Influence of different combinations of additional filters and tube voltage and tube current on crib side X-ray image quality and radiation dose

Abstract

Objective To measure the body surface dose under different confinations of additional filters, tube voltage and tube current and discuss the lowest amount of different additional filters, tube voltage and tube current combination for crib side X-ray radiation dose while the quality of the image is guaranteed. Methods Japan Shimadzu wireless tablet mobile DR machine and Dutch Artinis CDRAD 2.0 phantom were used. The tube voltage and tube current for children′s crib side X-ray normal work were 50 kV and 1.40 mAs to get the image quality figure inverse (IQFInv), respectively. Totally four filter combinations of 1 mm Al, 2 mm Al, 1+ 2 mm Al and 0.3 mm Cu were added to the opening of collimator system by mobile DR machine. Phantom was shot by respectively combination of 50, 66, 83 and 100 kV tube voltages and different tube currents. All images to get the IQFInv value, Pearson correlation and regression analysis of the influence of tube voltage and current on IQFInv value were analyzed. The IQFInv value of the additional filter corresponds to the image quality of normal work. The combination of the additional filter with the tube voltage and the tube current was also found. Swedish RTI Barracuda diagnostic level dosimeter was used to measure the entrance surface dose of these combinations after filtration, 20 times for each group. Results Comparisons among different filters, tube voltage and tube current combination with quality of daily work images: the tube voltage was positively correlated with IQFInv value in the test range(r=0.49, P<0.05), and tube current was positively correlated with IQFInv value (r=0.36, P<0.05). As the additional filters increase, it required greater tube current to acquire the desired value of images. Meanwhile, greater additional filters would increase the difference of IQFInv of tube voltage at each level. Comparisons among different filters, tube voltage and tube current combination with daily shooting dose, and after using additional filters, entrance surface dose changed from(30.58±0.21)to(10.49±0.09)μGy. There is a significant difference between each group (t=-15.306-514.585, P<0.05). All additional filters effectively reduced entrance surface dose. Meanwhile, as the filter and tube voltage increased, entrance surface dose showed a more significant reduction. However, when the tube voltage exceeded 83 kV, all entrance surface dose of additional filters showed an increasing trend. Conclusions Additional filter is an effective method to reduce the crib side X-ray entrance surface dose. Under the premise of ensuring image quality, additional filter with high atomic number and second high kilovolt tube voltage with paired tube current is the best condition for crib side X-ray. Key words: Child; Preschool; Radiography; Radiation dosage; Phantoms, Imaging