Exposure to diagnostic x-rays during pregnancy:
Radiation risks, challenges and recommendations
John Damilakis, PhDAssist. Professor of Medical Physics
University of Crete, Iraklion, Crete, [email protected]
X – ray exposure and the pregnant patient
IntentionalExposures
AccidentalExposures
Justification of the examination
Communication with the patient
Optimization of the exposure
Step 1: Justification of the examination
A program to manage a pregnant patientwho requires radiological examination
Justification of an x-ray examination
BenefitBenefit
RiskRisk
To justify an x-ray study
the risks to the unborn
child should be known
What is the estimated What is the estimated conceptus conceptus dose ?dose ?
What is the conception age ?What is the conception age ?
Conceptus radiogenic risk
AGE DOSE
No if:
• age less than 2 weeks
• conceptus dose is low
Is a detailed dose assessmentalways needed?
10 50 100 100 mGy=10 rad
Conceptus Dose (mGy)
Conceptus doses below 100 mGy should not be considered a reason for terminating a pregnancy
ICRP Publ. 84
Skull Radiograph < 0.01
Chest Radiograph < 0.01
CT (chest) < 0.2
Examination Conceptus dose (mGy)
Conceptus dose from extra – abdominalx-ray examinations
Pregnancy and pulmonary embolism
CONCEPTUS DOSE FROM A V/Q STUDY: 0.9CONCEPTUS DOSE FROM A V/Q STUDY: 0.9--1.8 1.8 mGymGy
CONCEPTUS DOSE FROM CHEST CT : 0.1CONCEPTUS DOSE FROM CHEST CT : 0.1--0.2 0.2 mGymGy
W. W. HudaHuda, , PediatrPediatr RadiolRadiol 35:45235:452--453, 2005453, 2005H. H. WinerWiner--MuramMuram et al., Radiology 224:487et al., Radiology 224:487--492, 2002492, 2002
A. Groves, S. Yates et al.Radiology 240: 765-770, 2006
Pregnancy and pulmonary embolism
Conclusion: This survey reveals that there is a lack of knowledgeof fetal dosimetry in the imaging of pregnant women suspectedof having pulmonary embolism.
J. J. DamilakisDamilakis, N. , N. TheocharopoulosTheocharopoulos, K. , K. PerisinakisPerisinakis et alet al
Circulation 104 : 893Circulation 104 : 893--897, 897, 20012001
Rf cardiac ablation proceduresand pregnancy
T. T. ShopeShope, , RadiographicsRadiographics, 1996, 1996Conceptus dose < 1 mGy
J. J. DamilakisDamilakis, N. , N. TheocharopoulosTheocharopoulos, K. , K. PerisinakisPerisinakis et al.et al.
Medical Physics 30 : 2594Medical Physics 30 : 2594--2601, 2601, 20020033
Fluoroscopically - assisted surgicaltreatment of hip fractures and
pregnancy
* J. Damilakis et al. Radiation Protection Dosimetry 72:61-65, 1997
Conceptus dose from abdominalX-ray examinations
Con
cept
us D
ose
(mG
y)
10
40
35
30
Abdominal radiography
IVU*
Barium Enema
CT (Abdomen)
Pregnancy
and
appendicitis
CONCEPTUS DOSE
FROM CT : 30 mGy
L. Wagner and W. Huda, Pediatr Radiol 34:589-590, 2004J. Fielding and D. Washburn, Journal of Women’s Imaging 7:16-21, 2005
Pregnancy
and
ureteral
stonesFigure from:C. Kalbhen, AJR 178:1285-1286, 2002
N. Theocharopoulos, J. Damilakis et al.
Spine 31:239-244, 2006
Fluoroscopically - assisted surgicaltreatment of spinal disorders
Conceptus Dose
< 4 mGy provided that the conceptus lies
outside the primarily irradiated region
up to 105 mGy when the conceptus is
primarily irradiatedImage from: K. Perisinakis, J. Damilakis et al.Radiology 232:701-707, 2004
J. Damilakis, D. Tsetis et al. Submitted for publication
Filter placement for the
prevention of pulmonary
embolism is appropriate
during pregnancy;
Filter placement is also
appropriate in women of
childbearing age.
