Evaluation of performance and quality control of High Dose Rate Ir-192 remote afterloading brachytherapy equipment

Abstract

Brachytherapy is the use of encapsulated radioactive sources to deliver a radiation dose at a short distance over a short time for treatment of malignant tumors. In Sudan, mainly in Radiation and Isotopes Centre – Khartoum (RICK) brachytherapy was introduced in 1989 using manual afterloading low dose rate 137Cs for treatment of carcinoma of the cervix, but for safety reasons now it replace by high dose rate 192Ir afterloading system (HDR) with remotely controlled device to deliver controlled radiation dose for treatment of carcinoma of cervix, esophagus and nasopharynx. This study was carried out in high dose rate 192Ir afterloading brachytherapy equipment (Gamma Med 12i unit) located at RICK to evaluate the performance and to perform comprehensive quality control of the treatment unit with respect to three poles: safety systems, physical parameters and calibration of Ir-192 source through some quality control checks, so as to ensure that the equipment meets the safety standard. The study shows that all the safety systems which include the mechanical checks are work properly; the average of the dose rate measured at different positions from the treatment unit which represent the leakage radiation by using RDS- 120 universal survey meter is less than10μSv/h. The physical parameters which include the check of a source position accuracy by using X-OMAT ready pack film and catheter guide tube is 1mm. The source strength that was obtained from the calibration procedures following the IAEA-TEC DOC 1274 protocol by using HDR 1000 plus well type ionization chamber is different from the value of International Standard Laboratory by 1.5%.It was found that the brachytherapy equipment and the source used in iv brachytherapy meets the user's requirements except some necessary requirements, so some recommendations was putted include these requirements