.

2. Safety of Diagnostic Imaging
Procedures During Pregnancy
Mansoura - Egypt

3. Diagnostic Radiography in Pregnancy
Risks & Reality
♣ Maternal illness during Pregnancy is not uncommon
& sometimes requires radiographic imaging with
ionizing radiation for proper diagnosis & treatment.
♣ The Patient & her Physician may be concerned about
Potential harm to the fetus from radiation exposure.
♣ It is necessary to balance the benefits of such
Procedures with an accurate assessment of the Risk.
)American Academy of Family Physicians 1999(

4. Radiation is all around us! It is naturally present in
our environment
♣ Everyone is exposed to low levels of ionizing
radiation from natural sources at all times which is
called natural background radiation
♣ Since natural back ground radiation can never be
minimized to zero level, our efforts are targeted at
reducing exposure from man made sources.
Radiation overview
)Ind J Radiol Imag 2002(

5. Annual Dose from
Background Radiation average person
in the U.S = 360 mrem/year
Total exposure Man-made sources
Radon
Internal 11%
Cosmic 8% Terrestrial 6%
Man-Made 18%
55.0%
Medical X-Rays
Nuclear
Medicine 4%
Consumer
Products 3%
Other 1%
11

6. ● Ionizing Radiation
♣ X-Rays
♣ Gamma Rays
♣ Beta Particles
♣ Alpha Particles
♣ Neutrons
● Non-Ionizing Radiation
♣ Microwaves
♣ Radio Waves
♣ Infrared
♣ Ultraviolet light
♣ visible light
♣ Radar
♣ Laser
♣ cellular phones
Radiation Overview

7. WHAT IS RADIATION?
Or should I say……...
Ionizing Radiation!
♣ Ionizing radiation : has sufficient energy to
dislodge orbital electrons from atoms.
♣ Risks of injury from exposure to ionizing radiation.

8. X-Rays
Characteristic X-Rays
Bremsstrahlung
L Shell
K Shell
Electron or Photon In
X-Ray
Electron or Photon Out
electron
Tungsten
Bremsstrahlung X-Ray

9. Compton Effect
An incident photon interacts with an orbital electron to produce a
recoil electron and a scattered photon of energy less than the
incident photon
Before interaction After interaction
-
--
Incoming photon
Collides with electron
-
-
--
Electron is
ejected from atom
-
Scattered Photon
nteraction of X or gamma rays (photons) with matter

10. The most critical target for ionizing
radiation in cell is DNA
Normal DNA
DNA damaged
by radiation

11. How does ionizing radiation damage DNA?

12. Incident X-ray photon
Photon absorption via Compton effect
Formation of free radicals
Radical induced DNA damage
Biologic effect )mutation, carcinogenesis, cell killing.(
Sequence of Radiation Effects
) American Nuclear Society February 19, 2004(

13. DNA damage and its consequences
● Four possible outcomes
♣ No damage
♣ Damage repaired
 Cells are damaged , repair the damage and
operate normally.
 cells are damaged , repair the damage and
operate abnormally (misrepair mutation).
♣ Cell death
)National Radiation Protection Board 1998(

15. Biological effects of Radiation
)Ind J Radiol Imag 2002(
1.Somatic effects )in the irradiated individual( :
♣ Non stochastic or deterministic effects
 Related with certainty to a known dose of radiation
 Dose threshold exists
Severity is dose related
♣ Stochastic effects
 Random events can not be predicted accurately
 No threshold
The Probability but not the severity of the effect increases with dose.
2.Genetic effects )in the future generations(

16. Exposure units
♣ Exposure is a measure of the ionization produced by
X or Gamma Radiation in air
♣ Unit of exposure is the Roentgen ( R )
Radiation units & terminology
)Review of radiologic physics 2003(

17. Absorbed Dose Units
♣ The absorbed dose is the amount of energy absorbed
by tissue per unit mass.
Non - S.I. Radiation Absorbed Dose )rad(
S.I. GRAY )Gy(
)Review of radiologic physics 2003(
1Gy =100 rad =1000 mGy

18. Dose Equivalent Units
♣ Dose equivalent is a measure of the biological effect
of radiation
Non - S.I Roentgen Equivalent Man )rem(
1 rem = rad x Quality Factor
S. I. SIEVERT )Sv(
1 Sv = Gy x Quality Factor
1Sv =100rem =1000msv
)Review of radiologic physics 2003(

