ESTRO 2023 - Abstract Book

S1767

Digital Posters

ESTRO 2023

Conclusion Our preliminary results indicate that relative dose constraints are a simple, practical, and generally-applicable tool to evaluate and determine re-irradiation OAR doses. Its accuracy is comparable with existing practices and the tool may also be applied to plans with different fractionation schemes delivered during the same treatment.

PO-1993 Dosimetric evaluation of heart substructures & coronaries free and DIBH in left breast carcinoma pts

S. Agarwal 1 , R. Patel 2 , A. Doshi 3 , M. Roy 4 , N. Kalyani 5

1 Jaslok hospital , Radiation oncology, Mumbai, India; 2 Jaslok Hospital and Research Centre, Radiation oncology , Mumbai, India; 3 Jaslok Hospital and Researchcentre, Radiation Oncology, Mumbai, India; 4 Jaslok Hospital and research centre, Radiation oncology , Mumbai , India; 5 Jaslok hospital and research centre, Radiation oncology , Mumbai , India Purpose or Objective The objective of our study was to document the radiation doses from external beam radiation using free breathing technique to the cardia and its substructures as well as to the coronaries and compare the same with deep inspiration breath hold technique and document the differences in the doses received. Materials and Methods This was prospective, observational, open label, single arm, non-interventional study. Eligible patients fulfilling the inclusion criteria were approached and history,patient characteristics and investigations were recorded. A detailed counseling session about treatment with DIBH technique was done for all participant and cases who were able to hold the breath for a minimum period of 20 seconds were enrolled . Informed consent was taken before enrolling in the study. All the eligible patients were taken up for planning image acquisition. All cardia and sub-structures including coronaries and other OAR’s were contoured on both DIBH and Free Breathing scans according to established cardiac contouring guidelines. Dosimetric evaluation of a plan to compare the dose distribution between free and DIBH scans was done. Results Thirty patients diagnosed with left breast IDC non metastatic and fulfilling criteria were enrolled in the study. All the patients received a prescribed dose of 40 Gy in 15 fractions in 3 weeks at 2.67 Gy per fraction to the breast or chest wall. Majority were treated with voluntary DIBH 26 (86.6% ) and 4 patients were treated with a respiratory gating method with