hazards of radiological imaging during pregnancy

1. Radiologic Imaging During
Pregnancy
Dr.Mohammed abdallah
Damietta general hospital

2. radiologic examinations in
pregnant women has increased
by 107% in the last 10 years .
Utilization of imaging in pregnant patients: 10-year
review of 5270 examinations in 3285 patients—1997–
2006. Radiology 2009;251(2): 517–524.

3. • Because of misconceptions about fetal risk of
radiation exposure, some women incorrectly
believed that pregnancy termination should be
considered ! ..
• The American College of Obstetricians and
Gynecologists clearly states that abortion
should not be recommended solely on the
basis of exposure to diagnostic radiation When
used appropriately during pregnancy
ACOG guidelines for diagnostic imaging during
pregnancy. Obstet Gynecol 2004

4. RADIATION EXPOSURE VALUES
DOSIMETRY
• Amount of energy deposited per kilogram of tissue
•Gray
•rad
1 rad =10 mGray

5. • no deterministic
effects ( fetal death ,
malformation ,
microcephaly and
mental retardation )
of practical
significance would
be expected to
occur below a dose
of 10 rad.
• Radiation has been
shown to increase
the risk of childhood
carcinogenic effect
with no absolute
dose threshold
,With fetal dose of
2-5 rad . the risk
increases
approximately by a
factor of 2 .
The 2007 Recommendations of the International Commission on Radiological
Protection. ICRP publication

6. Threshold radiation dose
The accepted cumulative maximum fetal exposure dose is 5 rad.

8. • 1250 plain hip X ray
• 50000 dental X ray
• 2500 cervical spine X ray
• 7100 chest X ray
• 25 vent. perfusion scan
• 5 IVP
• 1 fluoroscopic Barium enema .

10. • 100 head 10 slices CT.
• 10 chest 10 slices CT.
• 1 abdominal 10 slices CT.
• 1 lumber spine 5 slices CT.

12. Deterministic
• a threshold dose
ICPR 2000
stochastic
• threshold dose
european J . Of nuclear medicine 1998
Risk to unborn child from radiation
exposure

13. Risk to unborn child from radiation
exposure
Deterministic effect
damage to a number of cells
resulting
in malformations, growth
retardation, mental
retardation, and death
Threshold dose is 10 rad
Stochastic effect
damage to a single cell and
can lead to
carcinogenesis
There is no absolute dose
threshold, but with linear
association.
ICRP recommendations. J Radiol Prot 2008
the Royal College of Radiologists and the College of Radiographers. Documents of
the Health Protection Agency: Radiation, Chemical and Environmental Hazards.
United Kingdom, 2009

14. Deterministic radiation risks are most
significant during organogenesis and
in the early fetal period somewhat
less in the 2nd trimester and least in
the third trimester
Deterministic Risk to unborn child from
radiation exposure
Less LeastMost
risk

15. Less Least
Most
risk
Deterministic Risk to unborn child from
radiation exposure
As it depends on dose it also depends
on conceptus age .

16. Coceptus age at time of
exposure to 5 rads.or
more
• For exposures to ionizing
radiation prior to
conception, genetically
heritable risks have not
been documented in the
human population.
• Only cancer induction
needs considerations.
Prior to
Conception

17. All or non phenomenon
i.e abortion or no effect
• an exposure dose less than
5 rads. Is not
distinguishable from zero.
at Less Than 4
Weeks
Postconception
Coceptus age at time
of exposure to 5
rads.or more

18. • Embryonic stage (4-10 wk) :
deterministic effect and 2 fold
increase in cancer risk in doses > 5
rads.
• Early fetal stage ( 10-15 wk) : at
this stage CNS is radiosensitive
with risk of mental retardation
and declined IQ above threshold
• Mid fetal stage ( 16- 25 wk) :
threshold increase to 10 rads. To
deterministic but not to stochastic
effects, With CNS affection .
• Late fetal stage : no deterministic
effect but only stochastic effects
Post conception
((organogenesis
Coceptus age at time
of exposure to 5
rads.or more

19. Stochastic carcinogenic effect

20. • Radiation has been shown to increase the
risk with no absolute dose threshold.
• It is now believed it is fairly independent
on the stage of pregnancy after the first 3
to 4 weeks of gestation.
• The radiation exposure cancer risk in first
3-4 wks. Of pregnancy is much lower than
in subsequent stages of pregnancy .
Stochastic carcinogenic effect

21. Stochastic carcinogenic effect
• The latest estimate of the risk of developing
childhood cancer is approximately one in 500 in the
general population
• Most radiologic procedures increase the risk of
childhood cancer by less than one in 1000. With
larger doses (eg, a fetal dose 2-3 rad.received during
pelvic CT), the risk of carcinogenesis increases
approximately by a factor of 2 .
the Royal College of Radiologists and the College of Radiographers. Documents
of the Health Protection Agency: Radiation, Chemical and Environmental
Hazards. United Kingdom, 2009.

