Wilhelm Conrad Röntgen discovered X-rays on November 8, 1895, by producing and detecting electromagnetic radiation in the wavelength. He received the Nobel Prize in Physics in 1901 for this discovery. Röntgen used a photographic plate and had his wife, Frau Anna, place her hand in the path of the X-rays, creating the world’s first human radiograph. Medicine has not been the same since. How can X-rays harm you? Radiation from X-rays can injure your body by depositing energy in your cells, causing one or more electrons to be removed, thereby killing, or mutating the affected cells. According to the Occupational Safety and Health Administration (OSHA), “Workers may be exposed to ionizing radiation in several ways, depending on their job tasks. The health effects of a radiation dose depend on the type of radiation emitted, the radiation dose received by a worker, and the parts of the body that are exposed, among other factors." Radiation dose depends on the duration of exposure, the amount of radiation generated from the radiation source, the distance from the radiation source, and the amount and type of shielding in place. In general, radiation dose is received when a worker is: 1) In close proximity to an unshielded or partially shielded radiation source. 2) Unprotected when near unshielded radiation-generating machines (e.g. X-ray machine, accelerator, etc.) in operation. 3) Unprotected when handling radioactive materials (e.g. radionuclides). 4) In close proximity to surfaces or areas contaminated with radioactive materials (e.g. from small spills or leaks). 5) Contaminated with radioactive materials.1 Different cells react to radiation energy in varying degrees. The most rapidly dividing cells take the greatest amount of damage, which include epithelium (i.e. skin, lining of the GI tract), hair follicles, reproductive cells (i.e. ovaries, ovum, testicles, and sperm), blood generating cells (bone marrow), and fetus (See “Women in childbearing age”). On the other hand, cells that do not actively divide are more resistant to the effects of radiation, such as nerve and muscle cells. Radiation damage can be immediate or become evident after a long period of time has passed. Immediate damage can be seen as redness of the skin after radiation therapy (radiation burns). Latent damage can be seen as a tumor or cataracts or even as birth defects to children and grandchildren descended from the exposed person. Occupational effects of chronic radiation exposure include: 1) Chronic (repeated) low level radiation exposure is suspected of causing: Increased frequency of neoplasia Increased frequency of squamous cell carcinomas Increased frequency of leukemia Premature aging Increased frequency of cataracts Technologists who reported assisting with fluoroscopically guided interventional procedures (FGIP), particularly high-volume FGIP within three feet of the patient, had increased risk of cataracts. Additional investigation should evaluate estimated dose response and medically validated cataract type.4 Measuring and monitoring radiation Radiation is measured in rems. A rem is equal to the absorbed dose in rads multiplied by the quality factor (1 rem=0.01 sievert [SV]). A rad is equal to an absorbed dose of 100 ergs/gram or 0.01 joule/kilogram (0.01 gray). A sievert is the SI unit of any of the above quantities expressed as dose equivalent. The dose equivalent in sieverts is equal to the absorbed dose in grays multiplied by the quality factor (1 SV=100 rems). Radiation exposure is monitored using a variety of devices. Film badges or whole-body dosimeters are by far the most common device used in veterinary practices. Veterinary workers who work with fluoroscopy should also wear a ring or wrist badge. Personnel monitoring devices do not absorb or protect against radiation exposure. These devices only measure radiation. To receive accurate radiation exposure measurements, it is important to wear and store your badge correctly. It is vital you store your badge away from a radiation source at your place of employment. Do not take them home with you. Treat your badge like your toothbrush—never to be shared with anyone. The badge is meant to measure the radiation you are exposed to during your workday. Film badges should be worn at the thyroid level on the outside of the gown, or thyroid shield. Pocket dosimeters should be worn on the front of the body, over the main torso, anywhere from waist to neck. Individuals who wear lead garments should position the whole-body dosimeter at the collar level, outside of any lead protection. Ring badge/ring dosimeters should be worn on the hand closest to the radiation source so the label is on the palmar surface of the finger, toward the radiation source. A wrist badge should be worn when forearms are in the immediate proximity of radiation sources or in the