Download Radiation Exposure and Pregnancy

Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies for
distribution to your colleagues or clients, use the RadioGraphics Reprints form at the end of this article.
EDUCATION EXHIBIT
909
Radiation Exposure
and Pregnancy:
When Should We
Be Concerned?1
TEACHING
POINTS
See last page
Cynthia H. McCollough, PhD ● Beth A. Schueler, PhD ● Thomas D.
Atwell, MD ● Natalie N. Braun, BS ● Dawn M. Regner, MD ● Douglas L.
Brown, MD ● Andrew J. LeRoy, MD
The potential biological effects of in utero radiation exposure of a developing fetus include prenatal death, intrauterine growth restriction,
small head size, mental retardation, organ malformation, and childhood cancer. The risk of each effect depends on the gestational age at
the time of exposure, fetal cellular repair mechanisms, and the absorbed radiation dose level. A comparison between the dose levels associated with each of these risks and the estimated fetal doses from
typical radiologic examinations lends support to the conclusion that
fetal risks are minimal and, therefore, that radiologic and nuclear medicine examinations that may provide significant diagnostic information
should not be withheld from pregnant women. The latter position is
advocated by the International Commission on Radiological Protection, National Council on Radiation Protection, American College of
Radiology, and American College of Obstetrics and Gynecology. However, although the risks are small, it is important to ensure that radiation doses are kept as low as reasonably achievable.
©
RSNA, 2007
Abbreviation: IVP ⫽ intravenous pyelography
RadioGraphics 2007; 27:909 –918 ● Published online 10.1148/rg.274065149 ● Content Codes:
1From
the Department of Radiology, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905. Recipient of a Certificate of Merit
award for an education exhibit at the 2004 RSNA Annual Meeting. Received August 11, 2006; revision requested September 5 and received February
13, 2007; accepted February 13. C.H.M. received partial support from Siemens Medical Solutions for research not related to this article; all remaining
authors have no financial relationships to disclose. Address correspondence to C.H.M. (e-mail: [email protected]).
See the commentary by Togashi following this article.
©
RSNA, 2007
910
RG f Volume 27
July-August 2007
●
Number 4
Table 1
Fetal Effects from Low-Level Radiation Exposure
Most Sensitive
Period after
Conception
(d)
Effect
Prenatal death
Threshold Dose at Which
an Effect Was Observed
(mGy)
Animal
Studies
0–8
Preimplantation
Postimplantation
Growth retardation
Organ malformation†
Small head size
Severe mental retardation
Reduction of IQ
Childhood cancer
8–56
50–100
250
10
Human
Studies
Absolute
Incidence*
ND
ND
200
ND
Comments
If the conceptus survives, it
is thought to develop
fully, with no radiation
damage.
Atomic bomb survivors who
received ⬎200 mGy were
2–3 cm shorter and 3 kg
lighter than controls and
had a head circumference
1 cm smaller.
14–56
250
250
ND
None
14–105
100
No threshold 0.05%–0.10% About 25% of children with
observed
small head size were mentally retarded.
56–105
ND
100
0.04%‡
No increase in absolute incidence was observed for
exposure in the first 7
weeks or after the 25th
week.
56–105
ND
100
ND
Effects from a dose of 100
mGy or less were statistically unrecognizable. At
100 mGy or more, the IQ
reduction was 0.025
points per milligray.
0–77
No threshold No threshold
0.017%§
Leukemia is the most com(first trimester)
observed
observed
mon type of childhood
cancer.
Source.—Reference 1.
Note.—IQ ⫽ intelligence quotient, ND ⫽ no data.
*Absolute incidence is defined as the percentage of exposed fetuses in which an effect is expected to be observed
with a dose of 1 mGy.
†Organ malformation is defined as malformation of an organ outside the central nervous system. Data regarding
the most sensitive period after conception are from animal studies.
‡An absolute incidence of 0.02% also was observed after radiation exposure of more than 500 mGy at 112–175
days after conception.
§The baseline risk for unexposed fetuses is 1 in 1500 or 0.067%. An absolute incidence of 0.0043% per milligray
was observed for fetuses with radiation exposure in the second and third trimesters.
Introduction
The imaging of pregnant women presents a
unique challenge to radiologists because of the
concern about the radiation risk to the conceptus
(ie, embryo or fetus). This article reviews conceptus effects from in utero exposure to radiation;
identifies typical conceptus doses from common
radiologic examinations; summarizes statements
from international, national, and professional organizations regarding the risk from diagnostic
radiologic examinations; and describes the processes used to determine appropriate diagnostic
imaging examinations for common indications
during pregnancy. The article is primarily focused
on situations of known pregnancy, but the dose
data presented are relevant also to unintended
exposure in situations of unknown or undeclared
pregnancy.
