BMJ  2004;328:582 (6 March), doi:10.1136/bmj.328.7439.582-a

Letter

Ionising radiation in infancy and adult cognitive function

Wrong impression was created by study's publicity

The first 150 words of the full text of this article appear below.

EDITOR—The study by Hall et al on ionising radiation in childhood is flawed for several reasons.¹

Firstly, exposure to radiation in 1930-60 was without adequate collimation and shielding, and the machines used were far less accurate than recent models.

Secondly, the x ray treatments entailed mainly contact therapy at low (60 kVp) voltage, which means less penetration and lower energy photons, which are absorbed more in tissue. Some children were treated more than once, either by receiving several treatments for one haemangioma or by receiving individual treatments for several haemangiomas. This would have a stochastic effect. Today's average patient is not exposed to anything resembling what the paper quotes.

Thirdly, no consistent difference was seen between the two lowest dose categories (1-20 mGy and > 20-100 mGy), but the increment of exposure was limited, with median values of only 0 and 30-40 mGy. These are the maximum levels . . . [Full text of this article]

Royal United Hospital, Bath BA1 3NG drsanjuuk@yahoo.co.uk

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Relevant Article

Effect of low doses of ionising radiation in infancy on cognitive function in adulthood: Swedish population based cohort study

Per Hall, Hans-Olov Adami, Dimitrios Trichopoulos, Nancy L Pedersen, Pagona Lagiou, Anders Ekbom, Martin Ingvar, Marie Lundell, and Fredrik Granath
BMJ 2004 328: 19. [Abstract] [Full Text] [PDF]

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