Ionising radiation in infancy and adult cognitive function
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《英国医生杂志》
EDITOR—We agree with Meara et al that optimising computed tomography protocols is crucial.
Fogelholm raises the possibility of the study subjects having Sturge-Weber syndrome—cutaneous and cerebral haemangiomas linked to neurological symptoms such as epileptic seizures and mental retardation. We matched the cohort with the Swedish inpatient registry and compared the observed and expected number of admissions for epilepsy. In all, 19 boys had been admitted under this diagnosis, which was non-significantly fewer than expected. Sturge-Weber syndrome is not likely to have influenced our findings.
Ehrle says that we have ignored a large body of evidence and says that little is known about the effects of low doses of radiation or a possible threshold value. One of the most important studies in this field estimated cancer risks in 50 000 survivors of the atomic bomb, focusing on those having been exposed to < 500 mSv.1 A linear no threshold model fitted the data, but they could not exclude a possible threshold of 60 mSv.
Prabhu points out that x ray treatments during 1930-60 had less penetration than today. However, in our study only 6% received x ray treatment and the remaining patients were treated with radium-226 applicators. The envelopes of the applicators absorbed and rays and the main dose contribution to the brain came from the rays.
Prabhu also asserts that, at least in the United Kingdom, careful discussion takes place before deciding on computed tomography for young children and that only necessary examinations are conducted. Let's just hope that he is correct, that his colleagues follow his example, and that this behaviour quickly spreads outside the United Kingdom.
Per Hall, associate professor
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, S-171 76 Stockholm, Sweden per.hall@meb.ki.se
Marie Lundell, hospital physicist
Department of Hospital Physics, Karolinska University Hospital, S-171 76 Stockholm
Competing interests: None declared.
References
Pierce DA, Preston DL. Radiation-related cancer risks at low doses among atomic bomb survivors. Radiat Res 2000;154: 178-86.
Fogelholm raises the possibility of the study subjects having Sturge-Weber syndrome—cutaneous and cerebral haemangiomas linked to neurological symptoms such as epileptic seizures and mental retardation. We matched the cohort with the Swedish inpatient registry and compared the observed and expected number of admissions for epilepsy. In all, 19 boys had been admitted under this diagnosis, which was non-significantly fewer than expected. Sturge-Weber syndrome is not likely to have influenced our findings.
Ehrle says that we have ignored a large body of evidence and says that little is known about the effects of low doses of radiation or a possible threshold value. One of the most important studies in this field estimated cancer risks in 50 000 survivors of the atomic bomb, focusing on those having been exposed to < 500 mSv.1 A linear no threshold model fitted the data, but they could not exclude a possible threshold of 60 mSv.
Prabhu points out that x ray treatments during 1930-60 had less penetration than today. However, in our study only 6% received x ray treatment and the remaining patients were treated with radium-226 applicators. The envelopes of the applicators absorbed and rays and the main dose contribution to the brain came from the rays.
Prabhu also asserts that, at least in the United Kingdom, careful discussion takes place before deciding on computed tomography for young children and that only necessary examinations are conducted. Let's just hope that he is correct, that his colleagues follow his example, and that this behaviour quickly spreads outside the United Kingdom.
Per Hall, associate professor
Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, S-171 76 Stockholm, Sweden per.hall@meb.ki.se
Marie Lundell, hospital physicist
Department of Hospital Physics, Karolinska University Hospital, S-171 76 Stockholm
Competing interests: None declared.
References
Pierce DA, Preston DL. Radiation-related cancer risks at low doses among atomic bomb survivors. Radiat Res 2000;154: 178-86.