Radiology - Radiation Safety

Radiation Safety Dr. Lagamayo Fact #1. Many women will become ill while pregnant, requiring medical attention that can include radiographic imaging with ionizing radiation. Fact #2. Exposure of the fetus to ionizing radiation, in the process of imaging a sick gravid mother, can cause anxiety on the part of the parents regarding its potential harmful effect to the fetus. Fact #3. Even physicians approach the issue of exposing the fetus to ionizing radiation with bias and not infrequently with unscientifically founded principles and beliefs. Fact #4. Not infrequently, radiographic studies are performed on mothers who are not immediately recognized as gravid, causing undue anxiety and stress as to the possible outcome of these incidents to the fetus. Objective: 1. To review the risks of radiation to the fetus and list its harmful effects 2. Show the levels of radiation exposure incurred by the fetus during common radiographic studies Nature of Radiation: Ionizing radiation (X-ray) is made up of high energy photons that are quite capable of damaging DNA and generating caustic free radicals. Radiation Dose: • Gray (Gy) or rem: (roentgen equivalent man) • Rad: roentgen absorbed dose (when radiation penetrates a substance) 1 Sievery (Sv) = 100 rem 1 Gy = 100 rads Harmful Effects of Radiation Exposure: Much of the data on the effects of radiation to humans come from the study of atomic bomb survivors who were irradiated with high doses while in-utero in Nagasaki and Hiroshima. Effects of Radiation Exposure: • Teratogenesis (malformation)

• •

Carcinogenesis (malignancy) Mutagenesis (germ-line gene alteration)

Radiation-Induced Teratogenesis • CNS changes, e.g. : microcephaly and mental retardation • Many Japanese who were exposed to radiation in-utero to doses of 10-150 rad developed microcephaly • A linear, dose-related association between severe mental retardation and radiation exposure was found • Most cases of radiation exposure are at 10-17 weeks age of gestation • This trend reaches 40% at 100 rad

Radiation-Induced Malignancy • Background rate of leukemia is 3.6 per 10,000 population • Increasing radiation exposure by 1-2 rad increases the rate of malignancy to 5 per 10,000 Radiation-Induced Gene Mutation • Radiation can cause germ-line mutations that can potentially affect future generations • Radiation dosage required to double baseline mutation rate is 50 to 100 rad Baseline Risks: • In 4-6% of all deliveries, spontaneous malformation can occur • For this reason, it is important not to promise a perfect day; • Physicians should help patients to understand that birth defect frequently occur spontaneously, with no identifiable cause • Radiation from diagnostic X-ray is exceedingly unlikely to cause harm to the fetus • Yet if an anomaly is found, the parents’ natural inclination may be to blame radiation Using Reasonable Caution: • Diagnostic X-ray during pregnancy is relatively safe, yet physicians should use reasonable caution while remaining sensitive to the patient’s fears and concerns. • As with all patients, good communication promotes trusting relationships. • Unexpected outcomes often lead to anger and legal action Estimated Fetal X-ray Exposure Studies Dose per Total exams exam (Rad) to make 5 Rad (dangerous level) Chest (two 0.00007 71.429 views) Abdomen 0.245 20 (multi views) Thoracic Spine 0.009 555 Lumbosacral 0.359 13 Spine Intravenous 1.398 3 Pyelogram Pelvis 0.040 125 Hip (single 0.213 23 view) CT Scan (10 mm slices) Head (10 slices) Chest (10 slices)

Dose per exam (Rad) < 0.050

Total exams to make 5 Rad > 100

< 0.100

> 50

Abdomen (10) Lumbar spine (5) Pelvimetry (1 slice with scout film)

2.600 3.500

1 1

0.250

20

Fluoroscopic Studies

Dose per exam (Rad)

Upper GI series Barium swallow Barium enema

0.056 0.006 3.986

Total exams to make 5 Rad 89 833 1

Common Radiographic Studies

has largely replaced x-ray as the primary method of fetal imaging during pregnancy.” - American College of Obstetricians and Gynecologists “A pregnant woman who is ill and requires radiology imaging faces potential risks from her disease to her own health as well as that of her developing infant’s. These risks almost always outweigh the minor hazards posed by low-dose radiation exposure.” “Non-urgent X-rays should be avoided in weeks 10-17, the period of greatest CNS sensitivity.” “When diagnostic imaging is acutely needed, ultrasonography may represent an alternative to ionizing radiation and is considered safe throughout pregnancy.” - Toppenberg, KS; Hill AH; Miller DP: Safety of Radiographic Imaging During Pregnancy; American Family Physician; 04/04/1999

Diagnostic Radiology procedures should not be performed during pregnancy, unless the information to be gained from the study is necessary for the care of the patient and cannot be determined by other means, especially sonography. Iodine Contrast Agents Key Statements on Imaging During Pregnancy: “ No single diagnostic procedure results in a radiation dose that threatens the well-being of the developing embryo and fetus.” - American College of Radiology “ [Fetal] risk is considered to be negligible at 5 rad or less when compared to the other risks of pregnancy, and the risk of malformations is significantly increased above control levels only at disease above 15 rad.” - National Council on Radiation Protection “Women should be counseled that x-ray exposure from a single diagnostic procedure does not result in harmful fetal effects. Specially, exposure to less than 5 rad has not been associated with an increase in fetal anomalies or pregnancy loss.” - American College of Obstetricians and Gynecologists “Although there have been no documented adverse fetal effects (on MRI) reported, the National Radiologic Protection Board arbitrarily advices against its use in the first trimester.” - American College of Obstetricians and Gynecologists and National Radiologic Protection “There have been no report of documented adverse fetal effects for diagnostic ultrasound procedures, including duplex Doppler imaging.” “There are no contraindications to ultrasound procedures during pregnancy, and this modality