S2872
RTT - RTT education, training, and advanced practice
ESTRO 2026
Amsterdam UMC, aiming for a fully RTT-only workflow—without daily physician presence during treatment. Material/Methods: A protocol was developed and RTTs were trained to perform all steps of daily MRI-guided non-adaptive treatment. The improved soft-tissue visualization on MRI enabled reduction of the CTV–PTV margin from 10 mm to 5 mm compared to the CBCT-linac protocol, and due to real-time gating and target tracking, no ITV was required. Patients received 15 fractions of 2.4 Gy (5 fractions per week), combined with weekly gemcitabine (1000mg/m2). Treatment times, workflow irregularities and physician support were recorded. Figure 1: Visibility pancreas lesions on CBCT versus MRI-images (MRIdian). Results: Since May 2024, 28 patients with a borderline resectable pancreatic tumor have been treated. For two patients, suspicious locoregional lymph nodes were included in the gross tumor volume (GTV). After the first three patients, RTTs independently performed the complete workflow. In four fractions, physician support was requested due to image matching challenges. For two patients with large day-to-day anatomical variation, the team (RTTs, physician, and physicist) jointly decided to apply online plan adaptation if necessary. Median treatment delivery time for the MRI-guided workflow was 16 minutes — shorter than the 17 minutes in CBCT workflow, despite being delivered in breath-hold. Furthermore, treatment times on the CBCT-linac varied considerably (SD 7:20 min), while MRI-guided treatments were more consistent across patients (SD 4:30 min). Conclusion: Daily MRI guided RTT-only workflow for pancreatic cancer is feasible and efficient. Superior soft-tissue visualization and real-time gating reduced margins with lower expected toxicity, while keeping treatment time short and precision high. The option to scale up to adaptive delivery if necessary added more flexibility for challenging anatomies. This workflow demonstrates that RTTs can safely take a leading role in delivering complex MRI-guided treatments. Keywords: pancreas, RTT only, MRI Digital Poster 3088 An audit of using lights instead of auditory cues for
doses and normalized to prescription Results:
166 prostate ART patients were reviewed: 78 RO-led and 88 RTT-led. Median (min,max) PSA at 12-months was 0.5 (0.01-10.20) in RO-led and 0.22 (0.01-6.60) RTT- led cohorts (p = 0.092), with no biochemical recurrence in either group at 12-months. G2+ urinary toxicity is summarized in Table 1, with increased incidence in the RT-led cohort only during RT (9% vs. 26%; p = 0.007). G2+ rectal toxicity was not significantly different between the cohorts during RT (0.6%), nor at 1-month (0.6%), 6-months (0.6%) or 12-months (1.2%). Mean PTV D95 coverage, Bladder 1cc and mean Urethra dose were all statistically significantly (p < 0.007) higher in the RO-cohort, but the magnitude of the differences was not clinically significant (0.99% vs 0.98%, 1.05% vs 1.02% and 1.06% vs 1.02%). Mean Rectum 1cc and D50 were similar in both cohorts. Conclusion: Acute G2+ GU toxicity was higher in the RTT-cohort, however the incidence at 12 months was comparable to the RO-cohort. GI toxicity remained low for both cohorts and neither group experienced a biochemical relapse. Although longer follow-up is necessary, this work suggests that there was little clinical difference in dosimetry, toxicity and outcomes as a result of adopting RTT-led MRL adaptive workflows for prostate ART Keywords: adaptive radiation therapy, RTT-led, prostate RT Daily MRI-guided radiotherapy for borderline resectable pancreatic tumors: feasibility and efficiency of a RTT-only workflow Sonja Verheijen, Nienke W. Weitkamp, Miguel A. Palacios, Omar Bohoudi, Anna M.E. Bruynzeel, Eva Versteijne Department of Radiation Oncology, Amsterdam UMC, Amsterdam, Netherlands Purpose/Objective: Radiotherapy for borderline resectable pancreatic cancer remains technically challenging. On conventional CBCT-linacs, poor soft-tissue visibility requires fiducials (figure 1), large target margins and expiration gating, resulting in long, complex treatments with side effects. To overcome these limitations, a MRI-guided protocol on the MRIdian MR- linac (ViewRay Systems) was implemented at Digital Poster 3075
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