ABSTRACT
While in the open air the amount of radon gas is very small and does not pose a health risk, in confined spaces, radon can accumulate to relatively high levels and become a health hazard. Exposure to high levels of radon has been associated with an increased risk of lung cancer, depending on the time length of exposure. Radon level in dwelling of Shiraz with 1,200,000 populations has been sampled and analyzed in this study. Our study could be considered the largest radon study in Iran both time and area wise. In this study, radon [222Rn] concentration in residential dwellings in Shiraz-Iran was sampled and measured during two consecutive six month periods in 2009-2010. We used Solid State Nuclear Track Detectors [SSNTD], CR-39 polycarbonate films. The survey parameters of radon concentrations were floor types, construction materials and dwelling's age. Annual average indoor radon concentration for the survey period was 94 +/- 52 Bq/m3. The calculated mean annual effective doses in basements and different floors were less than the lowest limit recommended action level of 3 mSv by ICRP. High radon concentrations are measured in basements and old dwellings; however, due to rapidly changing housing structures and ventilation practices with no intervention, lower levels of radon concentration has been expected in Shiraz
Subject(s)
Radon/adverse effects , Air Pollutants, Radioactive , Carcinogens, EnvironmentalABSTRACT
In this work investigation of the normoxic PAGAT polymer gel dosimeter such as sensitivity, the R2-dose response with post time and the percentage depth dose [PDD] of PAGAT polymer gel dosimeter have been undertaken. Using MRI, the formulation to give the maximum change in the transverse relaxation rate R2 was determined to be 4.5% N,N'-methylenbis- acrylamide [C][bis], 4.5% acrylamid[AA], 5% gelatin, 5 mM tetrakis [hydroxymethyl]phosphonium chloride [THPC], 0.01 mM hydroquinone [HQ] and 86% HPLC [Water]. Irradiation of vials was performed using photon beams by Co-60 therapy unit and an Electa linear accelerator. Gel dosimeters were imaged in a Siemens Symphony 1.5 Tesla clinical MRI scanner using a head coil. Gel dosimeters were irradiated 1 day post-manufacture, and imaged 1 day post irradiation. The R2- dose response was linear up to 30 Gy. The response of the PAGAT gel is very similar in the lower dose region and the R2-dose response for doses less than 2 Gy is not exact. The R2-dose response of the PAGAT polymer gel dosimeters varies between 10 to 30 Gy with R2-dose sensitivities of 0.0905, 0.1037, 0.1023, 0.0907 and 0.123 S-1Gy-1 when imaged at 1, 8, 15, 29 and 38 days post-irradiation respectively. The percentage depth dose [PDD] of PAGAT gel dosimeter was determined and at depth of 21cm, the percentage depth dose for 1.25, 4, 6 and 18 MV photons were determined to be, 48%, 52%, 57.3% and 59.73% respectively. Calibration curve of the PAGAT polymer gel dosimeter, were found to be linear between 2-10 Gy and 10-30 Gy with different slopes of the R2-dose sensitivity also showed stability with post time imaging after 38 days. In this study, the percentage depth dose [PDD] of the PAGAT gel dosimeter was measured. It can be concluded that in case of higher energy of photon beams, higher doses can be delivered to deep-seated tumors