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Radiology

It is reported that only twenty percent of practicing orthodontists have converted to some form of digital radiography in their practices and as more of us continue to consider this change, we are faced with the decision to choose an indirect system, a direct one or make the jump to a cone beam system. There are no fewer than thirteen different radiology systems available today so this decision can be a complex one and it is the purpose of this presentation to assist you in being informed to make the best decision possible.

An orthodontic office might consider converting its film based system if it is currently outsourcing radiographs to a lab, the hardware is wearing out and soon faces replacement, you really want images to appear on your office network without scanning film, your darkroom is large and could be used for better purposes of if you simply desire to become more efficient.

There are two types of digital systems to consider. An indirect system allows you to continue using your existing hardware, remove the intensifying filters from the cassettes and replace the film with a phosphor plate. The phosphor sensor is then laser scanned for image acquisition. These systems are typically less expensive than the direct systems which call for all new hardware and allow exposing the patient with immediate acquisition of the image.

We can describe three basic scenarios that will help decide what to do about the issue. One might consider continuing to use a film based system simply because it works! If recapturing the darkroom space is of minimal advantage, viewing radiographs on a light box instead of a computer screen or if the staff has the time to scan film and the hardware is okay and appears to have some life left in it, film works just fine. Film is most likely the least expensive method of using radiographs in an orthodontic practice.

A phosphor sensor indirect system is for those whose hardware is in good shape, more efficiency is desired, images on the network with no scanning is a must and recapturing the darkroom has some advantage. This choice will be less expensive than choosing a direct system but demands hardware that has some life left in it.

The direct digital decision is for those who desire the above advantages over their film system, are willing to invest more to gain maximum efficiency time wise in acquiring radiographs on the network.

Let's consider the overall advantages of a digital system. It will get rid of:

Film processing time which may equal scanning time if a slow indirect system is used
The darkroom
The processor
Processor maintenance
Film and chemical costs
Chemical disposal costs
Film scanning time

There are five direct systems to consider and I shall say a few words about each.

The Sirona has been producing dental X-ray units longer than any other company. Their first direct machine had two problems that I mention here in the interest of history and the possibility that you may find one of these units up for resale. The first problem was that the scanning geometry was vertical rather than horizontal. A fan shaped beam moved from top to bottom thus creating horizontal magnification but none in the vertical dimension. Although I have asked many orthodontists if they feel this is of clinical significance, I have never gotten a solid answer so I plead I don't know. The second problem was that the ceph was portrait mode rather than landscape which lost some of the back of the cranium and some of the cervical vertebra information. Whether these missing parts are important is up to you. Sirona completely redesigned its direct machine in 2004 and resolved both of these problems. So we now have the company with the most experience producing the newest designed direct digital unit.

Planmeca appears to have the largest installed number of units of all the companies. It is available in three levels of features. The "simple" is less costly but has minimal features while the next level up adds the Planmeca mandible feature which appears to be unique to them. I will address this issue later. The third level adds a bit to the price and features what is called a tomogram image which appears to me to be a trimmed down exposure of a panorex. Most universities I have visited have purchased the top model but state they seldom use the tomogram feature. If you choose a Planmeca, I would advise you to check about the feature list compared to cost.

This company has advertised that it can convert a film machine newer than 1987 to direct digital for about 35 K. When I checked into this, I found that the converted result was missing several features when compared to a new machine and by the time I added features to the conversion, it appeared that selling the film machine and buying a new one might be the best decision.

Instrumentarium sells a very nice looking system and has a considerable installed base in the US. They allow you the choice of one or two sensors.

The Kodak 3000C is the newest kid on the block. Trophy, a French company, was purchased by Kodak who renamed the Trophy machine the Kodak 3000C. There was a time when these units were being sold prior to getting FDA approval but this has been done now. Their main claim to fame is their one second, no scanning required ceph acquisition, the only company to offer this feature. It eliminates the "wiggle factor" which will be discussed later. It is important to note that the ceph is acquired in the portrait mode so some of the cranium and cervical vertebrae are missing.

Most companies will talk with you about the tax deductions involved in this kind of purchase. There was a scenario where one could have a $5000 tax CREDIT when purchasing a new system. This was an ADA ruling that said if your new machine is now handicapped accessible and the old machine was not, the tax credit is yours. It appears the IRS was not privy to this ruling a few years back and I know of some who claimed it although accessibility was the same before and after. I have learned the IRS is now aware of this so we probably don't want to claim this tax credit.

The indirect systems allow you to continue using your existing hardware by removing the intensifying screens and substituting a phosphor plate for the film. The nice thing about these systems is that the phosphor plates can be handled in a normal lighting environment if it's not too bright so there is no necessity for a darkroom. Once scanned, the phosphor plate must be "cleared" for the next exposure by exposing it to a bright light. They do vary in price as well as acquisition times so these two issues will need to be considered if you choose to go this route.

Denoptix was the first indirect system developed some five years ago. The sensors are loaded onto a removable drum which is then placed in the scanner and scanned. It is the slowest machine and the phosphor plate must be placed on a light box for two minutes after scanning for clearing. It has always been able to accept all film sizes.

Digident was the next indirect system. Originally, it could only process panos and cephs due to some patent infringement issues but the latest model can now accept all film sizes. The sensor is placed on a non-removable drum inside the scanner and it is cleared after the scan while remaining on the drum. It is one of the faster indirect systems.

