ESTRO 2024 - Abstract Book

S5530

RTT - Patient care, preparation, immobilisation and IGRT verification protocols

ESTRO 2024

1305

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Impact of Abdominal Compression in SBRT for upper abdominal tumors

Lucia Angelini 1 , Mauro Loi 1 , Gabriele Simontacchi 1 , Beatrice Bettazzi 1 , Marco Banini 1 , Mariagrazia Carnevale 1 , Marianna Valzano 1 , Margherita Zani 2 , Livia Marrazzo 2 , Carlotta Becherini 1 , Daniela Greto 1 , Giulio Francolini 1 , Isacco Desideri 1 , Monica Mangoni 1 , Vanessa Di Cataldo 1 , Viola Salvestrini 1 , Pierluigi Bonomo 1 , Lorenzo Livi 1 1 Radiation Oncology, Azienda Ospedaliero Universitaria Careggi, Università di Firenze, Florence, Italy. 2 Medical Physics Unit, AOU Careggi, Florence, Italy

Purpose/Objective:

Stereotactic body radiotherapy (SBRT) has emerged as a valuable therapeutic modality for primary lesions (e.g. liver and pancreatic tumors) and for abdominal secondary tumors located in liver, pancreas and lymph nodes. However, it's important to note that the upper abdominal region is characterized by inherent motion, primarily driven by respiratory movements. This inherent motion can potentially compromise the precision and effectiveness of radiation therapy delivery. Abdominal compression (AC) has garnered attention as a potential solution to mitigate respiratory-induced motion and improve the outcomes of radiotherapy for abdominal metastases and primary liver/pancreatic tumors. This abstract aims to assess the impact of AC in SBRT in upper abdominal lesions.

Material/Methods:

We evaluated patients treated with SBRT to upper abdominal lesions. For all patients gender, age at diagnosis, primary tumor type, lesions site and number of lesions per patient were recorded. We included patients for whom both planning four-dimensional computed tomography (4DCT) with and without AC were available. Endovenous contrast medium was administered before the acquisition of planning CTs to enhance the visualization of the target lesions in both with and without AC CTs. For each lesion, gross tumor volume (GTV) and internal target volume (ITV) were manually delineated on both CTs, while planning target volume (PTV) was obtained by an isotropic expansion of 5mm. For each lesion, we calculated and compared, in the two plans with and without AC, the volume of PTV, and the shift from GTV to ITV in the cranio-caudal (CC), lateral-lateral (LL), and antero-posterior (AP) directions (respectively ΔPTV, ΔCC, ΔLL and ΔAP) (Fig.1). Wilcoxon test was performed on paired samples. Significance level of p=0.05 was applied