A Study of Heart and Thoracic Size and Cardiothoracic Ratio on Chest Radiography in Digital-Radiography System

Abstract

Due to changes to Digital-Radiography system (DR system), its distance of film and object is longer than that in Film-Screen system (F/S system). However, current chest radiography exam has been the same as in F/S system. The objective of this study was to present real Heart Size (HS), Thoracic Size (TS), and Cardiothoracic Ratio (CTR) on chest Posterior-Anterior (chest PA) and chest Anterior-Posterior (chest AP) in the DR system and to determine the statistical correlation between Focal-Film Distance (FFD) and HS, TS, or CTR during chest AP. Our results revealed that HS, TS, and CTR in chest PA and chest AP of the DR system were larger than their real sizes. HS was especially magnified 8% and 22% in chest PA and chest AP, respectively. HS, TS, and CTR all had significant (p<0.05) negative correlation with FFD. In addition, HS and TS as well as HS and CTR had significant (p<0.05) positive correlation.Keywords: Chest AP, Chest PA, Cardiothoracic Ratio, Heart Size, Thoracic Size