In recent months I have had three CT scans — one of my abdomen and two of my chest. I am 83 and wondered if this many scans is dangerous?
Doreen Roberts, via email.
Radiation from X-rays and scans is, in theory, risky if you have multiple investigations, but most people get more from natural sources than medical checks.
You may know that Marie Curie, who discovered radium (the radioactive material used in X-rays), died of aplastic anaemia at the age of 66, in 1934, from her long-term exposure to it.
But to put this in perspective, in an average year, we are exposed to about 3 millisieverts (mSv, the unit of measurement) of radiation from ‘background’ sources such as radon (a gas that leaks from rocky ground, especially where there is lots of granite, limestone or sandstone) or even cosmic rays from outer space.
Radiation from X-rays and scans is, in theory, risky if you have multiple investigations, but most people get more from natural sources than medical checks
X-ray images are created by passing ionising radiation through the body, but modern methods use much lower doses.
This also applies to CT scans (computerised tomography) which were first developed at the end of the 1970s. CT scans do require a higher dose of radiation than plain X-rays, but for the most part, exposure is still relatively low. For example, a typical chest X-ray may require just 0.1 mSv, while a low-dose CT lung scan involves around 1.5 mSv.
According to Cancer Research UK, a CT scan of the abdomen or pelvis can involve higher exposure — up to around 10 mSv.
But the point to remember here is that the medical information your doctors have gained from those three CT scans outweighs significantly the risk of any future health damage from the ionising radiation — so please don’t worry.
CT scans do require a higher dose of radiation than plain X-rays, but for the most part, exposure is still relatively low
I have white spots at the back of my mouth. My GP diagnosed oral thrush and has repeatedly prescribed the anti-fungal drug fluconazole, but it always returns after a few weeks. Could my tablets for osteoporosis and a daily steroid inhaler to control my asthma be to blame?
Emily Harris, Cambridgeshire.
This is indeed oral thrush – an infection of the mouth and throat caused by a yeast called Candida albicans.
The white flecks, if brushed off with a microbiology
