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Differential dose absorptions for various biological tissue equivalent materials using Gafchromic XR-QA2 film in diagnostic radiology

Alsadig AA, Abbas S, Kandaiya S, Ashikin NARNN, Qaeed MA

Appl Radiat Isot, 2017 Nov;129:130-134.
PMID: 28843699 DOI: 10.1016/j.apradiso.2017.08.021

Phantoms are devices that simulate human tissues including soft tissues, lungs, and bones in medical and health physics. The purpose of this work was to investigate the differential dose absorption in several commercially available low-cost materials as substitutes to human tissues using Gafchromic XR-QA2 film. The measurement of absorbed dose by different materials of various densities was made using the film to establish the relationship between the absorbed dose and the material density. Materials investigated included soft board materials, Perspex, chicken bone, Jeltrate, chalk, cow bone, marble, and aluminum, which have varying densities from 0.26 to 2.67gcm-3. The absorbed dose increased as the density and atomic number of the material increased. The absorbed dose to the density can be well represented by a polynomial function for the materials used.

Matched MeSH terms: Dose-Response Relationship, Radiation
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.

Matched MeSH terms: Dose-Response Relationship, Radiation
Fulltext Allocation of secondary metabolites, photosynthetic capacity, and antioxidant activity of Kacip Fatimah (Labisia pumila Benth) in response to CO2 and light intensity

Ibrahim MH, Jaafar HZ, Karimi E, Ghasemzadeh A

ScientificWorldJournal, 2014;2014:360290.
PMID: 24683336 DOI: 10.1155/2014/360290

A split plot 3 by 4 experiment was designed to investigate and distinguish the relationships among production of secondary metabolites, soluble sugar, phenylalanine ammonia lyase (PAL; EC 4.3.1.5) activity, leaf gas exchange, chlorophyll content, antioxidant activity (DPPH), and lipid peroxidation under three levels of CO2 (400, 800, and 1200 μ mol/mol) and four levels of light intensity (225, 500, 625, and 900 μ mol/m(2)/s) over 15 weeks in Labisia pumila. The production of plant secondary metabolites, sugar, chlorophyll content, antioxidant activity, and malondialdehyde content was influenced by the interactions between CO2 and irradiance. The highest accumulation of secondary metabolites, sugar, maliondialdehyde, and DPPH activity was observed under CO2 at 1200 μ mol/mol + light intensity at 225 μ mol/m(2)/s. Meanwhile, at 400 μ mol/mol CO2 + 900 μ mol/m(2)/s light intensity the production of chlorophyll and maliondialdehyde content was the highest. As CO2 levels increased from 400 to 1200 μ mol/mol the photosynthesis, stomatal conductance, f v /f m (maximum efficiency of photosystem II), and PAL activity were enhanced. The production of secondary metabolites displayed a significant negative relationship with maliondialdehyde indicating lowered oxidative stress under high CO2 and low irradiance improved the production of plant secondary metabolites that simultaneously enhanced the antioxidant activity (DPPH), thus improving the medicinal value of Labisia pumila under this condition.

Matched MeSH terms: Dose-Response Relationship, Radiation
Evaluation of irradiated salivary gland function in patients with head and neck tumours treated with radiotherapy

Baharudin A, Khairuddin A, Nizam A, Samsuddin AR

J Laryngol Otol, 2009 Jan;123(1):108-13.
PMID: 18452635 DOI: 10.1017/S0022215108002466

Radiotherapy is an important treatment modality for head and neck tumours. One of its major drawbacks is post-treatment salivary gland hypofunction. This study was performed to objectively evaluate the salivary gland function in post-irradiated head and neck tumour patients.

Matched MeSH terms: Dose-Response Relationship, Radiation
Carbon nanotubes buckypaper radiation studies for medical physics applications

Alanazi A, Alkhorayef M, Alzimami K, Jurewicz I, Abuhadi N, Dalton A, et al.

Appl Radiat Isot, 2016 Nov;117:106-110.
PMID: 26777569 DOI: 10.1016/j.apradiso.2016.01.001

Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In such circumstance, dosimeters with atomic number similar to human tissue are needed. Carbon nanotubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nanotubes (SWCNTs) buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2Gy. This finding suggests that carbon nanotubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance.

Matched MeSH terms: Dose-Response Relationship, Radiation
The thermoluminescence glow curve and the deconvoluted glow peak characteristics of erbium doped silica fiber exposed to 70-130 kVp x-rays

Alawiah A, Bauk S, Marashdeh MW, Nazura MZ, Abdul-Rashid HA, Yusoff Z, et al.

