ESTRO 2022 - Abstract Book

S1638

Abstract book

ESTRO 2022

significant 3.6%, 3.7% and 3.8% decrease respectively (p<0.01). The mean dose of heart was also decreased 1Gy on average (p=0.09). Between 2019 and 2021, 288 patients were treated with 2-field tangential breast conformal radiotherapy in 15fractions. 18 patients were treated with bra. There was no significant difference found on the acute skin reaction in the last treatment (p>0.05). No patient suffered from grade 3 or 4. Only 4 of patients with bra experienced grade 2 skin reaction at the last treatment.

Table 2: The acute radiation morbidity score distribution based on the weekly skin reaction assessment from 288 treatment patients

Conclusion The usage of bra lowered the radiation dose to both heart and ipsilateral lung without additional skin toxicity.

PO-1845 Surface guided adjuvant radiotherapy tattoo-free for breast cancer

R. Cuscito 1 , F. Fragnoli 1 , C. Indelicati 1 , G. Sanfrancesco 2 , C. De Pascali 1 , M. De Masi 1 , R. Parabita 1 , A. Aga 1 , F. Berloco 1 , L. Brana' 1 , A. Ciocia 1 , D. Curci 1 , G. Ladisa 1 , M. Nardiello 1 , D. Nardelli 1 , V. De Candia 1 , F. Gregucci 1 , A. Surgo 1 , R. Carbonara 1 , M.P. Cliliberti 1 , M. Caliandro 1 , I. Bonaparte 1 , A. Fiorentino 1 1 Miulli General Regional Hospital, Radiation Oncology, Acquaviva delle Fonti - Bari, Italy; 2 Miulli General Regional Hospital, Radiation Oncology, Miulli General Regional Hospital, Italy Purpose or Objective To test inter-fraction and intra-fraction variability of patients’ position in women with breast cancer (BC) that received radiation therapy (RT) using a tattoo-free treatment approach guided by a system of Surface Guided RT (SGRT). Materials and Methods Patients with BC received lumpectomy + adjuvant hypofractionated whole breast RT with simultaneous integrated boost on tumor bed for a total dose respectively of 40.5Gy and 48Gy in 15 fractions. During simulation procedures, all patients were immobilized in a supine position and underwent to a planning CT (2 mm slide thickness) without skin tattoo using a system of SGRT (Optical Surface Monitor System AlignRT®) to register and verify patients’ position. An expansion of 6mm in the transverse direction and 8mm in cranial–caudal direction was applied from CTV to PTV. The treatment was delivered using an FFF-VMAT technique. For each treatment session, match values of all 3 translational and 3 rotational axes were recorded. To evaluate inter-fraction variability, daily portal images were performed, revising setup treatment position, and acquiring data. To evaluate intra-fraction variations, SGRT was applied, acquiring data regarding final patient’s position at the end of RT. Data regarding acute side effects were collected weekly during RT and at the end of treatment according to RTOG radiation morbidity scoring system. Results Between 01/2021-04/2021, a total of 375 treatment sessions were analyzed in 25 women. Clinical data were summarized in Table 1. Inter-fraction mean values (±SD) (IC95%) were as follow: longitudinally 2.2mm (±1.6) (2-2.4), laterally 1.4mm (±1.1) (1.2-1.5), vertically 1.8mm (±1.5) (1.6-1,9), roll 0.0° (±0.3) (0.03-0.1), pitch 0.8° (±0.6°) (0.8-0.9), yaw 0.67° (±0.53°) (0.6-0.7). Intra-fraction mean values (±SD) (IC95%) were: longitudinally 0.12mm (±0.11mm) (0.1-0.13), laterally 0.07mm (±0.07mm) (0.06-0.08), vertically 0.12mm (±0.12mm) (0.1-0.13), roll 0.33° (±0.34°) (0.28-0.37), pitch 0.43° (±0.49°) (0.36-0.49), yaw 0.35° (±0.44°) (0.29-0.4). Median and IQR values were showed in Figure 1. All patients completed their treatment. G0 acute skin toxicity was recorded in 13 (52%) cases and G1 in 12 (48%) cases. No skin toxicity ≥ 2 was observed or other types of side effects. Conclusion The analysis shows that the SGRT-guided tattoo-free approach in breast RT is a reproducible and safe treatment suggesting that radiological imaging could be reduced to verify treatment patients’ position.

PO-1846 Implementation of a Surface Guide Radiotherapy (SGRT) system a Spain Multicenter Experience.

D. gonsalves 1 , E. Lopez 1 , P. Garcia 2 , L. Fernandez 3 , A. Carreras 4 , M. Perez 5 , L. Diaz 6 , F. Gongora 7

1 Genesis Care, Radiation Oncology, Madrid, Spain; 2 Genesis Care, Radiotherapy Technician , Madrid, Spain; 3 Genesis Care, Radiotherapy Technician, Malaga, Spain; 4 GenesisCare, Radiotherapy Technician, Barcelona, Spain; 5 Genesis Care, Radiotherapy Technician , Alicante, Spain; 6 GenesisCare, Radiotherapy Technician , Madrid, Spain; 7 GenesisCare, Radiation Physics, Malaga, Spain