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Chapter 16 Diagnostic Imaging and Endoscopy 299

The National Committee on Radiation Protection
Reflection and Measurements (NCRP) recommends using “as low
as reasonably achievable” (ALARA) exposures when tak-
Compare and contrast the different diagnostic ing radiographs. This means that the personnel taking
imaging systems. radiographs need to know what they are doing so the
image is right the first time. For every radiograph taken
there is more exposure to radiation increasing the
Quality Assurance chance of damage to the personnel over a lifetime. Some
states actually prohibit manual restraint of animals dur-
ing radiographic procedures. Patients are anesthetized
The usefulness of a radiograph is limited by the quality and positioning aids are used. This is a sensible guide-
of the image itself. It is the veterinary technician and the line even when not required by law. Another option is to
assistant who actually take the radiographs, so their rotate staff conducting radiographic procedures, espe-
ability to produce quality films is essential. A quality film cially in high volume practices.
has subtle shades of white to black contrasts depending Major safety measures are used to reduce the amount of
on the density of the body parts. For example, a leg radiation exposure to personnel. The following guidelines
bone is mostly white with shades of gray because of its must be followed to ensure a safe working environment:
different densities, whereas muscle tissue is a fairly uni-
form dark shade of gray because it is less dense and 1. Each person involved in the radiograph must wear
fairly uniform in density. This contrast allows the veteri- personal protection equipment (PPE) while
narian to see body structures and determine if there is exposing radiographs. This includes a lead apron
an injury or condition present. A quality film requires that covers the front of the body from the shoulders
accurate measurement of the body part, correct film to mid‐thigh, goggles, and a thyroid collar
exposure settings, accurate patient positioning, and (Figure 16.1).
proper developing of the exposed film. With the advent
of digital radiography, measurement and proper posi-
tioning are still very important but, because the image is
digital, the film exposure can be adjusted to be lighter
or darker and of course there are no “films” to develop.

Reflection

Discuss the reason for quality assurance and the
issues it would cause if films were not diagnostic.

Radiation Safety

The radiation produced by a radiography machine is
considered a hazard and regulations regarding use of
equipment and personnel safety are governed by the
Department of Health at the state level. Radiography
machines are registered with a Radiation Safety Board
which inspects the equipment to make sure it is operating
within parameters.
Radiation is odorless and colorless and it cannot be
felt or seen. Radiation causes damage to rapidly dividing
cells, such as those found in unborn and immature indi-
viduals, bone marrow, skin, and blood‐forming tissues.
Damage occurs when multiple small doses accumulate
over a lifetime or through a single massive dose. This
damage may not manifest for years or genetic damage
can appear in future generations. Consistently following
proper safety measures will prevent harm. FIGURE 16.1 Lead apron and thyroid collar.