Radiation and risk

The NEJM carries a concerning article: a woman having a CT of head was exposed, accidentally, to a radiation overdose. She became unwell afterwards, and she’s suing. However the article also points out that new imaging techniques, getting more information about brain structures and blood flow mean that radiation doses from scans can now be more -rather than less- than in the past.

I find this part of the paper, about CT scanning in the States, especially disturbing:

“..the threshold for use is so low that many tests now obtained are unlikely to enhance the patient’s health or clinical decision making. Ironically, technical improvements have led to increases in the identification of incidental (and almost certainly irrelevant) findings that result in follow-up CT scan for survellience. Currently, each year in the United States, approximatly 10% of the population undergoes a CT scan each year with a total of 75million scans conducted…”

10 % of the population! Ten percent! No doubt some of these scans are screening scans, when the well but nevertheless concerned US customer decides that he or she would like a check-up, pays for one, and exposes him or herself to radiation. It’s one thing getting a scan because you have symptoms that could represent a serious illness. It’s another to have a scan as a ‘check up – this radiation does not come with good evidence of benefit. Are customers told about the harms? I think not. Earlier on in the NEJM paper the risk of cancer from a CT scan – ie the risk you are exposed to because of the radiation – is given as 1 in 80. Any figure like this is an estimate, but given the potential for large scale harm in a country in love with CT scanning has to be taken seriously.  If you look at the NHS Breast Screening website you will find figures estimating breast cancers caused by the screening programme. Neither is this something women are routinely told about.

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