Patient Centring in CT: An International Survey of Clinical Practice and Future Directions

Accurate patient centring in computed tomography (CT) is essential for optimising radiation dose and ensuring consistent image quality. Mis-centring can affect automatic tube current modulation, compromise CT number accuracy and increase radiation exposure, but actual centring practices and knowledge differ widely. This study investigates CT centring practices, radiographers' knowledge of their implications and the use of advanced technologies for improved positioning accuracy.

An international survey was conducted among radiographers performing CT imaging using a 38-question questionnaire covering demographics, patient positioning, CT number variability, radiation dose management and auto-centring technologies. Translated into 12 languages, the survey was distributed through professional societies and social media, with data analysed using descriptive statistics and inferential tests.

A total of 321 radiographers from 43 countries completed the survey. Vertical mis-centring was frequently identified by respondents as the predominant positioning error, with 101 (31.5%) reporting that patients were commonly positioned below the gantry isocentre. 126 of the respondents (39.3%) believed HU values likely change with mis-centring, while 76 (23.7%) were unsure. Understanding of localiser direction varied, with 113 (35.4%) stating it 'probably' affects radiation dose and 45 (14.1%) unsure. Although 110 (34.3%) had access to automated centring technologies, only 56 (17.4%) used them consistently. Practitioners holding CT-specific qualifications were more likely to achieve a high knowledge score than those without (58.3% vs. 55.7%; OR 1.11, 95% CI 0.70-1.76; p = 0.72).

This global survey shows significant variability in CT patient-centring practices and knowledge. Improved training and more automated positioning tools are needed to optimise dose and image quality in CT.