Radiation in Pregnancy

1. RADIATION IN PREGNANCY
2016. 5. 10.
차의과학대학교
강남차병원 산부인과
조 연 경

2. • Ionizing Radiation IS a Teratogen!
• What is a teratogen?
• What is ionizing radiation?
• What are possible sources of ionizing radiation?
• When are the critical periods during pregnancy
that ionizing radiation could affect the fetus?

3. • What are the levels of ionizing radiation that
could affect the fetus?
• What could result if exposed to a high level of
ionizing radiation during pregnancy?
• How can I protect myself from ionizing radiation
poisoning?

4. Ionizing & Non-ionizing Radiation

5. Commonly used measurements for
ionizing radiation and their units
(Nuclear Wastelands, Makhijani et al., eds., Cambridge: MIT Press, 1995)
Units Description equivalent
Rem
(roentgen equivalent man)
A unit of equivalent absorbed
dose of radiation with relative
biological effectiveness
rem = rad x Q
Sievert (Sv) A unit of equivalent absorbed
dose equal to 100 rem.
1 Sv = 100 rem
Sv = Gy x Q
Rad
(radiation absorbed dose)
A unit of absorbed dose of
radiation. Rad is a measure of
the amount of energy
deposited in tissue
1 rad = 100
erg/gram
Gray (Gy) A unit of absorbed radiation
dose equal to 100 rad. Gray is
a measure of deposition of
energy in tissue
1 Gy = 100 rad

6. Health impact of high-dose
radiation from a nuclear disaster
• Cell death
– Alter DNA of normal cells
– Uncontrolled cell divisions
– Induce cancer
• Damage organs
– Acute radiation sickness (coagulopathy, immunity
disorders)
– Diarrhea
– Fever, burns, coordination & equilibrium
disturbances

7. Ionizing radiation from Natural source

8. Ionizing radiation from Natural source
(World Nuclear Association)

9. Effects of
Prenatal Radiation
Exposure

10. Effects of radiation in pregnancy
• Pregnancy loss
• Malformation
• Neurobehavioral abnormalities
• Fetal growth restriction
--- deterministic effect
--- Threshold or NOAEL (No-Adverse-Effect Level)
• Cancer
--- Stochastic effect
--- More radiation, greater the chance of the disease
--- No defined threshold

11. Effects of radiation in pregnancy
- Deterministic effect
• Radiation dose, the trimester of the pregnancy
Ex) Pregnancy loss
• During the 1st
2 weeks after conception, 100-200mGy
(10-20 rad)
• Shortly thereafter, 250-500 mGy (25-50 rad)
• 18weeks, 5000mGy (500 rad)
• At term, 20, 000mGy
(2000rad)

12. Exposure groups Preimplantation Embryo Fetus
Spontaneous
abortion
++ ± -
Congenital
malformation
- + -
Intrauterine growth
restriction
- + +
Mental retardation - + +
Effects of Radiation (1Gy)
Prenatal Exposure in Rodents
(Schull WJ and Otake al. 1999)

13. Effect
Most sensitive
period after
conception(d)
Threshold dose at effect was observed
(mGy)
Absolute
incidence
Animal studies Human studies
Perinatal death
Preimplantation
Postimplantation
0-8 50-100
250
ND ND
Growth retardation 8-56 10 200 ND
Organ malformation 14-56 250 250 ND
Small head size 14-105 100 No threshold observed 0.05-0.1%
Severe mental
retardation
56-105 ND 100 0.04%
Reduction of IQ 56-105 ND 100 ND
Childhood cancer 0-77 No threshold No threshold 0.017%
Fetal Effects from
Low-level Radiation Exposure
(Wagner LK, 1997)

14. Radiation and mental retardation
• 8-15 weeks,
: Risk of impaired CNS
development > 5 times
than 16~25 weeks
• < 8 weeks, or > 25
weeks
– No increased risk of
mental retardation

15. Radiation exposure &
Cancer

16. Cancer incidence (1950-1984) and
A-Bomb radiation exposure
DS86 maternal uterine dose (Gy)
0 0.01-0.29 0.30-0.59 >0.6
Mean dose (Gy) 0.000 0.087 0.416 1.372
No. at risk 710 682 129 109
Person-Years 21770 21659 4095 3287
Cancer cases 5 7 3 3
Adjusted rate per 100,000 22.4 32.5 77.8 97.0
Estimated RR 1.00 1.24 2.18 4.78
[1.01-2.10] [1.06-6.32] 1.19-7.93

17. Risks of leukemia in various groups
Group Approximate
risk
Increased risk
over control
population
occurrence
Siblings of
leukemic
children
1/720 4 To 10 years
Gestational
exposure 1/2000 1.5 <10 years
U.S. white
children <15 y.o. 1/2800 1 To 10 years
(Brent RL, Teratology, 1986)

18. Probability of birth with no
malformation and no childhood cancer
Dose to
conceptus (mGy)
No malformation
(%)
No childhood
cancer(%)
No malformation
and No
childhood
cancer (%)
0 96.00 99.93 95.93
0.5 95.999 99.926 95.928
1.0 95.998 99.921 95.922
2.5 95.995 99.908 95.91
5.0 95.99 99.89 95.88
10.0 95.98 99.84 95.83
50.0 95.90 99.51 95.43
100.0 95.80 99.07 94.91
(Wagner LK et al. 1982)

19. Thus…
• ICRP (The International Commission on Radiological Protection)
– < 100mGy (10 rad)
: Not medical ground for termination
• ACOG
– Threshold for medical concern ~ 50mGy (5 rad)
– > 1000mGy (100 rad)
: Serious risk to fetus’ CNS---severe mental retardation
– Single diagnostic radiation exposure? –10rad? 5 rad?