Appl Radiat Isot, 2015 Oct;104:197-202.
PMID: 26188687 DOI: 10.1016/j.apradiso.2015.07.011

In regard to thermoluminescence (TL) applied to dosimetry, in recent times a number of researchers have explored the role of optical fibers for radiation detection and measurement. Many of the studies have focused on the specific dopant concentration, the type of dopant and the fiber core diameter, all key dependencies in producing significant increase in the sensitivity of such fibers. At doses of less than 1 Gy none of these investigations have addressed the relationship between dose response and TL glow peak behavior of erbium (Er)-doped silica cylindrical fibers (CF). For x-rays obtained at accelerating potentials from 70 to 130 kVp, delivering doses of between 0.1 and 0.7 Gy, present study explores the issue of dose response, special attention being paid to determination of the kinetic parameters and dosimetric peak properties of Er-doped CF. The effect of dose response on the kinetic parameters of the glow peak has been compared against other fiber types, revealing previously misunderstood connections between kinetic parameters and radiation dose. Within the investigated dose range there was an absence of supralinearity of response of the Er-doped silica CF, instead sub-linear response being observed. Detailed examination of glow peak response and kinetic parameters has thus been shown to shed new light of the rarely acknowledged issue of the limitation of TL kinetic model and sub-linear dose response of Er-doped silica CF.

Matched MeSH terms: Dose-Response Relationship, Radiation
A review of radiation hazards with special reference to diagnostic radiology

Ang AH

Med J Malaysia, 1973 Dec;28(2):75-9.
PMID: 4276302
Matched MeSH terms: Dose-Response Relationship, Radiation
Macrophage response and surface analysis of dental cementum after treatment with high intensity focused ultrasound

Daood U, Fawzy AS

Arch Oral Biol, 2019 Feb;98:195-203.
PMID: 30502562 DOI: 10.1016/j.archoralbio.2018.10.019

OBJECTIVE: To investigate effects of HIFU on macrophage phenotype, surface micro-topography and nano-scale surface mechanical properties of dental cementum.
MATERIALS AND METHODS: Root discs (2 mm thickness) were cut apical to CEJ and sectioned into quadrants. HIFU setup with bowl-shaped piezo ceramic transducer submerged in a water tank was used for exposure on each specimen for 15 s, 30 s or 60 s. The specimens of the control group were left without any HIFU exposure. HIFU was generated with a continuous sinusoidal wave of 120Vpp amplitude, 250 KHZ resonance-frequency and highest ultrasonic pressure of ∼10 bar at the focus. Specimens for SEM were viewed, and micro-topography characterization performed, using AFM and Ra parameter and surface area (SA) calculated by specialized SPM surface analysis software. For nano-indentation testing, experiments were carried out using AFM. Macrophage cell isolation and culturing was performed on cementum to receive the HIFU treatment at different time periods. Raman spectroscopy were scanned to create spectra perpendicular to the cementum substrate to analyze generation of standard spectra for Raman intensity ratio of hydroxyapatite normalized to the peaks ν1 960 cm-1. Data was expressed as means ± standard deviations and analyzed by one-way ANOVA in term of Ra, SA, H and Er. Different points for fluorescence intensity ratio were analyzed by Raman using Wilcoxon rank sum test.
RESULTS: HIFU exposure at 60 s removed the smear layer and most of cementum appeared smoothened. AFM characterisation, showed a slight decrease in the irregularity of the surface as exposure time increased. Intact macrophages can be identified in control and all experimental HIFU groups. The level of fluorescence for the control and HIFU 15 and 30 s were low as compared to HIFU 60 s.
CONCLUSION: If HIFU can be successfully implemented, it may be a possible alternative to current methods used in periodontal therapy to achieve smooth root surfaces.

Matched MeSH terms: Dose-Response Relationship, Radiation
Dual-source CT coronary angiography: effectiveness of radiation dose reduction with lower tube voltage

Sabarudin A, Md Yusof AK, Tay MF, Ng KH, Sun Z

Radiat Prot Dosimetry, 2013;153(4):441-7.
PMID: 22807493 DOI: 10.1093/rpd/ncs127

This study was conducted to investigate the effectiveness of dose-saving protocols in dual-source computed tomography (CT) coronary angiography compared with invasive coronary angiography (ICA). On 50 patients who underwent coronary CT angiography was performed dual-source CT (DSCT) and compared with ICA procedures. Entrance skin dose (ESD), which was measured at the thyroid gland, and effective dose (E) were assessed for both imaging modalities. The mean ESD measured at the thyroid gland was the highest at 120 kVp, followed by the 100 kVp DSCT and the ICA protocols with 4.0±1.8, 2.7±1.0 and 1.1±1.2 mGy, respectively. The mean E was estimated to be 10.3±2.1, 6.2±2.3 and 5.3±3.4 mSv corresponding to the 120-kVp, 100-kVp DSCT and ICA protocols, respectively. The application of 100 kVp in DSCT coronary angiography is feasible only in patients with a low body mass index of <25 kg m(-2), which leads to a significant dose reduction with the radiation dose being equivalent to that of ICA.

