The validity and reliability of the exposure index as a metric for estimating the radiation dose to the patient

Introduction With the introduction of digital radiography, the feedback between image quality and over-exposure has been partly lost which in some cases has led to a steady increase in dose. Over the years the introduction of exposure index (EI) has been used to resolve this phenomenon referred to as ‘dose creep’. Even though EI is often vendor specific it is always a related of the radiation exposure to the detector. Due to the nature of this relationship EI can also be used as a patient dose indicator, however this is not widely investigated in literature. Methods A total of 420 dose-area-product (DAP) and EI measurements were taken whilst varying kVp, mAs and body habitus on two different anthropomorphic phantoms (pelvis and chest). Using linear regression, the correlation between EI and DAP were examined. Additionally, two separate region of interest (ROI) placements/per phantom where examined in order to research any effect on EI. Results When dividing the data into subsets, a strong correlation between EI and DAP was shown with all R-squared values > 0.987. Comparison between the ROI placements showed a significant difference between EIs for both placements. Conclusion This research shows a clear relationship between EI and radiation dose which is dependent on a wide variety of factors such as ROI placement, body habitus. In addition, pathology and manufacturer specific EI’s are likely to be of influence as well. Implications for practice The combination of DAP and EI might be used as a patient dose indicator. However, the influencing factors as mentioned in the conclusion should be considered and examined before implementation

Factors affecting digital radiography exposure indices: are radiographers achieving the recommended levels?

Introduction With digital radiography (DR), radiographers receive immediate feedback on detector exposure in the form of the exposure index (EI). Purpose To identify whether radiographers were meeting the manufacturer-recommended EI (MREI) value ranges for routine chest, abdomen and pelvis X-ray examinations under a variety of conditions and to examine factors that impacted upon EI levels. Methods Data on 5000 adult X-ray examinations were collected, including: EI values, examination parameters, patients’ gender, dates of birth, dates and times of examinations, grid usages and the presence of metallic implants or prostheses. Descriptive statistics were used to summarise data sets and Mann–Whitney U testing was performed to establish causal agents for EI value variations. Results EI values were often outside the MREI ranges. EI value variations were identified, with significantly higher EI values recorded for female compared with male patients for all manufacturers (P ≤ 0.04), indicating higher detector exposures except for Philips direct digital radiography (DDR), where increased EI values indicated lower exposures (P=0.01). Higher EI values were also noted for the following variables: out of hours radiography (P ≤ 0.02), the absence of secondary radiation grids with Philips DDR chest X-rays (P = 0.03), younger patients with Siemens DDR chest X-rays (P < 0.0001) and higher kVp for Carestream computed radiography (CR) chest X-rays (P = 0.02). Significantly lower median EI values were demonstrated for Carestream CR chest X-rays when a metallic implant or prosthesis was present (P = 0.02). Discussion Non adherence to MREIs has been demonstrated. EI value discrepancies have been identified as being dependent on patient gender, time/day of exposure, grid usage, the presence of a metallic implants or prostheses, patient age and use of ≥ 100 kVp. The value of careful retrospective evaluation of EI databases has been highlighted

Mimierung der vertikalen Schwingungsanregung des menschlichen Körpers in einem Traktor mittels einer Standard-Sitzaufhängung in der Schwerpunkt-Ebene

Es ist bekannt, daß bei Traktor-Fahrern verschiedene Beschwerden an der Wirbelsäule und am Stützapparat als Folge der mit geringer Frequenz (0,5—11 Hz) und großer Amplitude auftretenden Vertikalschwingungen vorkommen, die beim Fahrbetrieb auf dem Feld auftreten. Die Intensität dieser Schwingungen kann durch den Einbau von Standard-Sitz-Aufhängungen in der Schwerpunktebene des Traktors vermindert werden, wenn deren Parameter zweckmäßig gewählt werden. In dem vorliegenden Beitrag wird das System Fahrer-Traktor in einem Parameter-System mit punktförmiger Verteilung abgebildet und dieses Modell mittels Rechnersimulation in bezug auf seine Anregungen der einzelnen Körpersegmente als Folge vertikaler Schwingungsvorgaben an den Traktor-Rädern untersucht. © 1979, Walter de Gruyter. Alle Rechte vorbehalten

Retrospective evaluation of exposure index (EI) values from plain radiographs reveals important considerations for quality improvement

Introduction: Following X-ray exposure, radiographers receive immediate feedback on detector exposure in the form of the exposure index (EI). Purpose: To identify whether radiographers are meeting manufacturer-recommended EI (MREI) ranges for routine chest, abdomen and pelvis X-ray examinations under a variety of conditions and to examine factors affecting the EI. Methods: Data on 5000 adult X-ray examinations including the following variables were collected: examination parameters, EI values, patient gender, date of birth, date and time of examination, grid usage and the presence of implant or prosthesis. Descriptive statistics were used to summarize each data set and the Mann-Whitney U test was used to determine significant differences, with P < 0.05 indicating significance for all tests. Results: Most examinations demonstrated EI values that were outside the MREI ranges, with significantly higher median EI values recorded for female patient radiographs than those for male patients for all manufacturers, indicating higher detector exposures for all units except for Philips digital radiography (DR), where increased EI values indicate lower exposure (P = 0.01). Median EI values for out of hours radiography were also significantly higher compared with normal working hours for all technologies (P ≤ 0.02). Significantly higher median EI values were demonstrated for Philips DR chest X-rays without as compared to those with the employment of a grid (P = 0.03), while significantly lower median EI values were recorded for Carestream Health computed radiography (CR) chest X-rays when an implant or prosthesis was present (P = 0.02). Conclusions: Non-adherence to MREIs has been demonstrated with EI value discrepancies being dependent on patient gender, time/day of exposure, grid usage and the presence of an implant or prosthesis. Retrospective evaluation of EI databases is a valuable tool to assess the need of quality improvement in routine DR

Digital radiography exposure indices : a review

Digital radiography (DR) technologies have the advantage of a wide dynamic range compared to their film-screen predecessors, however, this poses a potential for increased patient exposure if left unchecked. Manufacturers have developed the exposure index (EI) to counter this, which provides radiographers with feedback on the exposure reaching the detector. As these EIs were manufacturer-specific, a wide variety of EIs existed. To offset this, the international standardised EI has been developed by the International Electrotechnical Commission (IEC) and the American Association of Physicists in Medicine (AAPM). The purpose of this article is to explore the current literature relating to EIs, beginning with the historical development of the EI, the development of the standardised EI and an exploration of common themes and studies as evidenced in the research literature. It is anticipated that this review will provide radiographers with a useful guide to understanding EIs, their application in clinical practice, limitations and suggestions for further research