an alternative to the conventional sulphur vulcanization method. This study aimed at determining the effect of electron beam dose, beam current and centrifugation to the tensile properties of field natural rubber latex. Irradiation dose and beam current ranged from 50 to 300 kGy and 1 to 15 mA respectively. The determination of tensile properties were done on cast film prepared from irradiated field latex before and after centrifugation. It was found that tensile properties increased with radiation dose but decreased with beam current. Rubber films made from centrifuged irradiated field latex were softer and showed higher tensile strength.

Matched MeSH terms: Radiation Dosage
Science, politics, and radiation

Wagner HN

JAMA, 1988 Aug 5;260(5):697-8.
PMID: 3392799
Matched MeSH terms: Radiation Dosage
The thermoluminescence response of doped SiO2 optical fibres subjected to fast neutrons

Hashim S, Bradley DA, Saripan MI, Ramli AT, Wagiran H

Appl Radiat Isot, 2010 Apr-May;68(4-5):700-3.
PMID: 19892557 DOI: 10.1016/j.apradiso.2009.10.027

This paper describes a preliminary study of the thermoluminescence (TL) response of doped SiO(2) optical fibres subjected to (241)AmBe neutron irradiation. The TL materials, which comprise Al- and Ge-doped silica fibres, were exposed in close contact with the (241)AmBe source to obtain fast neutron interactions through use of measurements obtained with and without a Cd filter (the filter being made to entirely enclose the fibres). The neutron irradiations were performed for exposure times of 1-, 2-, 3-, 5- and 7-days in a neutron tank filled with water. In this study, use was also made of the Monte Carlo N-particle (MCNP) code version 5 (V5) to simulate the neutron irradiations experiment. It was found that the commercially available Ge-doped and Al-doped optical fibres show a linear dose response subjected to fast neutrons from (241)AmBe source up to seven days of irradiations. The simulation performed using MCNP5 also exhibits a similar pattern, albeit differing in sensitivity. The TL response of Ge-doped fibre is markedly greater than that of the Al-doped fibre, the total absorption cross section for Ge in both the fast and thermal neutrons region being some ten times greater than that of Al.

Matched MeSH terms: Radiation Dosage
The thermoluminescence response of doped SiO2 optical fibres subjected to alpha-particle irradiation

Ramli AT, Bradley DA, Hashim S, Wagiran H

Appl Radiat Isot, 2009 Mar;67(3):428-32.
PMID: 18693114 DOI: 10.1016/j.apradiso.2008.06.034

Ion beams are used in radiotherapy to deliver a more precise dose to the target volume while minimizing dose to the surrounding healthy tissue. For optimum dose monitoring in ion-beam therapy, it is essential to be able to measure the delivered dose with a sensitivity, spatial resolution and dynamic range that is sufficient to meet the demands of the various therapy situations. Optical fibres have been demonstrated by this group to show promising thermoluminescence properties with respect to photon, electron and proton irradiation. In particular, and also given the flexibility and small size of optical fibre cores, for example 125.0+/-0.1 microm for the Al- and Ge-doped fibres used in this study, these fibres have the potential to fulfill the above requirements. This study investigates the thermoluminescence dosimetric characteristics of variously doped SiO(2) optical fibres irradiated with alpha particles from (241)Am. Following subtraction of the gamma contribution from the above source, the thermoluminescence characteristics of variously doped SiO(2) optical fibres have been compared with that of TLD-100 rods. The irradiations were performed in a bell jar. Of related potential significance is the effective atomic number, Z(eff) of the fibre, modifying measured dose from that deposited in tissues; in the present work, a scanning electron microscope and associated energy dispersive X-ray spectroscopy facility have been used to provide evaluation of Z(eff). For Ge-doped fibres, the effective atomic numbers value was 11.4, the equivalent value for Al-doped fibres was 12.3. This paper further presents results on dose response and the glow curves obtained. The results obtained indicate there to be good potential for use of variously doped SiO(2) optical fibres in measuring ion-beam doses in radiotherapeutic applications.

Matched MeSH terms: Radiation Dosage
The thermoluminescence response of doped SiO2 optical fibres subjected to photon and electron irradiations

Hashim S, Al-Ahbabi S, Bradley DA, Webb M, Jeynes C, Ramli AT, et al.

