An x-ray from this view is taken with the patient lying down on the side. it helps to assess suspected fluid (pleural effusion), and demonstrate whether the effusion is loculated or mobile. you can look at the non-dependent hemithorax to confirm a pneumothorax. Plain chest x-rays miss a diagnosis of lung cancer far too often. there are surprisingly few recent studies looking at the actual incidence of \"missed diagnoses\" of lung cancer, but the research that has been done is sobering. it can be frightening to hear about the incidence of missed lung cancers on chest x-rays, but this doesn't mean you need despair. as noted above, ct screening can decrease the risk of death from lung cancer among those who have risk factors. yet even for those without these risk factors, there are several things you can do: chest x-rays may be helpful in finding a lung cancer but cannot exclude the presence of cancer. in contrast, a normal chest x-ray may convey the false reassurance that...