X-ray technology has been a great asset to the medical and industrial industries for several decades. Progress has accelerated over the past few years pushing equipment turnover rate to an all time high. In spite of state-of-the-art innovations, the basic principles of radiology are often overlooked when taking day-to-day images.

I received a well-balanced education at the Ohio State University School of Vet Medicine in the early 1970's. I was certainly taught how to think like a veterinarian. Over the last 27 years of practicing veterinary medicine, though, I have learned that radiology was one of my weaker areas of focus early in my professional career. I desperately needed to hone my skills.

When I graduated from vet school, there were very few good sources of information that I could use to develop my radiographic skills. In 1975, I contacted Kodak® and they provided me with the Lannex medium and regular speed systems, which used single emulsion film. This was a great improvement over the PAR speed system that was being used at the time.

During this time, X-ray machines were also beginning to advance. I traded my wind-up Picker unit for a Phillips®, 90KVP, two-piece unit. It weighed around 50 pounds and provided good service, but it was a load. Kramex soon came out with a variable time, 80KVP, 20MAS unit, followed by several other companies that soon began offering the same type system.

In the 80's, I was still not satisfied with the detail and resolution I was getting from the Kodak® system. Therefore, I contacted Dupont; and together, we designed the asymmetric screen combination. This new system had a slow screen in front that set the precedent for film speed. It was similar to the film in a camera; the slower the speed the greater the resolution. For example, if you wanted to enlarge a portrait, you would use 100 speed film to take the initial picture. If you took the picture with 1000 speed film, the enlargement would be nothing but a series of dots that only resemble the actual image. This same technique occurs with x-ray images.

Conversely, the rear screen was quite fast, which significantly reduced the exposure time without significantly altering the resolution.

Today, 3M has become a leader in developing new film/screen technology. They offer faster film with greater resolution. At the same time, Min-X-Ray has pioneered the square wave, high-frequency inverters offering lightweight, high output portable x-ray machines. I am often asked, "What is the big deal? Isn't one x-ray machine as good as the next?"

Selecting an x-ray machine, screens and film is as complex as selecting a new camera. There are many cameras on the market, and all of them are designed with specific options. Your equipment must meet your demands and help you gain the information you need to treat your patients. Ask yourself these questions when trying to decide what type of x-ray equipment to purchase:

• Why am I taking film?
• What is the purpose of my exam?
• What am I hoping to find?
• How do I achieve my radiographic goals with consistent accuracy?

Pulling film from the processor, hoping that a few of them are informative, is not only frustrating but a tremendous financial black hole for everyone concerned. Over the years, my protocol has slowly evolved into its present day status. My protocol is disciplined, methodical and offers a consistent means of obtaining high-detail, high-resolution, non-distorted images.

What does it take to be a podiatrist?

From the farrier perspective, they must be proficient and competent in their ability to understand and shoe multiple breeds of horses with a variety of pathological problems. They must have a working knowledge of foot anatomy, physiology, function, form and how each of these relates to disease and injury. Farriers must also be able to read radiographs of the foot in addition to being able to explain to veterinarians how to obtain the radiographic views they need to do their job.

It is not humanly possible to accurately assess the precise position of the coffin bone within the capsule and how it relates to the ground forces without well-positioned, detailed radiographs. Any farrier who must shoe a horse that is lame, has imbalance, congenital deformities, various injuries and/or disease must have informative film. They must also know how to read the film because they are the blueprint for precision shoeing.

Veterinarians who wish to be proficient podiatrists need to possess horsemanship knowledge, develop a thorough working knowledge of foot anatomy, physiology, function and form and become proficient in taking radiographs that accurately describe the internal structures of the foot, how they relate to the hoof capsule and how the capsule relates to the ground.

Vets don't have to become competent farriers, but it is imperative that they understand the process of trimming and shoeing horses' feet. They must also be aware of the numerous mechanical limitations, in addition to the environmental and inherent risks associated with trimming and shoeing.

