S2696
RTT - Patient preparation, immobilisation, and verification protocols
ESTRO 2026
breast cancer at a high volume cancer center serving a diverse population who underwent DIBH assessment at the time of CT simulation. Material/Methods: Following ethics approval all patients who received adjuvant radiation for left breast invasive ductal cancer and ductal carcinoma in situ between January 1st and December 31st 2024 were included in this study. Included were patients receiving partial breast, whole breast and regional nodal radiation. Patient age, ethnicity, primary language, comorbidities affecting breathing and ability to do DIBH was recorded. Breathing traces were reviewed in the Varian Real-time Position Management (RPM) system to determine the reasons for failures in DIBH assessment. Results: The average age for the study population was 62.5 years (32-94 years). In our population, 37.1% (85/229) of patients were ineligible for DIBH and were therefore treated free breathing. 2.6% (n=6) of patients required shell immobilization and thus did not undergo DIBH assessment and 2.2% (n=5) of patients were flagged as possibly not being candidates for DIBH by the radiation oncologist. For patients who failed DIBH assessment, 38.0% (n=30) were non English speaking and 54.4 % (n=43) were identified as being non-white. 51.9% (n=41) of patients had no major medical comorbidities, while 8.9% (n=7) had respiratory disease affecting respiratory excursion. The majority of patients (51.5%) failed DIBH assessment due to two or more reasons. Reasons include inability to breath- hold for 25 seconds (35.9%), inability to displace the block by 1 cm (26.0%), unsteady breath-holds (13.7%), language barrier (6.1%), hearing difficulties (4.9%), other medical conditions (7.6%) and other unknown reasons due to lack of documentation (5.8%). Conclusion: Over one third of our patients were not eligible for DIBH treatment. This study examined modifiable factors for which intervention through a quality improvement program is possible. The use of a primary language interpreter, pre-CT simulation education and coaching in primary language and wearing of hearing aids are proposed interventions to improve the uptake of DIBH in our diverse population. References: 1.Deep inspiration breath-hold technique and IMRT as methods to reduce volume of heart and liver in breast radiotherapy Sidhu, K et al. International Journal of Radiation Oncology, Biology, Physics, Volume 54, Issue 2, 158 – 1592.Risk of ischemic heart disease in women after radiotherapy for breast cancer Darby, S.C. ∙ Ewertz, M. ∙ McGale, P N Engl J Med. 2013; 368:987-998 Keywords: deep inspiration breath hold
were minimal and not significantly different between cohorts. Absolute error analysis showed superior vertical (p=0.031) and longitudinal (p=0.013) accuracy for tattoos, while SGRT achieved significantly better lateral accuracy (p=0.004). Composite analysis demonstrated no significant differences in overall translational (p=0.073) or rotational (p=0.580) accuracy. Importantly, SGRT reduced median PFT from 13.9 to 10.9 minutes, representing a clinically meaningful efficiency gain. Conclusion: Conclusions:This retrospective study demonstrates that SGRT with ExacTrac Dynamic provides setup accuracy comparable to conventional tattoos while significantly improving reproducibility, efficiency, and patient experience by eliminating permanent skin markings. Prospective studies under standardized conditions are warranted to further validate these findings and assess long-term clinical outcomes. References: References:1. Freislederer, P., Kügele, M., Öllers, M., Swinnen, A., Sauer, T.-O., Bert, C. (2015). Recent advances in surface guided radiation therapy. Radiation Oncology, 10, 240.2. Fassi, A., Ivaldi, G., Meaglia, I., et al. (2016). Surface-guided radiotherapy for patient positioning in breast cancer radiotherapy: accuracy and advantages. Journal of Applied Clinical Medical Physics, 17(6), 124–136.3. Padilla, L., Kang, H., Colussi, V., et al. (2021). Clinical experience using surface guided radiation therapy (SGRT) for breast cancer patients with deep inspiration breath hold(DIBH).Journal of Radiotherapy in Practice, 20(3), 267–274. Keywords: SGRT, ExactTrac Dynamic, breast cancer Deep inspiration breath hold in patients with left sided breast cancer in a diverse population: causes for failure in DIBH assessment Dylan Narinesingh 1,2 , Vicky Huang 1,2 1 Radiation Oncology, BC Cancer, Surrey, Canada. 2 Surgery, UBC, Vancouver, Canada Purpose/Objective: The single most significant treatment technique for decreasing normal tissue dose is deep inspiration breath hold (DIBH) in breast radiotherapy (1). Darby et al, reported that exposure of the heart to ionizing Digital Poster 219 radiation during radiotherapy for breast cancer increases the subsequent rate of ischemic heart disease which begins within a few years after exposure, and continues for at least 20 years (2). This study examines the causes for DIBH assessment failure for women having adjuvant radiation for left
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