Radiological hazards to patients : second report of the Committee.

  • Great Britain. Committee on Radiological Hazards to Patients
Date:
1960
Catalogue details

Licence: Public Domain Mark

Credit: Radiological hazards to patients : second report of the Committee. Source: Wellcome Collection.

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    PART LI. DETERMINATION OF THE GENETIC DOSE TO THE POPULATION A. General diagnostic radiology General plan of survey 12. If the mutational effect of radiation is proportional to the dose received by the germ cells and is irreversible, the importance of a given dose will depend upon age. The potential effect of the dose on future generations will be greatest in a young person having a high expectancy of future parenthood, less in an older person and nil at an age when child expectancy has ceased. A genetic dose to the individual is therefore defined as the dose to the gonads, adjusted to allow for the child expectancy of that individual. The genetic dose to the population is then defined as the gonad dose which, if given to every member of that population, would have the same effect as the sum of the individual doses actually received.* 13. The determination of the genetic dose to the population from diagnostic radiology is based on three sets of information, (dq) statistical data of the number and types of radiological examinations carried out per year, in relation to the sex and ages of persons examined, (5) physical information on the average dose to the gonads for each type of examination which is representative of radiological practice throughout the country, and (c) fertility factors giving the average child expectancy, i.e. the average number of children to be expected subsequent to any given age. The required statistical data were obtained by means of questionnaires issued in May and December, 1957. The collection of the physical data was undertaken on a large scale by hospital physicists in all the hospital regions, some 13,800 measurements being made in 130 hospitals selected to give a representative cross-section of radiological practice in hospitals and chest clinics. The fertility data have been calculated from the 1951 census for England and Wales corrected to apply to 1956. 14. The dose to the male gonads has been measured directly and that to the female gonads has been derived either from a measurement of the dose received at a point on the abdomen or from the measured skin dose at the centre of the * The annual genetic dose, G, to the population is defined as the summation over all groups of the product of the average annual gonad dose D,; received by each person in age group 1, multiplied by the average chiid expectancy P; of the group, multiplied by the number of individuals N, in the group and divided by the expected number of offspring in the population :— yD; P; N; SPN, This is the same as the summation carried out for the exposed persons in each group, numbering N;x and receiving average gonad dose Djx, divided by the expected number of offspring in the whole population :— Da Dix P; Ne XP; Ni Both expressions assume the child expectancy P; for the whole group applies equally to the exposed fraction of the group.
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