Just as in human medicine, the use of ionising radiation in veterinary care serves to provide or assist in providing a diagnosis, to guide an interventional procedure or to provide a direct radiation-induced therapeutic benefit. The use of diagnostic radiology is widespread in veterinary care, in veterinary clinics or in private practices. Smaller companion animals are typically radiographed at the practice or clinic, whereas larger animals may also be radiographed at farms, zoos, or at riding and selling stables. Film-screen radiography is being replaced more and more by digital imaging techniques; CT and CBCT scanning have become routinely available in larger animal clinics. Fluoroscopically guided interventional procedures are also used in veterinary medicine. In these procedures, the radiation serves to provide dynamic, real-time images. The images will guide the anatomically correct delivery of treatments and will often allow real-time visualization of the results of the intervention.
Nuclear medicine techniques are used in veterinary care as well. Diagnostic nuclear medicine procedures provide more information on the functioning of organs and tissues than radiographies, but the morphological information provided is less detailed. For these reasons, diagnostic nuclear medicine is more and more being combined with CT-scanning. Such examinations are referred to as “mixed modality” or “hybrid imaging”, with SPECT-CT and PET-CT as typical representatives. A more recently developed combination of nuclear medicine with magnetic resonance imaging (MRI) is also possible and provides similar advantages.
In therapeutic nuclear medicine procedures a much higher dose (“activity”) of radioactive substances is administered to the animal. The radiation dose delivered to the targeted tissue or organ then becomes so high that cells within this tissue or organ are inhibited in their proliferation or even eliminated. If a cancer is being targeted, complete elimination of the cancerous growth is the desired objective. But in treating other diseases such as hyper functioning of the thyroid gland or inflammation of the joints, inhibition or partial destruction may be sufficient for achieving the desired clinical goal. In the more classical radiotherapy, radiation generated outside the animal patient is also used to eliminate tissues that are undesired. Most often this will be used for treating animal patients affected by cancer.
ICRP has recently established a task group (TG110) to develop recommendations on the protection of veterinary patients, veterinarians and their co-workers, animal owners and handlers providing care to the patients or comforting them. Radiation exposures to the veterinarians and their co-workers, as well as owners and handlers of the animal can be very different. Radiation dose resulting from a single examination is typically very low, but veterinarians and their co-workers performing multiple examinations may receive non-negligible dose. Some applications that are newer in veterinary medicine, such as CT-scanning, interventional radiology procedures, nuclear medicine diagnostic procedures and radiotherapy procedures, have the potential to cause much higher exposures and should therefore be performed with explicit attention to radiation protection. In the case of nuclear medicine procedures and the use of small implantable radioactive sources for radiotherapy purposes, radioactive substances and objects may be spread outside of the veterinary clinics and thus become an additional risk factor in the human environment.