Objective To investigate the value of dual-energy digital subtraction chest radiography in detection of small pulmonarynodules.Methods CT scanning,dual-energy digital subtraction chest radiographs and routine digital chest radiographs were obtainedrespectively from 27 consecutive oncology patients with pulmonary metastasis.The image quality of these two kinds of DR by quality control phantom of Kodak was compared. The images of dual-energy digital subtract radiographs and the routine digital radiography were analysedby two radiologists in biblind method and the detecting rate of pulmonary metastasis by both DR was compared based on the results CTscanning. Results The quality of dual-energy digital subtraction chest radiographs is equal to the routine one except the definition. The detectable rate of pulmonary nodules by dual-energy digital subtraction chest radiographs was 91.2%, by the routine DR was 85.0%. There was significant difference (P

Objective To investigate the optimal beam tube potential for amorphous silicon/cesium iodide flat panel digital chest radiography(indirect DR). Methods(1)60 healthy adults were undergone digital posteroanterior(PA) chest radiography at 80,100,150 kV respectively.The images quality of these three were compared by 5 independent observers.Several normal anatomy parts of the chest and the overall impression of the images were evaluated;(2)PA chest exposures of the anthropomorphic chest phantom to produce a constant ESDs(entrance skin doses) and exit dose were made using tube potential at 80,100,120,150 kV.The simulated chest nodules were scored. Results The quality of the adult chest radiography and the manifestation of the simulated chest nodules were superior at the lower tube voltages.The contrast of the images were best at 80 kV,while the appearance of the images look like that of the low potential radiography. Conclusion The optimal tube potential for chest DR is considered to be 80~100 kVp,while the high KV technique is no longer suitable for digital equipment.

Objective To Compare different methods of quantitative breast density measurement.Methods The study included sixty patients who underwent both mammography and breast MRI. The breast density was computed automatically on digital mammograms with R2 workstation. Two experienced radiologists read the mammograms and assessed the breast density with Wolfe and ACR classification respectively. Fuzzy C-means clustering algorithm (FCM) was used to assess breast density on MRI. Each assessment method was repeated after 2 weeks. Spearman and Pearson correlations of inter- and intrareader and intermodality were computed for density estimates. Results Inter- and intrareader correlation of Wolfe classification were 0. 74 and 0. 65, and they were 0. 74 and 0. 82 for ACR classification respectively.Correlation between Wolfe and ACR classification was 0. 77. High interreader correlation of 0. 98 and intrareader correlation of 0. 96 was observed with MR FCM measurement. And the correlation between digital mammograms and MRI was high in the assessment of breast density (r = 0. 81, P ＜ 0. 01). Conclusion High correlation of breast density estimates on digital mammograms and MRI FCM suggested the former could be used as a simple and accurate method.

Objective To assess the difference in detection of simulated chest nodules in different lung fields with dual-energy digital subtraction chest radiography by receive operating characteristic curve (ROC) analysis.Methods Dual-energy digital subtraction chest radiography was performed on 20 volunteers with simulated chest nodules. ROC analysis was made in the evaluation results on regular DR images and soft tissue images in different lung fields respectively.Results Az was greater on the soft tissue images than on the regular DR images in the superior lung fields and outer zone of middle lung fields. There were significant differences in the superior lung fields and outer zone of middle lung fields.Conclusion Dual-energy digital subtraction chest radiography is superior to regular DR image on detecting more chest nodule lesions, especially in the superior lung fields and outer zone of middle lung fields. So the two techniques should be united to diagnose.

Objective To evaluate the diagnostic accuracy of dual-energy subtraction chest digital radiography(DR) for detecting coronary artery calcification as compared with multi-detector row CT(MDCT).Methods 35 patients underwent dual-energy subtraction chest DR and ECG-gated MDCT for detection of coronary artery calcifications.The radiation dose of both DR and CT were noted respectively.Two senior and two junior radiologists reviewed the radiogram and assessed the calcifications in LAD,LCX and RCA totaling 105 vessels.ROC curve plotting were used for evaluation with CAC calculated from MDCT as the gold standard.Paired t test was calculated to compare the different radiation dose between DR and CT.Results 27.6% vessels(29/105) showed calcification on DR.The positive incidence in LAD was 48.5%(17/35),LCX 22.8%(8/35),and RCA 11.4%(4/35).The ROC area was 0.866,0.854,0.725,0.642 respectively,with a CAC score of more than 300.The average radiation dose was 0.469?0.22 mGy for DR,and 12.29?1.40 mGy for MDCT,showing significant differences.Conclusion Chest DR with dual energy subtraction can be used for screening of coronary artery calcification with relatively higher sensitivity for LAD.

ObjectiveTo conduct comprehensive assessment of internal and external cadmium exposure and health risks for Shanghai residents. MethodsCadmium levels in food samples were calculated by employing two dietary exposure assessment methods， total diet study （TDS） and food frequency questionnaire （FFQ）， to estimate the daily dietary cadmium exposure of Shanghai residents. The provisional tolerable monthly intake （PTMI） of cadmium set by joint food and agriculture organization/WHO expert committee on food additives （JECFA） was applied to evaluate the health risk. Differences in dietary and urinary cadmium were compared by rank-sum test among different regions， age， gender， smoking status， and BMI groups， and the association between internal and external cadmium exposure was investigated by correlation analysis. ResultsThe mean value of urinary cadmium for 1 300 respondents was 0.542 μg·L^-1. Urinary cadmium was higher in the population in central urban and urban-rural fringe areas than in the suburban area， higher in the older age group than in the younger age group， and higher in the smoking group than in the non-smoking group （all P<0.01）. The two assessment methods showed that the mean values of daily dietary cadmium exposure for Shanghai residents were 0.306 and 0.090 μg·kg^-1， with 3.69% and 0.85% of Shanghai residents exceeding the PTMI， respectively. Correlation analyses showed that dietary exposure to cadmium based on the FFQ method was positively correlated with the urinary cadmium level when smoking status， age， gender， and BMI were adjusted. ConclusionDietary exposure to cadmium of Shanghai residents is mainly derived from vegetables， aquatic products， cereals and potatoes， and is overall at a low-risk level. Dietary exposure assessment based on FFQ and risk monitoring data can effectively estimate long-term cadmium exposure.