22. • CT of the fetus should be avoided as
possible in all trimesters of pregnancy,
because it may cause up to a doubling
of the risk of fatal childhood cancer.
Stochastic carcinogenic effect

23. Risk of childhood
cancer
< 1 in
1000.000
Typical fetal dose
0. 001 rad.
examination
skullX ray
chestx-ray
teethx-ray
Thracic spinex-ray
Head and neckx-ray
Lung ventillation scanx-ray
Natural childhood risk is 1 in 500
Royal college of radiologists 2009
Estimated Risk of Cancer from Prenatal Radiation
Exposure

24. Risk of childhood
cancer
< 1 in 100.000
To
1 in 10.000
Typical fetal dose
0. 1 rad.
examination
abdomenX ray
Barium mealx-ray
plvisx-ray
hipx-ray
pelvimetryx-ray
Chist and liverx-ray
Natural childhood risk is 1 in 500
Royal college of radiologists 2009
Estimated Risk of Cancer from Prenatal Radiation
Exposure

25. Risk of childhood
cancer
1 in 10.000
To
1 in 1000
Typical fetal dose
1 rad.
LUMBER SPINE
ABDOMEN
Examination
CT
Natural childhood risk is 1 in 500
Royal college of radiologists 2009
Estimated Risk of Cancer from Prenatal Radiation
Exposure

26. Risk of childhood
cancer
1 in 1000
To
1 in 200
Typical fetal dose
1 : 5
rad.
pelvis
Pelvis and
abdomen
Examination
CT
Estimated Risk of Cancer from Prenatal Radiation
Exposure
Natural childhood risk is 1 in 500
Royal college of radiologists 2009

28. MRI
• MR imaging is not associated with any
radiation exposure but expose the fetus to a
three potential hazards:
1. static magnetic field,( biologic damage)
2. pulsed radiofrequency fields,( heating effects)
3. electromagnetic fields,( high acoustic noise).
THE FEW STUDIES ON PREGNANCY OUTCOME
FOLLOWING( MRI) HAVE NOT REVEALED ANY
ADVERSE EFFECTS .

29. American College
of Radiology (ACR)
• did not distinguish the first
trimester of pregnancy from
the second and third
trimesters in terms of risks of
MR imaging exposure ,
advising that risks versus
benefits should be
considered before
performing MR imaging in a
pregnant patient.
Kanal E, Barkovich AJ, Bell C, et al.;
ACR Blue Ribbon Panel on MR Safety.
ACR guidance document for safe MR
practices: 2007. AJR Am J Roentgenol
2007;188(6):1447–1474

30. Transfer of Intravenous Contrast Material to the Fetal
Circulation
• Nonionic iodinated and gadolinium-based
agents are water soluble and weigh
between 500 and 850 Da; they can cross
the placental barrier, but this movement
is somewhat restricted due to their high
molecular weigh (> 100 Da).

31. Use of Iodinated Contrast Material during Pregnancy
• No mutagenic or teratogenic effects have
been described , but The principal effect of
iodine-based compounds is their potential
impact on the neonatal thyroid gland.
American College of Radiology. ACR
committee on drugs and contrast media. ACR
Manual on Contrast Media. 7th ed. Reston, Va:
American College of Radiology, 2010.

32. Use of Iodinated Contrast Material during Pregnancy
• iodinated contrast media be given to the mother
only in exceptional circumstances, and that when
this occurs, neonatal thyroid function should be
checked in the 1st week of life
Webb JA, Thomsen HS, Morcos SK; Members of Contrast
Media Safety Committee of European Society of Urogenital
Radiology (ESUR). The use of iodinated and gadolinium
contrast media during pregnancy and lactation. Eur Radiol
2005;15(6): 1234–1240.

33. Use of Gadolinium-based Contrast Material during
Pregnancy
• Although the available literature suggests that
it is unlikely that gadolinium would have an
adverse effect on the developing fetus, even
the least strict authors recommend that
caution be exercised and that contrast-
enhanced MR imaging be performed only
when essential to the diagnosis
Webb JA, Thomsen HS, Morcos SK; Members of Contrast Media
Safety Committee of European Society of Urogenital Radiology
(ESUR). The use of iodinated and gadolinium contrast media
during pregnancy and lactation. Eur Radiol 2005;15(6): 1234–
1240.

34. Use of Gadolinium-based Contrast Material during
Pregnancy
• The U.S. Food and Drug Administration has
classified gadolinium-based agents as category
C drugs
• In its 2010 Manual of Contrast Media, the
ACR states that gadolinium-based agents
should be used with extreme caution
U.S. Food and Drug Administration website.
American College of Radiology. ACR committee
on drugs and contrast media. ACR Manual on
Contrast Media. 7th ed. Reston, Va: American
College of Radiology, 2010.

36. • Deterministic effects of radiation result from
damage to a number of cells, with a dose
threshold before damage occurs. No
deterministic effect of practical significance is
expected to occur below a dose of 100 mGy
Take home

37. • Stochastic effects of ionizing radiation originate
from damage to a single cell and can lead to
carcinogenesis. Fetal radiation doses up to 1
rad—used in most radiologic examinations below
the knees and above the diaphragm—are
considered acceptable,
• With larger doses (eg, a fetal dose of 2-5 rads.
received during pelvic CT), the risk of
carcinogenesis increases approximately by a
factor of 2
Take home

38. • There has been no documented damage to a
developing human fetus caused by MR
imaging exposure. However, caution is
advised, and risks and benefits must always be
weighed before evaluating a pregnant patient
with MR imaging.
Take home

39. • Because the fetal thyroid develops throughout
pregnancy, any iodine-containing product is
contraindicated in pregnant women.
• If iodinated compounds are used in the course
of pregnancy, neonatal thyroid function
should be checked during the 1st week of life.
This testing is already performed routinely for
all newborns .
Take home

40. • Because of limited scientific evidence
regarding their safe use during pregnancy in
humans, gadolinium-based contrast agents in
the course of pregnancy should be used with
extreme caution unless the benefits outweigh
the risks .
Take home

41. thank
you