[Comparison of indoor and outdoor dose rates from environmental gamma radiation in Kurdistan province]

Studying about background radiation is important because human beings are continuously exposed to these radiations which leave energy in tissues and the transferred energy leads to undesirable biologic effects. The level of background radiation differs in indoor and outdoor places. Since, people spend more time indoors, in this research environmental gamma dose rate for indoor and outdoor places of Kurdistan towns was determined and compared. To estimate dose rate at outdoors, four stations in the length of main directions and one in the center of each city were selected. To estimate dose rate at indoors, two stations in each town according to the type of buildings were selected. In each station gamma dose rate was measured for one hour by RDS-110 servimeter at one meter height from the earth. The average of outdoor and indoor environmental gamma dose rate for Kurdistan towns obtained as follows: Baneh 134 [SD=5], 166 [SD=25] nSv/h, Bijar 113 [SD=17], 141 [SD=8] nSv/h, Divandareh 110 [SD=8], 134 [SD=12] nSv/h, Saqez 105 [SD=12], 134 [SD=11] nSv/h, Sanandaj 110 [SD=12], 133 [SD-4] nSv/h, Qorve 114 [SD=20], 160 [SD=4] nSv/h, Kamyaran 92 [SD=4], 115 [SD=14] nSv/h, Marivan 110 [SD=9], 122 [SD=18] nSv/h. Data shows that indoor dose rates in Baneh [%24], Bijar [%24], Divandareh [%22], Saqez [%28], Sanandaj [%21], Qorveh [%40], Kamyaran [%25] and Marivan [%11] exceed outdoor dose rate in these towns

Gonad, bone marrow and effective dose to the population of more than 90 towns and cities of Iran, arising from environmental gamma radiation

Since 1996 the assessment of environmental gamma radiation dose in residential areas of Iranian towns and cities has been accomplished for 10 counties. As a practical method and based on the results of a pilot study, in order to attribute the final results to the whole residential area of a town five stations were selected for every town. The location of individual station was studied closely to comply with recommended conditions in the literature. RDS-110 was employed to measure gamma dose rate for one hour. Average annual dose rates plus conversion coefficients were employed to estimate gonad, bone marrow, equivalent and effective dose. Minimum and maximum annual bone marrow and gonad dose equivalent attributed to environmental gamma are 0.24 mSvy[-1] [for both tissues] and 1.44 and 1.46 mSvy[-1], respectively. Average gonad and bone marrow doses for North Khorasan, Boshehr and Hormozgan provinces were less than the corresponding values for normal area

Organ and effective dose arising from conventional diagnostic X-ray examinations by Monte Carlo simulation [MCNP-4C code]

Monte Carlo simulation has been used by many researchers to calculate organ and effective dose of patients arising from conventional X-ray examinations. In this study the radiation transport code, MCNP-4C, has been used to perform Monte Carlo simulations to estimate radiation dose delivered to different organs in conventional X-ray examinations. In this work we have made use of ORNL mathematical phantoms with few modifications which have been made. The source has been defined as a point source, emitting photons into a solid angle. The X-ray beam was shaped by a collimator to produce a rectangular field at the midline of the phantom. To validate the simulation executed in this study normalized organs doses to unit ESD for hermaphrodite phantom were computed. Our results were compared with corresponding values presented by NRPB. In general organs doses obtained by application of MCNP-4C [present study] and corresponding values presented in NRPB were in good agreement. For further evaluation of our phantom, the values acquired for organ and effective doses by MCNP-4C and ODS-60 were compared. The technique we have developed is capable of estimating organ and effective doses with a better accuracy than dose values obtained by employment of NRPB and ODS-60 technique

Quality assurance program for prototype stereotactic system developed for Neptun 10 PC linac

A prototype stereotactic radiosurgery set was designed and constructed for a Neptun 10 PC linac that is currently being used at Imam Reza hospital in Mashhad. A complete quality assurance program was designed and performed for the constructed system including isocentric accuracy test, localization accuracy test, dose delivery accuracy test and leakage radiation test. Target simulator, control alignment device and plexiglass phantom which were parts of the developed hardware were used to fulfill quality assurance program. The average isocentric shift resulted from the gantry rotation and couch turning were respectively obtained to be 1.4 and 2 mm. The average localization error in the three coordinates was found to be 2.2 mm. The total treatment uncertainty due to all of the probable errors in the system was equal to 4.32 mm. The dose delivery accuracy test was carried out, the result indicated a 3-7% difference between the given and measured dose. The quality assurance tests showed consistent performance of the constructed system within the accepted limits; however, some inconsistency might exist in certain cases. The safety of SRS method is increased when the overall uncertainty is minimized and the treatment of the lesions adjacent to critical organs is avoided