ESTRO 2024 - Abstract Book

S3666

Physics - Dose prediction, optimisation and applications of photon and electron planning

ESTRO 2024

1. Bazalova-Carter M, et al., Treatment planning for radiotherapy with very high-energy electron beams and comparison of VHEE and VMAT plans. Med Phys. 2015 May;42(5):2615-25. doi: 10.1118/1.4918923. PMID: 25979053. 2. Favaudon V, et al., Ultrahigh dose-rate FLASH irradiation increases the differential response between normal and tumor tissue in mice. Sci Transl Med. 2014 Jul 16;6(245):245ra93. doi: 10.1126/scitranslmed. 3008973. Erratum in: Sci Transl Med. 2019 Dec 18;11(523): PMID: 25031268.

3. G. Franciosini et al., GPU-accelerated Monte Carlo simulation of electron and photon interactions for radiotherapy applications. Physics in Medicine and Biology; 2023, DOI: 10.1088/1361-6560/aca1f2

4. Bohlen TT et al., Normal tissue sparing by flash as a function of single-fraction dose: A quantitative analysis. International Journal of Radiation Oncology*Biology*Physics 114 (2022) 1032–1044. doi:https://doi.org/10.1016/j.ijrobp. 2022.05.038. A Red Journal Special IssueOligometastasis, Part 2.

2403

Digital Poster

Specific dose optimization driven by late toxicity subregions in prostate cancer treatment plans

Lisa Alborghetti 1 , Roberta Castriconi 1 , Carlos Sosa Marrero 2 , Alessia Tudda 1 , Maria Giulia Ubeira Gabellini 1 , Sara Broggi 1 , Javier Pascau 3 , Lucia Cubero 3 , Cesare Cozzarini 4 , Renaud De Crevoisier 2 , Tiziana Rancati 5 , Oscar Acosta 2 , Claudio Fiorino 1 1 IRCCS San Raffaele Scientific Institute, Medical Physics, Milano, Italy. 2 Univ Rennes, CLCC Eugène Marquis, INSERM, LTSI—UMR1099, F-35000, Rennes, France. 3 Universidad Carlos III de Madrid, Bioengineering, Madrid, Spain. 4 IRCCS San Raffaele Scientific Institute, Radiotherapy, Milano, Italy. 5 Fondazione IRCCS Istituto Nazionale dei Tumori (INT), Data Science Unit, Milano, Italy

Purpose/Objective:

The feasibility of the selective sparing of specific symptom related subregions (SRSs) in the bladder and rectum, avoiding deterioration of PTV coverage, was recently assessed for prostate cancer radiotherapy with VMAT modality. [1] We achieved that by combining automatic knowledge-based (KB) plan prediction model with multi criteria optimization (MCO), using mean dose to SRSs, bladder and rectum as optimization objectives, combined with constraints on target homogeneity. The current study’s objective was to optimize the treatment plan strategy further, considering radiobiological response of the SRS and the corresponding NTCP. To fulfil this purpose, generalized equivalent uniform dose (gEUD) [2] to SRSs was chosen as optimization objective instead of the mean dose. The collection of the so-obtained optimized plans may serve as a library to train a new KB model, optimized to properly spare specific SRSs of the bladder and rectum.

Material/Methods:

Sixty high-risk prostate cancer patients previously treated in 28 fractions with Tomotherapy to prostate seminal vesicles and pelvic lymph-nodes at 74.2, 65.5 and 51.8 Gy, respectively, were selected. Two SRSs blinded generated