Radiation is all around us and has been present since the beginning of time. Naturally occurring radioactive materials were discovered in 1896. Less than 50 years later, the physicist Enrico Fermi split the atom, producing the first man-made radioactive materials (Robert Brent MD). We used radioactive materials for beneficial purposes, such as generating electricity, diagnosing and treating medical problems.
Man-made source of radiation from medical, commercial and industrial activities contribute about 310mrem to the annual radiation exposure. One of the largest of these sources of exposure is a CT scan, which account for about 150mrem. Radiation can cause adverse effects, including genetic defects in the children of exposed parents or mental retardation in the children of mother exposed during pregnancy. Most diagnostic procedures expose the embryo to less than 5 rad or 50mSv. This level of exposure will not increase reproductive risks. Potential radiation effects vary depending on the fetal stage of development and the magnitude of the dose.
In the first two weeks post-conception the embryo is very resistant to the malformation effects of x-rays. The embryo is, however, sensitive to the lethal affects of x-ray, although doses much higher than 5 rad or 50mSv can cause a miscarriage. From the third to eighth week of pregnancy the embryo is in the period of early embryonic development but is not affected with birth defects, pregnancy loss, or growth retardation unless the exposure is substantially above 20 rad or 200mSv. From eighth to the fifteenth week of pregnancy, the embryo or fetus is sensitive to the effects of radiation on the central nervous system but it has to be higher than 30rad (300mSv) before an effect can be seen on the IQ of the developing embryo. Beyond the 20th week of pregnancy, when fetus is completely developed it has become more resistant to