ESTRO 2022 - Abstract Book

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Abstract book

ESTRO 2022

H&N phantoms (216 TLDs) were evaluated. The maximum root-mean-square (RMS) errors in the MLCs, jaws, collimators, and gantry angles during treatment delivery were also analyzed for correlations with delivered dose. Results Compared to the average dose deviation (TPS vs TLD) of 2.4% (max = 11.6%) for the H&N phantom, and 2.6% (max = 9.6%) for the lung phantom, the dose perturbations predicted by log files were relatively small. The delivery errors ranged between -0.73% to 1.20% for the H&N phantom. Delivery played an even smaller role for the lung, which had a range of - 0.75% to 0.17%. Minimal correlation between dose deviation and delivery error was found: r = .13 (p = .04) for H&N, r = .03 (p = .7) for lung. Delivered dose was not strongly correlated with jaw, collimator, or gantry angle maximum RMS errors (-0.2 < r < ± 0.2). MLC RMS error results for the two Varian machine classes: Truebeam (including Edge) and the older Base model (iX, EX & Trilogy), showed that the Truebeam machine MLCs performed better among both phantoms. This difference, however, was not great enough to influence phantom irradiation accuracy (Fig. 1).

Conclusion Analysis of IROC H&N and lung phantom delivery log files showed minimal contributions to the total TLD dose deviations seen among these phantoms. This indicates that few delivery errors are present, or that these errors are not properly captured within the delivery log files. Future work will investigate the ability of this delivery data to catch/identify irradiation errors in IROC phantoms.

Poster Discussion: 18: Breast

PD-0739 Neoadjuvant chemo-radiotherapy in early breast cancer patients:long-term results of a phase II trial

J. Diane 1 , P. Loap 2 , J. Pierga 3 , F. Laki 4 , A. Salomon 5 , Y. Kirova 6 , A. Fourquet 6

1 Institut Curie, Department of Radiation Oncology, paris, France; 2 institut Curie, Department of Radiation Oncology, paris, France; 3 Institut Curie, Department of Medical Oncology, Paris, France; 4 Institut Curie, Department of Surgical Oncology, Paris, France; 5 Institut Curie, Department of Pathology, Paris, France; 6 Institut Curie, Department of Radiation Oncology, Paris, France Purpose or Objective Neoadjuvant concurrent radiochemotherapy makes it possible to increase the breast conservation rate. This study reports the long term outcome of this treatment. Materials and Methods From 2001 to 2003, 59 women with T 2-3 N 0-2 M 0 invasive breast cancer (BC) not amenable to upfront breast conserving treatment (BCS) were included in this prospective, non-randomized phase II study. Chemotherapy (CT) consisted of 4 cycles of continuous 5-FU infusion and Vinorelbine. Starting concurrently with the second CT cycle, normofractionated RT was delivered to the breast and LN. Breast surgery was then performed. Results Median follow-up (FU) was 13 years [3–18]. BCS was performed in 41 (69%) patients, and mastectomy in 18 patients, with pathological complete response rate of 27%. Overall and distant-disease free survivals rates at 13 years were 70.9% [95% CI 59.6–84.2] and 71.5% [95% CI 60.5-84.5] respectively . Loco regional and local controls rates were 83.4% [95% CI 73.2–95.0]