Radiation dose optimization research: Exposure technique approaches in CR imaging – A literature review

Perception of patient habitus and the influence on exposure factor selection and resultant imparted dose

INTRODUCTION

Exposure factor selection influences ionising radiation dose and image quality in projection radiography. Radiographers have a duty to comply with legislation, ensuring doses (resulting from exposure factor selection) are kept ALARP. Hence, this paper aims to explore variation in patient habitus perceptions among final-year student radiographers and any influence on imparted dose due to exposure factor selection.

METHODS

Institutional ethics was granted. Student radiographers engaged in a 2-stage primary research study. Students were asked to select exposure factors (kVp and mAs values) and the most appropriate BMI category for several models undergoing a routine anteroposterior abdomen projection. Monte-Carlo simulation software was utilised to establish the absorbed and effective dose for these exposures. SPSS software was used to conduct statistical analysis of this data.

RESULTS

A response rate of 19% (n = 14) was recorded. The findings identified variation in habitus perception with greater variation among female models. (p = 0.002). There was significant variation in exposure factor selection and ionising radiation dose, particularly between the male and female models. There was a significant difference between the healthy, overweight, and obese female models for absorbed (p = 0.032) and effective dose (p = 0.032) but not for the male models.

CONCLUSION

There was a distinct difficulty recognising overweight and obese models and inconsistency regarding the selection of exposure factors. It was concluded that male models were more likely to receive a greater dose than females due to higher proposed exposure factors.

IMPLICATIONS FOR PRACTICE

This study adds to the existing evidence base, providing insight into the perceptions of radiography students and the effect on exposure factor selection. This study will likely stand as a baseline for further investigation into competency levels among qualified radiographers to improve radiation protection.

Exposure index in digital radiography: initial results of awareness and knowledge from Nigerian digital radiography practices

INTRODUCTION

Exposure Index (EI) is incorporated into Digital Radiography (DR) systems to indicate incorrect exposure to enable matching exposure to the desired speed class of operation. However, knowledge of the utilization of EI by radiographers in a low-income country has not been investigated.

METHODS

A pre-tested questionnaire designed using Google forms, with open and close-ended questions was shared online with radiographers working with DR systems in public and private health facilities in some cities located in southern Nigeria. The 32-item questionnaire had two parts: Part A focused on socio-demographic characteristics and Part B focused on the respondents' awareness and knowledge of EI in DR systems. A 5-point Likert scale with 5 test items was used to assess the respondents' knowledge of EI. Statistical analyses were conducted using the Statistical Package for Social Sciences (SPSS) version 21.0. The probability value of p < 0.05 was considered statistically significant.

RESULTS

About 8.3% of the respondents had good knowledge of EI in DR systems in spite of the awareness level of 24.7%. The absence of the EI concept in DR curriculum for undergraduates, the lack of EI software in DR systems, and equipment training by the vendor engineers were reasons for the low level of knowledge of EI in DR systems.

CONCLUSION

There is low awareness and knowledge of EI by radiographers in this study, which suggests the need to maximize the benefits of EI concepts by ensuring its integration into clinical radiography practice and curriculum for undergraduates program, to improve knowledge, awareness, and practice in DR.

COMPUTED RADIOGRAPHY UTILIZATION FOR TELECOBALT60 TO ACHIEVE THE RADIATION CERTAINTY

OBJECTIVE

The aim: This research aimed to show the achievement of Telecobalt60 radiation certainty using computed radiography, in comparation with non-verified computed radiography.

PATIENTS AND METHODS

Materials and methods: This research is a quantitative study, randomized double-blind, and consecutive sampling design. The study was conducted by observing and com¬paring the data of verified computed radiography (VerC) computed radiograph for Telecobalt60 compared to the non-verified computed radiography (nVerC) Telecobalt60 data.

RESULTS

Results: The results showed that there are significant statistical differences in several measurement characteristics between the verified computed radiography arm and the non-verified computed radiography arm. All of the value divergences of the verified computed radiography arm are less than 7 mm while the non-verified computed radiography arm are 7 mm or more (P<0.050). Furthermore, all of the edge aspect of measurement in the verified computed radiography arms are less than the non-verified computed radiography, all without manual block utilization (P<0.050).

CONCLUSION

Conclusions: We conclude that Telecobalt60 radiation certainty is significantly better achieved by using computed radiography, when compared to non-verified computed radiography Telecobalt60 use. This research contributes to provide evidence based for better Telecobalt60 radiation accuracy and quality of radiotherapy outcome by using computed radiography.

