Introduction: Standard chest imaging is the most common examination in general radiology. When imaging the thoracic organs, we irradiate a large area of the body. It follows that a possible additional radiation exposure occurs if the investigation is repeated. The placement and delimitation of the field of view are therefore particularly important here. Purpose: The purpose of the master's thesis was to improve the placement and screening of the X-ray beam with the help of orientation points on the body. This can reduce the radiation field and at the same time reduce the number of failed exposures. Methods of work: In the research, we considered 4 orientation points and 6 target structures. On 2544 chest radiographs in posterior-anterior projection, three engineers performed measurements independently. We recorded the relative positions of the points on the radiographs, which we later converted into relative distances between them. The distances were corrected for a distance of 5 cm from the detector. Results: Because the relative positions of the points gave us a very large database, we did not limit ourselves to the key questions in the results, but we measured many relative distances. Thus, we obtained statistics of the position of the lungs with respect to the skeleton of the thorax. The relative position of the lungs relative to the skeleton allows us to screen and center with the help of orientation points. In 95% of cases, the pulmonary apexes were located 1.2 cm below the mandrel 7 of the cervical vertebra and 3.1 cm above the acromioclavicular joints. If we want to show the entire lung with the posterior phrenicocostal sinuses, the central beam must be set 3.5 cm caudally from the Th7 mandrel or 1.1 cm caudally from the Th7 mandrel if we want to show the lungs to the anterior phrenicocostal sinuses. The width of the lungs almost always requires a horizontal position of the image receiver. Discussion and Conclusion: Most of the literature mentions the image center at Th7. Through research, we have proven that the optimal center is lower. We also better defined the optimal edge of the image or the size of the lungs with the help of a skeleton. Adherence to the imaging center and the upper edge of the lungs may reduce the dose per patient and the number of repetitions of imaging.
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