The effect of inappropriate patient centring on CT numbers and radiation dose: A survey of current practices and knowledge.

Introduction: Patient positioning is known to impact CT number and patient dose. The aim of this study was to report current practice and the accuracy of the knowledge of radiographers in Australia regarding inappropriate patient centring during CT.

Methods: A survey of members of the Australian Society of Medical Imaging and Radiation Therapy (ASMIRT) was undertaken. The survey consisted of 36 questions about patient off-centring, CT number accuracy, and radiation dose. The survey was open from May to August 2021 and directed toward diagnostic radiographers with CT experience. Responses were evaluated as correct or incorrect based on evidence-based knowledge and theoretical definitions.

Results: Among 186 participants, a majority of 75.7 % followed the manufacturer's recommended guidelines for localiser radiographs direction. Despite higher radiation dose to anteriorly located radiosensitive organs, 63.64 % preferred the anterior-posterior (AP) localiser. Only 21.93 % agreed that localiser direction would definitely affect radiation dose if the patient was inappropriately centred. A knowledge-practice disparity is evident as 45.77 % rarely or never reviewed CT numbers post-image acquisition, even though 92.8 % acknowledged their significance on prognosis and clinical decisions. Significant discrepancies in the accuracy of responses were identified; inaccuracies were dependent on CT qualifications (p = 0.0199), experience (p = 0.0397), and workload (p = 0.0360). Knowledge gaps existed regarding factors affecting patient centring and its impact on radiation dose and CT numbers.

Conclusion: This study highlights inconsistent CT practices and knowledge gaps among Australian radiographers. Given the impact of inaccurate positioning on radiation dose and CT number, engagement with continuous professional development programs that focus on the importance of patient positioning and the utilisation of the latest advancements in dose management tools is urgently needed.

Implications For Practice: Where radiographers do not possess the necessary theoretical knowledge and understanding to maximise patient positioning accuracy to optimise dose and CT number accuracy, then patients may receive an unnecessary dose. Inaccurate CT number accuracy may lead to misdiagnosis or inaccurate delivery of treatment.