RG f Volume 27
●
Number 4
McCollough et al
911
Table 2
Probability of Birth with No Malformation and No Childhood Cancer
Dose to
Conceptus (mGy)
0
0.5
1.0
2.5
5.0
10.0
50.0
100.0
No Malformation
(%)
No Childhood
Cancer (%)
No Malformation and
No Childhood
Cancer (%)
96.00
95.999
95.998
95.995
95.99
95.98
95.90
95.80
99.93
99.926
99.921
99.908
99.89
99.84
99.51
99.07
95.93
95.928
95.922
95.91
95.88
95.83
95.43
94.91
Note.—Adapted, with permission, from reference 10.
Table 3
Estimated Conceptus Doses from Radiographic and Fluoroscopic Examinations
Examination
Cervical spine (AP, lat)
Extremities
Chest (PA, lat)
Thoracic spine (AP, lat)
Abdomen (AP)
21-cm patient thickness
33-cm patient thickness
Lumbar spine (AP, lat)
Limited IVP*
Small-bowel study†
Double-contrast barium
enema study‡
Typical Conceptus
Dose (mGy)
⬍0.001
⬍0.001
0.002
0.003
1
3
1
6
7
7
Note.—AP ⫽ anteroposterior projection, lat ⫽ lateral projection, PA ⫽ posteroanterior projection.
*Limited IVP is assumed to include four abdominopelvic images. A patient thickness of 21 cm is assumed.
†A small-bowel study is assumed to include a
6-minute fluoroscopic examination with the acquisition of 20 digital spot images.
‡A double-contrast barium enema study is assumed
to include a 4-minute fluoroscopic examination with
the acquisition of 12 digital spot images.
Conceptus Effects
from Radiation Exposure
Data regarding the potential biological effects on
the conceptus after in utero radiation exposure
are based on the results of animal studies and human exposures. The primary sources of human
data are studies of the 1945 atomic bomb survivors from Hiroshima and Nagasaki, a group that
includes approximately 2800 pregnant women
who were exposed to radiation, 500 of whom re-
ceived a conceptus dose of more than 10 mGy
(1–9). The potential effects of radiation on a
conceptus include prenatal death, intrauterine
growth restriction, small head size, severe mental
retardation, reduced intelligence quotient, organ
malformation, and childhood cancer. These effects depend on the radiation dose to the conceptus and the stage of conceptus development at
which the exposure occurs (Tables 1, 2) (1–10).
Modality-Specific
Dose Considerations
Radiography and Fluoroscopy
If the uterus is positioned outside the field of
view, the conceptus is exposed to scattered radiation only and the conceptus dose is minimal.
Higher conceptus dose values occur when the
uterus is positioned within the field of view. In
this case, the radiation dose to a conceptus from a
radiographic or fluoroscopic examination depends on the thickness of the patient (ie, the
amount of tissue the x-ray beam must penetrate),
the direction of the projection (anteroposterior,
posteroanterior, or lateral), the depth of the conceptus from the skin surface, and x-ray technique
factors. The dose to the conceptus may vary by a
factor of 10 for a specific examination or projection. The estimated conceptus doses in early
pregnancy from radiographic and fluoroscopic
examinations at our institution are listed in Table
3. These values can be compared with the dose to
the conceptus from naturally occurring background radiation of approximately 0.5–1 mSv for
the entire period of gestation (1). Depending on
the position of the conceptus within the mother, it
912
RG f Volume 27
July-August 2007
●
Number 4
Table 4
Estimated Conceptus Doses from Single CT Acquisition
Examination
Extra-abdominal
Head CT
Chest CT
Routine
Pulmonary embolus
CT angiography of coronary arteries
Abdominal
Abdomen, routine
Abdomen/pelvis, routine
CT angiography of aorta (chest
through pelvis)
Abdomen/pelvis, stone protocol*
Dose Level
Typical Conceptus
Dose (mGy)
Standard
0
Standard
Standard
Standard
0.2
0.2
0.1
Standard
Standard
4
25
Standard
Reduced
34
10
*Anatomic coverage is the same as for routine abdominopelvic CT, but the tube
current is decreased and the pitch is increased because standard image quality is
not necessary for detection of high-contrast stones.
may be possible to use a lead shield to protect the
uterus from external scattered radiation (scatter
emanating from the exposed tissue or imaging
equipment) if the area of interest is outside the
uterus. However, because the dose from external
scattered radiation is minimal, the use of lead
shielding is left to the discretion of the practitioner. Although lead shielding may be an unnecessary precaution, it may offer the patient a sense of
protection and reassurance.
