Embryonic and Fetal Effects of Radiation Exposure

Practice flashcards covering the biological sensitivity of the embryo and fetus to radiation, the stages of pregnancy in radiation protection, and specific teratogenic effects and their thresholds.

Law of Burgundy and Trivindo

A radiobiology principle stating that the most radio sensitive cells are immature, unspecialized (undifferentiated), and rapidly dividing with a high reproductive rate.

Teratogen

Anything introduced during pregnancy that impacts the typical development of a fetus, such as radiation exposure.

Teratogenic effects

Specific embryonic and fetal effects resulting from radiation exposure, organized into carcinogenic, lethal, malformation, and cerebral categories.

Carcinogenic effects

Effects where radiation exposure, even in utero, causes the development of cancer in living things.

Lethal effects

Effects such as spontaneous miscarriage that can be caused by even low doses of radiation, primarily during the early stages of pregnancy.

Malformations

Physical deformities and physical growth retardation caused by radiation damage to developing organs and appendages.

Cerebral effects

Effects involving the brain, including microcephaly (small head size), mental retardation, and developmental disorders.

Pre-implantation period

The first stage of pregnancy for radiation protection, occurring from $1$ to $10$ days post conception, before the conceptus implants into the uterine wall.

Organogenesis period

The second stage of pregnancy for radiation protection, occurring from $10$ days to $6$ weeks post conception, during which major organs are being formed.

Fetal period

The final stage of pregnancy for radiation protection, extending from $6$ weeks through birth, when organs are mostly formed and continuing to grow.

All or nothing effect

The response where radiation exposure during the pre-implantation period either causes death to the conceptus or results in no harmful effects at all.

Threshold for Lethal Effects

The effective threshold for lethal effects during the pre-implantation period is approximately $100\,mg$, with probability increasing to $80\%$ at $2\,Gs$ ($2000\,mg$).

Microcephaly

A condition characterized by a small head size that is considered both a malformation and a cerebral effect of radiation exposure.

Limb stunting

A malformation observed in animal studies involving radiation exposure during organogenesis that results in the shortening of appendages.

Anencephaly

A severe malformation where an animal is born without parts of the skull and brain.

Evisceration

A severe malformation where organs are formed outside of the body cavity.

Threshold for Malformations and Cerebral Effects

The apparent threshold for physical malformations, decreased IQ, and other cerebral effects is approximately $100\,milligray$.

Average fetal dose: AP Abdomen

An average fetal dose of approximately $3\,mG$ from direct exposure.

Average fetal dose: CT Pelvis

An average fetal dose of approximately $20\,milligram$.

Upper GI with small bowel series fetal dose

A procedure that results in a fetal dose up to approximately $40\,mG$.