The World Health Organization (WHO) has recommended the use of high-kV technique to ensure optimized practice for PA chest radiography. Evidences have highlighted remarkable successes using this technique, with good image quality obtained at significantly reduced doses to the patients (Lorusso et al. 2015; Masoud et al. 2015). Adherence to this recommendation, however, remains an issue in many settings (Ofori et al. 2014; Aliasgharzadeh et al. 2015).

The current study investigated the awareness and compliance to the practice of recommended high-kV technique for PA chest radiography among radiographers in South South Nigeria. Our study yielded an appreciable level of awareness, as a greater proportion of radiographers (74/%) in this region had knowledge of the recommended high-kV technique for optimized chest radiography. This trend was consistent among radiographers in private and public practice, and across the different years in service and the gender subgroup (Fig. 3). Observed high awareness was given from the survey to be due to the knowledge gained from attending the continuing professional development programmes (CPD) to update one’s knowledge on new trends in the profession. From our survey, radiographers with years in service less than 5 years (40%) were as much aware of this high-kV recommendation as those who have been in practice for at least 10 years (32%) (Fig. 3). This suggests that the number of years in service did not influence the level of awareness of the practice of high-kV technique in this region. The present study showed that compliance to the use of this technique was low, meaning knowledge gained did not translate into adherence to this recommended optimized practice in this region over the years. Poor knowledge based on radiation protection measures has also been reported as being responsible for poor compliance to evidence-based practices in some facilities in Nigeria (Ekpo et al. 2014). We expected that this high awareness would mean a considerably good level of compliance, but surprisingly this was not substantiated in this region. Only 13% of respondents accepted to have routinely incorporated this technique into PA chest X-ray for average-sized patients. The implication of this poor compliance is unnecessary radiation doses to patients during chest X-ray investigations. In this survey and related studies, facilities consistently used lower than recommended standard for chest X-ray, however, varied (Bamidele and Nworgu 2011; Ofori et al, 2014; Masoud et al. 2015; Aliasgharzadeh et al, 2015). The practice was similar in both private and public centres, as levels of compliance were comparable (Table 1). The survey revealed that the absence of departmental protocols for PA chest X-ray, imaging systems, X-ray tube rating and X-ray units with preset or manually set exposure factors, post-processing properties of digital radiography systems and performance characteristics of the X-ray unit underpinned observed low compliance (Masoud et al. 2015). Years in service did not change the trend in exposure settings. Low kV (< 100 kV) consistently ranked the highest tube potential settings in this region, followed by 100–119 kV, which was similar in public and private facilities. These low-kV settings were compared with the results of Bamidele et al. (2011), Zira et al. (2017) and Masoud et al. (2015). In a related study, Lorusso et al. (2015) noted that many facilities have not fully adopted the recommended optimized practice of high-kV technique as a departmental protocol. This low compliance to high-kV technique in this study, nonetheless, shows an improvement from an earlier study in Southwest Nigeria, which reported zero compliance (Bamidele and Nworgu 2011) (Table 1). This and the outcome of our research raise concerns knowing the high number of prescriptions for PA chest X-ray examinations and the implication of poor compliance to recommended practice on patient care. These results emphasize the need for radiographers’ regulatory bodies and relevant stakeholders to organize training and implementation programmes for optimized practices and dose reduction strategies such as high-kV technique in radiography. According to Fauber et al. (2011), high-kV technique has the potential to substantially reduce patient dose during X-ray examination, regardless of the image receptor type. We expected knowledge of the benefits of high-kV technique to improve compliance with the said technique among radiographers in this region. While more than half of the respondents knew the benefits of using high-kV technique for PA chest X-rays, compliance was, however, low and did not improve even with the number of years in service. Our survey revealed patient dose reduction (PDR) as the number one reason for recommending high-kV technique for chest radiography, while the reduction in ribs obscuring effects on underlying pulmonary lesion followed after. Patient dose reduction was foremost among male and female respondents, radiographers practising in private and public health facilities and those with 5 to 9 years in service in this region. For those with at least 10 years in practice, reduction in rib’s obscuring effects on underlying pulmonary lesions ranked the highest. However, all reasons provided by the study for recommending this technique which included patient dose reduction (PDR), better imaging of the mediastinum (BIM), better imaging of the airways (BIA), reduction in subject involuntary movement (RSIM) and reduction in rib’s obscuring effects on the underlying pulmonary lesion (RROPL) were fairly represented in our survey. Besides the reduction of radiation dose to patients, penetration of dense mediastinum, lung tissue behind the heart, diaphragm and lung bases strengthened reasons for high-kV technique in chest radiography patients (Bontrager and Lampignano 2014; Kahn and Santos 2015; Slavtchev and Manolov 2016). The concept of high-kV/low-mAs technique is a radiation dose reduction measure which produces more penetrating X-ray photons with less radiation dose to patients and has been shown to reduce entrance skin dose (ESD) by 20% while maintaining acceptable image quality (Lorusso et al. 2015). The survey underpins the performance characteristics of the X-ray unit (X-ray tube rating, preset and manually set X-ray unit) and the type of imaging system as factors influencing compliance to the recommended high-kV technique for PA chest X-ray. Fauber et al. (2011) noted that the transition from film-screen to digital imaging was responsible for the practice of low-kV technique in most non-adherent settings and that radiographers tend to apply low-kV settings leveraging the wide dynamic range in digital imaging systems. The tendency to use low kV and post-process is high, since digital imaging system allows the detection of both low and high intensities (Fauber et al. 2011).

Fig. 3
figure 3

Level of awareness of high-kV technique for PA chest X-ray amongst respondents (n = 77)

The overall implication of this low level of compliance indicates a potential increase in ionizing radiation dose to the patients and poor image quality. This survey is not without limitations as only a few facilities in South South Nigeria were included. However, the three included cities have the highest concentration of hospitals and diagnostic centres in South South Nigeria. In addition, the survey did not explore possible disadvantages of the use of high-kV technique.

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