Computed Tomography
Computed tomography (CT) is associated with
higher levels of radiation exposure than is radiography. At CT, the dose to the individual conceptus varies with the proximity of the uterus to the
anatomic location of the scan plane, the thickness
of the patient, the depth of the conceptus, and
x-ray technique factors. The conceptus dose can
vary by a factor of two to four for a specific examination. The estimated conceptus doses for extraabdominal and abdominal CT examinations at
our institution are listed in Table 4. These values
may vary because of the imaging techniques required to produce the desired image quality for
each type of examination, the required anatomic
coverage, or both.
Some CT scanner vendors have introduced
automated exposure control capabilities that provide real-time x-ray tube current modulation
based on the tissue attenuation (11). Such
mechanisms help minimize the radiation dose
Table 5
Estimated Conceptus Doses from Nuclear
Medicine Examinations
Typical Conceptus Dose
(mGy)
Examination
Bone scan
Whole-body PET
scan
Thyroid scan
Early First
Trimester
End of First
Trimester
5
4
15
0.2
10
0.1
Note.—The radiopharmaceuticals used for each
examination are as follows: for a bone scan, 20 mCi
of technetium 99m medronate (methylene diphosphonate); for PET, 15 mCi of fluorine 18 fluorodeoxyglucose; and for a thyroid uptake scan, 0.2 mCi
of iodine 123.
delivered to a patient with a small body habitus,
and hence to the conceptus, by preventing unnecessarily high tube current settings. In large patients, the radiation dose is increased to ensure
adequate image quality, yet much of the additional x-ray dose is absorbed by the additional
adipose tissue. Thus, doses to internal organs do
not increase linearly with increases in tube current settings (12,13). Monte Carlo simulations
indicate that an increase of the scanner output by
a factor of two in very large patients (weight, approximately 100 kg; lateral thickness, 50 cm or
less) results in an increase of only 25% in the effective dose. This is because the effective dose is
strongly dependent on the dose delivered to inter-
RG f Volume 27
●
Number 4
nal organs (12,13). CT projection radiography
delivers a minimal radiation dose to the conceptus, and the benefits of its use (eg, accurate localization of the CT scan) outweigh the small radiation risk. The CT projection radiograph is required for most automated exposure control
implementations, as an aid in the initial selection
of tube voltage and current settings before scanning.
At CT, lead shielding of the abdomen and pelvis may be used if it will not interfere with the
scan field, although the dose from external scattered radiation is minimal. The lead shield may
provide the patient more reassurance than actual
risk reduction, and its use is left to the discretion
of the practitioner.
Nuclear Medicine
The dose to the conceptus from radionuclide examinations is variable and depends principally on
factors related to maternal uptake and excretion
of the radiopharmaceutical, passage of the agent
across the placenta, and uptake in the conceptus.
Conceptus dose estimates from our institution are
provided in Table 5.
Policy Statements
Several well-recognized published documents
provide guidance regarding the radiologic imaging of pregnant women. In 1977, the National
Council on Radiation Protection and Measurements (6) issued the following statement: “The
risk [of abnormality] is considered to be negligible
at 50 mGy or less when compared to other risks
of pregnancy, and the risk of malformations is
significantly increased above control levels only at
doses above 150 mGy. Therefore, exposure of the
fetus to radiation arising from diagnostic procedures would very rarely be cause, by itself, for
terminating a pregnancy.” The American College
of Radiology (14) established the following as its
policy concerning the use of therapeutic abortion:
“The interruption of pregnancy is rarely justified
because of radiation risk to the embryo or fetus
from a radiologic examination.” According to a
statement published by the International Commission on Radiological Protection (5), “Prenatal
doses from most properly done diagnostic procedures present no measurably increased risk of
prenatal death, malformation, or impairment
of mental development over the background
incidence of these entities.” In addition, the commission stated, “Fetal doses below 100 mGy
should not be considered a reason for terminating
McCollough et al
913
a pregnancy.” More recently, the American College of Obstetricians and Gynecologists (15) published the following policy statement: “Women
should be counseled that x-ray exposure from a
single diagnostic procedure does not result in
harmful fetal effects. Specifically, exposure to less
than 5 rad [50 mGy] has not been associated with
an increase in fetal anomalies or pregnancy loss.”
Given these statements and the data in Tables
1 and 2, it is clear that the risk to the conceptus
from radiation doses of less than 50 mGy is negligible. With regard to doses of more than 50 mGy,
Table 2 shows that with double that dose (ie, 100
mGy), the increase over background incidence for
organ malformation and the development of
childhood cancer combined is only about 1%.
Developing Practice
Policies and Guidelines
The development of a practice policy regarding
radiation-based imaging of pregnant patients at
one’s institution should be a data-driven process
(16,17). Such policies should be derived from a
review of the available literature and the various
guidelines published by professional and radiation
protection societies (eg, the American College of
Radiology and the American College of Obstetricians and Gynecologists), as well as a critical review of recognized best practices. In our practice,
we followed that approach in creating guidelines
for imaging pregnant women who present with
common medical symptoms.