CIRSE, Standards of Practice
Percutaneous inferior vena cava filterplacement during pregnancy
2.5
0.5
1.5
Con
cept
us D
ose
(mG
y)
Internal JugularSuprarenal
Internal JugularInfrarenal
First trimester
Second trimester
Third trimester
Percutaneous inferior vena cava filterplacement during pregnancy
2.5
0.5
1.5
Con
cept
us D
ose
(mG
y)
FemoralSuprarenal
FemoralInfrarenal
First trimester
Second trimester
Third trimester
Percutaneous inferior vena cava filterplacement during pregnancy
Abdominal examinations deliver relativelyhigh doses to the conceptus
5.5 cm
Con
cept
us D
ose
(mG
yx
103 )
25
5
15
10
20
22 23 24 25 26 27 28 29 30AP thickness (cm)
8.5 cm
11.5 cm
J. Damilakis et al. Eur Radiol 13:406-412, 2003
Conceptus dose vs. maternal chestthickness (AP chest radiography)
How can we estimate conceptus dose?
PATIENT MODELS
SECOND TRIMESTER
CONCEPTUS DOSES
NORMALIZED
TO AIR KERMA
FOR AP AND PA
ABDOMINAL
EXPOSURES
J. J. DamilakisDamilakis et al. et al. Medical PhysicsMedical Physics29:264129:2641--48, 200248, 2002
First Trimester
AP
PA
70 80 90 100 110 120
0.40
0.45
0.50
0.55
0.60
70 80 90 100 110 1200.15
0.20
0.25
0.30
0.35
0.40
kVp
60 70 80 90 100
0.2
0.4
0.6
0.8
1.0
Nor
mal
ized
con
cept
us d
ose
(mG
y c/mG
y a)
60 70 80 90 100
0.1
0.2
0.3
0.4
12 cm
10 cm
8 cm
6 cm
4 cm
12 cm
10 cm
8 cm
6 cm
4 cm
kVp
Nor
mal
ized
con
cept
us d
ose
(mG
y c/mG
y a)
70 80 90 100 110 120
0.40
0.45
0.50
0.55
0.60
70 80 90 100 110 1200.15
0.20
0.25
0.30
0.35
0.40
kVp
Second Trimester Third Trimester
kVkV
4 cm4 cm
6 cm6 cm
8 cm8 cm
10 cm10 cm
12cm12cm
Conceptus Dose = ND Kair
60 70 80 90 100
0.2
0.4
0.6
0.8
1.0
Nor
mal
ized
con
cept
us d
ose
(mG
y c/mG
y a)
60 70 80 90 100
0.2
0.4
0.6
0.8
1.0
Nor
mal
ized
con
cept
us d
ose
(mG
y c/mG
y a)kVkV
6 cm6 cm
••FreeFree--inin--Air Dose Model (Panzer et al, 1989)Air Dose Model (Panzer et al, 1989)
•• CTDI Dose Model (CTDI Dose Model (FelmleeFelmlee et al, 1990)et al, 1990)
W. Panzer & M. W. Panzer & M. Zankl Zankl BJR 62:936BJR 62:936--39, 39, 1989
J. J. FelmleeFelmlee et al. AJR 154:185et al. AJR 154:185--90, 198990, 1989
Methods for estimating embryodose from CT studies
(Early period of pregnancy)
2
1
1
1121
mAs
mAs
knVkkn
i iV
n
kni idknVkn
i iVid
nCTDIwnCTDIwD ×
−+∑−
=
∑+−=−+∑
−
=×=
2
11
2
1
mAsmAs
n
d
CTDICTDID
n
ii
wn
wn××=
∑=
Late pregnancy: nCTDIw technique
J. Damilakis, K. Perisinakis et al, Invest Radiol 35:61-65, 2000
Work-in-progress
A method for estimating conceptus dosesfrom 16 and 64-slice CT examinations
9 months 6 months 3 months 0 months
-10 0 10 20 30 40 500.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
Distance (cm)
Nor
mal
ized
Con
cept
us D
ose
12 mm
24 mm
40 mm
What is the potential risk to the conceptus?