Appl Radiat Isot, 2009 Mar;67(3):423-7.
PMID: 18693024 DOI: 10.1016/j.apradiso.2008.06.030

Modern linear accelerators, the predominant teletherapy machine in major radiotherapy centres worldwide, provide multiple electron and photon beam energies. To obtain reasonable treatment times, intense electron beam currents are achievable. In association with this capability, there is considerable demand to validate patient dose using systems of dosimetry offering characteristics that include good spatial resolution, high precision and accuracy. Present interest is in the thermoluminescence response and dosimetric utility of commercially available doped optical fibres. The important parameter for obtaining the highest TL yield during this study is to know the dopant concentration of the SiO2 fibre because during the production of the optical fibres, the dopants tend to diffuse. To achieve this aim, proton-induced X-ray emission (PIXE), which has no depth resolution but can unambiguously identify elements and analyse for trace elements with detection limits approaching microg/g, was used. For Al-doped fibres, the dopant concentration in the range 0.98-2.93 mol% have been estimated, with equivalent range for Ge-doped fibres being 0.53-0.71 mol%. In making central-axis irradiation measurements a solid water phantom was used. For 6-MV photons and electron energies in the range 6, 9 and 12 MeV, a source to surface distance of 100 cm was used, with a dose rate of 400 cGy/min for photons and electrons. The TL measurements show a linear dose-response over the delivered range of absorbed dose from 1 to 4 Gy. Fading was found to be minimal, less than 10% over five days subsequent to irradiation. The minimum detectable dose for 6-MV photons was found to be 4, 30 and 900 microGy for TLD-100 chips, Ge- and Al-doped fibres, respectively. For 6-, 9- and 12-MeV electron energies, the minimum detectable dose were in the range 3-5, 30-50 and 800-1400 microGy for TLD-100 chip, Ge-doped and Al-doped fibres, respectively.

Matched MeSH terms: Radiation Dosage
Terrestrial gamma radiation dose study to determine the baseline for environmental radiological health practices in Melaka state, Malaysia

Ramli AT, Sahrone S, Wagiran H

J Radiol Prot, 2005 Dec;25(4):435-50.
PMID: 16340071

Environmental terrestrial gamma radiation dose rates were measured throughout Melaka, Malaysia, over a period of two years, with the objective of establishing baseline data on the background radiation level. Results obtained are shown in tabular, graphic and cartographic form. The values of terrestrial gamma radiation dose rate vary significantly over different soil types and for different underlying geological characteristics present in the study area. The values ranged from 54 +/- 5 to 378 +/- 38 nGy h(-1). The highest terrestrial gamma dose rates were measured over soil types of granitic origin and in areas with underlying geological characteristics of an acid intrusive (undifferentiated) type. An isodose map of terrestrial gamma dose rate in Melaka was drawn by using the GIS application 'Arc View'. This was based on data collected using a NaI(Tl) scintillation detector survey meter. The measurements were taken at 542 locations. Three small 'hot spots' were found where the dose rates were more than 350 nGy h(-1). The mean dose rates in the main population areas in the mukims (parishes) of Bukit Katil, Sungai Udang, Batu Berendam, Bukit Baru and Bandar Melaka were 154 +/- 15, 161 +/- 16, 160 +/- 16, 175 +/- 18 and 176 +/- 18 nGy h(-1), respectively. The population-weighted mean dose rate throughout Melaka state is 172 +/- 17 nGy h(-1). This is lower than the geographical mean dose rate of 183 +/- 54 nGy h(-1). The lower value arises from the fact that most of the population lives in the central area of the state where the lithology is dominated by sedimentary rocks consisting of shale, mudstone, phyllite, slate, hornfels, sandstone and schist of Devonian origin which have lower associated dose rates. The mean annual effective dose to the population from outdoor terrestrial gamma radiation was estimated to be 0.21 mSv. This value is higher than the world average of 0.07 mSv.

Matched MeSH terms: Radiation Dosage
Fulltext Co-visualization of DNA damage and ion traversals in live mammalian cells using a fluorescent nuclear track detector

Kodaira S, Konishi T, Kobayashi A, Maeda T, Ahmad TA, Yang G, et al.

J Radiat Res, 2015 Mar;56(2):360-5.
PMID: 25324538 DOI: 10.1093/jrr/rru091

The geometric locations of ion traversals in mammalian cells constitute important information in the study of heavy ion-induced biological effect. Single ion traversal through a cellular nucleus produces complex and massive DNA damage at a nanometer level, leading to cell inactivation, mutations and transformation. We present a novel approach that uses a fluorescent nuclear track detector (FNTD) for the simultaneous detection of the geometrical images of ion traversals and DNA damage in single cells using confocal microscopy. HT1080 or HT1080-53BP1-GFP cells were cultured on the surface of a FNTD and exposed to 5.1-MeV/n neon ions. The positions of the ion traversals were obtained as fluorescent images of a FNTD. Localized DNA damage in cells was identified as fluorescent spots of γ-H2AX or 53BP1-GFP. These track images and images of damaged DNA were obtained in a short time using a confocal laser scanning microscope. The geometrical distribution of DNA damage indicated by fluorescent γ-H2AX spots in fixed cells or fluorescent 53BP1-GFP spots in living cells was found to correlate well with the distribution of the ion traversals. This method will be useful for evaluating the number of ion hits on individual cells, not only for micro-beam but also for random-beam experiments.

Matched MeSH terms: Radiation Dosage

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links