One scenario that we considered in our analysis is the imaging evaluation of a pregnant woman
with symptoms of urolithiasis. In that setting, a
comprehensive examination with ultrasonography
(US) is recommended as the initial diagnostic
imaging evaluation. The US examination should
include not only the kidneys but also the bladder
to assess ureteral jet activity and transvaginal pelvic scanning to detect a distal ureteral stone.
Transvaginal pelvic scanning generally can be
performed safely at any stage of pregnancy unless
there is a ruptured membrane; rupture is a strong
relative contraindication to transvaginal scanning.
If no abnormality is found at this initial US examination, then a repeat US examination should
be performed 24 hours later. If the results of both
examinations are inconclusive and the clinical
diagnosis is urolithiasis complicated by unrelenting pain or new fever, further imaging must be
considered before intervention.
Teaching
Point
914
July-August 2007
RG f Volume 27
●
Number 4
Figure 1. Axial CT image from a renal stone study in
a pregnant woman shows a stone in a middle segment
of the right ureter (arrow).
The value of unenhanced CT for the detection
of urolithiasis is well established (Fig 1). CT is
more effective than excretory urography for the
detection of ureteral calculi (18), with sensitivity
and specificity ranging between 92% and 99%
(19). CT also is better than urography for diagnosing the complications of stone disease. CT has
the added capability of depicting abnormalities
outside the urinary tract, which is an advantage if
the cause of abdominal pain is not urolithiasis; for
this reason, it has emerged as the primary imaging
modality for evaluating patients in whom urolithiasis is suspected. CT is fast, noninvasive, and
readily available. Unlike excretory urography, CT
performed by using a stone detection protocol
does not necessitate the injection of an intravenous contrast medium.
Given the concern for radiation dose to the
conceptus from CT, the clinical utility of limited
intravenous pyelography (IVP) as an alternative
to CT also was considered (Fig 2). A limited IVP
examination includes initial unenhanced imaging;
nephrographic phase imaging; excretory phase
imaging of the kidneys, ureters, and bladder at
approximately 15–20 minutes after injection; and
delayed phase imaging to help confirm the level
and cause of urinary tract obstruction.
We determined the estimated conceptus dose
in a quantitative manner for these two imaging
scenarios (renal stone CT and limited IVP). It
was essential that this analysis be performed for
patients of varied thickness (Fig 3), because the
dose from a radiographic examination increases
Figure 2. One of four abdominopelvic radiographs
from limited IVP. Note that the requisite anatomic coverage results in full irradiation of the conceptus.
dramatically with the increasing girth that is typical late in pregnancy, when urolithiasis is most
common. As patient size changes, the change in
CT scanner technique factors varies by a much
smaller amount. For example, over the same
range of patient thicknesses given in Figure 3 for
radiographic examinations, the CT radiation output would vary by approximately a factor of three
instead of a factor of 10 as at radiography. In
small patients, for whom the CT scanner output
would be decreased, the peripheral attenuation
also would be decreased, causing an increase in
internal doses in relation to the scanner output. In
large patients, for whom the scanner output is
increased, the peripheral attenuation also is increased, with a resultant decrease in the internal
doses in relation to the scanner output (12,13).
The result is relatively constant organ doses when
scanner output is adjusted for patient size. Automated exposure control systems are particularly
beneficial in that they adjust the scanner output
on the basis of patient attenuation in a relatively
consistent manner. According to our calculations,
the fetal radiation dose from CT (approximately
10 mGy) is lower than that from limited IVP for a
patient with an anteroposterior thickness of 25
cm or greater (Fig 3). In our institution’s large
radiology practice, the average patient thickness
(men and women) is approximately 24 cm; thus,
Teaching
Point
RG f Volume 27
●
Number 4
Figure 3. Graph shows estimated fetal radiation
doses from CT and from limited IVP comprising four
abdominopelvic views for different patient thicknesses.
Values are representative of current technology.
Teaching
Point
we expect that most women in the second and
third trimesters of pregnancy would have an anteroposterior dimension of at least 25 cm.
Using these data, and considering the incremental value of CT in screening the remainder of
the abdomen and pelvis, we were able to reach a
consensus algorithm for the evaluation of pregnant women with suspected urinary tract calculi
(Fig 4). In a pregnant woman in whom urolithiasis is suspected, renal stone CT should be performed if the results of two consecutive comprehensive US examinations are inconclusive.
The same data-driven process can be applied
to achieve other imaging guidelines, as was done
by Winer-Muram et al with regard to pulmonary
embolus detection in pregnant women (20).
