Pregnancy and radiation

Radiation Biology:

Radiation in uteri? (10)   Figure 25.20

Severity of In-utero response to radiation exposure is related to TIME AND DOSE –

·         dose rate, quality, quantity and stage of development of the fetus.

TIME      Fetus is more sensitive early in pregnancy than late in pregnancy

Preimplantation               0-2 weeks           resorption of embryo – “all or nothing principle”

No other noticed response – (relative hypoxic state of embryo – contribute to radio resistance)

                                                                                Spontaneous abortion 30-50%

                                                                               

Major Organogenesis    2-8 weeks           period of major organ development

Congenital abnormalities coincide with the major development of various organs:

·         Early: skeletal deformities,

·         Later: Neurological deficiencies

·         1Gy associated with high incidence of CNS abnormalities

Fetal Growth stage         2^nd and 3^rdTrimester      

Childhood cancer (6% per Gy)/Malignant disease of childhood

§  Childhood leukemia – RR (Relative risk) =1.4

§  Low risk of congenital malformations

§  Growth retardation >100mGy

§  Abnormalities of the nervous system

                                                                               

Dose:    The higher the dose the more severe the response

                >200 rad – each of the effects above will occur

                <25 rad – unlikely to abort in first 2 weeks

                0.1% of conceptions (pregnancy) resorbed after a dose of 10 rad

Effort made to reduce the radiation exposure to the fetus of radiation workers and public – ALARA

·         0.5 mSv per month from the time a pregnancy is reported (5mSv in 9 months)

Enquire of female patients if they are pregnant