Radiation exposure to a fetus is kept as low as reasonably achievable
Radiation during pregnancy
- Avoiding unnecessary exposure to the developing fetus or embryo is essential due to the radiosensitivity of rapidly dividing cells.
- The relative risks of fetal exposure to radiation should be weighed against the risks of failing to diagnose serious disease in the mother and by realizing absolute risk remains very small1.
- Irradiation of the unborn fetus increases the risk of somatic effects as well as genetic effects that could be passed to subsequent generations2.
- Exposure of less than 50 mGy have not been associated with an increase in fetal anomalies or pregnancy loss3
Screening for pregnancy
- Every female patient of childbearing age (e.g., 10-55 years of age) is asked before a procedure or treatment if there is a possibility that she is pregnant2,4.
- An example of how an MRT might enquire about pregnancy: “Is there any chance that you might be pregnant?”
- Patients should be asked these questions in privacy3
- Responses to the questions are documented
- MRTs may find it useful to employ a standardized form to inquire about pregnancy3.
- A standardized form has the advantage of ensuring uniformity in the questioning process
- It can also serve in the documentation of pregnancy status for the medical record
- Pregnancy testing may be used to confirm a patient’s pregnancy status before procedures that have the potential for large doses of radiation to the fetus5,7:
- Irradiation of certain sensitive areas (e.g., pelvis)
- Examinations where radiation doses are high (e.g., radioiodine therapy)
- Signage posted in patient waiting areas advising patients to declare if they are pregnant can aid in identification, but doesn’t replace the requirement for asking the patient.
- If pregnancy is identified after the procedure or treatment, the MRT must notify the:
- Physician on duty
- Radiation Safety Officer or Radiation Protection Officer, as applicable
Procedures or treatment for pregnant patients
- The decision to undertake a procedure or a course of treatment, and the determination of the exact limitations to be imposed, are made collaboratively with the radiologist, radiation oncologist or referring physician, and the patient5,6,7.
- MRTs only proceed with procedures or treatment for pregnant patients after confirmation that the radiologist or radiation oncologist has been consulted
- As with all patients, the principles of ALARA guide decisions about pregnant or possibly pregnant patients2:
- Procedures or treatment are essential and the benefits outweigh the risks
- Procedures or treatment that cannot be delayed until after delivery
- Alternative investigations are considered where possible before proceeding (e.g., ultrasound)
- Reductions in dose are considered, if possible
- Department/facility guidelines should be consulted before proceeding with any procedure.
- If examination of a pregnant patient must be carried out, modifications may help to minimize the dose to the embryo or fetus5,7:
- For imaging the chest or extremities, a well collimated x-ray beam with abdominal shielding is used2
- For imaging of the pelvic area, full use of gonadal shielding is used (unless clinical objectives will be compromised)5
- Posterior-anterior (PA) positioning is used when possible to reduce radiation dose to the fetus
- In nuclear medicine procedures, a reduced dose is recommended8
- Exposures and dose are documented, as well as the names of healthcare professionals involved in the decision.
American College of Radiology. Image Wisely. The Pregnant Patient: Alternatives to CT and Dose-Saving Modifications to CT Technique. Available from: https://www.imagewisely.org/Imaging-Modalities/Computed-Tomography/Pregnant-Patient. [Accessed 12 Dec 2019]
Health Canada. Safety Code 35: Safety Procedures for the Installation, Use and Control of X-ray Equipment in Large Medical Radiological Facilities. Available from: http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/safety-code_35-securite/index-eng.php. [Accessed 12 Dec 2019]
American College of Radiology. ACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Adolescents and Women with Ionizing Radiation. Available from: https://www.acr.org/-/media/ACR/Files/Practice-Parameters/pregnant-pts.pdf. [Accessed 12 Dec 2019]
Martensen, Kathy. Radiographic Image Analysis. St Louis, MO: Saunders Elesvier, 2011.
Statkiewicz Sherer MA, Visconti P, Ritenour ER, et al. Radiation Protection in Medical Radiography. 7th ed. Maryland Heights, MO: Mosby Elsevier, 2013.
American College of Radiology. Image Wisely. PET-CT in the Pregnant Patient. Available from: https://www.imagewisely.org/~/media/ImageWisely-Files/NucMed/PETCT-in-the-Pregnant-Patient.pdf. [Accessed 12 Dec 2019]
Canadian Cancer Society. Cancer during pregnancy. Available from: http://www.cancer.ca/en/cancer-information/diagnosis-and-treatment/cancer-during-pregnancy/?region=on. [Accessed 12 Dec 2019]
Centers for Disease Control and Prevention (CDC). Radiation and Pregnancy: A fact sheet for physicians. Available from: https://www.cdc.gov/nceh/radiation/emergencies/prenatalphysician.htm. [Accessed 12 Dec 2019]