Search results for "radiation protection"
showing 10 items of 72 documents
Concentration-Dependent Protection by Ethanol Extract ofPropolis against γ
2011
[EN] Radioprotection with natural products may be relevant to the mitigation of ionizing radiation-induced damage in mammalian systems; in this sense, propolis extracts have shown effects such as antioxidant, antitumoral, anti-inflammatory, and immunostimulant. We report for the first time a cytogenetic study to evaluate the radioprotective effect, in vitro, of propolis against radiation-induced chromosomal damage. Lymphocytes were cultured with increasing concentrations of ethanol extract of propolis (EEP), including 20, 40, 120, 250, 500, 750, 1000, and 2000 ¿g mL-1 and then exposed to 2 Gy ¿-rays. A significant and concentration-dependent decrease is observed in the frequency of chromoso…
Light transmission and ultraviolet protection of contact lenses under artificial illumination
2016
Purpose: To determine the spectral transmission of contact lenses (CLs), with and without an ultraviolet (UV) filter to evaluate their capacity for protection under UV radiation from artificial illumination (incandescent, fluorescent, xenon (Xe) lamps, or white LEDs (light-emitting diode)). Methods: The transmission curves of nine soft CLs were obtained by using a PerkinElmer Lambda 35 UV-vis spectrophotometer. A CIE standard was used for the emission spectra of incandescent and fluorescent lamps, and Xe lamps and white LEDs were measured by using an International Light Technologies ILT-950 spectroradiometer. Results: Five of the nine soft CLs analysed state that they incorporate UV filters…
Cohort Profile: the EPI-CT study: a European pooled epidemiological study to quantify the risk of radiation-induced cancer from paediatric CT
2018
International audience; •The multinational EPI-CT study was set-up in 2011 to provide direct estimates of risk of solid tumours and leukaemia among children and young adults who underwent computed tomography (CT) scanning and to consolidate the scientific basis for optimization of paediatric CT protocols and patient protection.•Under a common protocol, cohort studies were conducted in Belgium, Denmark, France, Germany, the Netherlands, Norway, Spain, Sweden and the United Kingdom, coordinated by the International Agency for Research on Cancer (IARC). •The study recruited a total of about 950,000 patients having undergone at least one CT-scan before the age of 22 years. A total of 8.7 millio…
External photon radiation treatment for prostate cancer: Uncomplicated and cancer-free control probability assessment of 36 plans
2019
[Purpose] To perform a systematic and thorough assessment, using the Uncomplicated and Cancer-Free Control Probability (UCFCP) function, of a broad range of photon prostate cancer RT treatments, on the same scenario (a unique pelvic CT set). UCFCP considers, together with the probabilities of local tumour control (TCP) and deterministic (late) sequelae (NTCP), the second primary cancer risk (SPCR) due to photon and neutron peripheral doses.
PERIPHERAL SURFACE DOSE FROM A LINEAR ACCELERATOR: RADIOCHROMIC FILM EXPERIMENTAL MEASUREMENTS OF FLATTENING FILTER FREE VERSUS FLATTENED BEAMS
2020
Abstract There is a growing interest in the use of flattening filter free (FFF) beams due to the shorter treatment times. The reduction of head scatter suggests a better radiation protection to radiotherapy patients, considering the expected decrease in peripheral surface dose (PSD). In this work, PSD of flattened (FF) and FFF-photon beams was compared. A radiochromic film calibration method to reduce energy dependence was used. PSD was measured at distances from 2 to 50 cm to the field border for different square field sizes, modifying relevant clinical parameters. Also, clinical breast and prostate stereotactic body radiotherapy (SBRT) plans were studied. For square beams, FFF PSD is lowe…
Influence of a Commercial Lead Apron on Patient Skin Dose Delivered During Oral and Maxillofacial Examinations under Cone Beam Computed Tomography (C…
2017
The purpose of this paper is to investigate the impact of a commercial lead apron on patient skin dose delivered during maxillofacial CBCT in five critical regions by means of solid-state-dosimetry. Five anatomical regions (thyroid gland, left and right breast, gonads, back of the phantom torso) in an adult female anthropomorphic phantom were selected for dose measurement by means of the highly sensitive solid-state dosimeter QUART didoSVM. Ten repeated single exposures were assessed for each patient body region for a total of five commercial CBCT devices with and without a lead apron present. Shielded and non-shielded exposures were compared under the paired Wilcoxon test, with absolute an…
Study of the glow curves of TLD exposed to thermal neutrons.
2007
The glow curves of thermoluminescent dosimeters (TLD600, TLD700 and MCP), exposed to a mixed field of thermal neutrons and gamma photons are analysed. The fluence values of thermal neutrons used, comparable with those used in radiotherapy, allow one to define the reliability of the TLDs, in particular the most sensitive MCP, in this radiation field and to get information on the dose absorbed values. The glow curves obtained have been deconvoluted using general order kinetics and the observed differences for the different LET components have been analysed. In particular, the ratio of the n(0) parameter of two different peaks seems to allow to discriminate the different contributions of neutr…
SU-E-T-691: Shielding Evaluation of a Treatment Room with An Electronic Brachytherapy System
2015
Purpose: Esteya™ (Elekta) is a brachytherapy electronic system used for treating skin cancer lesions. This unit is based on a 69.5 kV X-ray source and a surface applicator which produces a circular beam of a specific diameter, which varies from 1 to 3 cm. This study aims to establish the radiation protection measures for the system. Methods: A characterization of the scattered and leakage radiation of the system was implemented by means of experimental measurements. The scattered radiation measurements were performed with a Berthold LB133 ionization chamber, evaluating the dose rate for different distances from the applicator surface. The patient was simulated through water equivalent solid…
Ultraviolet radiation at Mediterranean latitudes and protection efficacy of intraocular lenses.
2011
Summary Purpose After determining the mean intensity of ultraviolet radiation to which the human eye is exposed at Mediterranean latitudes, this data is used to evaluate the efficacy of the ultraviolet filters incorporated into various intraocular lenses. Methods Ultraviolet radiation measured at Mediterranean latitudes was used as a reference for the theoretical calculation of the amount of radiation to which the human eye is exposed. The spectral transmission curve from 290 to 380 nm was measured for 10 IOLs using a UV/VIS Perkins-Elmer Lambda 800 spectrometer. Results At Mediterranean latitudes, at sea level, with a mean annual solar irradiation of 50 j/cm 2 , the human eye receives a qu…
Air-kerma evaluation at the maze entrance of HDR brachytherapy facilities.
2014
In the absence of procedures for evaluating the design of brachytherapy (BT) facilities for radiation protection purposes, the methodology used for external beam radiotherapy facilities is often adapted. The purpose of this study is to adapt the NCRP 151 methodology for estimating the air-kerma rate at the door in BT facilities. Such methodology was checked against Monte Carlo (MC) techniques using the code Geant4. Five different facility designs were studied for (192)Ir and (60)Co HDR applications to account for several different bunker layouts.For the estimation of the lead thickness needed at the door, the use of transmission data for the real spectra at the door instead of the ones emit…