The impact of pitch values on image quality and radiation dose in an abdominal adult phantom using CT

Purpose: To identify the impact of different pitch values on image quality and effective radiation dose for axial and coronal plane in abdominal adult CT. Methods and materials: Three scans were conducted on an abdominal phantom using a Toshiba Aquilion 16-slice CT scanner with three different pitch values: standard (0.938), detail (0.688) and fast (1.438). Slices were taken from the upper, middle and lower abdomen in the axial plane and anterior, middle and posterior in the coronal plane. The six different anatomical structures were liver, intrahepatic vessels, spleen, pancreas, kidneys and renal vessels, retroperitoneum, aorta and vena cava. A two-alternative forced-choice (2AFC) method was used to evaluate images for each pitch with 8 observers using a 3-point Likert scale. SNR was calculated in every plane, slice and pitch factor using the ImageJ software. To estimate effective radiation dose the CT Expo software was used. Results: Detail pitch factor provides superior image quality compared to standard in axial plane when evaluating the liver (p<0.034) and pancreas (p=0.008). However, the results for spleen, kidney, renal vessels, retroperitoneum, aorta and vena cava are not significant when comparing detail vs standard. Standard provides a 26.3% reduction in effective radiation dose (mSv) compared to detail. Fast had the worst image quality in both the axial and coronal plane but the lowest dose. In the coronal plane, standard was superior to both detail (p=0.026) and fast (p=0.023) in terms of image quality. The differences in SNR results were not significant except in standard vs detail in the coronal plane (p=0.03). Conclusion: Detail pitch factor provides superior image quality to standard and fast in the axial plane. Standard had superior image quality to both detail and fast in the coronal plane. The augmentation of effective doses has been inversely proportional to the pitch factors. The most irradiant pitch mode was detail and the less was fast

Reducing the time-lag between onset of chest pain and seeking professional medical help: a theory-based review

Background: Research suggests that there are a number of factors which can be associated with delay in a patient seeking professional help following chest pain, including demographic and social factors. These factors may have an adverse impact on the efficacy of interventions which to date have had limited success in improving patient action times. Theory-based methods of review are becoming increasingly recognised as important additions to conventional systematic review methods. They can be useful to gain additional insights into the characteristics of effective interventions by uncovering complex underlying mechanisms. Methods: This paper describes the further analysis of research papers identified in a conventional systematic review of published evidence. The aim of this work was to investigate the theoretical frameworks underpinning studies exploring the issue of why people having a heart attack delay seeking professional medical help. The study used standard review methods to identify papers meeting the inclusion criterion, and carried out a synthesis of data relating to theoretical underpinnings. Results: Thirty six papers from the 53 in the original systematic review referred to a particular theoretical perspective, or contained data which related to theoretical assumptions. The most frequently mentioned theory was the self-regulatory model of illness behaviour. Papers reported the potential significance of aspects of this model including different coping mechanisms, strategies of denial and varying models of treatment seeking. Studies also drew attention to the potential role of belief systems, applied elements of attachment theory, and referred to models of maintaining integrity, ways of knowing, and the influence of gender. Conclusions: The review highlights the need to examine an individual’s subjective experience of and response to health threats, and confirms the gap between knowledge and changed behaviour. Interventions face key challenges if they are to influence patient perceptions regarding seriousness of symptoms; varying processes of coping; and obstacles created by patient perceptions of their role and responsibilities. A theoretical approach to review of these papers provides additional insight into the assumptions underpinning interventions, and illuminates factors which may impact on their efficacy. The method thus offers a useful supplement to conventional systematic review methods