Winer-Muram and colleagues calculated the conceptus dose from chest CT for pulmonary embolus and found that it was less than that from
nuclear medicine ventilation-perfusion scanning
for all three trimesters. These data are consistent
with our own and with other published data in
which the fetal absorbed doses at CT pulmonary
angiography were reported to be less than or similar to those incurred at ventilation-perfusion scanning (21,22). Such data are essential if one is to
make an informed choice regarding appropriate
imaging of a pregnant patient in whom a pulmonary embolus is suspected. CT pulmonary angiography has a sensitivity of approximately 86%,
a specificity of 94%, and a greater discriminatory
power than ventilation-perfusion scanning at normal or near normal probability thresholds (23).
The use of helical CT in conjunction with US
reportedly led to a diagnosis in 99% of outpatients evaluated for a suspected pulmonary embolus (24), and helical CT is considered preferable
to ventilation-perfusion scanning in nonpregnant
patients (25–28). Its use for pulmonary embolus
evaluation also has been documented in pregnant
McCollough et al
915
Figure 4. Flow diagram shows the recommended
imaging algorithm for urolithiasis evaluations in pregnant women.
women, and 31% of investigators in the Prospective Investigation of Pulmonary Embolism Diagnosis study (PIOPED II) recommended it in that
clinical situation (28,29). Therefore, chest CT is
an appropriate secondary imaging modality for
achieving a definitive diagnosis of pulmonary embolism when lower-extremity US is insufficient
(30).
General Clinical Guidelines
As detailed in Tables 3–5, the conceptus dose
from common radiographic, fluoroscopic, CT,
and nuclear medicine examinations is considerably lower than the established risk threshold of
50 –100 mGy. Notably, imaging examinations of
the head, neck, chest, and peripheral extremities
are associated with negligible risks to the conceptus. In imaging of the abdomen or pelvis, US is
preferred as the initial examination because it presents no risk from ionizing radiation to the conceptus. MR imaging is emerging as an alternative
for further evaluation of patients with indeterminate findings at US of the abdomen or pelvis, but
access to MR imaging is limited in many practices. Because the conceptus dose from a singleacquisition CT examination of the abdomen and
pelvis poses a minimal risk to fetal health, CT of
the abdomen, the pelvis, or both is appropriate
when imaging examinations based on the use of
nonionizing radiation fail to yield the necessary
clinical information, or in the setting of maternal
trauma (31).
916
July-August 2007
Conclusions
Teaching
Point
Teaching
Point
Radiographic, fluoroscopic, and CT examinations in areas of the body other than the abdomen
and pelvis deliver minimal radiation doses to the
fetus. Moreover, fetal radiation doses from radiographic, fluoroscopic, and CT examinations of
the abdomen and pelvis and from nuclear medicine studies rarely exceed 25 mGy. After comparing the doses from radiologic and nuclear medicine examinations with risk data from human in
utero exposures, we have concluded that the absolute risks of fetal effects, including childhood
cancer induction, are small at conceptus doses of
100 mGy and negligible at doses of less than 50
mGy. While this information may reassure pregnant women and their physicians about the risks
from necessary or unintended radiation exposures, conservative clinical management is the
best way of minimizing radiation risk in utero.
Radiologic or nuclear medicine examinations
should be performed in such patients only when
necessary, and—as with any drug or intervention
in pregnancy—the dose used for the examination
should be kept as low as reasonably achievable
(32).
References
1. Wagner LK, Lester RG, Saldana LR. Exposure of
the pregnant patient to diagnostic radiations: a
guide to medical management. Madison, Wis:
Medical Physics Publishing, 1997.
2. International Commission on Radiological Protection. Recommendations of the International Commission on Radiological Protection. Oxford, England: International Commission on Radiological
Protection, 1977.
3. International Commission on Radiological Protection. Developmental effects of irradiation on the
brain of the embryo and fetus. Ann ICRP 1986;
16:1– 43.
4. 1990 recommendations of the International Commission on Radiological Protection. Ann ICRP
1991;21:1–201.
5. International Commission on Radiological Protection. Pregnancy and medical radiation. Ann ICRP
2000;30:1– 43.
6. National Council on Radiation Protection and
Measurements. Medical radiation exposure of
pregnant and potentially pregnant women. NCRP
report no. 54. Bethesda, Md: National Council on
Radiation Protection and Measurements, 1977.
7. National Council on Radiation Protection and
Measurements. Recommendations on limits for
exposure to ionizing radiation. Bethesda, Md: National Council on Radiation Protection and Measurements, 1987.
8. National Council on Radiation Protection and
Measurements. Risk estimates for radiation protection. Bethesda, Md: National Council on Radiation Protection and Measurements, 1993.
