Recently, I have been getting alot of questions from veterinarians regarding digital radiography. Private practitioners are mainly interested in learning about the different types of digital radiography (CR vs. DR) and how they can implement these systems into their practice. Most veterinarians, however, are under the false impression that a digital radiography system will increase their diagnostic capabilities. Unfortunately, this is false. Digital radiographs give you (almost) the exact same information as a properly exposed film based radiograph. If this is so then why bother? Hopefully, in the following discussion, I will answer the question..."What are the real benefits of digital radiography?"

Before, I get to the benefits of digital radiography, let me first say that digital radiography has nothing (well very little) to do with the image! I realized this fact for the first time when I was sitting through an all day seminar put on by a DR vendor. It was nearly five hours into the talk before they even showed a radiograph produced by their machine. For the first five hours they talked about the cost savings of digital radiography, how efficient the system will make the radiology department, radiation safety, and a few other topics will get to shortly. The problem is that I am not sure that most veterinary practices will be able to realize the benefits that digital radiography was designed to provide to human medicine.

Benefit number 1 - Decreased Costs: Every digital radiography vendor will tell you that digital radiography will save you money in the long run. Cost savings come from a number of places. For example:

1. No film costs
2. No processor to maintain
3. No film jackets to purchase
4. No real estate costs for a room to store old films
5. No time spent searching for old films
6. No time spent filing films
7. With direct digital radiography (not necessarily computed radiography) there is increased throughput and increased efficiency of the radiology department

These cost savings all depend on you going to a completely filmless environment. Remember, there is no cost savings unless you go completely filmless. By filmless, I means just that...filmless..no hard copy image at all. If you intend to print your images on an inkjet printer or a dry laser printer you actually increase your costs (and decrease efficiency) compared to conventional radiography! Furthermore, human hospitals must take hundreds of films before these systems pay for themselves.

Unfortunately, the transition to a filmless environment may not be that easy. If you are considering going go filmless you must consider the following:

1. What are you going to do with the images?
2. Are you going to install computers in each exam room so clients can see their radiographs (which will require an in house computer network) or are you going to bring clients into the backroom to see them?
3. How will you archive the images so you can easily retrieve them?
4. What if your computer system crashes or catches a virus? In the case of a crash, do you have redundancy in your image archive?

These problems are not insurmountable but remember that all solutions to these problems cost money and take time to implement. Human hospitals have an IT staff to deal with these issues.

In practice, most human hospitals do not go completely filmless. They keep a functioning wet developer and radiography suite around just in case the computer system goes down (among other reasons which I will get to later).

Benefit number 2 - Decreased Retakes: In human medicine digital radiography has decreased the number of retakes dramatically which increases efficiency and decreases costs. Digital radiography allows you to decrease retakes because there is increased latitude of the imaging system (i.e. digital radiography is more forgiving with exposure problems).

Unfortunately, in veterinary medicine we may not see as dramatic of a decrease in retakes as they see in human medicine. I believe that we are position limited and not exposure limited. Since I invented those terms myself here is what I mean. In human medicine, technicians do not use a technique chart. Humans are all about the same size to the technicians guess at the best technique and repeat as necessary (NOTE: human RT's have tremendous experience so their guess is usually spot on which limits the number of repeat films!). Additionally, most people do as they are told and sit still for their radiographs, therefore, patient positioning is not a problem.

The case in veterinary medicine is the opposite. Our patients vary widely in size and we use a technique chart. If properly designed a technique chart works well most of the time. However, getting our patients to sit still is a problem. Recently, I kept track of 1000 cases in our hospital and only 25% of our repeat examinations were due to exposure problems! The vast majority of repeats were due to patient motion or positioning problems. Therefore, if you employ a technique chart designed for your system, you may not see a dramatic decrease in your repeat rate.

Benefit number 3- Decreased Radiation Dose to the Patient and Personnel : The claim is that the digital imaging systems need less radiation to function properly. This is is an indisputable fact. However, in practice most people I have talked to as well as most of the technicians in the audience at the seminar I attended actually increase the technique (i.e. more radiation) with these systems. The reason for this is simple and it goes back to the previous benefit of decreased retakes.