pathway of radiation beams. Occupational dose equivalent limits are: 1) Whole body (total effective dose equivalent): 5 rems 2) Skin and extremities (shallow dose equivalents): 50 rems 3) Lens of the eye: 15 rems Chemical restraint Encourage the use of chemical restraint in the form of pain relief, anxiety relief, and/or sedation for aggressive patients. You are your patients’ advocate, so when you notice your patient is uncomfortable, anxious, painful, or dangerous to your safety, respectfully ask to treat for the appropriate condition. The veterinarian must prescribe any medication used and the pet owner must give consent for their use. COLLIMATE, COLLIMATE, COLLIMATE! Collimating, or adjusting the length and width of the primary beam, reduces the area of exposure, focuses the ionizing radiation on the body part of interest, and decreases the amount of ionizing radiation emitted by the X-ray machine. Conclusion Radiation affects rapidly dividing cells in your body most severely. You can reduce your radiation exposure by staying out of the X-ray room and using hands-free techniques. If you must hold your patient, be especially careful to keep all human body parts out of the beam. Remember, OSHA will fine your practice upon violation of worker radiation safety guidelines (human body parts in an animal radiograph) and may demand jail time depending on the severity and number of violations. Always wear your radiation monitor and store the monitor at least six feet away from any radiation emitting source. If you are within recommended distance of the active primary X-ray beam, be sure to wear all protective equipment, including safety glasses. Don’t be afraid to advocate for your patients; ask for pain relief, anti-anxiety medication, and or sedation for aggressive patients. A calm and pain-free patient makes for a safe, accurate, and expedient radiograph. WOMEN OF CHILDBEARING AGE OHSA guidelines1 reiterate the recommendations of the National Institute of Occupational Safety and Health (NIOSH) and Centers for Disease Control and Prevention (CDC) be taken by “limiting exposure to young women, especially if they are pregnant. X-ray exposure to the abdomen of such workers would involve a radiation dose to the embryo or fetus.” Additionally, OSHA emphasizes the Nuclear Regulatory Commission (NRC) recommendations: “The NRC Standards for Protection Against Radiation (10 CFR 20) require licensees to limit exposure to the embryo/fetus of an occupationally exposed (worker) to 500 mrem (5 mSv) or less during pregnancy for a declared pregnant worker who is exposed to radiation from licensed radioactive materials (10 CFR 20.1208), including radionuclides. Under NRC's definitions (10 CFR 20.1003), a declared pregnant worker is a worker who has voluntarily informed the employer, in writing, of the pregnancy and the estimated date of conception. The declaration remains in effect until the declared pregnant worker withdraws the declaration in writing or is no longer pregnant.2,3 The NRC's Instruction Concerning Prenatal Radiation Exposure, Regulatory Guide 8.13, provides information to pregnant women, and other personnel, to help them make decisions regarding radiation exposure during pregnancy.”2 Allyne Moon, RVT, CCFP, has been working in veterinary medicine since 1992. Moon received her LVT license in 2003; her RVT license in 2004, is an expert witness for the State of California, and is a former VMB hospital inspector. Moon lectures nationally and locally on a variety of subjects, including veterinary forensics, shelter medicine, radiation safety, suicide prevention, compassion fatigue, and veterinary law. She now works as the assistant executive director of the Southern California Veterinary Medical Association. PROTECT YOURSELF! Gear up in proper attire to avoid or limit exposure. All X-ray gear must be at least 0.25 mm thick. However, 0.5 mm is more effective and readily available. To keep your gears functioning properly, ensure you store them properly. Check your gear periodically for tears and cracks by X-raying them at 85 kVp, 10 mAs, 40-inch focal distance References United States Department of Labor Occupational Safety and Health Administration “Ionizing Radiation Overview” https://www.osha.gov/ionizing-radiation. 2022 Centers for Disease Control and Prevention “Radiation- Ionizing- Reproductive Health” https://www.cdc.gov/niosh/topics/repro/ionizingradiation.html. 11,15,2019 United States Department of Labor Occupational Safety and Health Administration “Ionizing Radiation Health Effects” https://www.osha.gov/ionizing-radiation/health-effects. 2022 Raquel Velazquez-Kroned, MS et al, “Cataract Risk in US radiologic technologists assisting with fluoroscopically-guided interventional procedures: a retrospective cohort study” https://pubmed.ncbi.nlm.nih.gov/30890565/. Europepmc.org 2019