9. American Association of Physicists in Medicine. A
primer on low-level ionizing radiation and its biological effects. New York, NY: American Association of Physicists in Medicine, 1986.
RG f Volume 27
●
Number 4
10. Wagner LK, Hayman LA. Pregnancy and women
radiologists. Radiology 1982;145:559 –562.
11. McCollough CH, Bruesewitz MR, Kofler JM Jr.
CT dose reduction and dose management tools:
overview of available options. RadioGraphics
2006;26:503–512.
12. Schmidt B. Dose calculations for computed tomography. Reports from the Institute of Medical
Physics, vol 7. Aachen, Germany: Shaker, 2001.
13. Schmidt B, Kalender WA. A fast voxel-based
Monte Carlo method for scanner- and patientspecific dose calculations in computed tomography. In: Del Guerra A, ed. Physica medica: European Journal of Medical Physics. Vol 18, no. 2
(April–June). Pisa, Italy: Istituti Editoriali e Poligrafici Internazionali, 2002; 43–53.
14. American College of Radiology. ACoR 04 – 05
bylaws. Reston, Va: American College of Radiology, 2005.
15. ACOG Committee on Obstetric Practice. Guidelines for diagnostic imaging during pregnancy.
ACOG Committee opinion no. 299, September
2004 (replaces no. 158, September 1995). Obstet
Gynecol 2004;104:647– 651.
16. Fielding JR, Washburn D. Imaging the pregnant
patient: a uniform approach. J Womens Imaging
2005;7:16 –21.
17. El-Khoury GY, Madsen MT, Blake ME, Yankowitz J. A new pregnancy policy for a new era. AJR
Am J Roentgenol 2003;181:335–340.
18. Smith RC, Rosenfield AT, Choe KA, et al. Acute
flank pain: comparison of non-contrast-enhanced
CT and intravenous urography. Radiology 1995;
194:789 –794.
19. Ripolles T, Errando J, Agramunt M, Martinez MJ.
Ureteral colic: US versus CT. Abdom Imaging
2004;29:263–266.
20. Winer-Muram HT, Boone JM, Brown HL, Jennings SG, Mabie WC, Lombardo GT. Pulmonary
embolism in pregnant patients: fetal radiation dose
with helical CT. Radiology 2002;224:487– 492.
21. Cook JV, Kyriou J. Radiation from CT and perfusion scanning in pregnancy. BMJ 2005;331:350.
22. Hurwitz LM, Yoshizumi T, Reiman RE, et al. Radiation dose to the fetus from body MDCT during
early gestation. AJR Am J Roentgenol 2006;186:
871– 876.
23. Hayashino Y, Goto M, Noguchi Y, Fukui T. Ventilation-perfusion scanning and helical CT in suspected pulmonary embolism: meta-analysis of diagnostic performance. Radiology 2005;234:740 –
748.
24. Perrier A, Roy PM, Aujesky D, et al. Diagnosing
pulmonary embolism in outpatients with clinical
assessment, D-dimer measurement, venous ultrasound, and helical computed tomography: a multicenter management study. Am J Med 2004;116:
291–299.
25. Ryu JH, Swensen SJ, Olson EJ, Pellikka PA. Diagnosis of pulmonary embolism with use of computed tomographic angiography. Mayo Clin Proc
2001;76:59 – 65.
26. Blachere H, Latrabe V, Montaudon M, et al. Pulmonary embolism revealed on helical CT angiography: comparison with ventilation-perfusion radionuclide lung scanning. AJR Am J Roentgenol
2000;174:1041–1047.
RG f Volume 27
●
Number 4
27. British Thoracic Society Standards of Care Committee Pulmonary Embolism Guideline Development Group. British Thoracic Society guidelines
for the management of suspected acute pulmonary
embolism. Thorax 2003;58:470 – 483.
28. Stein PD, Woodard PK, Weg JG, et al. Diagnostic
pathways in acute pulmonary embolism: recommendations of the PIOPED II investigators. Radiology 2007;242:15–21.
29. Schuster ME, Fishman JE, Copeland JF, Hatabu
H, Boiselle PM. Pulmonary embolism in pregnant
patients: a survey of practices and policies for CT
pulmonary angiography. AJR Am J Roentgenol
2003;181:1495–1498.
McCollough et al
917
30. Matthews S. Short communication: imaging pulmonary embolism in pregnancy: what is the most
appropriate imaging protocol? Br J Radiol 2006;
79:441– 444.
31. Lowdermilk C, Gavant ML, Qaisi W, West OC,
Goldman SM. Screening helical CT for evaluation
of blunt traumatic injury in the pregnant patient.
RadioGraphics 1999;19(spec no):S243–S255;
discussion S256 –S258.