If the image you produce is overexposed (too black) the digital radiography system does a good job of "windowing down" to see the information on the image and you don't need to repeat the exposure. Conversely, if the image is underexposed (too white) the digital radiography system cannot retrieve any information form the white areas and the exposure must be repeated. Technicians (and vet students) learn this very quickly. As one student put it "..I am getting a digital radiography system...all you need to do is point the tube and crank up the technique !" This raises ethical problems for veterinarians since we have personnel holding animals during radiography.

Benefit number 4- Increased efficiency: There is no question that digital radiography (particularly DR) has increased the efficiency of human radiology departments dramatically. They have become so efficient that some hospitals have eliminated radiology suites (as well as the technicians jobs) because they no longer needed them. However, in most veterinary practices I doubt that we will see a substantial benefit with regard to efficiency. Remember, in veterinary medicine we must spend a good deal of time getting ready (fixin' to shoot as they said during my residency) to take a radiograph (i.e. positioning animals).

Most vendors also don't tell you is that postprocessing of the digital image is both necessary and time consuming. This decreases efficiency dramatically. In fact, at two veterinary schools I asked the technicians if digital radiography slowed things down or sped things up. Both of them laughed and said that the post processing of the images was an extra step that slowed them down dramatically.

Benefit number 5-Perk to the Radiologist: As a radiologist, I hope that every veterinarian installs a digital system. This way I can work from home like many of the human radiologists. Needless to say, this benefit will probably not help many veterinarians in private practice.

Benefit number 6- Increased Interactivity with Referring Clinicians: Many human hospitals have systems where referring clinicians can log into the radiology server and look at their patients radiographs. Many of these systems have methods where the radiologists can mark on the films and leave a message for the referring clinician. This keeps the referring clinician in the loop and increases referrals. This is not a benefit for most veterinarians in private practice.

Benefit number 7- No Lost Films: This is a tangible benefit provided that you have good method of archiving and retrieving your films. An archiving database may not be included with your system. Ask your vendor. If not, these database systems (properly called PACS systems) can be expensive.

Benefit number 8-Digital radiography is cool: This is not a joke. Digital radiography is very cool and for anyone that likes playing with computers this is a great toy for you to play with. I believe that this sentiment is so strong that it creates a disconnect between reality and perception in the veterinary practice.

I recently surveyed the members of the ACVR and every veterinary practice I could identify that utilized digital radiography. As part of the questionnaire I asked "Do you like the system and would you buy it again?" Remarkably, most of the respondents said "yes." However, those same respondents said that these systems did not increase efficiency nor did they generate any cost savings. I went back and asked some of the technicians at these facilities (i.e. the people who actually use the systems) and lets just say that they were not as happy about using these systems as the veterinarians who purchased them. Furthermore, I found in my survey that when I asked the same question to a person who was not responsible for making the decision to buy the system their response about the purchase was generally lukewarm. As you can see, there is a disconnect here. People love these systems if they are not responsible for purchasing or using them. From what I can tell, veterinarians really enjoy digital imaging even if it means their technical staff grumbles, it costs more than traditional radiography and, decreases the efficiency of the department.

Benefit 9-Increased Soft Tissue Visualization: Notice that nowhere in the benefits list did I even mention the radiograph. As I said before, digital imaging is not about the image. Digital images look beautiful but for the most part you get almost exactly the same information in a digital image that you get in a properly exposed conventional radiograph. I say almost exactly the same information because you do get more information about the soft tissues on musculoskeletal radiographs. This is, as Martha Stewart would say..a good thing. However, once upon a time, there was a thing called xeroradiography that promised increased latitude and increased soft tissue visualization (sound familiar); and it did just that. In fact digital radiographs look like xeroradiographs. However, xeroradiography is, for all practical purposes, a thing of the past. This is because the benefit of the increased latitude and soft tissue visualization did not outweigh the risk of increased exposure or increased cost compared to conventional radiography. Fortunately, digital radiography has alot more going for it that just increased latitude.

There you have it the benefits of digital radiography. And as you can see (for the third time) digital radiography is not about the image or increasing your diagnostic capability over traditional radiograph. In fact, during my survey, only one single veterinarian said that they thought that there was a lesion that they could see on a digital radiograph that they would have missed on a conventional radiograph. That lesion was a tiny osteophyte in the fetlock of a horse that could only be seen with digital magnification. Identification of this lesion, however, did not change the management of the case.

Part 2: Some problems with digital radiography

Like everything else in this world you have to take the good with the bad. Here are some of the issues that the vendors don't tell you about.

