Nuclear Medicine Now Safer Than Ever

The number of nuclear medicine procedures has increased by 36% over the last 10 years. 240 NHS sites around the country now use nuclear medicine, mostly for diagnostic scans on areas such as bone, lung perfusion, myocardium and the kidneys. Nuclear medicine is also used in cancer and thyroid therapy.

For most diagnostic procedures, radioactive compounds are injected into the body so that physiological images can be made with gamma cameras. Of course, the exact radioactivity of the dose is crucial, not only to the ultimate safety of the patient but also to the quality of the procedure. A low dose can result in inconclusive images whereas a high dose could cause harm to the patient.

A new instrument, called 'Fidelis', allows medical physicists to check their in-house instruments against the UK national standards for radioactivity. Once confident that their own instruments are measuring activity correctly, the right dose should always be given to the patient.

The instrument is comprised of an ionisation chamber designed by the National Physical Laboratory (NPL), the UK's national measurement institute and a brand new computer-controlled electrometer module from Southern Scientific Ltd (which manufactures and sells the instrument). An ionisation chamber is a gas filled enclosure between two conducting electrodes. When a radioactive source is placed near to the enclosure, gamma-rays emitted by the source ionise the gas -- thus creating a current that can be measured by the electrometer.

Previously hospitals have used off-the-shelf Radionuclide Calibrators which needed re-calibrating every time new applications for nuclear medicine or a new design of vial came on stream. With Fidelis, this problem is solved.

'The ionisation chamber is an identical version of the master chamber here,' says Piers de Lavison, the Head of Radionuclide Metrology at NPL. 'It's like having NPL in a box -- it is a great example of how our work contributes to quality assurance in healthcare, something that touches all our lives.'