This paper compares the performance of several single and system estimators of a two equation simultaneous model with unbalanced panel data. The Monte Carlo design varies the degree of unbalancedness in the data and the variance components ratio due to the individual effects. One useful result for applied researchers is that the feasible error components 2SLS and 3SLS procedures based on simple ANOVA type estimators of the variance components perform well with incomplete panels and are recommended in practice.

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BackgroundThe physician's hands are close to the X-ray field in C-arm fluoroscopy-guided pain interventions. We prospectively investigated the radiation attenuation of Proguard RR-2 gloves.MethodsIn 100 cases, the effective doses (EDs) of two dosimeters without a radiation-reducing glove were collected. EDs from the two dosimeters-one dosimeter wrapped with a glove and the other dosimeter without a glove- were also measured at the side of the table (Group 1, 140 cases) and at a location 20 cm away from the side of the table (Group 2, 120 cases). Mean differences such as age, height, weight, radiation absorbed dose (RAD), exposure time, ED, and ratio of EDs were analyzed.ResultsIn the EDs of two dosimeters without gloves, there were no significant differences (39.0 ± 36.3 µSv vs. 38.8 ± 36.4 µSv) (P = 0.578). The RAD (192.0 ± 182.0 radcm2) in Group 2 was higher than that (132.3 ± 103.5 radcm2) in Group 1 (P = 0.002). The ED (33.3 ± 30.9 µSv) of the dosimeter without a glove in Group 1 was higher than that (12.3 ± 8.8 µSv) in Group 2 (P < 0.001). The ED (24.4 ± 22.4 µSv) of the dosimeter wrapped with a glove in Group 1 was higher than that (9.2 ± 6.8 µSv) in Group 2 (P < 0.001). No significant differences were noted in the ratio of EDs (73.5 ± 6.7% vs. 74.2 ± 9.3%, P = 0.469) between Group 1 and Group 2.ConclusionsProguard RR-2 gloves have a radiation attenuation effect of 25.8-26.5%. The radiation attenuation is not significantly different by intensity of scatter radiation or the different RADs of C-arm fluoroscopy.

BackgroundAlthough a physician may be the nearest to the radiation source during C-arm fluoroscope-guided interventions, the radiographer is also near the fluoroscope. We prospectively investigated the radiation exposure of radiographers relative to their location.MethodsThe effective dose (ED) was measured with a digital dosimeter on the radiographers' left chest and the side of the table. We observed the location of the radiographers in each procedure related to the mobile support structure of the fluoroscope (Groups A, M and P). Data about age, height, weight, sex, exposure time, radiation absorbed dose (RAD), and the ED at the radiographer's chest and the side of the table was collected.ResultsThere were 51 cases for Group A, 116 cases for Group M and 144 cases for Group P. No significant differences were noted in the demographic data such as age, height, weight, and male to female ratio, and exposure time, RAD and ED at the side of the table. Group P had the lowest ED (0.5 ± 0.8 µSv) of all the groups (Group A, 1.6 ± 2.3 µSv; Group M, 1.3 ± 1.9 µSv; P < 0.001). The ED ratio (ED on the radiographer's chest/ED at the side of the table) of Group A was the highest, and the ED radio of Group P was the lowest of all the groups (Group A, 12.2 ± 21.5%; Group M, 5.7 ± 6.5%; Group P, 2.5 ± 6.7%; P < 0.001). ConclusionsRadiographers can easily reduce their radiation exposure by changing their position. Two steps behind the mobile support structure can effectively decrease the exposure of radiographers by about 80%.

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