Room: ePoster Forums
Purpose: To study the variation of dose-assessment parameters on the interatrial septum (IAS) and interventricular septum (IVS) in different phases during cardiac cycle, and investigate the effect of heartbeat on the dose-assessment of IAS and IVS.
Methods: 20 patients were enrolled. All patients underwent electrocardiogram-gated four-dimensional computed tomography (4D-CT) scanning with inspiration breath-hold. CT images were sorted into 20 phases with every 5% interval in the cardiac cycle. Then, contoured the IAS and IVS in all phases. The treatment plan for esophageal cancer were designed on 0% phase CT images, and then planned dose were recalculated in 20 phases. The dose distribution in 0%, end-systolic and end-diastolic phase were named as Dose-0%, Dose-ES, Dose-ED, respectively. The dose distribution of remaining 19 phases were deformed to 0% phase images, and then calculated accumulation dose, named Dose-4D. The dose-assessment parameters on IAS and IVS were compared among Dose-0%, Dose-ES, Dose-ED, Dose-4D. The dose-assessment parameters on IAS and IVS were Dmean, V20, V30, V40; Dmean, V10, V20, V30, respectively.
Results: (1) The V20 and V30 of IAS were similar in of Dose-0%, Dose-ES, Dose-ED, Dose-4D, and the variation range were (92.59-93.35)%, (88.31-90.22)%, respectively. The difference were not statistically significant (P>0.05). (2) The Dmean and V40 of IAS in Dose-ED were higher than that in remaining phases, and the difference were statistically significant (P<0.05). (3) The dose-volume parameters of IVS in Dose-0% were similar with Dose-4D. The differences of dose-volume parameters on IVS were statistically significant in Dose-0%, Dose-ES, Dose-ED, Dose-4D (P<0.05).
Conclusion: The V20 and V30 of IAS were stable indicators during the cardiac cycle, which could be used for dose-assessment on IAS and the prediction of radiation damage. The accurate dose-assessment of IVS must depended on the dose-volume parameters in accumulation dose.