Many veterinary technicians have an unreasonable fear of the harmful effects of ionizing radiation. Though a healthy concern about the potential harm is expected, an unhealthy concern may adversely affect job performance. All veterinarians should ensure that their technical staff is comfortable working with radiation and educate them about the potential hazards and ways to reduce the harmful effects. Positioning and Technique Count Radiographs are an economical, highly informative tool to diagnosis illness and injury in small-animal patents, but not any old radiograph will do. The best radiographs are obtained when good X-ray technique is combined with good patient positioning,” says Anne Bahr, DVM, Dipl. ACVR, MS. “Often, veterinarians have good X-ray equipment but don’t take the time to position properly and end up with suboptimal images. Dr. Bahr, a veterinary radiology specialist with PetRays, a telemedicine consulting company in Spring, Texas, says sedating a stressed animal can “do wonders for the quality of the images. John Feleciano, DMV, Dipl. ACVR, is manager of radiology at VDIC, part of the Idexx Telemedicine Division of Idexx Laboratories Inc. of Westbrook, Maine. A well-positioned study gives the veterinarian and interpreting radiologist the best chance to achieve an accurate diagnosis,” he says. “Asymmetrical positioning can lead to uncertainty in interpretation and even missed diagnoses. Complex structures like the skull can be difficult to evaluate even with the best positioning. In imaging nasal cavities, standard lateral and ventrodorsal or dorsoventral views should be performed. It’s important to also provide radiographs of the nasal cavity without superimposition of the mandible by performing an open-mouth ventrodorsal view. He reminds veterinarians that “digital radiography may offer more forgiveness in exposure, but you can still produce poor images.” — Lynn M. Tiffany Ionizing radiation has the potential to cause mutations that can be passed to future generations or that can result in the development of cancer. Technicians routinely ask me, “How much radiation is too much?” or “How many films can I take before I get cancer?” The answers are involved because all ionizing radiation is harmful and data is not available to indicate whether a threshold exists below which no harmful effects will occur. In other words, no one really knows just how much radiation is tolerable. I know, this discussion so far doesn't bode well for allaying your technicians’ fears. Hang in there. The National Council on Radiation Protection and Measurements (NCRP) is responsible for setting guidelines regarding radiation exposure. Currently, the NCRP guidelines state that 5000mrem (5rem) a year is the maximum permissible dose (MPD) for occupational exposure. In other words, the NCRP recommends that veterinary technicians obtain less than 5000mrem of exposure during the course of a year. The appropriate interpretation of this recommendation is that in light of the present knowledge, this dose is not expected to cause appreciable bodily injury to a person at any time during her lifetime, but in actual practice radiation levels should be kept as low as practical. We should not think of permissible doses as being perfectly safe. To put things in perspective, technicians need to remember that we live in a radiation-filled environment. Cosmic rays constantly bombard us from outer space, radon is present in our basements and radionuclides in the rocks used to make our buildings and food we eat emit radiation. On average, we can expect to get 360mrem of radiation a year just from living on Earth. Understanding that 5000mrem is the MPD, you can now have a meaningful discussion and help allay technicians’ fears. To begin this discussion, you will need the technician’s quarterly radiation monitoring badge reading. Technicians should be given their badge readings and this number should be related to their MPD for the quarter, year, and lifetime cumulative dose. I recently worked with a clinic where a technician was terrified that she had an exposure of 28mrem for her lifetime dose. After our discussion, she understood that her MPD was 5000mrem a year, so 28mrem was more than 100 times less than her exposure for a single year. Furthermore, her 28mrem was her lifetime occupational exposure. She had been working for three years. Therefore, her lifetime dose was 10,000 times less than her lifetime MPD of 5000 multiplied by 3, or 15,000! After our discussion, she understood that she was well below her MPD. In most practices I evaluate, the exposure to technicians generally falls in the range of 10 to 20mrem a quarter. I recommend that any technician receiving greater than 125mrem a quarter (i.e., 10 percent of the allowable dose) be counseled about radiation safety and safety practices enacted and enforced in the hospital to reduce the radiation exposure to the technical staff. f a technician’s dose is persistently greater than 125mrem a quarter, proper radiation safety practices likely are not being followed, or the technician may be mishandling her badge—leaving it in the X-ray room, on the dashboard of the car, etc. Reducing Exposure What guides radiation safety in the veterinary hospital is the ALARA principle, for “as low as reasonably achievable.” It cannot be overstated that the last two words in ALARA are “reasonably achievable.” Reasonably achievable is very different from “as low as possible.” If the guiding principle was to obtain radiation exposure levels as low as possible, that would indicate a zero tolerance for exposure. A goal of zero exposure would place unrealistic economic, design and workflow constraints on the veterinary profession to the point that obtaining radiographs in a general practice would likely be impractical or cost-prohibitive. Veterinary technicians should understand that by accepting their jobs, they are accepting some, albeit small, risk of harmful effects of radiation exposure for the tangible benefit of gainful employment. The veterinary hospital owner is duty-bound to instruct and provide the technician with the tools necessary to obtain radiation exposures as low as reasonable achievable. These tools fall into three categories: Time: Always use the shortest exposure time possible and decrease repeats. Using a technique chart that has been customized for your practice will decrease repeats. Distance: Always stay as far from the radiation source as practical. Small increases in distance will dramatically decrease exposure. The use of sedation to allow for sandbag and non-manual restraint is recommended. Shielding: Use proper lead shielding equipment such as lead aprons and thyroid shields. Technicians hate wearing lead shielding. Lead gloves are uncomfortable, decrease dexterity and they smell awful. Nonetheless, technicians should be advised that not wearing gloves is not an option in any circumstance. Human fingers should not be present in the radiograph. Lead gloves do not provide protection from the primary X-ray beam. In other words, wearing a lead glove and putting your hand in the radiograph offers no protection at all. The lead only protects the hands from scatter radiation arising at the periphery of the radiographic image. Every practice should have a radiation safety education plan in place to educate technicians about the hazards of working with ionizing radiation as well as to instruct them on the proper methods of reducing exposure to it. This education process will help allay their fears about working with ionizing radiation. Matt Wright, DVM, Dipl. ACVR, is a veterinary radiologist who works with the DVMinsight.com teleradiology company. This article was adapted from his book “Radiation Safety and Non-manual Patient Restraint in Veterinary Radiography,” which includes topics such as radiation safety for the pregnant technician and creating a technique chart. More information about the book can be found at This article first appeared in the August 2010 issue of Veterinary Practice News. Click here to become a subscriber.
