NEW DELHI: Children subjected to CT scans with high radiation doses face a three time increased risk of suffering from leukaemia and brain cancer during their lifetime.
In the most conclusive evidence till date, a study published in British medical journal Lancet on Wednesday says radiation exposure received from two to three CT scans of the head in childhood (aged under 15 years) — giving a cumulative dose of around 60 milli-Grays (mGy) can triple the risk of later developing brain cancer.
On the other hand, around 5 to 10 such scans (cumulative dose around 50 mGy) could triple the risk of developing leukemia.
The authors from the Newcastle University studied around 180,000 patients who underwent a CT scan between 1985 and 2002 from 70% of the UK's hospitals.
These data were then linked to cancer incidence and mortality reports in the UK National Health Service Registry between 1985 and 2008.
From this, they calculated excess incidence of leukemia and brain tumours. The dose of radiation received by the brain and bone marrow varied by age and body part scanned. A total of 74 from 178,604 patients were diagnosed with leukemia and 135 of 176,587 were diagnosed with brain cancer.
The authors say that, of every 10,000 people between the ages of 0-20 years receiving 10 mGy from a CT scan, there would be about one expected excess leukemia case, whereas there were would be one excess case of brain cancer for every 30,000 people. Applying the dose estimates for one head CT scan before the age of 10 years, this would translate into approximately one excess case of leukaemia and one excess brain tumour per 10,000 patients in the decade after the first exposure.
In the most conclusive evidence till date, a study published in British medical journal Lancet on Wednesday says radiation exposure received from two to three CT scans of the head in childhood (aged under 15 years) — giving a cumulative dose of around 60 milli-Grays (mGy) can triple the risk of later developing brain cancer.
On the other hand, around 5 to 10 such scans (cumulative dose around 50 mGy) could triple the risk of developing leukemia.
The authors from the Newcastle University studied around 180,000 patients who underwent a CT scan between 1985 and 2002 from 70% of the UK's hospitals.
These data were then linked to cancer incidence and mortality reports in the UK National Health Service Registry between 1985 and 2008.
From this, they calculated excess incidence of leukemia and brain tumours. The dose of radiation received by the brain and bone marrow varied by age and body part scanned. A total of 74 from 178,604 patients were diagnosed with leukemia and 135 of 176,587 were diagnosed with brain cancer.
The authors say that, of every 10,000 people between the ages of 0-20 years receiving 10 mGy from a CT scan, there would be about one expected excess leukemia case, whereas there were would be one excess case of brain cancer for every 30,000 people. Applying the dose estimates for one head CT scan before the age of 10 years, this would translate into approximately one excess case of leukaemia and one excess brain tumour per 10,000 patients in the decade after the first exposure.
