RÉSUMÉ
Objective To optimize the exposure parameters and reduce the irradiation dose level in infants and young children during digital radiography (DR) chest radiography under the premise of satisfied image quality.Methods The thoracic thickness of 100 patients were measured.Determined the aluminum equivalent of the thoraxes of the infants and young children by comparing the grayscale value and the aluminum step wedge.Another 100 infants and young children of experimental exposure were performed with the aluminum step wedge as a phantom,under AEC control,kV was the only variant to explore the optimal exposure parameters with dose monitor simultaneously.At last,clinical validation was performed.Images quality was compared with x2 test.The radiation dose of two groups was compared with t test.Results The maximum,minimum,average thoracic thickness and their correspondent aluminum equivalent were 13.5 and 2.3 cm,8.0 and 1.4 cm,(10.6 ± 1.3) and 2.0 cm,respectively.The average thoracic thickness of experimental group was (10.1 ± 2.2) cm.The range of entrance surface dose was 0.068-0.056 mGy while the tube voltage range was 55-65 kV.The exposure index range was 0.60-0.74.The visual inspection of aluminum step wedge was from grades 8 to 11 with satisfying image quality at lower radiation.The infant chest X-ray photography exposure parameters formula have been optimized,that was kV =thoracic thickness (cm) × 2 + 38 (constant),mAs (0.8-1.0) with SID =100 cm,without filter grid.Compare to the conventional parameters,the image quality of new method had no significant differences (P ＞ 0.05).The actual average entrance surface dose was (0.048 ± 0.007) mGy,lower than AEC group (0.066 ± 0.008) mGy.The difference was statistically significant (t =16.781,P ＜ 0.001).Conclusions The optimized formula kV =thoracic thickness (cm) ×2 + 38(constant),mAs (0.8-1.0) with SID =100 cm was credible for lowering the radiation exposure with good image quality for clinical diagnosis.
RÉSUMÉ
Objective To evaluate the difference of adaptive exposure dose in two digital X-ray imaging systems. Methods Resin phantom and contrast-detail test phantom were used on Cesium iodide and Gadolinium oxide sulfide plate imaging detector DR systems using difference exposure parameters. All entrance surface dose were recorded, Image quality index (IQFinv ) was calculated by CDRAD analysis software. The optimal exposure radiation dose was determined according to the sensitivity and IQFinv. Results There were no significant differences of entrance surface dose between two digital X-ray systems on two different exposure parameters with 70 kV ( P > 0. 05) , while there were significant differences with 125 kV(P < 0.05) . The maximum difference was 28. 57% . The mean IQFinv value of Cesium iodide detector DR and Gadolinium oxide sulfide detector DR with 125 kV and 70 kV were 4. 89 ±1. 01 and 2.47 ±0.25, 5. 10 ±1.05 and 2.38 ±0.43, respectively. There were significant diferences between the two systems under the same exposure parameters (t = 6. 509,10. 158, P < 0. 05). The optimal exposure dose ratio between Cesium iodide and Gadolinium oxide sulfide detector DR system was 1:2. Conclusion According to the IQFinv value, the adaptive exposure parameter can be adjusted to achieve good image quality with low radiation dose on different digital radiography systems.
RÉSUMÉ
Objective To explore the photographic parameter for CR image splicing of double total length lower extremities and the evaluation of clinical application. Methods The suitable X-ray exposure conditions for full-leg digital radiograph was chosen according to the application of FCR-5000 CR imaging system and the exposure conditions of CR in osseous system. Results Optimal tube voltage and milliamp-second of parameters for the full-length leg projection was acquired in terms of the distribution of spatial resolution under different parameters of exposure. Conclusion The exposure parameter of CR in full-leg image stitching should be based on the characteristics of CR imaging system and the results of experiment. It is important to choose the most appropriate exposure parameters to ensure image quality and reduce radiation dose on patients to provide veracious image data for clinical application with osteoarthritis of the knee.