effects of radiation exposure on the developing fetus hannah connolly, janessa gioia, gillian reid,...
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Effects of Radiation Exposure on the Developing Fetus
Hannah Connolly, Janessa Gioia, Gillian Reid, Nadine Savoie, Suzanne Taylor
University of New Brunswick
Problem Statement Pregnant women may be denied diagnostic and therapeutic
radiation procedures because physicians fear the radiation will cause harm to the developing fetus. Thus, fewer options are available for improving the health of pregnant women when they require medical attention. Understanding the effects of radiation on the developing fetus may help physicians better counsel their patients on the risks involved. This education would allow for an informed decision to be made on whether to proceed with radiation procedures.
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Research Question
Are diagnostic and therapeutic radiation procedures harmful to the developing fetus?
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Harmful Teratogenic- causing congenital malformations
Carcinogenic- cancer causing
Mutagenic- causing genetic changes
(Whitt, 2010)
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Related Diseases
Major Mutations
Other abnormalities
The major risk is of course, embryonic loss. (Brent 1999).
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Radiation: DNA Damage
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History of why these studies emerged
Hiroshima and Nagasaki, Chernobyl
In 1956: prenatal exposure to radiation from diagnostic X-ray (Naumburg et al. 2001; Doll & Wakeford, 1997)
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Fetal Stages and Radiation Sensitivity
(1) Preimplantation (days 0 to ~14)
(2) Organogenesis (week 2 to week 8)
(3) Fetal (week 9 to term)
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Methods Quantitative
Experimental
Non Experimental
Retrospective
Prospective
Surveys
Time frames
LongitudinalRetrieve from http://www.faqs.org/photo-dict/photofiles/list/664/1074test_tubes.jpg
Health Concerns From our studies these are some health concerns that would bring
pregnant woman to our departments
Pulmonary Embolism
Loss of bone density
Cancer
Abdominal/Pelvic issues
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Pulmonary Embolism
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Pulmonary Embolism Chest X-ray + V-P Scan + Helical CT + Pulmonary Angiograpy with brachial
approach = ~ 1000 uGy.
Ventilation perfusion scans:
The presence and absence of PE is inconclusive in up to 80% of these scans
Prior episodes of PE may cause a false-positive result (Winner-Muram et al., 2002)
Fetal dose > 10 cGy, the probability of congenital defects rises 10%. (Tutty, 2001)
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Bone Density
There is evidence that some pre-existing disorders as well as heparin treatments may lead to significant diminution of bone mass during pregnancy.
Treatment would be administered to patients who demonstrate rapid bone lose during the first postconception months.
Emryo/fetus doses were found to be lower than the average daily natural background from a proximal femur scan.
Benefits Outweigh Risks! (Damilakis, 2002)
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Abdominal and Pelvic Procedures
Medical imaging such as CT may be required of the abdominal/trunk/pelvic area due to trauma, acute abdominal pain, appendicitis, or renal issues in a pregnant patient.
Ultrasound
Survey respondents are more likely to choose CT for trauma in all three trimesters.
For acute abdominal indications they were more likely to choose CT in the second and third trimester, and MRI in the first trimester.
The trend found in radiology literature is that CT is fast, readily available and allows immediate surgical intervention if needed. (Jaffe,
2007)Retrieve from http://www.lakeridgehealth.on.ca/patient_care/interventional_radiology/presentations/radiology/slide25.htm
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Abdominal and Pelvic Procedures
Literature suggests that for most radiologic procedures, the risk of fetal demise in the first 2 weeks after conception is less than 1% (Jaffe, 2007).
Radiologists may also opt for a modified CT protocol to reduce the exposure by reducing the power of the x-rays (kVp or mAs) (Damilakis et al., 2000).
No direct radiation to the fetus. (Hurtwitz et al. 2006; Kal & Struikmans, 2005)
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Cancer Diagnosis & Treatment when Pregnant
Cancer: 1 per 1000 pregnancies (Kal & Struikmans, 2005; Pavlidis & Penteroudakis, 2005)
Most common cancer types (Greskovich & Macklis, 2000; Pavlidis & Penteroudakis, 2005).
Carcinoma of the cervix: is the most common Breast cancer pregnant patient 1 in 3000 (Berry et al. 1999; Greskovich & Macklis, 2000; Kal & Struikmans,
2005; Pandit-Taskar et al. 2006)
Radiation therapy is not usually offered during pregnancy (Pavlidis & Penteroudakis, 2005; Kal & Struikmans, 2005)
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Diagnosing Oncology Patients
To diagnose:
Fine-needle biopsy, ultrasound, mammography, MRI (Berry
et al. 1999; Greskovich & Macklis, 2000; Pavlidis & Penteroudakis, 2005; Kal & Struikmans, 2005, Hurtwitz et al., 2006; Doll & Wakeford, 1997; Nicklas & Baker, 2000)
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Delaying Radiation
All chemotherapy drugs: crossing the placenta.
