atoms, template CXR NORMAL HEARTIn the P-A projection the normal heart takes up about 30% of the diaphragmatic surface. Similarly in the lateral projection the heart takes up a third of the diaphragmatic surface. In addition the heart takes up the bottom 1/3 of the retrosternal air space.Ashley Davidoff MD NORMAL HEART ? GOOD INSPIRATIONThis a normal frontal chest X ray of a 40 year old male with a good inspiration.Ashley Davidoff MD NORMAL HEART ? MILD PECTUS EXCAVATUMThis a normal lateral chest X ray of a 40 year old male with mild pectus excavatumAshley Davidoff MD SAME PATIENT – NORMAL HEART ? POOR INSPIRATIONThis a normal frontal chest X ray of a 40 year old male with a poor inspiration which results in the false appearance of cardiomegaly and crowding of the lung markings.Ashley Davidoff MD