Precise and Automatic Patient Positioning in Computed Tomography

Saltybaeva, Natalia; Schmidt, Bernhard; Wimmer, Andreas; Flohr, Thomas; Alkadhi, Hatem

doi:10.1097/rli.0000000000000482

Cited by 70 publications

(32 citation statements)

References 22 publications

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“…In a recent advancement, one vendor utilizes a 3D camera to detect body contours via infrared light and fits the camera data to an avatar [ 7 ]. The patient’s isocenter is then determined based on the avatar and the body region to be scanned by artificial intelligence (AI) algorithms, and the table height is adjusted accordingly.…”

Section: Introductionmentioning

confidence: 99%

The Improvement of Patient Centering in Computed Tomography Through a Technologist-Focused Education Initiative

et al. 2022

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Proper patient centering is fundamental to the operation of CT. Misalignment of the patient is known to have a negative impact on image quality and dose. The purpose of this study was to improve patient centering in CT and examine the efficacy of several educational methods that could be implemented at any clinical site. The IRB determined the study was not human subjects research, and oversight was waived. Three interventions were examined. The first intervention involved a discussion on patient centering at a staff meeting. As the second intervention, an educational presentation was developed and delivered to CT technologists addressing the physics behind the importance of patient centering in CT. As the third intervention, individual technologist centering performance reviews were conducted by the modality supervisor. Clinical scan data was collected for each study period via a cloud-based software to examine the efficacy of each intervention in terms of lateral and vertical offset. The mean vertical offset of the baseline data was −1.97 cm. After the staff meeting, the mean vertical offset decreased to −1.60 cm ( p < 0.001). Following the educational presentation, the mean vertical offset decreased to −1.14 cm ( p < 0.001). After the technologist performance reviews, the mean vertical offset decreased to −0.86 cm ( p < 0.001). This research examined a quality improvement initiative to improve patient centering at our institution which focused on communication and education. Through this initiative, the mean vertical positioning error decreased, the percentage of exams within 0–1 cm of isocenter increased, and the percentage of exams misaligned by greater than 3 cm decreased. This work has shown that patient centering can be improved with education.

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Section: Introductionmentioning

confidence: 99%

The Improvement of Patient Centering in Computed Tomography Through a Technologist-Focused Education Initiative

et al. 2022

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“…Initial studies on adult and paediatric patients have shown that the 3D camera developed by Siemens Healthineers allows precise positioning of the patient, limiting the variability of centering between radiographers 7 – 9 . However, the authors also concluded that the patient's centering could sometimes be corrected by the radiographer when the system fails or in challenging cases 7 .…”

Section: Introductionmentioning

confidence: 99%

Impact of additional mattresses in emergency CT on the automated patient centering proposed by a 3D camera: a phantom study

Greffier

Frandon

Forges

et al. 2021

Sci Rep

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To assess the impact of the use of additional mattresses of different thicknesses on radiation dose and image noise based on the patient centering proposed by a 3D camera for CT. An anthropomorphic phantom was placed on mattresses of different thicknesses (from 3.5 to 13.5 cm) on the table of a CT scanner. The automated patient centering proposed by a 3D camera was analysed as a function of mattress thickness and corrected for table height. For this purpose, the impact on image noise in the lung tissues in the chest area and in the soft tissues in the abdomen-pelvis area, modulated mAs (mAsmod) by the tube current modulation system (TCM) and volume CT dose index (CTDIvol) was assessed slice-by-slice along the z-axis after CT scans. With the use of a mattress, the automated centering proposed by the 3D camera resulted in placement of the phantom above the isocentre. This incorrect positioning led to a significant increase in the mAsmod along the z-axis (p < 0.05) and in the CTDIvol. Image noise was significantly higher (p < 0.05) for automated phantom centering than with manual phantom centering. Differences of image noise between acquisitions with mattresses after automatic and manual phantom centering increased with the mattress thicknesses. The use of an additional mattress placed between the patient’s back and the table-top would require correcting the vertical centering proposed by the 3D camera. This manual correction is essential to avoid increased dose delivered to the patient and higher image noise.

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“…By decreasing X-ray fluence to peripheral, less attenuating regions of the body, these filters reduce dose and equalize image quality throughout the field-of-view (FOV). [10][11][12][13] Incorrect patient positioning is known to increase radiation dose 14 and, consequently, vendors have sought to improve the process by developing automated, camera-based patient position detection 15,16 and moving tables. 17 The conventional design of beam-shaping filters and a body-centered patient positioning strategy does not take into account the fact that clinical interest in cardiac imaging is limited to the heart: an off-center subsection of the larger chest cavity.…”

Section: Main Text Introductionmentioning

confidence: 99%

Heart-centered positioning and tailored beam-shaping filtration for reduced radiation dose in coronary artery calcium imaging: a MESA study

Colvert

Rigolli

Craine

et al. 2021

Preprint

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Purpose: Cardiac CT has a clear clinical role in the evaluation of coronary artery disease and assessment of coronary artery calcium (CAC) but the use of ionizing radiation limits clinical use. Beam shaping 'bow-tie' filters determine the radiation dose and the effective scan field-of-view diameter (SFOV) by delivering higher X-ray fluence to a region centered at the isocenter. A method for positioning the heart near the isocenter could enable reduced SFOV imaging and reduce dose in cardiac scans. However, a predictive approach to center the heart, the extent to which heart centering can reduce the SFOV, and the associated dose reductions have not been assessed. The purpose of this study is to build a heart-centered patient positioning model, to test whether it reduces the SFOV required for accurate CAC scoring, and to quantify the associated reduction in radiation dose. Methods: The location of 38,184 calcium lesions (3,151 studies) in the Multi-Ethnic Study of Atherosclerosis (MESA) were utilized to build a predictive heart-centered positioning model and compare the impact of SFOV on CAC scoring accuracy in heart-centered and conventional body-centered scanning. Then, the positioning model was applied retrospectively to an independent, contemporary cohort of 118 individuals (81 with CAC>0) at our institution to validate the model's ability to maintain CAC accuracy while reducing the SFOV. In these patients, the reduction in dose associated with a reduced SFOV beam-shaping filter was quantified. Results: Heart centering reduced the SFOV diameter 25.7% relative to body centering while maintaining high CAC scoring accuracy (0.82% risk reclassification rate). In our validation cohort, imaging at this reduced SFOV with heart-centered positioning and tailored beam-shaping filtration led to a 26.9% median dose reduction (25-75th percentile: 21.6 to 29.8%) without any calcium risk reclassification. Conclusions: Heart-centered patient positioning enables a significant radiation dose reduction while maintaining CAC accuracy.

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Precise and Automatic Patient Positioning in Computed Tomography

Abstract: Automatic individualized patient positioning using a 3D camera allows for accurate patient centering as compared with manual positioning, which improves radiation dose utilization.

Cited by 70 publications

References 22 publications

The Improvement of Patient Centering in Computed Tomography Through a Technologist-Focused Education Initiative

The Improvement of Patient Centering in Computed Tomography Through a Technologist-Focused Education Initiative

Impact of additional mattresses in emergency CT on the automated patient centering proposed by a 3D camera: a phantom study

Heart-centered positioning and tailored beam-shaping filtration for reduced radiation dose in coronary artery calcium imaging: a MESA study

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