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RADIATION & PREGNANCY

RADIATION & PREGNANCY. By. ABDULRAOF MAIMANI, ABR, ABNM Radiology Dept. King Abdulaziz University Hospital Jeddah. RADIATION & PREGNANCY. RADIATION & PREGNANCY.

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RADIATION & PREGNANCY

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  1. RADIATION & PREGNANCY By ABDULRAOF MAIMANI, ABR, ABNM Radiology Dept. King Abdulaziz University Hospital Jeddah

  2. RADIATION & PREGNANCY

  3. RADIATION & PREGNANCY Diagnostic & Therapeutic procedures causing exposure of the abdomen of women likely to be pregnant should be avoided unless there is a strong clinical indications

  4. STOCHASTIC EFFECTS

  5. STOCHASTIC EFFECTS Stochastic Effects are caused by mutations in a cell or in small group of cells

  6. STOCHASTIC EFFECTS The absorbed dose is not important for severity of the effect, but for probability of the effect depend on the absorbed dose

  7. STOCHASTIC EFFECTS Examples of stochastic effect malignancies and hereditary effects. No threshold dose.

  8. DETERMINISTIC EFFECTS

  9. DETERMINISTIC EFFECTS Result from killing of cells. There is a threshold dose. e.g.: Fetal death, gross malformation

  10. DETERMINISTIC EFFECTS Pre-Implantation: 0 – 8 days post-conception Death of embryo 5 cGy rats 0.9 cGy mice Threshold dose: 10 cGy

  11. DETERMINISTIC EFFECTS Embryonic = 9 – 60 days Risk of embryonic death remain. higher threshold dose. Risk of malformation is in the order of 0.5% per cGy Threshold dose = 10 cGy Small head size 1% per cGy Threshold dose = 10 – 20 cGy Growth retardation threshold dose = 5 – 25 cGy

  12. DETERMINISTIC EFFECTS Early fetal = 61 – 104 days Threshold dose for lethality = 0.5 Gy Mental retardation 0.4% per cGy Threshold dose = 12 cGy 0.3 IQ points per cGy Unprovoked seizures 4 – 8 cGy threshold dose All seizure 11 – 15 cGy threshold dose

  13. DETERMINISTIC EFFECTS Mid fetal = 105 – 175 days post-conception Risk of fetal death remain in this period, but seems to be lower than in the earlier period Threshold doses 0.65Gy for mental retardation 0.5 Gy for small head size 0.5 Gy for growth retardation

  14. DETERMINISTIC & EFFECTS Late fetal = more than 175 days post-conception Risk of fetal death seem to be low Risk of malformation & mental retardation are negligible

  15. STOCHASTIC EFFECTS

  16. STOCHASTIC EFFECTS Excess Fatal Cancer Natural prevalence of fatal childhood cancer up to the age of 15-year (1:1300) 0.03% per cGy 0.04% - 0.05% cGy Higher risk for those irradiated in the second trimester than those in third trimester

  17. TUMOURS

  18. TUMOURS Leukemia, tumours of CNS

  19. RISK OF GENETIC DISEASE

  20. NATURAL PREVALENCE IS 1.6%

  21. Maternal age > 35 Total chromosal abnormality is 2.26% & 9.6% age above 45 1 cGy 0.012% It is clear that risk of radiation effects is smaller than risk effect by age

  22. Normal risk that a child will have congenital defect is 3% – 6%

  23. When dose exceed 10 cGy probability increase to 10%

  24. A dose of 10 cGy – 20 cGy is radiologically not accepted as an indication for an abortion

  25. Dose to the embryo of 20 cGy at 3-Weeks could be accepted as a reason for “Therapeutic Abortion” Whalen & Batter

  26. Dose from Nuclear Medicine Diagnostic test is at’s highest estimate 1 cGy

  27. Threshold dose for deterministic effect is in the order of 10 cGy – 60 cGy

  28. The risk of cancer induction is 0.03% - 0.06% per cGy If patient received 0.5 cGy (1.5 – 2.5) out of 10,000 Risk of genetic defect (0.5 – 5) out of 10,000

  29. COMPARISON OF THE ESTIMATED MEAN & RANGE OF FETAL DOSE Mean values in square brackets & values curly brackets (representing only maximum values) are adapted from Sharp et al a – Reported mean & range are adapted from Shrimpton et al b – Reported mean & range are adapted from Wagner et al

  30. COMPARISON OF THE ESTIMATED MEAN & RANGE OF FETAL DOSE Mean values in square brackets & values curly brackets (representing only maximum values) are adapted from Sharp et al a – Reported mean & range are adapted from Shrimpton et al b – Reported mean & range are adapted from Wagner et al

  31. MEAN FETAL ABSORBED DOSE PER EXAMINATION (GXR) a – Average for the various projections b – For only one examination Contd…

  32. MEAN FETAL ABSORBED DOSE PER EXAMINATION (GXR) a – Average for the various projections b – For only one examination

  33. MEAN FETAL ABSORBED DOSE PER EXAMINATION (CT)

  34. COMPARISON OF THE ESTIMATED MEAN & RANGE OF FETAL DOSE MIBG, Metaiodobenzylguanidine; MDP, methylene diphosphonate; HDP, hydroxydiphosphonate; MAA, macroaggregated albumin; MAG3, mercaptoacetyltriglycine

  35. COMPARISON OF THE ESTIMATED MEAN & RANGE OF FETAL DOSE MIBG, Metaiodobenzylguanidine; MDP, methylene diphosphonate; HDP, hydroxydiphosphonate; MAA, macroaggregated albumin; MAG3, mercaptoacetyltriglycine

  36. 131I-Therapy &Pregnancy

  37. 131I-Therapy & Pregnancy 10 – 12 Weeks thyroid gland of fetus start to function. For every 10mCi the mother receive, the fetus will receive 1 cGy. .

  38. Radiation Worker’s & Pregnancy Radiation worker who is pregnant should not receive more than 1 mSv during the whole pregnancy.

  39. CONCLUSION

  40. CONCLUSION For diagnostic examination whether radiological or Nuclear Medicine, the risks for the fetus are Extremely low For therapeutic dose The doses may be high enough to cause unacceptable tissue damage.

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