Performance of automatic exposure control on dose and image quality: comparison between slot-scanning and flat-panel digital radiography systems

BACKGROUND

EOSedge™^* (EOS Imaging, Paris, France) is an X-ray imaging system using automatic exposure control (AEC) with tube current modulation, in order to optimize dose deposition in patients.

PURPOSE

This study aims at characterizing EOSedge organ dose deposition in comparison to a digital radiography (DR) system and the previous EOS system (EOS-1st generation), in relation to their respective image quality levels.

METHOD

Organ doses were measured in an anthropomorphic female adult phantom and a 5-year-old pediatric phantom using optically stimulated luminescence (OSL) dosimeters, which were carefully calibrated within the studied energy range. Organ doses were recorded on the EOSedge and the Fuji Visionary DRF (Fujifilm Medical Systems U.S.A., Inc, Lexington, MA). The resulting effective doses were compared to the EOS-1st-generation values present in the literature. Image quality assessment was carried out on end-user images. Quantitative image quality metrics were computed for all tested modalities on a quality assurance phantom. Qualitative assessment of EOSedge image quality was based on anthropomorphic phantom acquisitions against the EOS-1st-generation system, and on clinical images against the tested DR system.

RESULTS

For a full-spine exam, and on the female adult phantom (respectively, the pediatric phantom), an effective dose of 92 μSv (respectively, 32 μSv) was obtained on EOSedge, and 572 μSv (respectively, 179 μSv) on the DR system; these values were compared to effective dose values of 290 μSv (respectively, 200 μSv) from the literature on EOS-1st generation, leading to an effective dose reduction factor of 6 with respect to the DR system, and of 3-6 with respect to EOS-1st generation. EOSedge provides the best compromise between contrast-to-noise ratio (CNR) and dose, with more consistent CNR values than the other tested modalities, in a range of attenuation from 10 to 40 cm of poly(methyl methacrylate) (PMMA). Within this range, EOSedge is also comparable to DR for 10 and 20 cm of PMMA, and better than DR for 30 and 40 cm of PMMA, both in terms of spatial resolution and low-contrast detection. The anatomical landmarks of interest in the follow-up of spinal deformities can be detected in all tested modalities.

CONCLUSION

Results showed that EOSedge provides significant dose reduction factors for full spine imaging in both adults and children compared to the other tested modalities, without compromising image quality. We believe that this work could help raise awareness on the capabilities of modern X-ray systems, when equipped with appropriate AEC strategies, to perform ultra-low-dose, long-axis images.

Understanding radiographic decision-making when imaging obese patients: A Think-Aloud study

Introduction

The incidence of obesity has been steadily rising over the last few decades and is having a significant impact upon the health system. In radiography, a particular challenge of imaging obese patients is implementing the as low as reasonably achievable (ALARA) principle when determining radiation dose, and technical and patient‐care adaptations. This study aimed to better understand the decision‐making strategies of experienced radiographers in determining imaging and exposure factor selection in the context of imaging obese patients.

Methods

This study employed a ‘think‐aloud,’ methodology, and eight experienced diagnostic radiographers working in clinical education were recruited to perform routine AP abdominal X‐ray projections on an anthropomorphic phantom. They were asked to simultaneously verbalise emerging thoughts as they considered positioning, exposure selection and image evaluation. This process was repeated with three different phantom sizes, each representing an increased BMI from ‘healthy,’ to, ‘morbidly obese.’ Audio recordings were transcribed and interpreted via Bowman’s (1997) theory of radiographic judgement and decision‐making.

Results

Analysis of interview transcripts identified 12 key concepts considered by experienced radiographers. Differences in radiographic concepts were considered when imaging phantoms of different sizes was demonstrated. A shift from segmental (e.g. positioning) to more environmental factors (e.g. patient comfort) and an increase in the number of verbal considerations with increasing phantom size were identified. The shift in focus of decision‐making stages identified the greater need to consider contextual factors such as patient comfort and repeatability when imaging obese patients.

Conclusion

Experienced radiographers find imaging obese patients challenging and alter their perception of image quality to accommodate for patient presentation. The findings will help inform future research, practice guidelines and learning resources to provide optimal imaging and care for obese patients, especially for student education.

Evaluating the use of exposure indicators in digital x-ray imaging system: Gauteng South Africa

INTRODUCTION

Exposure indicators (EIs) are the only indicator of correct exposure technique in digital x-ray imaging systems but the use of such indicators remains largely unexplored in a South African setting. With exposure creep in the digital radiography age being a worldwide phenomenon, the study investigated radiographers' familiarity and use of EIs, providing insight into current exposure technique practices in this setting.