Radiation risks are related to the stage of pregnancy
STOCHASTIC EFFECTS (no dose threshold)
DETERMINISTIC EFFECTS (dose threshold)
WEEKS RESULT THRESHOLD RISK POSTCONCEPTION (Gy-1)
0-2 CONCEPTUS DEATH
3-8 MALFORMATIONS 0.1+
8-15 MENTAL RETARDATION 0.1+ 30 IQ points/Gy
4-36 CARCINOGENESIS 0.06
0-36 GENETIC EFFECTS 0.01
Thresholds & risk factors
Radiation risk for fatal cancer : 6% per Gy (6% per 1000 mGy)
If the conceptus dose from a diagnostic examination is 10 mGy
the risk of excess childhood fatal cancer is 0.06%
Conceptus radiogenic risk
Probability that a child will develop cancer
0.26
Prob
abili
ty o
f ca
ncer
(%
)
1.0
0.2
0.6
0.4
0.8
10 20 30 40 50 60 70 80 90 100 Conceptus dose (mGy)
Step 2: Communication with the patient
Step 1: Justification of the examination
A description of the method used to estimate dose
A table presenting exposure data
A table presenting conceptus dose estimation
Radiation protection recommendations
Reporting dose results
Informed consent forms
J. Fielding and D. Washburn, Journal of Women’s Imaging 7:16-21, 2005G. El-Khoury, M. Madsen, M. Blake, J. Yankowitz, AJR 181:335-340, 2003
THERE IS A CHANCE THAT A WOMAN WILL
GIVE BIRTH TO CONGENITALLY MALFORMED
CHILDREN, REGARDLESS OF ANY EXPOSURE
TO RADIATION
Step 2: Communication with the patient
Step 3: Optimization of the exposure
Step 1: Justification of the examination
Conceptus Depth (cm)
Prevoid 6-10 (8.4)
Postvoid 4-8 (5.8)
Conceptus dose is dependent onconceptus depth
K. Perisinakis, J. Damilakis, et al. Investigative Radiology 34:449-454, 1999
Reduction of conceptus dose
Reduction of conceptus dose: MDCT and z-overscanning
A. Tzedakis, J. Damilakis, et al. Medical Physics 32:1621-1629, 2005
z-overscanning
z-overscanning
Although the conceptus isprimarily irradiated, it is not depicted on the MDCTimages.
In MDCT, the tissue volume of patient irradiated differsfrom the volume imaged.
•• Reduction of fluoroscopy Reduction of fluoroscopy timetime
FLUOROSCOPY
‘Accidental‘Accidental embryo irradiation during barium enema examinations:embryo irradiation during barium enema examinations:
Conceptus Conceptus doses can approach or exceed 50 doses can approach or exceed 50 mGymGy, especially if the, especially if the
fluoroscopy time exceeds 7 minutes’fluoroscopy time exceeds 7 minutes’
J. Damilakis, K. Perisinakis et al. Investigative Radiology 31:242-245, 1996
Reduction of conceptus dose
IntentionalExposures
AccidentalExposures
Justification of the examination
Communication with the patient
Optimization of the exposure
CARECARESS
Accidental exposures
Before the examinationNo pre-examination actions
During the examinationNo radiation protection measures
After the examinationWe do not know the exact technical parametersanxiety, consideration of abortion
Accidental irradiation: A different case
S. S. RatnapalanRatnapalan et al. AJR 182:1107et al. AJR 182:1107--1109, 2004 1109, 2004
Physicians’ perception of risk associated with diagnostic x-rays
40 %
Family physicians
70 %
Obstetricians
40% of family physicians and 70% of obstetricians recommended
abortion for women exposed to diagnostic x-rays in early pregnancy
Fink D, Glick S. Fink D, Glick S. HarefuahHarefuah 124:717124:717--719, 1993 719, 1993
Physicians’ perception of risk associated with diagnostic x-rays
How can we avoid accidental
irradiation?
