measurement of radon concentration in selected houses in ibadan nigeria

Radon is a natural radioactive gas without colour or odour and tasteless. The World Health Organization (WHO) grouped radon as a human lung carcinogen. For this reason, there has been a lot of interest on the effects of radon exposure to people all over the world and Nigeria is no exception. The aim of this study is to investigate the radon concentration in selected houses in three local government areas of Ibadan. The indoor radon was measured in both mud and brick houses. Fifty houses were considered from the three Local government areas. A calibrated portable continuous radon monitor type (RAD7) manufactured by Durridge company was used for the measurement. A distance of 100 to 200 m was maintained between houses in all the locations. The living room was kept closed during the measurements. The mean radon concentration measured in Egbeda is 10.54 ±1.30 Bqm -3; Lagelu is 16.90 ± 6.31 Bqm -3 and Ona-Ara is 17.95 ± 1.72 Bqm -3. The mean value of the annual absorbed dose and annual effective dose for the locations in the three local government areas was 0.19 mSvy-1 and 0.48 mSvy-1 respectively. The radon concentration for location 10 in Ono-Ara local government exceeded the recommended limit. However, the overall average indoor radon concentration of the three local governments was found to be lower than the world average value of 40 Bqm -3. Hence, there is need for proper awareness about the danger of radon accumulation in dwelling places

Dosimetric effect of the gantry rotations of a novel trunk phantom using an area integration algorithm

Background: Treatment planning systems (TPSs) have proved to be a useful tool in predetermining how a treatment outcome will be in radiotherapy. The accuracy of any TPS to calculate dose to any arbitrary point within a material is largely dependent on the mathematical algorithm used. Aims: The purpose of this study was to design a local trunk phantom and use the phantom to check the percentage dose accuracy of the Area Integration Algorithm of a Precise PLAN 2.16 TPS if it is in agreement with results obtained from manufacturer's verification by varying the gantry angle and whether it is within ± 5% International Commission on Radiation Units and Measurements (ICRU) minimal limit. Materials and Methods: The study was executed with a locally designed phantom made of Plexiglas with six insert and an ionization chamber port. The phantom was simulated using a HiSpeed NX/i computed tomography scanner and Precise PLAN 2.16 TPS for application of beam setup parameters. The mimicked organs for the inserts were: 25%–75% Glycerol-Water for liver, pure carboxyl methyl cellulose was used for lungs, 30%–70% Glycerol-Water for muscle, 40%–60% Glycerol-Water was used for adipose, pure Sodium hypochlorite was used for bone and pure sodium laureth sulfate (Texapon) for kidney. Results: The maximum percentage (%) deviation with a large field for six inhomogeneous inserts and with bone only homogeneous inserts were 3.4% and 2.9%, respectively. The maximum % deviation with a small field for six inhomogeneous inserts was 3.2%. The % deviation between the solid water phantom and the locally designed phantom was 3.5%. Conclusion: The Area Integration Algorithm has shown an overall accuracy of 4% below 5% ICRU minimal limit. There was no statistically significant difference in field sizes and in inhomogeneity/homogeneity, respectively. Variation exists in % deviation for small field size with parallel opposed field between our verification and the manufacturers