Quantitative Evaluation of Patient Movement during Simulated Acquisition of Cephalometric Radiographs

Abstract

The objective of this study was to perform the quantitative three-dimensional analysis of the patients' movements at the different time points during the simulated acquisition of cephalometric radiographs. Fifty-three subjects (32 men, 21 women) were divided into four groups according to their age (Group 1: 9-12, Group 2: 13-19, Group 3: 20-25, and Group 4: 26-30 years old). The experiment (Exp) consisted in providing the subjects with three different kinds of verbal instructions as follows; Exp 1: they were simply instructed not to move, Exp 2: detailed instructions were provided, and Exp 3: they were specifically instructed to clench their molars. The amount of their movement during the 20 s of the cephalomatric X-ray exposure was measured using an optical marker and tracker. The maximum movement was analyzed three-dimensionally at 0.5, 2, 5, 10, 15, and 20 s. There was minimal vibrating movement every 0.3-0.5 s and relatively large movement every 3-5 s. The youngest group showed the largest amount of movement among the four age groups, and their movement was more significant in the up and down direction (pG0.05). There was no significant difference in the amount of movement according to the instructions. The longer exposure time showed the larger amount of the movement. Children can show the significant movements during X-ray taking, and the longer exposure time can also result in the larger movement during acquisition of cephalometric radiographs. Therefore, the shorter exposure time is recommended in order to improve image quality.

Laser-driven x-ray and proton micro-source and application to simultaneous single-shot bi-modal radiographic imaging

“…Both reference shots on foils show the familiar broadband spectra; their emission angle is limited around the target normal and the laser propagation direction, respectively. For the thin-foil target, the maximum proton kinetic energy exceeds 60 MeV at much reduced particle counts around~10 9 protons/(MeVsr).…”

“…Hence, the most common method to combine information from both has been to use complex algorithms, registering images obtained in completely separate image acquisition processes on top of each other 7,8 . Different acquisition geometries for both modalities, or dynamic objects, e.g., living organisms 9 or plasma-instabilities 10 , represent natural challenges that could lead to imperfections in the resulting combined images. In parallel to advances in imaging, soon after the construction of the first laser 11 , laser-driven particle 12 , and secondary light sources 13 have been studied.…”

Image-stitching artefacts and distortion in CCD-based cephalograms and their association with sensor type and head movement: ex vivo study

“…5 Image artefacts are among the possible causes that could interfere with the true representation of the patient's anatomy in cephalograms. [5][6][7][8] When the radiation source and the image receptor move during image acquisition, as it is common for most digital cephalometric units, the image is more likely to include artefacts. [8][9][10] Most digital cephalometric units use a collimator with a narrow, line-shaped slit opening that exposes the head in a continuous exposure, and move either horizontally from the nose to the back of the head, or vertically from the top of the head to the chin.…”

“…[5][6][7][8] When the radiation source and the image receptor move during image acquisition, as it is common for most digital cephalometric units, the image is more likely to include artefacts. [8][9][10] Most digital cephalometric units use a collimator with a narrow, line-shaped slit opening that exposes the head in a continuous exposure, and move either horizontally from the nose to the back of the head, or vertically from the top of the head to the chin. 8 Some of the digital cephalometric units used in dentistry have acquisition sensors, which are smaller than the requested FOV, and the final image is composed of the data originating from multiple sensors.…”

“…[8][9][10] Most digital cephalometric units use a collimator with a narrow, line-shaped slit opening that exposes the head in a continuous exposure, and move either horizontally from the nose to the back of the head, or vertically from the top of the head to the chin. 8 Some of the digital cephalometric units used in dentistry have acquisition sensors, which are smaller than the requested FOV, and the final image is composed of the data originating from multiple sensors. [10][11][12] When the segments of a cephalogram are blended to form a single image, image-stitching artefacts may appear.…”