• Investigation of the reproductive status of a female Investigation of the reproductive status of a female of of childbearing age prior to xchildbearing age prior to x--ray ray imagingimaging..
•• IIt is prudent to consider as pregnant any woman t is prudent to consider as pregnant any woman of reproductive age presenting herself for an X of reproductive age presenting herself for an X ––ray examination at a time when a menstrual ray examination at a time when a menstrual period is overdue, or missed, unless there is info period is overdue, or missed, unless there is info ––rmation rmation that precludes a pregnancy.that precludes a pregnancy.(ICRP Publication 84, 2000) (ICRP Publication 84, 2000)
Determination of pregnancy before irradiation
‘PLEASE INFORM THE STAFFBEFORE YOUR X-RAY EXAMINATION
IF YOU THINK YOU MAY BE PREGNANT’
Avoid accidental irradiation
Evaluate conceptus dose for abdominal studies
Conceptus doses below 100 mGy, should not beconsidered a reason for abortion
Avoid accidental irradiation
Messages to take home (part I)
Pregnant employees working indiagnostic radiology
Dose limits
Program to evaluate andcontrol conceptusdose
Declaration ofpregnancy
Evaluation of theworking conditions
Conceptus dose anticipation
Work restrictions
Counseling
Dose monitoring
‘Once pregnancy has been declared, the conceptus shouldbe protected by applying a supplementary equivalent dose limit to the surface of the woman’s abdomen of 2 mGy for the remainder of the pregnancy.’
1990 Recommendations of the1990 Recommendations of the ICRP, Publication 60ICRP, Publication 60
International Commission on Radiological Protection (ICRP)
2 mGy = 200 mrad = 200 mrem (for X-rays)
‘The working conditions of a pregnant worker, afterthe declaration of pregnancy, should be as such tomake it unlikely that the additional dose to the conceptus will exceed about 1 mGy during the remainderof pregnancy.’
Annals of the ICRP, Publication 84, 2000
1 mGy = 100 mrad = 100 mrem (for X-rays)
International Commission on Radiological Protection (ICRP)
‘As soon as a pregnant woman informs the undertaking, inaccordance with national legislation and/or national practice, of her condition, the protection of the child to beborn shall be comparable with that provided for membersof the public. The conditions for the pregnant woman in thecontext of her employment shall be such that the equivalentdose to the child to be born will be ALARA and that it will beunlikely that this dose will exceed 1 mGy during at leastthe remainder of the pregnancy’
DIRECTIVE 96/29 EURATOM (13/5/96)Safety standards for the protection of workers
(Article 10)
‘… ensure that the dose to an embryo/fetus during the entire pregnancy, due to occupational exposure of adeclared pregnant woman, does not exceed 5 mGy.’
‘…make efforts to avoid substantial variation above auniform monthly exposure rate to a declared pregnantwoman.’
