ESTRO 2024 - Abstract Book

S2357

Clinical - Urology

ESTRO 2024

1) Huddart RA et al and the SPARE trial Management Group. Life and death of spare (Selective bladder preservation or radical excision): reflections on why the spare trial close. BJU Int 2010; 106(6):753-5.

2) James ND et al. BC2001 Investigators. Radiotherapy with or without chemotherapy in muscle invasive bladder cancer. New Eng J Med. 2012 Apr 19; 366(16):1477-98.

3) Hoskin PJ et al. Radiotherapy with concurrent carbogen in bladder carcinoma. J Clin Oncol 2010 Nov 20; 28(33): 4912-8.

4) El-Sayed MI, El-Azab AS, El-Gammal MA. Quality of life in bladder cancer patients treated with radical cystectomy and orthotopic reconstruction versus bladder preservation protocol. J Cancer Sci Ther 2013; 5:190-193.

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Revolutionizing prostate stereotactic treatment with a novel simulation-free approach using MR-Linac

Jeremiah de Leon 1 , Madeline Carr 1,2 , Urszula Jelen 1 , David Crawford 1 , Maddison Picton 1 , Charles Tran 1 , Laura McKenzie 1 , Michael Jameson 1,2,3 , Vikneswary Batumalai 1,3 1 GenesisCare, Radiation Oncology, Sydney, Australia. 2 University of Wollongong, Centre for Medical Radiation Physics, Wollongong, Australia. 3 University of New South Wales, School of Clinical Medicine, Sydney, Australia

Purpose/Objective:

The removal of simulation computed tomography (CT) scans from standard radiotherapy treatment workflows can reduce patient burden and lessen demands on departmental resources [1]. The adaptive capabilities of the MR Linac is well suited to a simulation-free workflow [2]. In this novel work, we report the feasibility of using a simulation-free workflow on the MR-Linac for the first 15 prostate cancer patients treated with stereotactic body radiotherapy (SBRT).

Material/Methods:

The initial 15 patients referred to our centre, who had a prostate specific membrane antigen positron emission tomography/CT (PSMA-PET/CT) scan as part of their standard diagnostic workup, were eligible for treatment using the simulation-free workflow. Thirteen patients underwent rectal spacing in the time between the PSMA-PET/CT and fraction 1. A reference plan was generated using the PSMA-PET/CT scan, with priority given to organs at risk (OAR) constraints. The prescribed doses for the clinical target volume (CTV) were 38Gy (n=1), 40Gy (n=3) and 40Gy with a boost to 45Gy to the dominant intraprostatic lesion (n=11). The planning target volume (PTV) was prescribed 36.25Gy for all patients. A forced electron density override was applied based on previously determined population based values [3] for plan generation. At fraction 1, the PSMA-PET/CT reference plan was deformably registered to