Comparative study between IBT or EBRT boost doses at organs at risk in cervical cancer treatment

Abstract

Purpose: To perform a comparative study between the two techniques, IBT versus EBRT, in terms of OAR's doses, in cervix cancer boost treatments. Methods: From a group of patients treated in our department, we selected three cases. The patients underwent an external beam course of 40Gy to the whole pelvis plus 10Gy with median protection and two 192Ir PDR IBT boost treatments of 20Gy (tandem and ovoids CT/MR compatible applicator, ICRU 38 prescription points A, dose rate of 90cGy/h). For the same patients, a boost volume was contoured on CT images and EBRT plan was calculated (four fields, 15MV, 20Gy to the isocenter). DVH were generated for OAR, for both techiques. Dose values were biologically normalised to equivalent doses in 2Gy fractions, based on GEC-ESTRO recommendations, in order to compare them. Results: Dose values ranges for volume of 0.1cc were within 128.8-179.5cGy for rectum and 187.7-447.7cGy for bladder, in IBT, and within 167-205cGy for rectum and 196.8-206.4cGy for bladder, in EBRT. Conclusion: This study shows that IBT aplication has the best dose values for patients, in terms of OAR. Prescription doses were higher, with pronounced reduction in OAR doses. © 2009 Springer-Verlag.