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

Abstract

IntroductionFollowing X-ray exposure, radiographers receive immediate feedback on detector exposure in the form of the exposure index (EI).PurposeTo 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.MethodsData 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.ResultsMost 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).ConclusionsNon-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

“…Although this article is based on the imaging of paediatric patients, many of the suggestions therein are also relevant to the imaging of adults. For example Mothiram et al highlighted gender variation in terms of EI when imaging adults, with female patient radiographs recording significantly higher median EI values than males in a number of instances 22. Mothiram et al have indicated that data on patient size and body part thickness could have provided useful information relating to the EI gender variations demonstrated in their study, as men and women have variations in tissue distribution,22 this would appear to validate a back to basics approach in terms of imaging adults utilising DR.…”

“…It has been reported that EI variations between examinations taken within hours and out of hours can occur, with higher EIs being recorded in the latter situation 22,32. This may be linked to staffing levels and levels of staff experience,22 with radiographers reluctant to have to repeat an exposure during these busy shifts 22,32.…”

“…It has been reported that EI variations between examinations taken within hours and out of hours can occur, with higher EIs being recorded in the latter situation 22,32. This may be linked to staffing levels and levels of staff experience,22 with radiographers reluctant to have to repeat an exposure during these busy shifts 22,32. A survey of a cross section of the American Society of Radiologic Technologists (ASRT) members was undertaken to evaluate radiologic technologists' knowledge about image quality and dose management in paediatric DR examinations; they concluded that there is a need for comprehensive practical digital imaging technology education for technologists 3.…”

“…Thereby providing the radiographer with a guide to optimal technique factors to use on subsequent CXRs on the same patient 12. Variation in EI values between genders has also been demonstrated with women often obtaining higher values compared to their male counterparts 22,39. The lack of an adequate exposure chart for female patients has been suggested as a possible cause of this gender variation 39.…”

“…The lack of an adequate exposure chart for female patients has been suggested as a possible cause of this gender variation 39. However, information on patient's size and body part thickness has been suggested as potentially providing useful information relating to EI gender variation 22. Zhang et al established a method to set appropriate exposure parameters (mAs) to achieve a target EI based on a child's height and weight, thus enabling a significant reduction in dose–area product (DAP) and ESD in paediatric radiography 40.…”