‘U.S. Nuclear Regulatory Commission’‘U.S. Nuclear Regulatory Commission’
US regulationsCode of federal regulations
5 mGy = 500 mrad = 500 mrem (for X-rays)
Dose limits
Program to evaluate andcontrol conceptusdose
Declaration ofpregnancy
Evaluation of theworking conditions
Conceptus dose anticipation
Work restrictions
Counseling
Dose monitoring
Voluntary declaration of pregnancy
A FEMALE WORKER SHOULD, IN
BECOMING AWARE THAT SHE IS
PREGNANT, NOTIFY THE EMPLOYER
IN ORDER THAT HER WORKING
CONDITIONS MAY BE MODIFIED IF
NECESSARY
Dose limits
Program to evaluate andcontrol conceptusdose
Declaration ofpregnancy
Evaluation of theworking conditions
Conceptus dose anticipation
Work restrictions
Counseling
Dose monitoring
Take into account:Take into account:
Doses received during the previous Doses received during the previous years by the woman or other workersyears by the woman or other workersdoing a similar jobdoing a similar job
1 1 mSvmSv 5 5 mSvmSv
Evaluation of the working conditions
‘The employer shall provide pregnant ‘The employer shall provide pregnant workers the option of a mutuallyworkers the option of a mutuallyagreeable work assignment, withoutagreeable work assignment, withoutloss of pay or promotional opportunityloss of pay or promotional opportunitysuch that further occupational such that further occupational radiation exposure is unlikely.’radiation exposure is unlikely.’
Evaluation of the working conditions
Dose limits
Program to evaluate andcontrol conceptusdose
Declaration ofpregnancy
Evaluation of theworking conditions
Conceptus dose anticipation
Work restrictions
Counseling
Dose monitoring
Conceptus dose anticipation
TABLE
A. Divide the space around table into two gridsA. Divide the space around table into two grids
B. Measure scatter air B. Measure scatter air kerma kerma rate at each cellrate at each cell
Conceptus dose anticipation
C.C. Derive DAPDerive DAP--normalized air normalized air kerma kerma values by dividing thevalues by dividing themeasured dose rates by the DAP rate of the expmeasured dose rates by the DAP rate of the exposure.osure.
E.E. Use measurements and conversion factors provided bUse measurements and conversion factors provided by y literature* to calculate literature* to calculate conceptus conceptus dose at the first, 2dose at the first, 2ndnd and and 33rdrd trimesters.trimesters.
*J. *J. DamilakisDamilakis, A. , A. TzedakisTzedakis, L , L Sideri Sideri et al., Medical Physics, 29:2641et al., Medical Physics, 29:2641--48, 2002 48, 2002
J. J. DamilakisDamilakis, K. , K. PerisinakisPerisinakis, et al., JCE 16:1, et al., JCE 16:1--8, 20058, 2005
D.D. Plot Plot isodose isodose curves around the table for each projectioncurves around the table for each projectioninvolved in a study. involved in a study.
Conceptus dose prior to declaration
PREGNANT ??PREGNANT ??What is the dose received by my babyduring the last 5 weeks?
DAPDAP--normalized doses for heart PA, LAO and RAO projectionsnormalized doses for heart PA, LAO and RAO projections
Figures from: J. Figures from: J. DamilakisDamilakis, K. , K. Perisinakis Perisinakis et al. et al. Journal of CardiovascularJournal of Cardiovascular ElectrophysiologyElectrophysiology 16:116:1--8, 20058, 2005
Conceptus dose anticipation:Iso-dose curves
DAPDAP--normalized doses for lumbar spine LAT and AP projectionsnormalized doses for lumbar spine LAT and AP projections
Fig. from: N. Fig. from: N. TheocharopoulosTheocharopoulos, J. , J. DamilakisDamilakis et al. Spineet al. Spine 15;29:257315;29:2573--8080,, 2004 2004
Conceptus dose anticipation:Iso-dose curves
UNIVERSITY HOSPITAL OF IRAKLIONIRAKLION, CRETE, GREECE
