I spend a fair amount of time reviewing X-rays with clients. They’re an important diagnostic tool for us. At one time, when ultrasound. cat scan, and MRI were’t available, they were really the only way to get assess the inside of a pet without surgery to open them up and visually look. They remain a valuable diagnostic test for things like heart disease, cancer diagnosis, bone and joint disease, and dentistry (among others). The proper term for an x-ray is a radiograph. The x-rays are the invisible particle beam that exposes special film, which is then developed as a radiograph.
The position we put a pet in will vary depending on what we need to learn from a radiograph. I’ll give examples of the basic positions that we use most often. Just to help everyone understand some of the terminology, here’s an image that illustrates the terms we use for various parts of the body:
Lateral Thorax or Abdomen
In this position, the patient is laying on the right side. The head is toward the left of the image, the tail toward the right. It’s important to make sure that the chest is perfectly level, which is sometimes harder than it sounds. Many dogs’ chests are narrower at the ventral edge (the sternum/breastbone), so we have to lift the breastbone up a bit. We put the crosshairs of the X-ray beam at the back (caudal) edge of the shoulder blade for a chest film. We put the crosshairs on the last rib if we’re taking an image of the abdomen. This view is very important for evaluating the size and shape of the heart and liver.
Ventrodorsal Thorax or Abdomen
In this position, a pet is laid on its back. The name of this positioning describes which surfaces the beam travels through in order. First, the sternum/breastbone, then the body cavity, then the spine (which is dorsal when the pet is standing normally). We generally abbreviate the term as “VD.” This view is useful for looking at the kidneys individually, and it helps a great deal with evaluation of the heart.
When we’re taking a radiograph of a limb, we often use two views. The first is a lateral view, or side view. On the hind leg this is a bit easier since the leg is ‘flat’ in the lateral dimensions. In the foreleg, it’s a lot harder, as the leg is essentially round. We have to make sure we’ve got the leg positioned in a perfectly sideways orientation. (If you’re off on your rotation, you’ve taken what’s known as an oblique view.)
When we shoot from front to rear on a limb, as seen in this foreleg shot, it’s called an “AP” view. AP stands for Anteroposterior. It refers to the anterior(front) surface of the limb to the posterior(back) surface of the limb. In the front leg, those surfaces are also known as the dorsal and palmar surfaces.
The skull is a very difficult structure to radiograph. The most interesting view we take is called an open-mouth ventrodorsal view. That’s shown below. This helps us look at the back of the skull and the TMJ (temperomandibular joint).
That concludes a brief tour of the views we use to evaluate the body cavities and limbs. I’ll come back to this topic to guide everyone through an evaluation of the images we take. I’ll find some interesting radiographs in the hospital archives and try to take photos of them. Digital photos of radiographs are challenging, but I should be able to make them workable. We have a few cool radiographs from as far back as 1977!
I hope that those of you celebrating Christmas have a safe, wonderful, and happy day. Take care!