[Effect of Brachytherapy Source Dwell Position on Dose Distribution in Cervical Cancer Therapy].

Purpose: To investigate the effect of different source dwell positions on dose distribution in the treatment of cervical cancer with brachytherapy.

Methods: Treatment planning data for cervical cancer patients were used. Treatment plans were created at 1 mm intervals, varying up to 5 mm. For intracavitary brachytherapy and intracavitary and interstitial brachytherapy, the following dose parameters were evaluated: 90% high-risk clinical target volume (HR-CTV D), rectum 2 cm dose (Rectum D), small intestine 2 cm dose (Small D), sigmoid colon 2 cm dose (Sigmoid D), bladder 2 cm dose (Bladder D), point A dose.

Results: In intracavitary brachytherapy, the HR-CTV D, Rectum D, Small D, and Sigmoid D doses increased as the source dwell position changed in the direction. On the other hand, the dose of Bladder D increased when the source position changed in the outward direction. The same trend was observed in the case of intracavitary and interstitial brachytherapy.

Conclusion: It was shown that a 1 mm change in the source dwell position can affect the dose by up to 2% or more. The accuracy of the source dwell position is very important and should be checked before using the device.