exposure to diagnostic x-rays during pregnancy - medical...

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


2.5

0.5

1.5

Con

cept

us D

ose

(mG

y)

FemoralSuprarenal

FemoralInfrarenal

First trimester

Second trimester

Third trimester


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


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


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


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


Dose limits





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





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





Work restrictions

Counseling

Dose monitoring


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


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





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





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


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


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





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

exposure to diagnostic x-rays during pregnancy - medical...

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