The effect of intravenous contrast agent on lung cancer treatment

OBJECTIVES: The effects of intravenous contrast agent on two different 3D conformal radiotherapy treatment planning systems with different algorithms were studied. METHODS: Contrast-enhanced and non-contrast computed tomography (CT) data sets belonging to a lung cancer patients were studied with XiO (CMS) and Eclipse (Varian). The convolution, Clarkson, fast superposition and standard superposition algorithms of XiO and modified Batho, Batho power law and equivalent TAR algorithms of Eclipse were studied with different field sizes and angles. The correlations between the changes of monitor units (MU) with both field sizes and total Hounsfield unit (HU) changes were investigated. RESULTS: The mean MU change was +1.3% (-1% to +3.2%). There was a strong linear correlation between HU and MU changes of XiO algorithms (r2=0.79) and no correlation in Eclipse. CONCLUSION: Although 3D planning of the lung could be done with contrasted CT dataset, according to our findings, it should ideally be planned with non-contrast CT fusing with created volumes in contrasted ones.