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Dosimetric Comparison of Brachytherapy Sources for High Dose Rate Treatment of Endometrial Cancer:Electronic Brachytherapy,192Ir and 60Co Sources
S Lozares*, J Font Gomez , A Gandia , A Miranda Burgos , M Gascon Ferrer , Hospital Universitario Miguel Servet, Zaragoza, Zaragoza
Presentations
SU-I-GPD-T-20 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: To compare 36 endometrial cancer patients treated in our center with cylindrical applicators and Axxent (Xoft Inc.) electronic brachytherapy with an equivalent planning made for Ir-192 and Co-60 sources.
Methods: 36 patients previously treated with Axxent (50 kV source) have been replanned with Ir-192 and Co-60 sources. The calculation for both types of sources were performed on BrachyVision (Varian Inc.) treatment planning system.The prescription was 5 Gy per fraction applied in 3 fractions or 5 fractions depending on previous radiotherapy treatment.The planning parameters of the planning target volume (PTV) countoured from the cylinder surface to 5 mm along the active length were evaluated. V150 and V200 data for PTV and D2cc, V50% and V35% for organs at risk (OAR) were evaluated, the percentage of the volume receiving 35% and 50% of the prescription dose, respectively, and D2cc, highest dose to a 2 cubic centimetre volume of an OAR. Results for bladder, rectum and sigmoid are showed.
Results: We may observe a reduction in dose at V35% and V50% in all OAR and also a reduction in D2cm3 occurs in the patienets treated with electronic brachytherapy (Table 1).PTV parameters increase in the case of Axxent, as reported previously, but only one case of vaginal mucositis have been reported in our center with grade 2. All patients were treated between 2015 and 2016, enough time to develop early problems.
Conclusion: Preliminary results are very optimistic about the adequacy of Xoft equipment for treatment of endometrial cancer with a clear reduction of the physical dose in organs at risk and very few development of acute mucositis despite the considerable increase V150 in the treatment volume.Further studies will be necessary to take into account the RBE in treatments with such sources.
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