A 70-year-old male patient received ticagrelor 90 mg twice daily and aspirin 100 mg once daily as dual antiplatelet therapy after operation for coronary stent implanting. On day 2 of treatment,he developed traces of blood in sputum. The hemoptysis became worse and times became more after that. On day 42,the patient developed massive hemoptysis about 100 ml. Ticagrelor was discontinued by himself. The patient then was given oxygen inhalation,expectorant drug and hemostatic agents. Anticoagulant therapy was adjusted for the combined use of clopidogrel 75 mg once daily and aspirin 100 mg once daily. On day 4 of the ticagrelor withdrawal,the amount of hemoptysis was obviously reduced. On day 7,the hemoptysis ceased.

A 70-year-old male patient received ticagrelor 90 mg twice daily and aspirin 100 mg once daily as dual antiplatelet therapy after operation for coronary stent implanting. On day 2 of treatment,he developed traces of blood in sputum. The hemoptysis became worse and times became more after that. On day 42,the patient developed massive hemoptysis about 100 ml. Ticagrelor was discontinued by himself. The patient then was given oxygen inhalation,expectorant drug and hemostatic agents. Anticoagulant therapy was adjusted for the combined use of clopidogrel 75 mg once daily and aspirin 100 mg once daily. On day 4 of the ticagrelor withdrawal,the amount of hemoptysis was obviously reduced. On day 7,the hemoptysis ceased.

Objective To analyze the distribution of image noise in low-dose chest CT scan and optimize the relative scanning parameters.Methods The CT images of the Chinese anthropomorphic chest phantom( CDP-1 C) were simulated into six groups of low-dose images with different noise indexs by using an image noise addition tool.The difference between the preset noise index and analog noise value was compared.The CT images of 20 volunteers were also simulated into nine groups of low dose scans with the tube currents of 10,30,50,80,100,120,150,180 and 240 mA.The noise values of images were recorded and analyzed.Results There was no statistical difference between the analog noise value and the noise index.The image noise of low-dose chest scan was increased with the decrease of tube current.The noise was increased quickly when the current was decreased from 50 to 30 mA ( F =24.09 - 40.79,P ＜ 0.05),but the noise increased slowly when the current decreased from 240 to 80 mA.There was no statistical difference between the noise of 80 mA group and that of 120 mA(P ＞ 0.05).Conclusions The noise addition tool can be used to evaluate the image noise of low-dose chest CT scan.Adoption of 80 mA in chest CT scan would result in low radiation dose without adding image noise.