20. Estimated fetal radiation
per procedure or event
Clinical suspicion Procedure Estimated fetal
absorption (mGy)
Estimated fetal
absorption (rad)
pnemonia X-ray chest < 0.01 <0.001
Pulmonary
embolism
CT scan 0.06-0.96 0.006-0.096
Appendicitis CT scan 8-49 0.85-4.9
Nephrolithiasis Pyelogram 1.7-10 0.17-1
Breast nodule Mammogram 0.07-0.2 0.007-0.02
Colon pathology X-ray abdomen 1-4.2 0.1-0.42
Barium enema 7 0.7
Spine injury X-ray lumbar
spine
6 0.6
X-ray skull <0.001 <0.001
(Groen RS et al, 2012)

21. Estimated fetal radiation
per procedure or event
Clinical suspicion Procedure Estimated fetal
absorption (mGy)
Estimated fetal
absorption (rad)
Pelvic injury X-ray pelvis 1-1.4 0.11-0.4
CT scan pelvis 20-79 2.0-79
Background
radiation
None 1 mSv 0.1rem
Commercial flight Round
trip(toronto~frank
furt)
0.1mSv 0.01rem
100h of
commercial flying
1mSv 0.1rem
(Groen RS et al, 2012)

22. It is estimated that about 3,500 new cases of cancer
are diagnosed annually in pregnant women in the
U.S., which is equivalent to one case every 1,000
gestations
(Pavlidis NA. Coexistence of Pregnancy and Malignancy. Oncologist 2002)
Tumor type Incidence
Breast cancer 1:3,000-10,000
Cervical cancer 1.2:10,000
Hodgkin’s disease 1:1,000-6,000
Malignant
melanoma
2.6:1000
Leukemia
1:75,000-
100,000
Ovarian cancer
1:10,000-
100,000
Colorectal cancer 1:13,000
Site N %
Breast 298 26
Cervical 294 26
Leukemia 174 15
Lymphoma 119 10
Melanoma 193 8
Thyroid 45 4
Miscellaneous 111 11
Total 1,134 100

23. Radiotherapy during pregnancy
malignancyNo. Treatment dose
(Gy,median)
Fetal dose
(Gy, median)
GA at
RT
No. of adverse
outcomes
Brain
7
40.0–54.0(42.0) 0.00270–
0.08000
(0.03000)
18–28
(21)
1
Breast
23 30.0–78.0(41.0
0.03900–
0.16000
(0.15000)
2–24
(17.5)
2
Hodgkin’s
lymphoma 58
6.0–44.0(36.0) 0.00100–
10.00000
(0.08500)
1–33
(20)
3
NHL 3
2.0–52.0(26.0)
0.01800–
0.10000
(0.06000)
4–30
(23)
1
(Luis SA et al, J Med Imaging Radat Oncol 2009)

24. Radiotherapy during pregnancy
: Cases with adverse outcomes
malignancy Region treated Tx dose
(Gy)
Fetal dose
(Gy)
GA at
RT
No. of adverse
outcomes
Brain
Brain
54.0 0.00270 20 Died in utero
Breast chest, axilla Perinatal death
Hodgkin’s
lymphoma
Mediastinum,
Supraclavicular
fossa
28 Slow learner,
spontaneous
abortion
NHL Mediastinum,
chest wall 26 <0.1 30
Fetal distress,
short stature,
attention deficit,
delayed motor
development
(Luis SA et al, J Med Imaging Radiat Oncol 2009)

25. Radiation exposure on
infants and lactating women
• Direct exposure to radiation on breast
• Ingestion of radioactive pharmaceuticals
• Mammogram ---- breastfeeding (O)
• The highest radiation conc. in breast milk
– 3-4 hours after adm. of radioactive pharmaceuticals
– radiation absorbed by fetus < 3-10% of the total dose absorbed
by a woman
– But, no negligible dose !
– 1 Gy in infant :thyroid cancer(x10)
• CDC: if radioactive iodine ----stop breastfeeding !

26. Protection of pregnant women and
fetuses from radiation exposure
• Maintaining a safe distance
• Shielding one’s body from exposure
• Avoiding ingestion of food and water contaminated
with radioactive particles in the air, rain, or soil
• In disaster, minimize the exposure
• Lead-containing vest
• In radioactive pharmaceuticals, hydration + voiding!
• If safe protocol, < 1mSv /year

27. Gestational
age
Fetal Absorbed Dose
<5 rad 5-15 rad >15 rad
<2 wk Recommended Recommended Recommended
2-8 wk Recommended
Maybe consider
termination (in
presence of other
severe risks)
Maybe consider
termination (in
presence of other risks)
8-15 wk Recommended
Maybe consider
termination (in
presence of other
risks)
Higher risk conditions
exist, but termination is
not necessarily
recommended
15 wk to term Recommended Recommended Recommended
Wagner LK et al : Exposure of the pregnant patient to diagnostic radiations, 1997
Continuing a pregnancy after exposure