19. Diagnostic Radiation in
Pregnancy
Diagnostic Radiation in
Pregnancy

20. Fetal radiation risks
♣ Radiation risks are most significant during
organogenesis and in the early fetal period,
somewhat less in the 2nd
trimester, and least in
the 3rd
trimester
Less Least
Most
risk
)ICPR 2000(

21. Conceptus radiogenic riskConceptus radiogenic risk

22.  Intrauterine cell death
 Teratogencity
 Carcinogenesis
 Genetic effects or mutations
in germ cells
● Ionizing radiation (X-rays exposure) can result in
)ACOG 2004(
Risks of ionizing Radiation in pregnancy

23. ♣ Deterministic effects : (dose threshold)
Intrauterine cell death:
The most sensitive period: the preimplantation period (0-9
days) post conception.
Growth retardation
The most sensitive period (8-56 days post conception)
Microcephaly
The most sensitive period (2-15 weeks post conception)
Mental retardation
The most sensitive period (8-15 weeks post conception)
Risks of ionizing Radiation in pregnancy
)CDC May 2005(

24. Risks of ionizing Radiation in pregnancy
♣ Stochastic effects : (No dose threshold)
Carcinogenesis
Genetic mutations
)European journal of nuclear medicine 1998(
For congenital malformations & C.N.S damage & death
a threshold of 100 – 200 m Gy or higher exists for
all gestations.
♣ Deterministic effects : (dose threshold)
)ICPR 2000(

25. ♣ The embryo is most sensitive to the Lethal effects of
ionizing radiation during the Preimplantation Period
(days o to 9 after conception).
♣ Cell death is most likely as" All or None
Phenomenon" in early embryonic development.
♣ During this Period, the exposed embryo will Survive
undamaged or will be resorbed (failure to implant or
undetectable death of the conceptus)
( the effect of embryonic & Fetal exposure to x ray . semin oncol. 1989)
Intrauterine Fetal death

26. ♣ In the preimplantation period, there is no measurable
risk of malformations or growth restriction regardless
of the amount of radiation exposure, the greatest
concern is death of the embryo
♣ For human exposure, the best current estimate of
the threshold for preimplantation death is >10 rads.
(Massachustts general hospital MGH 2004)
Intrauterine Fetal death

27. Radiation induced malformations
(teratogenecity)
♣ During the period of organogenesis fetal growth restriction
& congenital malformations particularly of the C.N.S are
the major sequelae of radiation damage at this stage.
♣ The most common fetal malformations caused by high dose
radiation are of the C.N.S primarily microcephaly &
mental retardation
♣ Radiation is a dose dependant teratogen
(American Academy of family physicians 1999)

28. Radiation induced teratogenesis
♣ For congenital malformations & C.N.S damage
a threshold of 100 – 200 m Gy or higher exists for
all gestations.
(ICPR 2000)
♣ The most sensitive time period for C.N.S. teratogenesis
based on data from ABS is ( 8 to 15 weeks after
conception)
♣ Non urgent radiographs should be avoided during this
sensitive period .
(American Academy of family physicians 1999)

29. ♣ Fetal doses in the range of 1000 mGy can result in
severe mental retardation & microcephaly, particularly
during 8-15 weeks and to a lesser extent at 16-25 weeks
♣ No increase in severe mental retardation was observed
for irradiation occurring prior to 8 weeks post
conception or after 25th weeks.
(ICPR 2000)
Radiation induced teratogenesis

30. ♣ Fetal Risk of congenital anomalies, growth
Restriction or abortions are not increased with
Radiation exposure of less than 5 rad (a level
above the range of exposure from diagnostic
procedures).
♣ In all stages of gestation , radiation induced non
cancer health effects are not detectable for fetal
absorbed doses < 5 rad
(ACOG sept . 2004)
(CDC May 2005)
Commentary

31. Radiation induced Carcinogenesis
♣ The Risk of carcinogenesis as a result of in utero
exposure to ionizing radiation is probably very small.
♣ It is estimated that a 1 - 2 rad fetal exposure may
increase the risk of leukemia by a factor of 1.5 - 2
over natural incidence.
♣ An estimated 1 in 2000 children exposed to
ionizing radiation in utero will develop childhood
leukemia ….
(this is increased from a back ground rate of
approximately 1 in 3000)
(ACOG sept . 2004)

32. ♣ The risk of radiation induced carcinogenesis are not
likely to exceed 1 in 1.000 children per rad, thus
abortion should not be recommended solely on the
basis of exposure to diagnostic radiation
♣ It would be necessary to abort 1999 exposed fetuses to
prevent one case of leukemia.
(ACOG 2004)
( American academy of family physician 1999)
Radiation induced Carcinogenesis

