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

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ABSTRACT

An important aspect of general quality assurance program for brachytherapy dosimetry is source calibration. Vendors assign large uncertainties 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%.

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APA

Frontiers, E. & KAMBAUWA, J (2022). Calibration of High Dose Rate Cobalt-60 Source Using a Farmer Type Chamber in A Locally Constructed Hollow Phantom. Afribary. Retrieved from https://afribary.com/works/calibration-of-high-dose-rate-cobalt-60-source-using-a-farmer-type-chamber-in-a-locally-constructed-hollow-phantom

MLA 8th

Frontiers, Edu, and JAROME KAMBAUWA "Calibration of High Dose Rate Cobalt-60 Source Using a Farmer Type Chamber in A Locally Constructed Hollow Phantom" Afribary. Afribary, 19 Jun. 2022, https://afribary.com/works/calibration-of-high-dose-rate-cobalt-60-source-using-a-farmer-type-chamber-in-a-locally-constructed-hollow-phantom. Accessed 04 Jul. 2022.

MLA7

Frontiers, Edu, and JAROME KAMBAUWA . "Calibration of High Dose Rate Cobalt-60 Source Using a Farmer Type Chamber in A Locally Constructed Hollow Phantom". Afribary, Afribary, 19 Jun. 2022. Web. 04 Jul. 2022. < https://afribary.com/works/calibration-of-high-dose-rate-cobalt-60-source-using-a-farmer-type-chamber-in-a-locally-constructed-hollow-phantom >.

Chicago

Frontiers, Edu and KAMBAUWA, JAROME . "Calibration of High Dose Rate Cobalt-60 Source Using a Farmer Type Chamber in A Locally Constructed Hollow Phantom" Afribary (2022). Accessed July 04, 2022. https://afribary.com/works/calibration-of-high-dose-rate-cobalt-60-source-using-a-farmer-type-chamber-in-a-locally-constructed-hollow-phantom