ESTRO 36 Abstract Book

S984 ESTRO 36 _______________________________________________________________________________________________

the advantage of preserving the main nose functions with relevant implication for the quality of life of surviving patients. EP-1793 High-dose-rate brachytherapy for lip and oral cavity tumors C. De la Pinta 1 , T. Muñoz 1 , A. Montero 2 , J. Dominguez 1 1 Hospital Ramon y Cajal, Radiation Oncology, Madrid, Spain 2 Grupo Hospital Madrid, Madrid, Spain Purpose or Objective The aim of this study was to evaluate the clinical and cosmetic outcomes and recurrence-free and overall survival in patients treated with high-dose-rate brachytherapy for lip and oral cavity tumors. Material and Methods All patients referred for interstitial high-dose-rate brachytherapy in our centre from 2007 to 2016 with histologically confirmed squamous cell carcinoma (17p) and basaloid carcinoma (2p) of the lip or oral cavity were retrospectively analysed. Tumor sites included the lips (15p), mouth (3p) and gingiva (1p). Treatment consisted of brachytherapy alone (11p) or recurrence or adjuvant after surgery (8p). All patients were treated with interstitial brachytherapy median implant dose 51 Gy (range 50- 60Gy). Inclusion criteria were as follows: head and neck location and malignant tumors. Results With a median follow-up of 55 months (range 3-246 months), local control was achieved on clinical examination or CT scan. Acute toxicities (11/19p) consisted of ephitelitis grade 1 (3p), grade 2 (4p) and grade 3 (4p). Not acute toxicity grade 4 was reported. Late toxicities (9/19p) were hypopigmentation and fibrosis. One patient had necrosis. Among 19 patients studied, 2 lost follow-up and they were excluded from the survival analysis. Preservation of organ functions was in all patients. Using Kaplan-Meier analysis overall survival after minimum follow-up of 55 months was 94,1% and disease-free survival was 89,4%. One patient had a locoregional recurrence and died of tumor. Conclusion Interstitial brachytherapy is a good choice to deliver high- dose radiation in lip and oral cavity tumor after surgery or as an exclusive treatment. This treatment offers adequate locoregional control with acceptable range of complications. EP-1794 Intra-op check of ONCURA Rapid Strand (Model 7000) seeds radioactivity in LDR prostate brachytherapy V. Stserbakov 1 , K. Aru 2 1 North-Estonian Regional Hospital Cancer Center Radiotherapy, Department of Radiotherapy and Oncology, Tallinn, Estonia 2 North-Estonia Medical Centre- Cancer Center, Department of Radiotherapy and Oncology, Tallinn, Estonia Purpose or Objective To introduce into clinical practice procedure for checking the radioactivity of Oncura rapid strand seeds for LDR prostate brachytherapy deriving the expected value for the strand activity from measurement of activity for each single seed. To perform measurement in possibly more Electronic Poster: Brachytherapy: Physics

clean radiation safety conditions with minimal exposure dose to personal by optimizing every step of the procedure. Material and Methods For measurement the radioactivity of ONCURA single seed, cut off from the strand, it was used well-chamber HDR 1000 Plus (calibration factor for I-125(9011) 2,388 E11 µGy·m 2 /h/A of Standard Imaging) with special insertion for seed. CHARGE mode of Unidos (PTW-Freiburg) electrometer was LOW (≤230 pC). Collected time was 1 min. Setting-up for measurement of the radioactivity of rapid strand (containing 4/5/6 seeds) is shown in the figure (a). The well-chamber (7) was placed into plastic container (5), which one then was covered by sterile coating (4) in order to keep external sterile conditions. Plastic container, as well, prevents of not needed external contacts with well-chamber, since its electrometer is working in most sensitive mode. Tweezers (2) with rapid strand (6) and short transport container (1) was mounted into sterile cylindrical tube (barrel) of BBraun Oroginal- Perfusor Syringe® 50 ml (3), which was used as holder for inserting into well-chamber cavity. Devices for performing radiation safely operating with strands are shown on figure (c, d).

On figures: a) Assembly for rapid strand radioactivity measurement. 1- short transport container; 2- tweezers to hold strand; 3- cylindrical tube (barrel); 4- sterile coating; 5- plastic container; 6- rapid strand seeds; 7- well-chamber. b) Measured values of Rapid strand seeds radioactivity. c) Strand cutting procedure devices. 8- Transport container with cut-outs for 'safely and clean outside cutting” of required strand; 9- spacing jig; 10- seat for container to prevent its rotation on the table; 11- cut-out for finger in container to prevent rotating of spacing jig inside the container. d) Removing of cut-up strands from container. 12- container; 13- metal shielding cover; 14- lead glass; 15- seat for container. Results Summarizing the measurement of every single seed activity might be found the intra-op calibration factors for