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Utilizing a Radiology-Based Informatics System to Impact Clinical Practice: A Study to Improve and Track Patient Alignment in Computed Tomography

A Moody1*, L DeWeese2, T Griglock3, (1) UT Health San Antonio, San Antonio, TX, (2) Oregon Health & Science Univ, Portland, OR, (3) Oregon Health & Science Univ, Portland, OR


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library


Ideal use of Computed Tomography (CT) imaging systems relies on accurate patient positioning. Suboptimal alignment degrades the efficacy of tube current modulation algorithms and bowtie filters leading to losses in image quality and potential increases in radiation dose. A Quality Improvement (QI) approach is presented aimed at mitigating the inaccuracies of patient alignment at our facility through an educational initiative. This study employs a radiology-based informatics system to more efficiently and accurately evaluate the progress of the initiative.


CT technologists at our facility were instructed via a presentation on the deleterious effects of misalignment and methods to improve accuracy as the primary action of our QI program. Informatics software was used to streamline the acquisition of data pertaining to alignment improvements. Efficacy of the presentation was evaluated according to shifts in accuracy and average vertical displacement from isocenter. Radiation dose changes were evaluated in the context of patient alignment shifts.


Vertical alignment increased toward isocenter by 0.49 cm on average following the presentation (p < 0.0001). Accuracy within 3 cm of isocenter improved from 68.80% to 77.68%, which corresponded to a 30-percentile improvement in a peer ranking among other hospitals. Alignment shifts were not large enough to significantly impact dosimetry. Modest increases of 1.37 mGy (p = 0.14) and 0.12 mGy (p = 0.43) were noted in CTDIVOL and SSDE, respectively, but were considered to be insignificant.


Improvements in vertical alignment accuracy and offsets showed that the QI initiative was effective. Dosimetry gains were inappreciable from the small decreases in vertical displacement. The informatics system and data acquisition methods employed by this study were essential to the success of the QI program. Analytical and educational methods utilized by this study provide our facility and others with new methods for future QI initiatives.


Quality Assurance, Patient Positioning, Data Acquisition


IM- CT: Quality Control and Image Quality Assessment

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