In 2001, Wilde and colleagues reviewed the role of radiation awareness in cardiology in general.¹ They described the legislative framework and its consequences, particularly the then novel Ionising Radiation (Medical Exposures) Regulations 2000 (IRMER).² In the cardiac catheterisation laboratory, cardiologists act as “referrers”, “practitioners”, and “operators” under the regulations. As practitioners, they are responsible for the act of justification for any exposure, which can be partitioned into three questions that demand answer:

• Does the investigation proposed answer the clinical question set by the referrer?

• Could the same question be answered by an alternative non-ionising technique?

• Do the benefits of the procedure outweigh the individual detriment of the radiation dose?

IRMER fits with disciplines where the practitioner is often in the best position to rule on questions 1 and 2—for example, in radionuclide imaging. In the cardiac catheter laboratory they are more a matter of specialist cardiological knowledge. Question 3 requires deeper knowledge of radiation risk. Even so, it is not an easy task to reconcile small but significant radiation risks with the clinical risk of not doing the procedure if no non-ionising alternative is available. Whenever serious congenital or acquired heart disease is present, the decision to justify is relatively easy to make, as the condition is usually life threatening. In less serious disease, or in the younger patient when disease is being screened for and may not be present, the decision is less easy. There is no binding legislation or direction to help; IRMER simply demands that someone competent makes the decision.

The other situation that requires a difficult balance is when alternative ionising procedures are available. For example, it is becoming clear that multidetector computed tomography (CT) can produce images of the coronary arteries that compete with selective coronary angiography, but at a higher radiation dose. …