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Lung cancer is the leading cause of cancer death worldwide and the early diagnosis of lung cancer has recently become more important. For early screening lung cancer, computed tomography (CT) has been used as a gold standard for early diagnosis of lung cancer [1]. The major advantage of CT is that it is not susceptible to the problem of misdiagnosis caused by anatomical overlapping while CT has extremely high radiation dose and cost compared to chest radiography.
Chest digital tomosynthesis (CDT) is a recently introduced new modality for lung cancer screening with relatively low
radiation dose compared to CT [2] and also showing high sensitivity and specificity to prevent anatomical overlapping
occurred in chest radiography. Dual energy material decomposition method has been proposed for better detection of pulmonary nodules as means of reducing the anatomical noise [3]. In this study, possibility of material decomposition in CDT was tested by simulation study and actual experiment using prototype CDT. Furthermore organ absorbed dose and effective dose were compared with single energy CDT. The Gate v6 (Geant4 application for tomographic emission), and
TASMIP (Tungsten anode spectral model using the interpolating polynomial) code were used for simulation study and
simulated cylinder shape phantom consisted of 4 inner beads which were filled with spine, rib, muscle and lung
equivalent materials. The patient dose was estimated by PCXMC 1.5 Monte Carlo simulation tool [4]. The tomosynthesis scan was performed with a linear movement and 21 projection images were obtained over 30 degree of angular range with 1.5° degree of angular interval. The proto type CDT system has same geometry with simulation study and composed of E7869X (Toshiba, Japan) x-ray tube and FDX3543RPW (Toshiba, Japan) detector. The result images
showed that reconstructed with dual energy clearly visualize lung filed by removing unnecessary bony structure. Furthermore, dual energy CDT could enhance spine bone hidden by heart effectively. The effective dose in dual energy
CDT was slightly higher than single energy CDT, while only 10% of average thoracic CT [5]. Dual energy tomosynthesis is a new technique; therefore, there is little guidance for its integration into the clinical practice and this
study can be used to improve diagnosis efficiency of lung field screening using CDT
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