32. Linton OW, Mettler FA, Jr. National conference
on dose reduction in CT, with an emphasis on
pediatric patients. AJR Am J Roentgenol 2003;
181:321–329.
RG
Volume 27 • Volume 4 • July-August 2007
McCollough et al
Radiation Exposure and Pregnancy: When Should We Be
Concerned?
Cynthia H. McCollough, P hD et al
RadioGraphics 2007; 27:909 –918 ● Published online 10.1148/rg.274065149 ● Content Codes:
Page 913
The American College of Obstetricians and Gynecologists (15) published the following policy
statement: “Women should be counseled that x-ray exposure from a single diagnostic procedure does
not result in harmful fetal effects. Specifically, exposure to less than 5 rad [50 mGy] has not been
associated with an increase in fetal anomalies or pregnancy loss”.
Page 914
According to our calculations, the fetal radiation dose from CT (approximately 10 mGy) is lower
than that from limited IVP for a patient with an anteroposterior thickness of 25 cm or greater.
Page 915
Winer-Muram and colleagues calculated the conceptus dose from chest CT for pulmonary embolus
and found that it was less than that from a nuclear medicine ventilation-perfusion scan for all three
trimesters.
Page 916
Radiographic, fluoroscopic, and CT examinations in areas of the body other than the abdomen and
pelvis deliver minimal radiation doses to the fetus. Moreover, fetal radiation doses from radiographic,
fluoroscopic, and CT examinations of the abdomen and pelvis and from nuclear medicine studies
rarely exceed 25 mGy.
Page 916
After comparing the doses from radiologic and nuclear medicine examinations with risk data from
human in utero exposures, we have concluded that the absolute risks of fetal effects, including
childhood cancer induction, are small at conceptus doses of 100 mGy and negligible at doses of less
than 50 mGy.
RadioGraphics 2007
This is your reprint order form or pro forma invoice
(Please keep a copy of this document for your records.)
Reprint order forms and purchase orders or prepayments must be received 72 hours after receipt of form either
by mail or by fax at 410-820-9765. It is the policy of Cadmus Reprints to issue one invoice per order.
Please print clearly.
Author Name _______________________________________________________________________________________________
Title of Article _______________________________________________________________________________________________
Issue of Journal_______________________________
Reprint # _____________
Publication Date ________________
Number of Pages_______________________________
KB # _____________
Symbol RadioGraphics
Color in Article? Yes / No
(Please Circle)
Please include the journal name and reprint number or manuscript number on your purchase order or other correspondence.
Order and Shipping Information
Reprint Costs (Please see page 2 of 2 for reprint costs/fees.)
________ Number of reprints ordered
Shipping Address (cannot ship to a P.O. Box) Please Print Clearly
$_________
________ Number of color reprints ordered $_________
________ Number of covers ordered
$_________
Subtotal $_________
Taxes
$_________
(Add appropriate sales tax for Virginia, Maryland, Pennsylvania, and the
District of Columbia or Canadian GST to the reprints if your order is to
be shipped to these locations.)
First address included, add $32 for
each additional shipping address
TOTAL
$_________
$_________
Name ___________________________________________
Institution _________________________________________
Street ___________________________________________
City ____________________ State _____ Zip ___________
Country ___________________________________________
Quantity___________________ Fax ___________________
Phone: Day _________________ Evening _______________
E-mail Address _____________________________________
Additional Shipping Address* (cannot ship to a P.O. Box)
Name ___________________________________________
Institution _________________________________________
Street ___________________________________________
City
________________ State ______ Zip ___________
Country _________________________________________
Quantity __________________ Fax __________________
Phone: Day ________________ Evening ______________
E-mail Address ____________________________________
* Add $32 for each additional shipping address
Payment and Credit Card Details
Invoice or Credit Card Information
Enclosed: Personal Check ___________
Credit Card Payment Details _________
Invoice Address
Please Print Clearly
Please complete Invoice address as it appears on credit card statement
Checks must be paid in U.S. dollars and drawn on a U.S. Bank.
Credit Card: __ VISA __ Am. Exp. __ MasterCard
Card Number __________________________________
Expiration Date_________________________________
Signature: _____________________________________
Please send your order form and prepayment made payable to:
Cadmus Reprints
P.O. Box 751903
Charlotte, NC 28275-1903
Name ____________________________________________
Institution ________________________________________
Department _______________________________________
Street ____________________________________________
City ________________________ State _____ Zip _______
Country ___________________________________________
Phone _____________________ Fax _________________
E-mail Address _____________________________________
Cadmus will process credit cards and Cadmus Journal
Services will appear on the credit card statement.
Note: Do not send express packages to this location, PO Box.
