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

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

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_90%), rectum 2 cm³ dose (Rectum D_{2 cc}), small intestine 2 cm³ dose (Small D_{2 cc}), sigmoid colon 2 cm³ dose (Sigmoid D_{2 cc}), bladder 2 cm³ dose (Bladder D_{2 cc}), point A dose.

In intracavitary brachytherapy, the HR-CTV D_90%, Rectum D_{2 cc}, Small D_{2 cc}, and Sigmoid D_{2 cc} doses increased as the source dwell position changed in the direction. On the other hand, the dose of Bladder D_{2 cc} increased when the source position changed in the outward direction. The same trend was observed in the case of intracavitary and interstitial brachytherapy.

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.