Thomas Adejoh, Chukwuemeka H. Elugwu, Emeka E. Ezugwu, Mohammed Sidi, Michael E. Aronu


Background: Digital radiographic technology comprising computed radiography (CR) and direct digital radiography (DDR) have significantly reduced repeats due to inappropriate exposure factors in film-screen radiography (FSR). The opportunity cost, however, is the introduction of dose creep which jeopardizes radiation protection. Minimizing or elimination of dose creep is, therefore, imperative but this is difficult to achieve. A radiographic exposure chart can forestall dose creep as it minimizes unnecessary arbitrariness in the selection of exposure intensity. This work was an attempt to use exposure index (EI) and deviation index (DI), two imaging software tools found at the workstation, to derive an exposure chart for addressing dose creep in computed radiography.

Results: Three hundred sthenic and hyposthenic adult patients and 150 paediatric patients were enlisted in this study, and with focus on seven specific anatomical regions. With standard exposure index of 250 – 350, deviation index was reduced from a range of -11.1 to +8.1 to a lower range of -2.6 to +1.4 without loss in image quality. There was however, an 8 to 28 % upward adjustment in tube current (mA) to reduce quantum noise. A new exposure chart was derived at the end of the study that has great potential to address digital dose creep in hyposthenic and sthenic Negroid subjects.

Conclusion: Dose creep in digital radiographic technology can be mitigated with an empirically-derived exposure chart.

Keywords: Dose, Radiography, Charts, Exposure, dose creep, ALARA, Digital Radiography

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