Matched MeSH terms: Dose-Response Relationship, Radiation
Effect of ionizing radiation on some quality attributes of nutraceutically valued lotus seeds

Bhat R, Karim AA

Int J Food Sci Nutr, 2009;60 Suppl 4:9-20.
PMID: 19462319 DOI: 10.1080/09637480802241626

Radiation processing has been employed successfully for value addition of food and agricultural products. Preliminary studies were undertaken to evaluate the changes induced by ionizing radiation (up to 30 kGy), in the form of gamma irradiation and electron beam irradiation, on some quality attributes and nutritive values of nutraceutically valued lotus seeds. Significant loss in seed firmness was recorded between control and irradiated seeds, irrespective of radiation source. Similarly, the specific viscosity of irradiated lotus seeds decreased significantly up to a dose of 7.5 kGy. Starch increased after exposure to gamma or electron beam irradiation, whereas the total phenolic contents were decreased. Gamma irradiation revealed an enhancement in protein, while the electron beam showed a decrease. Partial oxidation of the seeds during radiation treatments might have occurred as evidenced from the decomposition profiles (thermogravimetry) during heating. It is evident that ionizing radiation brought about significant and variable changes in the quality and nutritive values of lotus seed. Further exploration of this technology for safety and quality is warranted.

Matched MeSH terms: Dose-Response Relationship, Radiation
Iodination improves the phototoxicity of an amphiphilic porphyrin

Topkaya D, Ng SY, Bretonnière Y, Lafont D, Chung LY, Lee HB, et al.

Photodiagnosis Photodyn Ther, 2016 Dec;16:12-14.
PMID: 27475243 DOI: 10.1016/j.pdpdt.2016.07.008
Matched MeSH terms: Dose-Response Relationship, Radiation
Eosinophil-Associated Gene Pathways but not Eosinophil Numbers are Differentially Regulated between Synchrotron Microbeam Radiation Treatment and Synchrotron Broad-Beam Treatment by 48 Hours Postirradiation

Ibahim MJ, Yang Y, Crosbie JC, Stevenson A, Cann L, Paiva P, et al.

Radiat Res, 2016 Jan;185(1):60-8.
PMID: 26720800 DOI: 10.1667/RR14115.1

Synchrotron microbeam radiation treatment (MRT) is a preclinical radiotherapy technique with considerable clinical promise, although some of the underlying radiobiology of MRT is still not well understood. In recently reported studies, it has been suggested that MRT elicits a different tumor immune profile compared to broad-beam treatment (BB). The aim of this study was to investigate the effects of synchrotron MRT and BB on eosinophil-associated gene pathways and eosinophil numbers within and around the tumor in the acute stage, 48 h postirradiation. Balb/C mice were inoculated with EMT6.5 mouse mammary tumors and irradiated with microbeam radiation (112 and 560 Gy) and broad-beam radiation (5 and 9 Gy) at equivalent doses determined from a previous in vitro study. After tumors were collected 24 and 48 h postirradiation, RNA was extracted and quantitative PCR performed to assess eosinophil-associated gene expression. Immunohistochemistry was performed to detect two known markers of eosinophils: eosinophil-associated ribonucleases (EARs) and eosinophil major basic protein (MBP). We identified five genes associated with eosinophil function and recruitment (Ear11, Ccl24, Ccl6, Ccl9 and Ccl11) and all of them, except Ccl11, were differentially regulated in synchrotron microbeam-irradiated tumors compared to broad-beam-irradiated tumors. However, immunohistochemical localization demonstrated no significant differences in the number of EAR- and MBP-positive eosinophils infiltrating the primary tumor after MRT compared to BB. In conclusion, our work demonstrates that the effects of MRT on eosinophil-related gene pathways are different from broad-beam radiation treatment at doses previously demonstrated to be equivalent in an in vitro study. However, a comparison of the microenvironments of tumors, which received MRT and BB, 48 h after exposure showed no difference between them with respect to eosinophil accumulation. These findings contribute to our understanding of the role of differential effects of MRT on the tumor immune response.

Matched MeSH terms: Dose-Response Relationship, Radiation