While a radiograph can be taken with a pet in nearly any position, depending on the veterinarian’s goals and the specific area to be imaged, there are certain views that are utilized more often than others.
As a vet tech student, it’s important to be familiar with these commonly-ordered images, so that you are prepared to assist on externships or at your first job.
If a pet presents with signs of cardiac or pulmonary disease, the veterinarian will likely order thoracic radiographs. Thoracic radiographs are also recommended in the workup of some gastrointestinal diseases (especially if esophageal involvement is suspected) and to rule out pulmonary metastasis in pets with neoplasia.
A veterinarian may request either 2-view or 3-view chest radiographs. Two-view radiographs include one lateral and one ventrodorsal (or dorsoventral) radiograph, while 3-view radiographs include both lateral views. Three-view radiographs are preferred in most cases, as they provide more information. However, 2-view radiographs are still utilized in some circumstances to minimize the cost to the client.
Remember that a “VD view” means ventrodorsal. Radiographic views are named for the direction that the beam travels; in a VD view, the beam enters the patient’s ventrum and exits dorsally. For a VD thoracic radiograph, the dog is positioned in dorsal recumbency with its forelimbs extended as far cranially as possible and the hindlimbs pulled caudally. The beam should be centered over the thorax and collimated appropriately.
A “DV view” is dorsoventral. In this view, the image will look similar to that obtained with a VD view, but the animal is placed in sternal recumbency. This image may be preferred in animals that are showing signs of respiratory distress, because it is often easier for these pets to breathe in a sternal position than when restrained on their back.
Lateral views are performed with the patient lying on its side. Remember that lateral views are named for the side that is down (against the table), so a right lateral view, for example, is taken with the pet in right lateral recumbency. In some cases, the veterinarian may request a specific lateral view. This is done because the “up” lung inflates better than the “down” lung. If the veterinarian suspects a lesion in the left lung lobes, for example, he or she might specifically request a right lateral thoracic radiograph, and vice versa.
Abdominal radiographs are taken for a wide variety of reasons, any time that abdominal involvement is suspected in a disease process. Two-view abdominal radiographs are common, but 3-view abdominal radiographs may be requested in some circumstances.
A VD abdominal radiograph is typically performed with the pet in dorsal recumbency.
However, if the pet is very fractious, a DV view may be taken instead.
The lateral view may be either a right or left lateral, depending on the veterinarian’s preference and clinical suspicions. A right lateral radiograph is typically preferred for the diagnosis of gastric dilatation and volvulus (GDV), while a left lateral radiograph may be requested if pyloric disease is suspected.
When taking a lateral radiograph, it’s important to make sure that the patient is even; overweight patients often tend to roll onto their bellies. Palpate the iliac crests to ensure that they are perpendicular to the table, in order to be sure that the patient is positioned correctly. You can also use a foam wedge to prop up the stifles and aid in positioning.
Collimating for abdominal radiographs can be a challenge, because it can be difficult to assess the cranial and caudal boundaries of the abdominal cavity. Use these landmarks as the boundaries of your collimation:
- Cranial border: two finger widths cranial to the xiphoid process
- Caudal border: greater trochanter of the femur
Radiographic views of the forelimbs and hindlimbs may vary widely, depending on the suspected disease or injury. For most screening radiographs (in a suspected case of trauma or osteoarthritis), the veterinarian will request two views of the area of interest: a lateral view and a craniocaudal view.
When performing a lateral radiograph, the limb of interest should be closest to the table. For example, a dog with right forelimb lameness localized to the carpus should have carpal radiographs taken in right lateral recumbency. This facilitates straight positioning and minimizes distortion.
Craniocaudal radiographs of the forelimbs are typically performed with the pet in sternal recumbency and the forelimbs held down flat against the table. Craniocaudal radiographs of the hindlimbs are typically performed with the pet in dorsal recumbency. When taking craniocaudal radiographs, it is often preferable to include both limbs when collimating. This allows the veterinarian to draw a comparison between the healthy and unhealthy limb.
In some situations, more specialized radiographic views may be needed for limb evaluation. For example, dogs with suspected elbow dysplasia may require a flexed lateral or a 45-degree oblique radiograph. If you are in a practice that regularly performs orthopedic radiographs, you will become familiar with the positioning for these views through regular practice.
There are countless radiographic views that can be recommended, depending on the situation. However, being able to obtain high-quality diagnostic radiographs of the thorax, abdomen, and limbs will carry you through many common scenarios in general practice. Fortunately, when the need arises to take a more uncommon radiograph, such as a temporomandibular oblique or bullae radiograph, there are always textbooks that you can consult to help with proper patient positioning!