engleski

Radiation therapy photon beams dose conformation according to dose distribution around intracavitary applied brachytherapy sources

Intracavitary application of brachytherapy sources followed by external beam radiation is essential for the local treatment of carcinoma of the cervix. Due to very high doses to the central portion of the target volume delivered by brachytherapy sources, this part of target volume must be shielded while irradiate by photon beams. In practice are several shielding techniques ; from rectangular block and standard cervix wedge to, more precise, customized step wedge filters. Since the calculation of a step wedge filter’s shape was usually based on effective attenuation coefficient, an approach accounting for the scattered radiation in more precise way is suggested. Method was verified under simulated clinical conditions using film dosimetry. Measured data for various compensators were compared to the numerically determined sum of the dose distribution around brachytherapy sources and that one of compensated beam. Improvements in total dose distribution using our method are demonstrated. Agreement between calculation and measurements were within 3%. Sensitivity of the method on sources displacement during treatment has been also investigated.

radiation therapy ; compensators

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