S2737
RTT - Patient preparation, immobilisation, and verification protocols
ESTRO 2026
Purpose/Objective: SGRT is becoming progressively used in radiotherapy with different purposes. However, the use of a complete SGRT-based tattoo-less workflow still leaves doubts in part of the clinical community. Before implementing a tattoo-less workflow for breast patients in our department we decided to quantify the advantages in using SGRT for setup. Our data can be useful to other centers with the aim of implementing an SGRT-based setup workflow. Material/Methods: Two groups of nine breast patients > 60 years old, each composed of four that underwent the fast- forward protocol (i.e., 26 Gy in 5 fractions without boost) and five that underwent the conventional protocol (i.e., 40.5 Gy to the breast and 48 Gy as simultaneously boost, in 15 fractions), were irradiated with a Varian TrueBeam linac in tangential 3DCRT technique. Radiotherapy was performed in supine position, using a breast board immobilization system. The study group followed a completely tattoo-less protocol adjusting the position of the patients on the couch with VisionRT/AlignRT in 6DoF. Patients belonging to the control group were positioned on the couch through alignment of three tattoos (two laterals and one central in the ideal plan of the nipples) with the linac external lasers and subsequent application of delta couch shifts to reach the treatment isocenter. In both groups, for each fraction, a total of MV-kV orthogonal image pair were acquired and compared with DRRs. The 6DoF residual set-up variations between MV-KV imaging and planning imaging were recorded along with the time interval between the entrance of the patient in the treatment room and the exit of the RTTs after complete patient positioning. Set-up time and differences in translations and rotations were analyzed with an unequal variance Bonferroni corrected t-test, along with the magnitude of the translational setup variations. Results: Longitudinal and lateral translations variations between the tattoo-less and the control groups were non-significant (p>0.008), while vertical and associated magnitude variations were statistically significant (p=0.007 and p<0.001, respectively). Regarding rotations the main differences between groups were obtained for pitch (p=0.018). Setup time was significantly lower in the tattoo-less group (p=0.028). The reported box plots of translations magnitude and setup time distributions over treatment fractions clearly show an advantage in the reduction of both of them in tattoo-less group.
Conclusion: With regards to participant comfort, imaging on an MR Linac is well tolerated at similar durations to treatment. Further work assessing the impact of immobilisation on accuracy for treatment is required. References: 1. PRIMER: Development of Daily Online Magnetic Resonance Imaging for Magnetic Resonance Image Guided Radiotherapy [Online] Available at: https://clinicaltrials.gov/study/NCT02973828?term=NC T02973828&rank=1, accessed 11 November 2025. Keywords: immobilisation, MR Linac Implementing a tattoo-less workflow for breast patients: an institutional quantitative analysis Stefania Linsalata 1 , Laura Belluomini 2 , Sabrina Montrone 3 , Erica Piccioni 3 , Caterina Colosimo 3 , Martina Cantarella 3 , Taiusha Fuentes 3 , Noemi Giannini 3 , Cecilia Trippa 3 , Katerina Kharkauskaya 3 , Paola Puccini 3 , Patrizio Barca 1 , Antonio Claudio Traino 1 , Fabiola Paiar 3 1 Medical Physics Unit, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy. 2 School for Medical Radiology Technicians, University of Pisa, Pisa, Italy. 3 Radiotherapy Unit, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy Digital Poster 3148
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