Influence of breathing state on the accuracy of automated patient positioning in thoracic CT using a 3D camera for body contour detection

Abstract

Objective To assess the influence of breathing state on the accuracy of a 3D camera for body contour detection and patient positioning in thoracic CT. Materials and methods Patients who underwent CT of the thorax with both an inspiratory and expiratory scan were prospectively included for analysis of differences in the ideal table height at different breathing states. For a subgroup, an ideal table height suggestion based on 3D camera images at both breathing states was available to assess their influence on patient positioning accuracy. Ideal patient positioning was defined as the table height at which the scanner isocenter coincides with the patient’s isocenter. Results The mean (SD) difference of the ideal table height between the inspiratory and the expiratory breathing state among the 64 included patients was 10.6 mm (4.5) (p < 0.05). The mean (SD) positioning accuracy, i.e., absolute deviation from the ideal table height, within the subgroup (n = 43) was 4.6 mm (7.0) for inspiratory scans and 7.1 mm (7.7) for expiratory scans (p < 0.05) when using corresponding 3D camera images. The mean (SD) accuracy was 14.7 mm (7.4) (p < 0.05) when using inspiratory camera images on expiratory scans; vice versa, the accuracy was 3.1 mm (9.5) (p < 0.05). Conclusion A 3D camera allows for accurate and precise patient positioning if the camera image and the subsequent CT scan are acquired in the same breathing state. It is recommended to perform an expiratory planning image when acquiring a thoracic CT scan in both the inspiratory and expiratory breathing state. Key Points • A 3D camera for body contour detection allows for accurate and precise patient positioning if the camera image and the subsequent CT scan are acquired in the same breathing state. • It is recommended to perform an expiratory planning image when acquiring a thoracic CT scan in both the inspiratory and expiratory breathing state.

Patient Positioning Assistive Technology Applicable to the Existing Computed Tomography System: Estimation by Pixel Value of Scout Image

“…As compared with previous studies using a CT system equipped with a 3D camera, our proposed method demonstrated comparable or superior accuracy to that of the 3D camera system (Table 3). 9,11,13 Booij et al 12 stated that aligning the positioning using the camera system results in accurate patient positioning, if the camera image and subsequent CT scan are acquired in the same breathing state. Scout images are generally performed under the same breathing control as the scanning is, and thus, a difference in breathing state does not occur.…”

“…As compared with previous studies using a CT system equipped with a 3D camera, our proposed method demonstrated comparable or superior accuracy to that of the 3D camera system (Table 3). 9,11,13 Booij et al 12 stated that aligning the positioning using the camera system results in accurate patient positioning, Figure 6 shows a case of cecal cancer in a 62-year-old man with idiopathic scoliosis. As shown in the scout and axial images, the contour of the chest to the upper abdomen was greatly deformed because of scoliosis.…”

“…Some recently developed CT scanners allow for automated positioning technology using a 3-dimensional (3D) camera system 9–12 . The 3D camera, which is positioned above the patient, has an infrared light source, a sensor, and a visible light camera.…”

“…7,8 Some recently developed CT scanners allow for automated positioning technology using a 3-dimensional (3D) camera system. [9][10][11][12] The 3D camera, which is positioned above the patient, has an infrared light source, a sensor, and a visible light camera. The 3D camera measures the distance from the camera to the object surfaces and intelligently aligns the body region to be scanned with the isocenter of the scanner, ensuring precise and optimal scanning results.…”

Computed Tomography 2.0

“…Optical and depth information are processed to automatically adjust the table height to match the isocenter of the patient with the isocenter of the scanner and to support the definition of the scan range. [30][31][32][33] Manava et al 31 analyzed data from 3118 patients who underwent CT of the chest and abdomen: 1575 patients were positioned laser-guided by a radiographer, 1561 patients with 3D camera guidance. Although the radiographers were highly trained, isocenter positioning was significantly improved with the 3D camera.…”