Radiation Exposure of Children in Pediatric Radiology Part 4: Entrance Doses Achieved During the X-ray Examination of the Chest

Purpose: Reconstruction of the entrance dose from radiographic settings and exposure data acquired during chest X-ray examinations of children of various age groups performed at Dr. von Hauner's Kinderspital (children's hospital of the university of Munich, DvHK), between 1976 and 2007. Comparison of these entrance doses with dose values published by other radiological departments. Materials and Methods: All relevant data of all X-ray examinations performed since 1976 at DvHK, in particular the individual radiographic settings and dose measurements (dose area product), were stored electronically in a database. After 30 years of data gathering, the database now covers 305 107 radiological examinations (radiographs and fluoroscopies), especially 119 150 chest radiographs of all age groups. With the computer program PADOS developed by the authors, a specific algorithm was created to calculate radiation doses from the database using the individual dose area product values and other known exposure parameters. Results: The entrance dose values of the chest Xrays at DvHK were able to be reduced in the last 30 years by a factor of 2 to 3 depending on the patients' age group and the beam projection. In our sample, the measured dose values for chest Xrays were far below the reference dose levels set by the Bundesamt fur Strahlenschutz (BFS) in 2003 and far below the entrance dose values reported by other radiological departments in Europe as well. Nevertheless, in the last years an increase in the entrance doses has been observed that easily corresponds to the introduction of a digital storage phosphor system in the department. Conclusion: Chest radiography is a frequently performed X-ray examination at a very low dose level. However, because of its frequency, it makes a notable contribution to the collective radiation risk of the population. Therefore, for the reduction of the collective radiation exposure, the optimization of the dose level required by chest Xrays continues to be of great importance. A reduction can be achieved with a consistent and simultaneous optimization of beam quality, exposure field and image processing system. Because of the statistically relevant number of analyzed cases, the entrance dose values presented in this paper can provide a basis for the definition of new reference dose levels.