They also need to be proficient in regard to reading film. They should be capable of teaching farriers to do the same. This is a big mission because these two professions differ greatly. Vets are professionally trained, just not in the field of podiatry. Farriers have very little formal training but have a great deal of "on the job training" in regard to trimming and shoeing feet that fall within the range of norm. When both professions learn to work together and use informative radiographs as their shoeing blueprint, the discovery and planning stage become very meaningful. More importantly, a great success rate can be obtained with most all foot problems.

Farriers who routinely shoe sound horses do not need to refer to radiographs as long as everything is going along in a normal fashion. However, when mechanical decisions are required, x-rays are essential for a full assessment of the foot. Farriers who manipulate the hoof capsule to gain optimum mechanics, without the aid of film, often find their efforts to be counter productive.

Post shoeing radiographs are just as valuable as the radiographs taken prior to shoeing. How do you ever learn precise manipulation of the digit without seeing what you have actually done to change the load zones? Veterinarians, trainers and owners who cannot appreciate the value of good foot film when dealing with problem feet are often the same individuals who do not understand why a farrier would ever need to be a competent film reader. The same can be said for farriers who violently resist using films to help better understand the finite details hidden within the internal structures. The bottom line is that we must be responsible for each other.

What podiatrists need to see radiographically is dependent upon the purpose of the exam. For example, a high-level performance horse presents with what the client calls either foot soreness or lameness. A thorough examination of both feet reveals one foot with a high heel and the other with a low heel. This horse has a low grade club foot that can be identified both radiographically and grossly. The horse was also well shod approximately two to three weeks ago, the growth patterns are strikingly different, and there is no noticeable increase in sensitivity from hoof testers. We suspect that the sole is thin on the high heel foot (grade 2 club). The heel is shallow on the other foot, which may possibly be caudal rotation.

What do I want to obtain from my radiographs?

I want to learn from the lateral view precisely the amount of sole depth, the palmar angle, the length of digital breakover, and the exact measurements of the horn-lamellar (HL) zone. From the DP view I want to discover the amount of sole depth and medial/lateral balance.

Having these basic parameters in mind, and accurately defining them, sets the stage for the examination. As you define these parameters on more and more feet, you will soon develop a feeling for the range of normal as it relates to age, breed, use and environment. Knowing the parameters will help you design your lameness examination and offer great insight to areas that are mechanically compromised before you start blocking. The radiographs also become your blueprint for designing a mechanical protocol that reverses the forces at play.

If we could adopt a universal dialog concerning these parameters, then professionals could communicate in a much more meaningful fashion. When I speak with proficient farriers and veterinarian podiatrists, I can actually draw the foot as they describe the soft-tissue parameters. What more do you need to start a meaningful conversation about a particular foot?

Along the same line of thought, if you are able to describe the parameters as they change during the course of a significant foot problem, it helps the team design a mechanical protocol detailed for the specific problem.

Being able to take and interpret informative film is only a small part of the picture. We must be able to go to the foot and find landmarks that help us see through the capsule and visualize the internal structures. You must learn to look at film as if they are three-dimensional.

Guidelines for Taking Consistent Lateral and DP Radiographs

Use two wooden blocks when taking radiographs: one for each foot. The blocks should be designed so that the height is ¾ inch lower than the x-ray beam. Lame horses will love you for using two blocks instead of one.

Set the blocks beside each foot. Place the good (healthy) foot on the block first, followed by the injured/diseased foot. It is critical that you maintain a perpendicular film-beam relationship and a consistent focal distance that is predetermined by your technique (24-28 inches is a good standard for most portable units). You must also maintain a film-subject distance of zero.

A soft exposure 65 degree DP and 45 degree, 65 degree oblique DP reveal the margin of PIII. The articular surface and the navicular bone can also be easily demonstrable with more penetration.

Radiographs taken with the foot sitting on a plate that is parallel to ground produces severe distortion of the image every time. Your detail may be great, but so is your distortion.

Let's review what farriers need from informative radiographs: