The news that hundreds of X-rays may have to be re-examined following glaring errors by a locum radiologist aged 74 is alarming, and not only for the unfortunate patients involved.

The news that hundreds of X-rays may have to be re-examined following glaring errors by a locum radiologist aged 74 is alarming, and not only for the unfortunate patients involved.

Shortages in particular specialities, including radiology, and the difficulty of attracting specialists to rural areas with a low volume of cases have made temporary staff a necessity. That has increased with the new contract which reduced hours for GPs and changes in the training process for junior doctors.This has resulted in disquieting recent practices such as doctors from outwith Scotland travelling long distances to provide weekend cover after completing a working week at home.

NHS trusts employing locum staff must be confident that they are competent and capable, including being fully versed in the latest good practice, a requisite in any profession. Experience is an advantage, but it is no substitute for technical competence regularly updated to take account of the latest techniques. It appears health boards, driven by the need to provide cover, have not fully taken on board the lessons of previous errors. Last year, for example, an audit of breast cancer care revealed that two surgeons close to retirement age in Inverclyde were continuing to use surgical biopsy as a diagnostic procedure, when modern practice is for needle biopsies.

Such use of older techniques is not life-threatening, but is not best practice. Misreading X-ray images, however, can be life-threatening if conditions such as cancerous growths are missed. Salaried doctors can request to continue working after the age of 65 and there should not be discrimination on the grounds of age.

Recently-retired doctors provide a bank of expertise that health boards should be able to call on to fill temporary gaps, but this latest blunder points to the need for much more robust procedures for ascertaining the competence of medical staff. The General Medical Council (which has no upper age limit for those on its register) is currently consulting on proposals for regular re-certification. This has obvious merits in requiring practitioners to ensure they benefit from advances in knowledge and would be of particular value to specialists who practise in rural areas without the advantage of discussions with a wide range of colleagues.

However, there is also a requirement on health boards to check doctors' fitness to practise before employing them, and it is the least that patients trusting their health to professionals should be entitled to. Failure to obtain a full pre-employment history puts filling vacancies before the interests of the patients.