A comparison of treatment duration for Cobalt-۶۰ and Iridium-۱۹۲ sources with different activities in HDR brachytherapy using tandem-ovoid applicator

Introduction: The long-half-life Cobalt-۶۰ source with high dose rate (HDR) brachytherapy is an appropriate alternative to Iridium-۱۹۲ (HDR) source in the treatment of GYN patients in developing countries. This study aimed to compare HDR cervical cancer treatment duration using Cobalt-۶۰ and Iridium-۱۹۲ sources for the Tandem-ovoid applicators. Material and Methods: In the present study, BEBIG Cobalt-۶۰ source model Co۰.A۸۶ and Iridium-۱۹۲ source model mHDR-v۲r were utilized. The treatment time required for both radionuclides was calculated using the TG-۴۳ formalism. To calculate the treatment time for the Iridium source, the absorbed dose was used in the TG-۴۳ formalism and treatment data. Then the dwell times were determined after repeating the calculations with Cobalt-۶۰. Finally, the comparison was made for the treatment duration for the two sources. Results: According to our findings, the treatment time for the cobalt source with the activity of ۲.۱۳۱ Ci is somehow the same as that of the iridium source with the activity of ۵.۶۹۰ Ci. If the maximum treatment duration is supposed to be ۱۶ minutes in a treatment session, the effective time window for Iridium-۱۹۲ is about ۱۶۰ days. This is, however, the effective time window is ۲۰۰۰ days for Cobalt-۶۰. Conclusion: According to the findings, the use of Cobalt-۶۰ instead of Iridium-۱۹۲ is economically beneficial for equipment selection in newly constructed departments. Changes in the activities of Cobalt-۶۰ in comparison with Iridium-۱۹۲ requires editing the total treatment time of the treatment planning system for patients. Such editing may raise errors and reduce accuracy.

Keywords:

Treatment Time , Absorbed Dose Brachytherapy