Journal of Basic and Applied Sciences  -   Volume 8 Number 2

Dosimetric Evaluation and Verification of External Beam 3-D Treatment Plans in Humanoid Phantom Using Thermoluminescent Dosimeters (TLDs)

Rizwana Siddique, Zaheer Uddin and Muzaffar Hussain

http://dx.doi.org/10.6000/1927-5129.2012.08.02.65

Abstract: Dosimetric Evaluation & Verification Of External Beam 3-D Treatment Plans In Humanoid Phantom have been carried out. In this study male anthromorphic phantom, model no.702 D, manufactured by Atom Ltd has been used. The plan was delivered to phantom and TLD- 100 was placed in cavities to evaluate and verify the dose delivered by implementing 3D treatment plans. TLD 100 was calibrated using SIEMENS PRIMUS PLUS Linear Accelerator with calibrated 6 MV X ray beam. We chose phantom skull, abdomen and pelvis region for making treatment plans and then doses by treatment plans have been verified by TLDs. 4%, 3.5% and 3% variation in the results was found for skull, pelvis and abdomen region respectively which is within the safe limit of accuracy i-e from 3% to 5 %. Before working with TLDs, it has also been found that thermoluminescent dosimeters were showing the linear response and results are reproducible for the dose range from 50 cGy to 200 cGy. This study has been performed at Karachi Institute of Radiotherapy and Nuclear Medicine (KIRAN) during the year 2010-2011.

Keywords: Thermoluminescent (Tlds) Dosimeters, anthromorphic phantom, vitro Dosimetry, vivo Dosimetry, Linear accelerator.

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The Effect of Grain Size on Radon Exhalation Rate in Soil Samples of Dera Ismail Khan in Pakistan

Tabassum Nasir and Nisar Ahmad

http://dx.doi.org/10.6000/1927-5129.2012.08.02.29

Abstract: Radon concentration and its exhalation rate has been measured from twenty five soil samples collected from seven different locations of Dera Ismail Khan, in the north west of Pakistan. These samples were crushed after drying and passed through sieves with different sizes of pores to get three grain sizes, £0.595 mm, 0.595-2.00 mm and 2.00-4.00 mm of soil. CR-39 based NRPB (National Radiological Protection Board) radon dosimeters have been used to measure the radon concentration and exhalation rates. The maximum average value of radon exhalation rate has found to be: (3.57±0.38) Bq m-2 hr-1 in the samples having grain size 2.00-4.00 mm and the minimum as: (2.21±0.26) Bq m-2 hr-1, in the samples with grain size £ 0.0595 mm. This indicates that the radon exhalation rate increases with the grain size. The maximum average value of radon exhalation rate has been found in samples collected from river side where soil texture is silty clay loam. The obtained values of radon exhalation rate for all the samples are well below the world average value of 57.60 Bq m-2 hr-1.

Keywords: Radon concentration, Radon exhalation rate, grain size, soil texture.

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