FEIN #:541274108
If you don’t mail your order form, you may fax it to 410-820-9765 with
your credit card information.
Signature __________________________________________
Date
_______________________________________
Signature is required. By signing this form, the author agrees to accept the responsibility for the payment of reprints and/or all charges
described in this document.
RB-9/22/06
Page 1 of 2
RadioGraphics 2007
Color Reprint Prices
Black and White Reprint Prices
Domestic (USA only)
# of
Pages
1-4
5-8
9-12
13-16
17-20
21-24
25-28
29-32
Covers
50
$213
$338
$450
$555
$673
$785
$895
$1,008
$95
100
200
300
$228
$260
$278
$373
$420
$453
$500
$575
$635
$623
$728
$805
$753
$883
$990
$880 $1,040 $1,165
$1,010 $1,208 $1,350
$1,143 $1,363 $1,525
$118
$218
$320
Domestic (USA only)
400
500
$295
$495
$693
$888
$1,085
$1,285
$1,498
$1,698
$428
$313
$530
$755
$965
$1,185
$1,413
$1,638
$1,865
$530
# of
Pages
1-4
5-8
9-12
13-16
17-20
21-24
25-28
29-32
Covers
International (includes Canada and Mexico)
# of
Pages
1-4
5-8
9-12
13-16
17-20
21-24
25-28
29-32
Covers
50
100
200
300
400
500
$218
$343
$471
$601
$738
$872
$1,004
$1,140
$95
$233
$388
$503
$633
$767
$899
$1,035
$1,173
$118
$343
$584
$828
$1,073
$1,319
$1,564
$1,820
$2,063
$218
$460
$825
$1,196
$1,562
$1,940
$2,308
$2,678
$3,048
$320
$579
$1,069
$1,563
$2,058
$2,550
$3,045
$3,545
$4,040
$428
$697
$1,311
$1,935
$2,547
$3,164
$3,790
$4,403
$5,028
$530
International (includes Canada and Mexico))
50
100
200
300
400
500
$263
$415
$563
$698
$848
$985
$1,135
$1,273
$148
$275
$443
$608
$760
$925
$1,080
$1,248
$1,403
$168
$330
$555
$773
$988
$1,203
$1,420
$1,640
$1,863
$308
$385
$650
$930
$1,185
$1,463
$1,725
$1,990
$2,265
$463
$430
$753
$1,070
$1,388
$1,705
$2,025
$2,350
$2,673
$615
$485
$850
$1,228
$1,585
$1,950
$2,325
$2,698
$3,075
$768
Minimum order is 50 copies. For orders larger than 500 copies,
please consult Cadmus Reprints at 800-407-9190.
Reprint Cover
Cover prices are listed above. The cover will include the
publication title, article title, and author name in black.
# of
Pages
1-4
5-8
9-12
13-16
17-20
21-24
25-28
29-32
Covers
50
100
200
300
400
500
$268
$419
$583
$742
$913
$1,072
$1,246
$1,405
$148
$280
$457
$610
$770
$941
$1,100
$1,274
$1,433
$168
$412
$720
$1,025
$1,333
$1,641
$1,946
$2,254
$2,561
$308
$568
$1,022
$1,492
$1,943
$2,412
$2,867
$3,318
$3,788
$463
$715
$1,328
$1,941
$2,556
$3,169
$3,785
$4,398
$5,014
$615
$871
$1,633
$2,407
$3,167
$3,929
$4,703
$5,463
$6,237
$768
Tax Due
Residents of Virginia, Maryland, Pennsylvania, and the District
of Columbia are required to add the appropriate sales tax to each
reprint order. For orders shipped to Canada, please add 7%
Canadian GST unless exemption is claimed.
Ordering
Shipping
Shipping costs are included in the reprint prices. Domestic
orders are shipped via UPS Ground service. Foreign orders are
shipped via a proof of delivery air service.
Multiple Shipments
Reprint order forms and purchase order or prepayment is
required to process your order. Please reference journal name
and reprint number or manuscript number on any
correspondence. You may use the reverse side of this form as a
proforma invoice. Please return your order form and
prepayment to:
Cadmus Reprints
P.O. Box 751903
Charlotte, NC 28275-1903
Orders can be shipped to more than one location. Please be
aware that it will cost $32 for each additional location.
Delivery
Your order will be shipped within 2 weeks of the journal print
date. Allow extra time for delivery.
Note: Do not send express packages to this location, PO Box.
FEIN #:541274108
Please direct all inquiries to:
Rose A. Baynard
800-407-9190 (toll free number)
410-819-3966 (direct number)
410-820-9765 (FAX number)
[email protected] (e-mail)
Page 2 of 2
Reprint Order Forms
and purchase order
or prepayments must
be received 72 hours
after receipt of form.