“Familiarity breeds contempt” – Aesop’s Fables

A patient is brought to the veterinary hospital in very poor condition. Following a preliminary examination the veterinarian requests an x-ray. The staff comply and the patient is moved to the x-ray room. All this is familiar procedure. What happens next determines whether the staff comply with the ALARA principle. The ALARA principle states that radiation doses to the staff and the patient must be kept “As Low As Reasonably Achievable”. 

If possible the patient should be sedated or anaesthetized so that the staff may position the patient and then leave the room for the brief time of the radiation exposure. This is not always practical or possible due to the condition of the patient. If the patient must be held in position the staff must wear leaded protection. Leaded aprons, gloves and thyroid collars must be in good condition. The aprons should have a tie or Velcro® fixed across the scapulae so that the apron does not fall off the shoulders. The gloves should remain out of the direct x-ray beam. The radiation dosimeter for veterinary use should be worn on the outside of the thyroid collar. 

When the animal is being held in position the staff members should stand at the end of the table and should lean away from the table as much as possible. They should not lean into the animal or stand at the side of the table.

Scattered radiation is produced from the anatomy of the animal. The larger the animal the more scatter will be produced. It is also exacerbated by the amount of kilovoltage used for the exposure. The higher the kV, the more penetrating the beam and more scattered radiation produced. Every technique chart should be reviewed to ensure that the kilovoltage used is sufficient to penetrate the animal and maintain contrast in the image. Density in the image is controlled by mAs.

Repeating exposures frequently can add to the readings on dosimeters especially if there is a worst case scenario. A very large dog, very high kV and incorrect restraint of the patient. The images below demonstrate the correct and incorrect way to restrain an animal if it must be restrained. Every examination should be treated with the respect that it deserves and just because we cannot see it or feel it we must be aware that radiation is damaging to cells when over exposure occurs.

Rules your clinic should live by:

1. Never lean over the table when the exposure is taken.
2. Always stand at the end of the table, lean away from the table and turn your head to the side when the exposure is made.
3. Leaded gloves must be worn when restraining an animal.
4. Leaded eyewear should be worn in the x-ray room.
5. The x-ray beam must be collimated to the anatomy within the field of view. If the animal is very large a piece of leaded rubber should be placed along the table in front of the animal to prevent scattered radiation from affecting the image.
6. Dosimeter must be worn outside the apron attached to the thyroid collar.