ESTRO 2023 - Abstract Book

S1823

Digital Posters

ESTRO 2023

The risk for chest wall pain (CWP) in lung SBRT is positively related to several ribs’ dose-volume parameters: D0.5cc, D1cc, D2cc, D5cc and V30 (Ma et al, 2019). This study aimed to determine the relationship between any DVH parameter of the ribs and CWP incidence in a single-institution lung SBRT series. Materials and Methods We reviewed medical records to identify CWP in a series of 54 lung patients treated with a prescription dose of 60 Gy in 5 or 8 fractions, using SBRT at our institution between 2012 and 2017. We calculated the ribs’ mean Vx and Dx DVHs and performed heteroscedastic t-tests at each point (bin s of 0.06 Gy and 0.05 % respectively) to evaluate the significance (p<0.01) of the differences between patients with and without CWP. We performed all calculations with the Acuros XB algorithm implemented in the Eclipse treatment planning system (Varian Medical Systems; Palo Alto, CA, USA), reporting dose-to-medium. Results We observed CWP in 15 patients. Fig.1 shows that patients with CWP had slightly lower Vx values in the low-dose region, while this trend reversed in the intermediate and high-dose regions. Fig. 2 shows that patients with CWP had higher Dx values, especially for high dose volumes. Near-maximum rib doses showed the highest correlation, as expected. Although our findings are in accordance with the literature, none of these differences was statistically significant, probably due to a lack of statistical power.