Calibration of High Dose Rate Cobalt-60 Source Using a Farmer Type Chamber in A Locally Constructed Hollow Phantom

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dc.contributor.author Kambauwa, J.D
dc.date.accessioned 2016-11-03T13:41:13Z
dc.date.accessioned 2017-10-13T17:44:33Z
dc.date.available 2016-11-03T13:41:13Z
dc.date.available 2017-10-13T17:44:33Z
dc.date.issued 2015
dc.identifier.uri http://197.255.68.203/handle/123456789/8886
dc.description.abstract An important aspect of general quality assurance program for brachytherapy dosimetry is source calibration.Vendors assign large uncertainities of up to ±10 % for the stated source calibrated values. It is thus important to check the vendor stated calibration. There are three main methods of calibrating brachytherapy sources and they are the “Free- in – air” method, using a re-entrant( well ) type chamber and using a thimble (Farmer) type ionization chamber in a phantom. The main objective of this study was to compare values of source strength obtained by using the re-entrant chamber method and the thimble (farmer) type ionization chamber in a phantom method. A cylindrical hollow phantom was constructed from Poly methyl methacrylate (PMMA) having four holes located at a distance of 8cm from the centre and the angle between each of the holes being 90° from the centrally located source holder . The experimental set up followed International Atomic Energy Agency (IAEA) Technical Document 1274 (IAEA-TECDOC-1274) for the re-entrant chamber method and DIN 68909-2 in combination with DGMP report 13 for the thimble ionization chamber in a phantom method. Measurements carried out using the well type chamber deviated from the theoretical value of the source by -1.36% whereas those measured by the Farmer type ionization chamber in a locally constructed phantom deviated from the theoretical air kerma strength value by -2.1%. The difference in measured values from the two measuring methods was found to be0.8%. en_US
dc.language.iso en en_US
dc.publisher University of Ghana en_US
dc.subject CALIBRATION en_US
dc.subject HIGH DOSE en_US
dc.subject COBALT-60 en_US
dc.subject SOURCE en_US
dc.subject FARMER en_US
dc.subject CHAMBER en_US
dc.subject LOCALLY CONSTRUCTED en_US
dc.subject HOLLOW PHANTOM en_US
dc.title Calibration of High Dose Rate Cobalt-60 Source Using a Farmer Type Chamber in A Locally Constructed Hollow Phantom en_US
dc.type Thesis en_US


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