Protective lead shielding of patients is not routinely used in veterinary radiology. The probable reason: A general belief that because the dosage of radiation received during routine radiographs is small, the timeline for the possible development of related cancer would exceed the lifespan of the animal.
However, in a recent study published in the May 2015 issue of Veterinary Record, Dr. Sarah Nemanic, Assistant Professor of Radiology at OSU College of Veterinary Medicine, notes that there is evidence that species with shorter lifespans may take less time than humans to develop radiation-induced cancer from high-energy radiation sources (Raabe, Health Physics, 2010, 2011). If the effects of lower energy x-rays are similar, then dogs may develop cancer faster than humans.
“Reducing the amount of radiation exposure to veterinary patients may be important to reduce the risk of carcinogenesis over their lifetime, especially in dog breeds with an increased risk of neoplasia,” says Dr. Nemanic.
The study, conducted at the OSU Veterinary Teaching Hospital, measured the effect of protective shielding on the dosage of radiation, as detected by dosimeters during 54 radiographic visits in an ongoing elbow development study of dogs. The goal was to determine if the use of lead aprons and thyroid shields on the bodies and eyes of the dogs would significantly reduce the dose of scatter and tube leakage radiation.
Scatter radiation is low energy radiation that results when the x-rays of the primary beam interact with matter and are deflected in an unpredictable direction. Tube leakage radiation comes through the shielding and housing around the source assembly.
The results of the study indicated that use of protective shielding significantly decreased the dose of scatter and tube leakage radiation to dogs, with the greatest protective effect at the head (see chart).
Because companion animals are so highly valued by their owners, Dr. Nemanic advocates for a level of radiation safety that is similar to human medicine. “Reducing radiation exposure to individual veterinary patients through all means reasonably achievable is a worth-while goal,” she says. “Even though the risk of cancer to veterinary patients from routine radiographs is low, it is reasonable to try to decrease it further through the use of shielding with readily available radiation safety equipment.”
Read the paper: “Decreased dose of radiation to dogs during acquisition of elbow radiographs using draped shielding.”
