Experimental Study of Detection of Nodules Showing Ground-Glass Opacity and Radiation Dose by Using Anthropomorphic Chest Phantom

Abstract

The purpose of this study was to compare chest digital tomosynthesis (DTS) and multidetector computed tomography (MDCT) for the detection of pulmonary ground-glass opacity (GGO) nodules and estimation of radiation dose using an anthropomorphic chest phantom and simulated nodules. A male anthropomorphic chest phantom equipped with thermoluminescent dosimeters and simulated pulmonary nodules showing GGO was scanned by MDCT and DTS. The organic radiation doses were recorded and converted into effective doses. The density, diameter, and position of pulmonary nodules were reviewed; and the sensitivities of nodule detection were compared using the Fisher exact test. The radiation dose levels of DTS and MDCT were compared using paired t tests. The sensitivities of nodule detection by DTS and MDCT were 60% and 80%, respectively (P < 0.05), whereas the sensitivities of detection of -630-Hounsfield unit (HU) GGO nodules were 73.3% and 86.7%, respectively (P > 0.05), and the detection sensitivities of 5- and 8-mm diameter -800 HU GGO nodules were 33.3% and 58.3%, respectively (P < 0.05). The effective doses of DTS and MDCT were 0.65 and 7.71 mSv, respectively, and the mean effective dose of DTS for the chest was 91.6% lower than that of MDCT. Multidetector computed tomography is preferable to DTS for the detection of GGO pulmonary nodules. Although the detection sensitivities of DTS and MDCT were similar for the nodules with a density of -630 HU, the detection sensitivity of MDCT was significantly superior to that of DTS for the 5- and 8-mm nodules with a density of -800 HU. The mean effective dose of DTS to the chest was significantly lower than that of MDCT.