RESUMEN
PURPOSE: The aim of our study was to compare single-energy (SECT) and dual-energy (DECT) abdominal computed tomography (CT) examinations in matched patient cohorts regarding the differences in effective radiation dose (ERD) and image quality performed in a third-generation dual-source computed tomography (DSCT) scanner. MATERIAL AND METHODS: Our study included 100 patients, who were divided randomly into 2 groups. The patients included in Group A were scanned by SECT, and Group B members were scanned by DECT. Volume CT dose index (CTDIvol), dose length product (DLP), and ERD for venous phase acquisition were recorded in each patient and were normalised for 40 cm. Analyses were performed by using statistical software (SPSS version 20.0 for windows), and Bonferroni correction for multiple comparisons was applied for p-values and confidence intervals. RESULTS: Average ERD based on DLP values normalised for 40 cm acquisition were obtained for both Group A and Group B. The mean ERD for Group A was 11.89 mSv, and for group B it was 6.87 mSv. There was a significant difference in these values between Group A and Group B as shown by a p-value of < 0.001. On subjective and objective analysis, there was no statistically significant difference in image quality between the 2 groups. CONCLUSIONS: The protocols in third-generation DSCT using dual-energy mode resulted in significant reductions in the effective radiation dose (by approximately 58%) compared to SECT in routine abdominal examination in matched cohorts. Therefore, the quantitative imaging potential of DECT can be utilised in needed patients with decreased radiation dose in third-generation DSCT.
RESUMEN
Two field experiments were conducted in the Business Information Technology Department of a major retail industry to analyze the impact of positive task performance reinforcers. The employees were divided into two broad groups - those performing complex tasks and those performing relatively simpler tasks. The first group was further divided into two subgroups, one being reinforced with money and paid leave and the other with feedback. Both the subgroups showed a significant improvement in performance behavior. However, feedback had a stronger effect on task performance even after the reinforcement was withdrawn. The second group of employees was allowed to choose reinforcers of their liking. Two simple techniques, a casual dress code and flexible working hours chosen by them, had a positive effect on their performance, which continued even after 6 months into the intervention. Besides, the procedure for the second group required no monetary or work-time loss to the employer.