ABSTRACT Iodine-125 brachytherapy (BT) sources have gained a wide application in the treatment of prostate and intraocular cancers. Determination of the source strength of I-125 seeds is, therefore, mandatory to ensure accurate and optimal dose delivery to a patient undergoing BT treatment. There is the need to verify source strength stated or provided by a manufacturer of any BT source prior to clinical use of the source in fulfillment of American Association of Physicists in Medicine and European Society for Therapeutic Radiology and Oncology (AAPM-ESTRO) recommendations for low energy BT sources. For low energy source, this process is sometimes ignored due to unavailability of appropriate equipment to facilitate the measurement of the source strength under clinical conditions. The present study sought to find ways of measuring source strengths of I-125 BT seed sources (model number STM1251) in use at Korle-Bu Teaching Hospital (KBTH) for permanent low dose rate (LDR) prostate BT with a well-type ionization dosimetry system, which is dedicated to high dose rate (HDR) BT source calibration. The BT seed implants are manufactured by Bard BT Inc., and are loaded in a Mick® cartridge which has maximum loading capacity of 15 seeds. To achieve this, a source holder which could be accommodated within the well-type ionization chamber (WTIC) was designed and constructed from Perspex (PMMA). The constructed source holder was designed to hold a whole cartridge of I-125 BT seeds within the WTIC to facilitate batch source strength measurement. The source holder ensuring reproducibility of I-125 seeds placements during source calibration, also enabled placement of a cartridge such that the point of concentration of activity of I-125 seeds coincided with the most sensitive part of the WTIC. Calibration coefficient was established for the dosimeter system (including source holder) through correlation and regression analysis of source strength measurements performed with the dosimeter system which were compared to source strengths with national institute of standards and technology (NIST) traceability provided by manufacturer of the I-125 seed sources. The obtained calibration coefficient was validated by performing I-125 seed source calibrations with the dosimetry system and comparing the source strengths with their counterparts stated by manufacturer of the I-125 seed sources. The dosimeter system was found to have calibration coefficient of 3.372 ± 0.200 ×1011U/A for the I-125 seed sources. The mean percentage deviation of the source strengths was found to be 2.588% which is in agreement with AAPM-ESTRO recommendations. The constructed low cost source holder is, therefore, recommended to be used for Bard I-125 seed source calibration with a HDR 1000 plus WTIC. This source calibration approach comes in handy for BT departments with limited resources.
SSA, R (2021). DESIGN AND CONSTRUCTION OF A SOURCE HOLDER FOR THE DETERMINATION OF SOURCE STRENGTH OF IODINE-125 LOW DOSE RATE BRACHYTHERAPY SOURCES. Afribary.com: Retrieved May 06, 2021, from https://afribary.com/works/design-and-construction-of-a-source-holder-for-the-determination-of-source-strength-of-iodine-125-low-dose-rate-brachytherapy-sources
Research, SSA. "DESIGN AND CONSTRUCTION OF A SOURCE HOLDER FOR THE DETERMINATION OF SOURCE STRENGTH OF IODINE-125 LOW DOSE RATE BRACHYTHERAPY SOURCES" Afribary.com. Afribary.com, 30 Mar. 2021, https://afribary.com/works/design-and-construction-of-a-source-holder-for-the-determination-of-source-strength-of-iodine-125-low-dose-rate-brachytherapy-sources . Accessed 06 May. 2021.
Research, SSA. "DESIGN AND CONSTRUCTION OF A SOURCE HOLDER FOR THE DETERMINATION OF SOURCE STRENGTH OF IODINE-125 LOW DOSE RATE BRACHYTHERAPY SOURCES". Afribary.com, Afribary.com, 30 Mar. 2021. Web. 06 May. 2021. < https://afribary.com/works/design-and-construction-of-a-source-holder-for-the-determination-of-source-strength-of-iodine-125-low-dose-rate-brachytherapy-sources >.
Research, SSA. "DESIGN AND CONSTRUCTION OF A SOURCE HOLDER FOR THE DETERMINATION OF SOURCE STRENGTH OF IODINE-125 LOW DOSE RATE BRACHYTHERAPY SOURCES" Afribary.com (2021). Accessed May 06, 2021. https://afribary.com/works/design-and-construction-of-a-source-holder-for-the-determination-of-source-strength-of-iodine-125-low-dose-rate-brachytherapy-sources