L 12: Effect of radiation on Embryo or Fetus

Question 1

Radiation effects on embryo/fetus

Answer 1

1. Lethal effects
2. Malformations
3. Growth disturbances without malformations

Question 2

Pre-Implantation

Answer 2

• Most sensitive stage to LETHAL effects of radiation
• No growth retardation
• If embryo survives, it grows normally
• If too many cells are killed, embryo dies

Question 3

Organogenesis

Answer 3

• Congenital abnormalities of a structural nature if irradiated
• 2 Gy to mouse during this period = 100% malformations

Question 4

Fetal malformations

Answer 4

• > 14 d. in mouse / > 6 weeks in humans
• effects on kidneys, hemotapoietic system, liver, gonads

Question 5

Imp chart to memorize

Answer 5

Question 6

Dose Limits

Boards questions

Answer 6

• Occupational of mother 0.05 rem or 5mSv (NCRP)
• Monthly limit of 0.5 mSv
• Protection is based on both stochastic effects in the fetus, not just
• deterministic effects.

Question 7

Summary

Answer 7

• Radiation exposure in utero causes effects on the developing embryo that are dose- and time of gestation-dependent.
• Results in humans and animals are similar.
• Exposure during preimplantation usually causes death of the embryo, during organogenesis leads to malformations, and during fetal period leads to growth and mental retardation.