PENETRATION Penetration is one of the five technical factors that help you in determining whether a radiograph is technically adequate. ADEQUATE PENETRATION If a frontal chest radiograph is adequately penetrated, you should be able to see the thoracic spine through the heart shadow. In the radiograph above, we can see the thoracic spine through the heart shadow (solid white line). UNDER PENETRATION It means that the penetration is inadequate. The radiograph will appear as too white. We will not be able to see the thoracic spine through the heart. This can lead us into making interpretation errors. 1) The pulmonary markings may appear more prominent and these can be mistaken for being due to a congestive heart failure or pulmonary fibrosis. 2) The left lung base will appear opaque thus obscuring the left hemidiaphragm. This can mimic or hide a true disease in the left lower lung field e.g. left lower lobe pneumonia or left pleural effusion. To avoid these misin