title: A comparative study of collimation in bedside chest radiography for preterm infants in two teaching hospitals.
abstract: OBJECTIVE
  Unnecessary exposure of the abdomen, arms or head may lead to a substantial increase of the radiation dose in portable chest X-rays on the neonatal intensive care unit. The objective was to identify potential factors influencing inappropriate exposure of non-thoracic structures in two teaching hospitals.
  
  
  METHODS
  The study analysed 200 consecutive digital chest radiographs in 20 preterm neonates (mean gestation 25 ± 1 weeks). Demographical data, tube settings and exposure parameters were recorded. To grade the collimation, we used a scoring system with a maximum of 12 exposed non-thoracic structures. Length of gestation, age, the radiographer, years of experience in performing X-rays and the number of in situ catheters or lines, were correlated with collimation quality.
  
  
  RESULTS
  There was no significant difference between the rates of optimal images obtained in the two hospitals (0.32 vs 0.39, n.s.). Scores showed that most suboptimal images had only mildly reduced image quality (1.40 ± 1.38 vs 1.20 ± 1.43, n.s.). Length of gestation or presence of surgical drains, catheters and tubes had no obvious effects on the exposure of non-thoracic structures. Large intra-individual variation in optimal collimation (14-86%) was noted for the radiographers in both hospitals; this was unrelated to their respective years of experience.
  
  
  CONCLUSIONS
  In our study, the only identifiable factor influencing the collimation of portable chest radiographs in preterm infants was the radiographer's dedication and awareness. There were no apparent differences between the hospitals investigated. Exposure of non-thoracic structures was relatively frequent and mainly involved the proximal humeri.
authors.affiliation: Institute for Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr. 22, D-81675 Munich, Germany; Department of Radiology and Nuclear Medicine, Klinikum Memmingen, Bismarckstr. 23, D-87700 Memmingen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Stollfuss
authors.affiliation: Institute for Clinical Radiology, Department of Paediatric Radiology, Ludwig Maximillians Universität München, Lindwurmstr. 4, D-80337 Munich, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Schneider
authors.affiliation: Institute for Clinical Radiology, Department of Paediatric Radiology, Ludwig Maximillians Universität München, Lindwurmstr. 4, D-80337 Munich, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Krüger-Stollfuss
keywords: Chest X-ray; Image quality; Paediatric patients; Preterm infants; Radiation dose