Asymptomatic coronary artery disease detection: update 1996. A screening protocol using 16-lead high-resolution ECG, ultrafast CT, exercise testing, and radionuclear imaging

Cancer risks from diagnostic radiology

In recent years, there has been a rapid increase in the number of CT scans performed, both in the US and the UK, which has fuelled concern about the long-term consequences of these exposures, particularly in terms of cancer induction. Statistics from the US and the UK indicate a 20-fold and 12-fold increase, respectively, in CT usage over the past two decades, with per caput CT usage in the US being about five times that in the UK. In both countries, most of the collective dose from diagnostic radiology comes from high-dose (in the radiological context) procedures such as CT, interventional radiology and barium enemas; for these procedures, the relevant organ doses are in the range for which there is now direct credible epidemiological evidence of an excess risk of cancer, without the need to extrapolate risks from higher doses. Even for high-dose radiological procedures, the risk to the individual patient is small, so that the benefit/risk balance is generally in the patients' favour. Concerns arise when CT examinations are used without a proven clinical rationale, when alternative modalities could be used with equal efficacy, or when CT scans are repeated unnecessarily. It has been estimated, at least in the US, that these scenarios account for up to one-third of all CT scans. A further issue is the increasing use of CT scans as a screening procedure in asymptomatic patients; at this time, the benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established.

The use of pulmonary function testing in piloting, air travel, mountain climbing, and diving

Millions of people engage in occupational or leisure activities at high altitude or at variable depths below sea level. This article presents an overview of the utility of pulmonary function testing in evaluating complications and other consequences of exposure to high and low pressure environments. The authors review recent literature concerning expected changes in pulmonary function with hyperbaric and hypobaric exposures. The article provides guidance for clinicians evaluating mountain climbers, pilots, aircrew members, airline passengers and deep sea divers.