Lung Nodules Detection with Spiral CT:Experimental Study

Objective To investigate the factors that affect the detection rate by scanning a lung nodule model.Methods The lung and the thoracic cage were simulated with a roll bandage surrounded by a cyst filled with water.Flour,butter and paraffin wax were mixed together in a certain ratio to simulate lung nodules 10mm and 5mm in diameter that CT values ranging from -10 to 50Hu.Spiral CT scans were performed at different pitch (1,1.5,2).The images of the simulated nodules were combined with the CT images of a normal adult's lung.Three radiologists interpreted the images and the number of the nodules they detected including both the real ones and the false-positive ones were calculated to investigate weather there was any difference between different pitch group and different locations.Results The detection rate of the 10mm and 5mm nodules were 100% and 89.6% respectively.The detection rate of the 5mm nodules declined when large pitch was used.Conclusion The detection rate was affected by the pitch,nodule locations and the relation between the nodules and lung vessels.