| Autor: |
Clarkson, D. McG., Brennen, S. E. |
| Zdroj: |
The British Journal of Radiology; November 1987, Vol. 60 Issue: 719 p1119-1123, 5p |
| Abstrakt: |
It is a principle of radiological protection that radiation exposure to a fetus should be avoided or minimised. Nevertheless, instances do occur when a fetus irradiated, for example when a woman's clinical condition requires urgent radiological investigation or when the pregnancy is undiagnosed.Radiation Protection Advisers are often requested to make an estimate of the dose to the fetus in these cases. The fetal dose is assumed to be equal to the dose to the uterus; this assumption is valid for irradiation in early pregnancy.The determination of the dose to the uterus is specific example of organ dosimetry. Organ doses may be determined by: direct measurement at the site of interest; measurement in a phantom (if available); direct measurement at the skin followed by a calculation of dose at depth; or measurement of exposure in the X-ray beam followed by calculation of internal dosage from published data.For retrospective dose studies, where a phantom not available, fetal doses can be estimated most easily by the last method. The method uses either central-axis depth-dose data with backscatter factors or tissue–air ratio (TAR) data. The TAR data method has been used as this method is the same whether the organ of interest is exposed to both primary and scattered radiation or only to scattered radiation. The procedure conventionally includes manual calculations which are both time consuming and prone to error. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
