Production of a novel high strength heavy concrete using tourmaline and galena for neutron and photon radiation shielding

High density concrete is extensively used for efficient radiation attenuation in radiotherapy rooms and nuclear reactors. Over the past eight years, some efficient galena-based concrete samples for shielding X or gamma rays was produced. The goal of this study was to produce a novel high density concrete against neutron and photon radiations using tourmaline and galena. Attenuation of gamma photons was measured using a Farmer type ionization chamber with a standard [60]Co buildup cap on a Theratron[60] Co therapy unit. Neutron shielding characteristics were measured by using an Am-Be source. The MCNP4C radiation transport computer code was used to investigate the effects of various shield thicknesses on the attenuation of gamma-ray photons and neutrons. The concrete samples had a density of 4.0- 4.2 g/cm[3]. The compressive strength was 326 - 560 kg/cm2. The calculated value for Half Value Layer [HVL] of the tourmaline-galena concrete samples for 60Co gamma rays was 2.72 cm, which is much less than that of ordinary concrete [6.0 cm]. The MC-derived HVL for photons with the same energy was 2.77 cm, which is in a good agreement with the experimental data. Moreover, ToGa concrete had up to 10 times greater neutron attenuation compared to that of the reference concrete. Tourmalin-Galena Concrete opens a new horizon in economic and efficient gamma/neutron shielding in high-energy radiotherapy bunkers, nuclear power plants, and shielding of radioactive sources

effects of internal wall covering materials on hazards of indoor radon concentrations in houses of Iran

Radon gas emanating from underground can concentrate indoor and reach levels, which represent a risk to people's health. According to WHO [World Health Organization] and ERA [Environmental Protection Agency], radon is the second leading cause of lung cancer in the world. Due to the direct correlation of lung cancer and radon exposure, it is ideal to evaluate the hazards of radon accumulation in the Iran dwellings with different materials by direct measurement of the radon concentrations using accurate, simple and fast method. The aim of this study was to measure variation of radon concentrations with different covering materials on internal building surfaces including walls, which are used in Iran dwellings. A special chamber with changeable walls of different covering materials [gypsum, wallpaper, oil dye, plastic dye, wood board, and Belka] was made. Radioactive lantern mantles were used for elevating the radon [220]Rn] levels in the chamber artificially. Ventilation in the chamber had been such way that accumulation of radon could be possible. Active measurement by Prassi portable radon gas surveyor was performed for staging purposes. The average radon concentration for wood and plastic dye was 869.0 +/- 66.7 and 936.8_60.6 [bq/m[3]], respectively, while that for wallpaper and gypsum was 449.2 +/- 101.7, 590.9 +/- 49.0 [bq/m[3]], significantly lower than other covers. The average radon concentration for oil dye and Belka cover was 668.3 +/- 42.3, 697.2 +/- 136.7 [bq/m[3]], respectively. Individuals living in a house with internal wall covering materials of gypsum and wallpaper receive an average annual dose smaller than one living in a house with internal wall covering materials of wood board and plastic dye. Using wallpaper and gypsum as an internal cover for the dwellings suggested

Evaluation of the changes in the shape and location of the prostate and pelvic organs due to bladder filling and rectal distension

A steep dose gradient between prostate and organs at risk [rectum and bladder] is ideal in treatment modality, so prostate displacement and deformation due to bladder filling and rectal distension play an important role in critical organs dose. This study aims to evaluate the changes in the shape and location of the prostate and pelvic organs due to bladder filling and rectal distension. Three patients who referred for transrectal prostatic biopsy [Shahid Faghihi Hospital, Shiraz, Iran] with different prostate sizes were enrolled. A 1.5-Tesla MRI system [Avanto, Siemens, Germany] and an ultrasound system [Logiq 500, GE medical systems, USA] were used to collect images of patients prostate at different stages of bladder and rectum fullness. The mean displacement of the prostate after bladder filling in the supine and left decubitus positions along the Anterior-Posterior [AP] axis was posterior by 4.9 mm [range: 0.7-6.3 mm] and along the Superior-Inferior [SI] axis was inferior by 3.4 mm [range: 1.4-5 mm]. Prostate displacement in the Left-Right [LR] axis was negligible. The mean prostate displacement after rectal distension was anterior by 7.1 mm in the supine position, 5.1 mm anterior in the left decubitus position and along the SI axis was inferior by 2.5 mm in the supine and left decubitus positions. The maximum prostate deformation due to rectal distension and bladder filling in the supine position was as large as 3.2 mm, 1.9 mm and 1.2 mm in the AP, SI and LR directions respectively. While in the left decubitus position, it was 2.6 mm, 1.2 mm and 1.3 mm in the AP, LR and SI axis respectively. It is probably of importance to evaluate the influence of the changes in the shape and location of the prostate due to bladder filling, rectal distension and patient position in post-implant brachytherapy dosimetry. Using images of the patients in the left decubitus position with full bladder and distended rectum for planning a treatment are suggested

Production of a datolite-based heavy concrete for shielding nuclear reactors and megavoltage radiotherapy rooms

Biological shielding of nuclear reactors has always been a great concern and decreasing the complexity and expense of these installations is of great interest. In this study, we used datolite and galena [DaGa] minerals for production of a high performance heavy concrete. Datolite and galena minerals which can be found in many parts of Iran were used in the concrete mix design. To measure the gamma radiation attenuation of the DaGa concrete samples, they were exposed to both narrow and wide beams of gamma rays emitted from a cobalt-60 radiotherapy unit. An Am-Be neutron source was used for assessing the shielding properties of the samples against neutrons. To test the compression strengths, both types of concrete mixes [DaGa and ordinary concrete] were investigated. The concrete samples had a density of 4420-4650 kg/m[3] compared to that of ordinary concrete [2300-2500 kg/m[3]] or barite high density concrete [up to 3500 kg/m[3]]. The measured half value layer thickness of the DaGa concrete samples for cobalt-60 gamma rays was much less than that of ordinary concrete [2.56 cm compared to 6.0 cm]. Furthermore, the galena concrete samples had a significantly higher compressive strength as well as 20% more neutron absorption. The DaGa concrete samples showed good shielding/ engineering properties in comparison with other reported samples made, using high-density materials other than depleted uranium. It is also more economic than the high-density concretes. DaGa concrete may be a suitable option for shielding nuclear reactors and megavoltage radiotherapy rooms