S2914
RTT- RTT operational practice and workflow innovations
ESTRO 2026
This project aimed to optimize the prostate SGRT workflow using lean management principles, emphasizing multidisciplinary collaboration between RTTs, physicists, and quality managers. A brownpaper session identified two key challenges: reference surface cropping and pitch/roll overrides. Three studies addressed these: (1) development of an automatic cropping method, (2) retrospective comparison of SGRT versus markerline positioning, and (3) evaluation of C-RAD’s predictive accuracy for pitch, roll, and rotation. These studies guided targeted workflow improvements. Material/Methods: Retrospective analyses used the C-RAD database of 29 prostate cancer patients treated with SGRT (230 fractions) and 25 patients treated using markerlines (150 fractions). An in-house script calculated differences between C-RAD surface positioning and online CBCT matching. Automatic cropping of reference surfaces was implemented in RayStation and validated with test groups of 10 patients. Bladder contours were auto-generated on CBCTs using RayStation’s segmentation tools to assess the impact of bladder filling on pitch alignment differences between surface-based positioning and CBCT matching. Results: SGRT-based positioning showed improved accuracy compared to markerlines, especially in the longitudinal direction (mean: 0.14 mm vs. -2.34 mm; stdev: 3.1 mm vs. 18.3 mm) and laterally, where variability was reduced (stdev: 1.5 mm vs. 3.5 mm). Vertical deviations were comparable for both methods.Figures 1 and 2 show cropping comparison. Manual and automatic cropping achieved similar translational accuracy, though rotational variability was slightly higher with auto-crop. Non-cropped surfaces performed comparably and showed slightly better pitch values, suggesting workflow simplification.Correlation analysis revealed strong agreement between C-RAD and CBCT for roll (r = 0.63) and rotation (r = -0.61), but poor predictive accuracy for pitch (r = 0.10). A moderate correlation between pitch deviations and bladder filling (r = 0.23) suggests that bladder volume changes partly explain pitch variability.
when the bladder volume was larger during the treatment. In this case, the median volume receiving 45.8 Gy increases by 10 cc.
Conclusion: Adaptive treatment enables margin reduction while maintaining target coverage and minimizing irradiated volume. OAR exposure remains influenced by bladder volume variations between planning and treatment. References: Dees-Ribbers, et al. (2014). Inter-and intra-fractional bladder motion during radiotherapy for bladder cancer: a comparison of full and empty bladders.Radiotherapy and Oncology,113(2), 254- 259.Åström, Lina M., et al. "Online adaptive radiotherapy of urinary bladder cancer with full re- optimization to the anatomy of the day: Initial experience and dosimetric benefits." Radiotherapy and Oncology 171 (2022): 37-42. Keywords: Bladder adaptative radiotherapy
Digital Poster 1940
Optimizing Prostate SGRT Workflow Using Lean Principles: Improving Efficiency in Clinical Practice Matthias Hermans 1 , An Sprangers 1 , Ali Dabach 1 , Jana Decraene 1 , Hannelore Van Dyck 1 , Jolien Cleijman 2 , Klaartje Steensels 2 , Dirk Verellen 1 1 Physics, Iridium, Antwerp, Belgium. 2 Radiotherapy, Iridium, Antwerp, Belgium
Purpose/Objective:
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