33. ♣ The only adverse effects statistically proven at the
dose levels associated with diagnostic radiation
procedures is a very small increase in childhood
malignancy with an estimated increase of one
additional cancer death per 1700 / 10 m Gy
exposures.
(Australian & New Zealand journal of obstetrics& gynecology 2004)
Radiation induced Carcinogenesis

34. Radiation induced gene mutation
(Mutagenesis)
♣ Potentially affecting the future generations
♣ No radiation induced transmissible gene mutations
have ever been demonstrated unequivocally in humans
♣ Radiation does not produce new, unique mutations, but
simply increases the incidence of the same mutations that
occur spontaneously in the general population
(Australian & New Zealand journal of obstetrics& gynecology 2004)
(committee on biological effects of ionizing Radiation 1990)

35. Types of diagnostic imaging
modalities
● Ionizing Radiation:
♣ Plain X Rays
♣ Fluoroscopy
♣ Angiography
♣ Computed Tomography (C.T)
♣ Nuclear medicine studies
● Non-ionizing Radiation :
♣ Ultra Sound
♣ Magnetic resonance imaging (MRI)
(Up to date 2003)

36. Fetal absorbed dose
♣ The currently accepted maximum limit of ionizing
radiation exposure to the fetus during pregnancy
is accumulative dose of 5 rad.
♣ No single diagnostic procedure exceeds this maximum.
(American family physicians 1999)

37. Common Radiographic Studies

38. Examination type
Estimated fetal
dose per
examination (rad)*
Number of
examinations
required for a
cumulative 5-rad
dose+
Chest (two views) 0.00007 71,429
CT scans Chest (10 slices)
Non-helical
<0.100 >50
Ventilation-perfusion scan (total) 0.215 23
Environmental background
radiation (cumulative dose over
nine months)
0.100 N/A
)American family physicians 1999(

39. Chest for Pulmonary Embolism
CT Helical
Scan
Estimated fetal dose per examination )rad(
1st
Trimester 2nd
Trimester 3rd
Trimester
2.5 mm slice
.00033
–.00202
.00079-.00767
.
000513-.00130
8
)American family physicians 1999(

40. Commentary
♣The benefit far outweighs the risk with regard to
diagnostic imaging with a predicted fetal absorbed
dose of less than 1m Gy this includes all x ray &
CT scanning not involving the abdomen / pelvis.
♣Skull, cervical spine, chest and extremity examinations
fall into this category.
(Imaging & Therapeutic Technology 1999)
(Australian & New Zealand journal of obstetrics& gynecology 2004)

41. Radiation exposure of pregnant
workers
♣ Once pregnancy has been declared by a
worker exposed to radiation the dose to the
fetus should be limited to lees than 1msv for
the remainder of the pregnancy
(U.S environmental protection agency Feb. 2004)

42. Pre-conception irradiation
♣ Pre-conception irradiation of either parent’s
gonads has not been shown to result in
increased risk of cancer or malformations
in children.
(ICPR 2000)

43. Abortion counseling
♣ Medically the additional risk imposed by diagnostic
radiation is simply too small to justify terminating
pregnancy.
♣ Termination of pregnancy at fetal doses of less
than 100 mGy is NOT justified based upon
radiation risk
(ICPR 2000)
(ACOG 1995)

44. (American college of obstetricians & gynecologist sept 2004)
Guidelines on diagnostic Imaging modalities
during pregnancy
♣ X-Ray exposure from a single diagnostic procedure does
not result in harmful fetal effects, specifically exposure to
< 5 rad has not been associated with an increase in fetal
anomalies or pregnancy loss & is not an indication for
therapeutic abortion.
♣ Concern about possible effects of high dose radiation
exposure should not prevent medically indicated
diagnostic X ray procedures from being performed
on a pregnant woman .

45. ♣ During pregnancy, other imaging procedures not associated
with ionizing radiation e.g. U.S. & MRI should be
considered instead of X ray when appropriate.
♣ U.S. & MRI are not associated with known adverse fetal
effects.
♣ Radiopaque & paramagnetic contrast agents should be used
during pregnancy only if the potential benefit justifies the
potential risk to the fetus.
(ACOG 2004)
Guidelines on diagnostic Imaging modalities
during pregnancy

46. ♣ Although the safety of radiation exposure during
pregnancy is a common concern, the perceived
risk of radiation exposure is much greater
than the actual risk.
♣ Actually, most diagnostic radiologic procedures
are associated with little, if any known significant
fetal risks.
Conclusion
(ACOG 2004)

47. Thank you