METHODS

An explorative and descriptive quantitative study was conducted at 10 randomly selected radiography clinical training facilities in Gauteng, South Africa. The study used a questionnaire consisting of 26 questions based on familiarity with and use of EIs and radiographers' attitude to ionising radiation.

RESULTS

A response of rate of 49.3% was achieved. Results show a low number of respondents (54.3%) had a perfectly correct understanding of the exposure indicator (EI) and only 55.7% of respondents made correct use of the EI.

CONCLUSION

Observable lack of familiarity and use of the EI suggests that improvements could be made to the training radiographers receive on digital imaging systems. Moreover radiographers need to be vigilant against making decisions in digital radiography using knowledge that may relate exclusively to analogue radiography.

Retrospective evaluation of exposure indicators: a pilot study of exposure technique in digital radiography

INTRODUCTION

Digital radiography lacks visual clues of exposure techniques used to obtain radiographs, therefore manufacturers have included exposure indicators (EIs). EIs provides feedback about exposure techniques used and evaluating EIs will yield much needed information about exposure trends used in digital radiography.

METHODS

A retrospective explorative quantitative study was conducted at nine randomly selected imaging departments in Gauteng, South Africa. Data pertaining to EI was retrospectively collected using quota sampling and compared to manufacturer recommended (MR) standards.

RESULTS

A total of 1422 EIs were collected. 50% of these were within the MR standard. 27% of EI indicated overexposure and 23% indicated underexposure.

CONCLUSIONS

Greater evidence of overexposure was noted in the retrospective analysis of the EI. This pilot study shows the need for further investigation into exposure technique practices in digital radiography and the need for measures to halt the evidenced overexposure.

Digital imaging and radiographic practise in diagnostic radiography: An overview of current knowledge and practice in Europe

INTRODUCTION

Recent research has identified the issue of 'dose creep' in diagnostic radiography and claims it is due to the introduction of CR and DR technology. More recently radiographers have reported that they do not regularly manipulate exposure factors for different sized patients and rely on pre-set exposures. The aim of the study was to identify any variation in knowledge and radiographic practice across Europe when imaging the chest, abdomen and pelvis using digital imaging.

METHODS

A random selection of 50% of educational institutes (n = 17) which were affiliated members of the European Federation of Radiographer Societies (EFRS) were contacted via their contact details supplied on the EFRS website. Each of these institutes identified appropriate radiographic staff in their clinical network to complete an online survey via SurveyMonkey. Data was collected on exposures used for 3 common x-ray examinations using CR/DR, range of equipment in use, staff educational training and awareness of DRL. Descriptive statistics were performed with the aid of Excel and SPSS version 21.

RESULTS

A response rate of 70% was achieved from the affiliated educational members of EFRS and a rate of 55% from the individual hospitals in 12 countries across Europe. Variation was identified in practice when imaging the chest, abdomen and pelvis using both CR and DR digital systems. There is wide variation in radiographer training/education across countries.

CONCLUSION

There is a need for standardisation of education and training including protocols and exposure parameters to ensure that there is continued adherence to the ALARA principle.

Image acquisition in general radiography: The utilisation of DDR

OBJECTIVE

This article explores image acquisition with DDR. General radiographic technology continues to advance therefore it remains paramount to continually reflect on DDR hardware and software amongst radiographers in an imaging modality that constitutes approximately 90% of all radiological examinations.

METHOD

This article reports findings from a wider ethnographic study of two general radiography environments in the United Kingdom (UK). Participant observation and semi-structured interviews were the methods used to uncover original data.

RESULTS

Two key themes are discussed. Firstly, 'the extent of DDR knowledge' amongst radiographers is examined. The findings uncover that not all radiographers have an adequate knowledge base with DDR technology. Secondly, 'pitfalls and near misses with DDR' is discussed. This theme highlights the potential danger of radiographers 'over-repeating' X-ray examinations, coincided with the occurrence of radiological incidents whereby a patient is exposed to ionising radiation with no added benefit.

CONCLUSION

This paper concludes by challenging the current 'skill base' to operate DDR equipment. In addition, new pitfalls and near misses are highlighted, which may help forestall radiation incidents in the future. Dose and image optimisation remain central tenets to the role of the radiographer.

ADVANCES IN KNOWLEDGE

Few studies have challenged image acquisition with DDR. This study adds to existing knowledge by uncovering original phenomena that may initiate discussions within the radiography community and continually enhance healthcare delivery.