<p>Thoracic aortic calcification (TAC) is a valuable predictor for assessing the risk of cardiovascular disease. However, there is limited evidence clarifying the specific determinants of TAC and its impact on the thoracic aortic diameter. A total of 446 patients who underwent lung nodule screening between August 2020 and April 2023 were included. TAC volume and thoracic aortic diameter were measured separately based on three predefined aortic segments on unenhanced computed tomography. Univariate analysis and regression models were used to identify independent determinants of TAC volume. Additionally, univariate and multivariate generalized linear regression analyses were conducted to explore the association between TAC volume and thoracic aortic diameter.&#xa0;The mean age of the patients was 55.6 years, and 45.5% were men. Using the absence of TAC as a reference, age, hypertension, smoking, elevated blood urea nitrogen, and increased circulating alkaline phosphatase levels were identified as independent risk factors for the presence of TAC (all P &lt; 0.05). Independent of age and other factors, total TAC volume was positively correlated with aortic diameter across three different thoracic aortic planes (all P &lt; 0.05). Notably, each TAC segment contributed differently to thoracic aortic dilation.&#xa0;Beyond traditional risk factors, serum alkaline phosphatase concentrations emerge as a novel predictor of TAC burden. Increased TAC volume leads to enlargement of thoracic aortic segments in a characteristic pattern, where an increased TAC volume in the lower aortic segment appears to drive the expansion of the upper aortic segment</p> Graphical abstract <p></p>