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Congress: ECR25
Poster Number: C-16314
Type: Poster: EPOS Radiologist (scientific)
Authorblock: D. Penka1, N. Egenrieder1, S. Tschauner2, A. P. Wunderlich1, M. J. Beer1; 1Ulm/DE, 2Graz/AT
Disclosures:
Dominik Penka: Nothing to disclose
Nadine Egenrieder: Nothing to disclose
Sebastian Tschauner: Nothing to disclose
Arthur Peter Wunderlich: Nothing to disclose
Meinrad Johannes Beer: Nothing to disclose
Keywords: Thorax, Conventional radiography, Digital radiography, Image manipulation / Reconstruction, Computer Applications-General, Radiation safety, Quality assurance
Methods and materials

For this retrospective study, conventional chest radiographs of 500 adult patients from everyday clinical practice from the months of April and May 2023 were analyzed, 250 of which were taken in the upright position and 250 in the supine position at the University Hospital of Ulm (105 women and 145 men in the standing position, 102 women and 148 men in the supine position). The average age was 64 years for the images in the upright position (women and men the same, range: 19 - 96 years) and 70 years for the images in the supine position (males 68 years and females 72 years, range: 19 - 102 years).

The minimum exposure area (Minimal FieldSize: MinFS) according to the guidelines of the European Commission was analyzed in relation to the actually exposed area (AEA). The images were analyzed following the procedure of Tschauner et al. [1] in the open-source image processing program ImageJ using a macro add-on programmed for this purpose. The centers of thoracic vertebral bodies 1 and 12 were marked in order to align the images with the spine. MinFS and AEA were then annotated (figure: annotations). The identification of the AEA is based on the aperture boundaries shown or - if not shown - on the edge of the image. The MinFS was determined based on the specifications of the European Commission. The entire thorax above the diaphragm and the lateral costophrenic angles on both sides had to lie within the MinFS. The areas of MinFS and AEA were compared to determine the relative overexposure.

The overexposed area was divided into smaller areas to the left, right, cranial and caudal of the MinFS to determine the direction of overexposure. A distinction was made between tissue and air in the overexposed areas. For differentiation, the gray levels of the images were transferred into a biphasic black and white image by defining a threshold in order to calculate the proportions of air and patient tissue. The threshold value was determined for each image by displaying a preview. The statistical analysis was carried out using SPSS.
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