Problem 1- Cost: Just so we dont forget...these systems are expensive. Can you justify thousands of dollars to take a radiograph if your current system works fine? Remember, there are no cost savings unless you go filmless and it may be some time before you realize any cost savings.

Problem 2-Unhappy Surgeons: Surgeons generally don't like digital systems for two reasons. First, it is difficult to measure for an implant on a computer screen. For accurate measurement you have to ensure that the image in the screen is exactly the same size of the image that the implant measurement templates are designed for. You could print out a full size digital image of the radiograph but some systems can't do this. To get around this problem you could just go and use conventional film radiography for patients where you would need an implant but..oops..there go your cost savings. You still need to maintain a processor in working order and have an inventory of film for these cases.

The second reason surgeons don't like digital radiography is because it may be difficult to asses infection around an implant. As you can see in the images below (Courtesy of Dr. Kneller DVM) there is a lucent halo surrounding the implant on the digital image where there is no halo in the conventional image.

It cannot be overstated that t his phenomenon is due to using an overzealous sharpening algorithm in postprocessing. This is not a problem of digital radiography in general. Most modern systems do not demonstrate this artifact. However, this will remain a problem in veterinary digital radiography as veterinarians have been known to purchase old technology. It is recommended to ask your vendor to demonstrate that their system is free from this artifact before you consider purchasing their system. Always ask to see images of metal implants before you purchase a digital radiography system. The only system I am aware of that is marketed toward veterinarians that is free of this artifact is sold by Eklin.

Problem 3-Old technology: This is a general problem plaguing all computer based technology more than anything else. Current technology becomes obsolete so quickly that it is hard to invest in something that will take years to see a return on. For example, one vet school recently purchased their second CR system because their first one, after 7 years, was "obsolete". Keep in mind that if in the future your computer system crashes and you get one with a new operating system that doesn't communicate with your old digital radiography software you may be looking at an expensive problem. Additionally, it may be difficult to find support for, or repair, an old digital systems in the future.

This problem is a serious consideration for veterinarians. In the past, out of necessity, we have purchased "older" human equipment. In the past this model worked fine. However, this model may not work for digital radiography because purchasing old technology may mean that you will not be able to get support in the (near) future. We have already seen this with ultrasound. Any veterinarian who purchased (or was given) a used ultrasound machine from a human hospital will tell you that if a probe breaks there is a good chance that it either cannot be replaced or the replacement cost is exorbitant.

Problem 4-Not plug and play: It would be great if these systems were as easy to set up as the manufacturers claim. However, for many CR systems at least, this is not the case. Rather, expect some degree of frustration learning how to use these systems and getting the algorithms correct for your system. Generally, this is a problem that can be overcome with some dedication, However, at one vet school, the problem was so bad that the unit had to get reprogrammed in Japan in order for them to get a diagnostic image.

Some facilities that currently use digital radiography actually use a combination of digital radiography and traditional radiography to improve their success with digital radiography. For example, one hospital does three of the four equine tarsal projections with digital but one of the four with conventional radiography. Another hospital does their DP equine feet with traditional radiography and the other projections with digital.

Part 3: Conclusion

In conclusion, digital radiography is an exciting new method of obtaining radiographs. Digital radiography does not provide a diagnostic advantage over properly exposed conventional radiographs. The benefits of digital radiography are more economic than anything else. However, in order to realize these economic benefits you must employ a completely filmless radiology environment and have a high caseload to offset the initial cost of the digital system.

Is digital radiography right for your practice? That all depends...

Personally, I would love a digital system in my practice. I am a radiologist working at a high volume referral practice with an IT department to maintain the computer system. For me, the main benefits are the ability to work from home or on the road, the ability to send radiographs to referring clinician's to increase their awareness of the case so they can communicate better with their clients, no more lost films, and somewhere down the road, there may be a cost savings since we do alot of films. Again, in my case digital radiography may make sense.

The case for digital radiography is not so clear cut for many private practitioners. If you are starting a practice and do not currently have a radiography suite perhaps you should consider digital radiography. If you are having problems generating diagnostic radiographs with your current equipment and a radiologist or radiology technician has identified that the cause is your equipment perhaps you should consider a digital radiography system. However, if you are happy with the radiographs you currently produce maybe you should leave well enough alone and use the money to go on vacation to reward yourself for taking quality radiographs in the first place.