The first trimester: spontaneous abortion.
ethical balance must be achieved (Pavlidis &
Penteroudakis, 2005; Kal & Struikmans, 2005).
Delaying treatment until the second and third trimester. (Greskovich & Macklis, 2000; Pavlidis &
Penteroudakis, 2005, Doll & Wakeford, 1997; Departement of Health and Human Services, 2005).
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Staging for Oncology Patients
The benefits vs. risks(Greskovich & Macklis, 2000; Osei & Faulkner, 2000).
Main concerns of doctors (Pavlidis & Penteroudakis, 2005).
The medical staff and patient need to decide as a team whether to begin treatment or to postpone it (Kal & Struikmans, 2005).
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How much radiation is to much?
It is concluded that radiation doses of the order of 10 mGy received by the fetus in utero produce a consequent increase in the risk of childhood cancer. (Doll & Wakeford, 1997)
Lymphoscintigraphy for sentinel lymph node mapping (SLN) led to a neglible dose to the fetus (0.014 mGy or less) (Pandit-Taskar, 2006).
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Oncology Studies
Relative risk are higher: first (Greskovich & Macklis, 2000; Pavlidis & Penteroudakis, 2005; Doll, & Wakeford, 1997;
Department of Health and Human Services, 2005). Mastectomy with postpartum radiation (Berry et al. 1999)
Patients received a median of four cycles of chemotherapy (Berry et al. 1999; Doll, & Wakeford, 1997; Department of Health and Human Services, 2005).
Neonates: no unusual complications or malformations. (Berry et al. 1999)
Fetal dose was much less than the NCRP limit. Pandit-Taskar et al. (2006)
Oncology- Thyroid Cancer
Radioiodine (131I) Therapy Abnormalities Indirect exposure to: the uterus, 131I uptake in the
blood, bladder, gut, kidneys Within a year after the therapy: miscarriages and
induced abortions. A number of stillbirths after radioiodine therapy:
high. Thyroid hormone DO NOT: conceive one month prior the therapy and
postponing conception until the thyroid hormone status has been verified.
(Garsi, J-P., et al. 2008, Bohuslavizki, 1999)
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Childhood Development
Preschool aged children
No damaging effects of diagnostic imaging, low dose x-radiation. (Ornoy et al., 1996)
Large radiation doses (Department of Health and Human Services, 2005)
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Childhood Cancer
The USNCRP: doses of 50 mGy or less is negligible
Baseline risks
However…
increases in use of of CT and nuclear medicine radiodiagnostic procedures
Inadvertent exposure in early pregnancy may occur
(Ratnapalan et al., 2003; Ray et al. 2010)
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Childhood CancerLeukemia
Leukemia is the most common malignancy among children.
Study: children born in Sweden between 1973- 1989.
Association between leukemia and diagnostic x-rays is likely to be small.
(Naumburg et al., 2001)
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Childhood CancerMalignancy
Ontario study: Between April 1, 1992 and March 31, 2008.
Researchers looked at the incidence of malignancy in those children
Exposed mothers vs. unexposed mothers
They concluded: no difference noted
(Ray et al., 2010)
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Perception of the Risks
Ontario survey
Misperceptions of physicians
Could lead to anxiety, delay of care among pregnant woman (Ratnapalan et al., 2004)
Misperception of patients may be caused by misinformation (Bentur et al. 1991)
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Recommendations & Precautions
Menstrual Cycle (Vollman, 1977; Zanotti-Fregonara et al. 2009)
Modify daily procedures ALARA- as low as reasonably achievable Radiation Therapy Do treatment planning and risk management. (Bednarz & Xu, 2008).
Lead shielding (Sechopoulos et al. 2008) http://www.youtube.com/watch?v=eziUXYwl_Cs
Serum testing (Ray et. al, 2010)
MRI and Ultrasonography Bone densitometry on a pregnant patient Physician education (Ratnapalan et al., 2004)
Brief counseling Pregnant nuclear workers (Damilakis et al. 2005)
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Limitations Randomization
Small sample size
The use of phantoms instead of real-life subjects.
Phantom does not take into account all different body variation
Retrospective designs
Results are only approximations.
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Conclusion The amount of radiation absorbed by the fetus varies
Misperceptions exist
2 most important determining factors : dose & stage of gestation
The effects of radiation may be harmful: threshold value of 50 mGy
ALARA
Benefits outweigh risks
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References