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

ABSTRACT

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 D90%), rectum 2 cm3 dose (Rectum D2 cc), small intestine 2 cm3 dose (Small D2 cc), sigmoid colon 2 cm3 dose (Sigmoid D2 cc), bladder 2 cm3 dose (Bladder D2 cc), point A dose. RESULTS: In intracavitary brachytherapy, the HR-CTV D90%, Rectum D2 cc, Small D2 cc, and Sigmoid D2 cc doses increased as the source dwell position changed in the direction. On the other hand, the dose of Bladder D2 cc 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.