RADIATION

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

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STOCHASTIC EFFECTS
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STOCHASTIC EFFECTS

• Stochastic Effects are caused by mutations in a
  cell or in small group of cells

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STOCHASTIC EFFECTS

• The absorbed dose is not important for severity
  of the effect, but for probability of the effect
  depend on the absorbed dose

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STOCHASTIC EFFECTS

• Examples of stochastic effect
• malignancies and hereditary effects.
• No threshold dose.

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DETERMINISTIC EFFECTS
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DETERMINISTIC EFFECTS

• Result from killing of cells.
• There is a threshold dose.
• e.g. Fetal death, gross malformation

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DETERMINISTIC EFFECTS

• Pre-Implantation 0 8 days post-conception
• Death of embryo 5 cGy rats
• 0.9 cGy mice
• Threshold dose 10 cGy

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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

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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

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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

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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

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STOCHASTIC EFFECTS
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STOCHASTIC EFFECTS

• Excess Fatal Cancer
• Natural prevalence of fatal childhood cancer up
  to the age of 15-year (11300)
• 0.03 per cGy
• 0.04 - 0.05 cGy
• Higher risk for those irradiated in the second
  trimester than those in third trimester

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TUMOURS
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TUMOURS

• Leukemia, tumours of CNS

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RISK OF GENETIC DISEASE
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NATURAL PREVALENCE IS 1.6
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• Maternal age gt 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

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• Normal risk that a child will have congenital
  defect is 3 6

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• When dose exceed 10 cGy probability increase to
  10

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• A dose of 10 cGy 20 cGy is radiologically not
  accepted as an indication for an abortion

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• Dose to the embryo of 20 cGy at 3-Weeks could be
  accepted as a reason for Therapeutic Abortion

Whalen Batter
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• Dose from Nuclear Medicine Diagnostic test is
  ats highest estimate 1 cGy

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• Threshold dose for deterministic effect is in the
  order of 10 cGy 60 cGy

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• 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

