X-rays were discovered in the late 1880s, but one of the biggest advances arrived in the 1970s, with the introduction of CT (Computed Tomography) scans. Whereas a plain x-ray takes just one picture, during a CT scan many x-ray images can be taken of cross sections of our body. To a patient and “layman”, It’s a wonder of modern medicine that when something wrong is expected, a doctor no longer needs to cut a patient open just to see what’s going on – they can now take pictures of insides to establish the diagnosis. In fact, it is said that the large sales generated by Beatles records enabled EMI to establish EMI Central Research Labs, Great Britain. It was there in 1972 that Sir Godfrey Hounsfield invented the first commercially viable CT scanner. Sir Hounsfield and Alan McLeod McCormick shared the Nobel Prize for Medicine in 1979 for the invention of CT scanning.

From humble beginnings in 1972, today a CT scan machine represents the forefront of fusion of physics and medicine, with development of powerful computers and electronics enabling Radiologists to quickly establish diagnosis in virtually all body systems. The modern CT scanners are so fast that they take just a few seconds to complete and offer an alternative to even coronary angiograms.

Doctors everywhere have used it to diagnose patients and save lives. An estimated 72 million scans were performed in the United States in 2007. Both fast and painless, it’s probably no surprise that Australia, like many other countries, is seeing growth in the use of CT every year. However, with increased use, there have been concerns of possibility of tumours developing from the radiation used for CT scans. Many articles have appeared in the popular media about these risks, leading to concerns amongst the patients and physicians alike.

The estimation of risk from radiation is a grey area as so far adverse effects have been seen in the context of nuclear bomb explosion and accidents involving nuclear facilities, which have resulted in a very high dose of radiation exposure. A recent study in the reputed journal Lancet in June 2012 reported that use of CT scans might almost triple the risk of leukaemia and brain cancer. At the same time, the journal reported that as these cancers are relatively rare, the cumulative absolute risks are small: in the 10 years after the first scan for patients younger than 10 years, one excess case of leukaemia and one excess case of brain tumour per 10 000 head CT scans is estimated to occur.

Following the recognition of these concerns, there have been many technological innovations in the recent years enabling reduced radiation dose during CT examinations. Also, the ALARA principle – As Low As Reasonably Achievable, has been implemented by the Royal Australian and New Zealand College of Radiologists (RANZCR). RANZCR also states that we are also exposed on a daily basis through activities like driving and bike riding to risks to our health that are greater than the potential risks of radiation exposure.

At the same time, we had a recent report from Western Australia where the parents of a boy, who died in 2009 as a result of severe brain swelling related to a blocked shunt, alleged at a coronial inquest that his life could have been saved if a CT scan was performed early.

So while the debate goes on, it is essential that this powerful tool is used judiciously and radiation exposure is minimized. At the same time, it is important that panic is avoided and we do not throw out the baby with the bathwater. There is potential for recent news reports sensationalising the risks of CT scanning to do more harm than the small potential risk of CT scanning, by deterring people from undergoing medically indicated CT. While radiation exposure is undesirable, especially in children and young adults, nobody wishes missed diagnosis and delayed, inappropriate or lack of necessary treatment.