DEPARTMENT OF MEDICAL PHYSICS
DATA
COLLECTION
FORM
Dose limits
Program to evaluate andcontrol conceptusdose
Declaration ofpregnancy
Evaluation of theworking conditions
Conceptus dose anticipation
Work restrictions
Counseling
Dose monitoring
Workload determination
0 w 5 w 0 w 5 w 40 w40 w
DOSE PRIOR TO DECLARATION
0.3 mGyDOSE ALLOWED FOR EACH WEEK OF THE REMAINING GESTATION PERIOD
0.134
0.02= 6.7
5 – 0.3
35= 0.134 mGy/week
6 PROCEDURES/WEEK (1st trimester)MAXIMUM WORKLOAD
13 PROCEDURES/WEEK (2nd and 3rd trimester)
Anticipated conceptus dose: 0.02 mGy/procedure (1st trimester)0.01 mGy/procedure (2nd and 3rd trimester)
0.134
0.01= 13.4
Dose limits
Program to evaluate andcontrol conceptusdose
Declaration ofpregnancy
Evaluation of theworking conditions
Conceptus dose anticipation
Work restrictions
Counseling
Dose monitoring
Counceling of the expectant mother
Description of possible effects of exposureDescription of possible effects of exposure
Radiation protection recommendationsRadiation protection recommendations
Description of factors affecting staff doses
Figures from: N. Figures from: N. TheocharopoulosTheocharopoulos, J. , J. DamilakisDamilakis et al. et al. Clinical Clinical OrthopaedicsOrthopaedics and Related Researchand Related Research 430:182430:182--188,188, 20052005
The scattered radiation is not uniform
Using Using isodose isodose curves, the pregnant worker shouldcurves, the pregnant worker should
select a position that allows her to do her jobselect a position that allows her to do her job
properly and decrease her doseproperly and decrease her dose
Counceling of the expectant mother
Description of possible effects of exposureDescription of possible effects of exposure
Radiation protection recommendations
Description of factors affecting staff dosesDescription of factors affecting staff doses
Protective devices
Maternity aprons
Counceling of the expectant mother
Description of possible effects of exposure
Radiation protection recommendationsRadiation protection recommendations
Description of factors affecting staff doses
Radiation risk for fatal cancer : 6% per Radiation risk for fatal cancer : 6% per Gy Gy (6% per 1000 (6% per 1000 mGymGy) )
If the If the conceptus conceptus dose is 5 dose is 5 mGy mGy the risk of excess childhoodthe risk of excess childhood
fatal cancer is 0.03% fatal cancer is 0.03%
Radiogenic risk
Background risk of childhood cancer : 0.3 % (NCIBackground risk of childhood cancer : 0.3 % (NCI--SEER 1994) SEER 1994)
FOR EMPLOYEES OF CHILDBEARING AGE:
KEEPING EXPOSURE TO PELVIS AREA ATKEEPING EXPOSURE TO PELVIS AREA ATTHE LOWEST PRACTICABLE LEVELS MAYTHE LOWEST PRACTICABLE LEVELS MAYBE BENEFICIAL DURING THE FIRST WEEKSBE BENEFICIAL DURING THE FIRST WEEKSOF GESTATION WHEN THE WOMAN ISOF GESTATION WHEN THE WOMAN ISUNAWARE OF HER PREGNANCY AND THEUNAWARE OF HER PREGNANCY AND THECONCEPTUS IS VULNERABLE TO RADIATIONCONCEPTUS IS VULNERABLE TO RADIATION
Working with radiation?… No. Why should I riskmy health?
Counseling of the expectant mother
Dose limits
Program to evaluate andcontrol conceptusdose
Declaration ofpregnancy
Evaluation of theworking conditions
Conceptus dose anticipation
Work restrictions
Counseling
Dose monitoring
Dose monitoring
Messages to take home (part II)
US REGULATIONS: Conceptus dose limit for pregnant workers: 5 mGy during the entire pregnancy
DECLARATION OF PREGNANCY is very importantbecause dose recommendations are based on the declaredterm of the pregnancy
Determination of the MAXIMUM WORKLOAD allowedfor each week of the remaining gestation period is neces-sary for fluoroscopic procedures
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