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COMPARISON OF THE ESTIMATED MEAN RANGE OF FETAL
DOSE
Projection Examination Estimated Fetal Dose per Examination (mGy) Estimated Fetal Dose per Examination (mGy) Estimated Fetal Dose per Examination (mGy) Estimated Fetal Dose per Examination (mGy)
Projection Examination Mean (this work) Reported Mean Range (this work) Reported Range
AP Abdomena 2.9 1.9 0.26 15.0 0.16 9.2
PA Abdomena 1.3 0.53 0.64 3.0 0.35 0.82
Abdomenb 2.6 2.5 1.4 0.26 15.0 0.25 19.0 4.2
AP Chesta lt 0.01 lt 0.01 lt 0.01 lt 0.01
PA Chesta lt 0.01 lt 0.01 lt 0.01 lt 0.01
Chestb lt 0.01 0.01 lt 0.01 0.002 0.43 lt 0.01
AP Lumbar Spinea 7.5 1.9 0.31 40.0 0.20 15.0
LAT Lumbar Spinea 0.91 0.41 0.09 3.5 0.09 3.1
Lumbar Spineb 4.2 4.0 1.7 0.09 40.0 0.27 40.0 10.0
LAT Lumbosacral Jointa 1.1 0.56 0.10 2.03 0.09 2.4
AP Pelvisb 3.4 2.0 1.1 1.4 15.0 0.55 22.0 4.0
AP Thoracic Spinea lt 0.01 lt 0.01 lt 0.01 lt 0.01 0.03
PA Thoracic Spinea lt 0.01 lt 0.01 lt 0.01 lt 0.01 0.01
Thoracic Spineb lt 0.01 lt 0.1 lt 0.01 lt 0.01 lt 0.1-0.55 lt0.01
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
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COMPARISON OF THE ESTIMATED MEAN RANGE OF FETAL
DOSE
Projection Examination Estimated Fetal Dose per Examination (mGy) Estimated Fetal Dose per Examination (mGy) Estimated Fetal Dose per Examination (mGy) Estimated Fetal Dose per Examination (mGy)
Projection Examination Mean (this work) Reported Mean Range (this work) Reported Range
IVU 4.8 6.0 1.7 2.9 6.8 0.7 55.0 10.0
Barium Enema 6.1 10.0 6.8 0.3 10.4 0.28 130.0 24.0
Barium Meal 1.5 - 1.1 0.1 2.3 - 5.8
Cholecystography 0.6 1.0 0.08 1.1 0.05 16.0
AP Urinary Bladder 3.9 0.56 11.0
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
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MEAN FETAL ABSORBED DOSE PER EXAMINATION (GXR)
Projection Examination Fetal dose per examination (mGy) Fetal dose per examination (mGy)
Projection Examination Range Mean
AP Abdomen 0.26 15.0 2.9
PA Abdomen 0.64 3.0 1.3
Abdomena 0.26 15.0 2.6
AP Chest lt 0.01 0.01 lt 0.01
PA Chest lt 0.01 lt 0.01
Chestb gt 0.01 0.01 lt 0.01
a Average for the various projections b For
only one examination
Contd
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MEAN FETAL ABSORBED DOSE PER EXAMINATION (GXR)
Projection Examination Fetal dose per examination (mGy) Fetal dose per examination (mGy)
Projection Examination Range Mean
AP Hip joint 0.11 2.1 0.9
AP Lumbar Spine 0.31 40.0 7.5
LAT Lumbar Spine 0.09 3.5 0.91
OBL Lumbar Spine 0.61 2.0 1.3
Lumbar Spinea 0.09 40.0 4.2
LAT Lumbosacral Joint 0.10 2.0 1.1
AP Pelvis 1.4 15.0 3.4
AP Thoracic Spine lt 0.01 lt 0.01
LAT Thoracic Spine lt 0.01b
Thoracic Spineb lt 0.01 lt 0.01
a Average for the various projections b For
only one examination
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MEAN FETAL ABSORBED DOSE PER EXAMINATION (CT)
Examination No. of Cases Fetal dose per examination (mGy) Fetal dose per examination (mGy)
Examination No. of Cases Range Mean
Liver 4 2.0 4.4 3.6
Lumbar Spine 1 2.8
Lung 2 1.0 1.4 1.2
Pelvis 2 65.0 114.0 89.0
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COMPARISON OF THE ESTIMATED MEAN RANGE OF FETAL
DOSE
Radiopharmaceutical Conversion factor (cGy/MBq) 1,3 Activity (MBq Route of Administration Dose to the Uterus (cGy)
123I-Sodiumiodide 1.4x10-3 20 i.v. 2.8x10-2
123I-MIBG 1.1x10-3 30 i.v. 3.3x10-2
131I-MIBG 8.0x10-3 300 i.v. 2.4
67Ga-citrate 7.9X10-3 150 i.v. 1.18
201Tl-chloride 5.0x10-3 100-150 i.v. 5-7x10-1
99mTc-tetrofosmin (1-day protocol, rest) 8.4x10-4 150 i.v. 1.3x10-1
99mTc-tetrofosmin (1-day protocol, effort) 7.3x10-4 450 i.v. 3.3x10-1
MIBG, Metaiodobenzylguanidine MDP, methylene
diphosphonate HDP, hydroxydiphosphonate MAA,
macroaggregated albumin MAG3, mercaptoacetyltrigl
ycine
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COMPARISON OF THE ESTIMATED MEAN RANGE OF FETAL
DOSE
Radiopharmaceutical Conversion factor (cGy/MBq) 1,3 Activity (MBq Route of Administration Dose to the Uterus (cGy)
99mTc-sestamibi (1-day protocol, rest) 7.8x10-4 150 i.v. 1.2x10-1
99mTc-sestamibi (1-day protocol, effort) 7.2x10-4 450 i.v. 3.2x10-1
99mTc-MDP 6.1x10-4 400 i.v. 2.4x10-1
99mTc-HDP 6.1x10-4 400 i.v. 2.4x10-1
99mTc-MAA 2.4x10-4 100 i.v. 2.4x10-2
81mKr-gas 6.0x10-8 (per minute) Generator 450-750 MBq/minute Inhalation lt 10-3
99mTc-MAG3 1.2x10-3 40 i.v. 4.8x10-2
MIBG, Metaiodobenzylguanidine MDP, methylene
diphosphonate HDP, hydroxydiphosphonate MAA,
macroaggregated albumin MAG3, mercaptoacetyltrigl
ycine
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131I-Therapy Pregnancy
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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.
• .

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Radiation Workers Pregnancy

• Radiation worker who is pregnant should not
  receive more than 1 mSv during the whole
  pregnancy.

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CONCLUSION
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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.