Page 25 - A Practical Guide to Equine Radiography

6 A PRACTICAL GUIDE TO EQUINE RADIOGRAPHY

(CR) or digital radiography (DR) systems and diagnostic quality radiographs with portable
VetBooks.ir these are now the mainstay systems used in machines might be now accessible.

equine practice.
Plates come in different sizes. Smaller plates
Computerized systems still use cassettes that
are then digitized in a laser scanner whereas are preferable for the distal limb, whereas larger
plates are helpful for the spine, pelvis and tho-
digital systems use a digital plate that transmits rax. While shoulder and stifle radiographs can
the image directly to a computer for display. be taken with smaller plates, people often find
CR cassettes need cleaning on a regular basis these easier with larger plates.
and erasing if they have not been in use for a
while. Both DR and CR systems produce digital
images that are manipulated and viewed on a Grids
computer. Care should be taken that the spatial Grids can be used to reduce scatter. This is espe-
and contrast resolution of the viewing screen is cially an issue in upper body radiographs that
not compromising image quality. require high exposures and where there are lots
CR and DR systems offer a multitude of of soft tissues present. Some users also find
options during and after image acquisition. them helpful for the navicular bone. Many DR
Some image quality parameters are specific to and CR systems have digital grids that make the
the individual system and it is well worth pay- use of hardware grids redundant and it is well
ing attention to those when choosing a system worth testing out if the use of a grid is neces-
to buy. It is advisable to spend time with an sary since grids have the disadvantage that they
application technician of the specific company require an increase in exposure and perfect
where you bought the system and include this alignment.
time in the purchase price. Application tech-
nicians are people trained to have the skills
and knowledge to get the best possible quality Stands and holders for equipment
image out of a system while keeping the expo- It is common in equine practice to hand-hold
sures to a minimum. portable X-ray generators, since it is easy to do
What is considered the best image differs and speeds up the procedure. This is not advis-
between individuals and also between applica- able since it leads to an unnecessary increase
tions and hence depends on case load but also in radiation exposure to the operator. It also
personal preference. For example, in racehorse increases the likelihood of movement artefacts,
practice, subtle changes to bone trabecular pat- especially with higher exposure radiographs
tern might be more important than the ability where the time of exposure is longer. There are
to appreciate soft tissue changes on radiographs several stands for X-ray generators on the market
and hence the standard settings of the way (Fig. 2.1). These stands are height adjustable and
the image is acquired, processed and viewed fold, so can be fitted in a car. If a purpose-made
will differ from that of a general riding horse stand is not available, one can also be inventive
population. Of course, the standard settings and use blocks of wood or buckets to position
can and should be adapted to each individual an X-ray generator at the required height.
case. Plates/cassettes should not be held by hand
The world of imaging technology is changing since this brings the hand very close to the
rapidly and it is well worth checking standard primary beam and also results in unnecessary
procedures regularly; for example, DR plates are radiation exposure to the person holding it.
becoming more and more sensitive to X-rays Long-handled plate holders should be avail-
and hence exposures can be decreased and areas able so that the person holding the plate can
where it was previously impossible to acquire step away as far as possible from the primary

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