Digora, built is Sweden, is a fairly large device that accepts a sleeve into which you have placed the sensor(s) and then completes a scan and clearing process fairly quickly. It stands about three feet off the floor so it is one of the larger devices. It will accept only the larger film sizes so if periapicals and/or occlusals are desired, you must purchase an entirely separate device to scan these sensors.

ScanX is the quickest of them all. It is a 24" tall unit that allows dropping the sensor into a slot without having to load it on/in anything. It is quite fast and will accept all film sizes.

There is yet another alternative to all these systems and it is film based. I mention it here because for some, a film based system may make sense. The Panoramic Corporation will place a film based machine in your office for free, show you how to use it and remove it whenever you so desire. They will charge you $25 per film so their intention is to allow you to have a radiograph solution and avoid the cost of a large capital expenditure.

An important consideration with all these systems is how they relate to your imaging software. For all of the above mentioned digital systems, a radiograph is captured using the proprietary software belonging to the system. This will create a situation in which your photos are stored in the imaging folder (imaging.jpg) while the radiographs for the same patient are being stored in the radiographic systems folder (xray.jpg). What you want is to be able to access your images directly from your practice management software and have all photos and radiographs right there. Moving X-rays from the proprietary folder over to the imaging folder can be quite cumbersome and is to be avoided. Your imaging software should have an interface to your radiographic machine that will allow you to capture the X-rays with imaging software but save them directly in your patients imaging file. Most of the better imaging software programs do have this feature so be sure to look for it when deciding on your radiographic system.

Here is a summary of the direct and indirect systems available today. These cost values were gathered at the October 2004 PCSO meeting and are to be considered ballpark numbers only! They were meeting prices quoted me by various salesperson.

New system costs:

Panoramic/film or $25/film 12.5 K
Digident/indirect 18 K
Denoptix/indirect 20 K
ScanX/indirect 22 K
Digora/indirect 28 K
Trophy/direct 50 K
Gendex 57 K
Instrumentarium/direct 59 K
Planmeca/direct 72 K
Sirona/direct 72 K

Acquisition speed...

Kodak/direct 1 sec/ceph, 20 sec pano
Instrumentarium/direct 20 sec
Sirona/direct 20 sec
Planmeca/direct 20 sec
ScanX/indirect 30 sec
+ load time and 30 seconds clearing time
Digident/indirect 90 sec
+ load time and 60 seconds clearing time
Digora/indirect 90 sec
+ load time
Denoptix/indirect 4.5 min
+ load time and 2 minute clearing time

I will finish the digital section of this presentation with nine questions you should consider before making a final decision. They are questions for which I do not have answers but they are good questions for you to consider.

Support:
You will want to know who to call and what will happen in the event your system goes down. You will typically get glowing answers from the vendors selling these systems but they really don't know the answers. The only reliable source of support information is a current user of that system so you will need to check this issue out by visiting an office using the system you are considering.

Radiation levels:
There is much misinformation going around on this issue. The only article I have been able to find thus far was published the Angle Orthodontist, June 2001 in which a Sirona film machine was compared to a Sirona direct system. The radiation levels were reduced by 50%. It appears to me that in general, the direct systems do significantly reduce radiation but the indirect systems use as much or more radiation than the film systems.

Image quality:
Image quality looks great at every booth at the AAO meeting for all systems. But bearing in mind that a human is positioning the patient, choosing settings and pushing buttons, image quality can be quite inconsistent. Again, you need to visit an office to answer this question.

Planmeca mandibles:
Planmeca has long presented the concept that the anode and the sensor should follow a different path for the panorex if one desires to get a through the contact image. Therefore, they have a touch screen choice of eight mandibular anatomies going from tapered to square. This appears to me to be a good assumption and others have agreed.

Ceph orientation:
All direct systems except the old Sirona and the new Kodak 3000C provide us with a landscape oriented ceph which gets most if not all of the cranium. These two systems eliminate some of the posterior parts of the cranium and the cervical vertebrae so if these areas are of interest to you, it might be best to check this feature out.

The wiggle factor:
Understanding that all but the Kodak 3000C obtains a ceph by an anode scanning a moving sensor for some 13 seconds, we are asking a small child to keep very still for some period of time. Planmeca claims that since it scans from the front to the back and the wiggle will most likely occur during the end of the scan, the wiggle factor is not important. Instrumentarium scans from the back to the front so the theory is that critical points in the anterior part of the face may be blurred. The only system that virtually eliminates this consideration is the Kodak 3000C with its one second ceph exposure.

One or two sensors:
Since a second sensor will cost about 10 K, a decision is necessary about having only one and moving it between the pan and the ceph or having two fixed sensors. The concern is dropping the device which may break it. You should discuss this issue with the vendor.

Phosphor plate life:
The indirect systems have a major question I have not been able to answer and that is, how long do the plates last? This is important because a pan or ceph plate will cost about $850 to replace. The manufacturers are all over the ballpark with estimates that are probably no better than guesses rather than test results. You probably need to talk with a user of this system to get the best answer possible.

Cost:
There is a huge discrepancy between suggested retail cost and meeting cost on all these systems but more so on the direct systems. I have seen a direct machine sell for a full 40 K under suggested retail at the AAO meeting so be sure to shop the price when you are about to make your final decision.

Film cost comparisons:
You will hear from vendors, Doc, you’re gonna’ save so much money on film and chemicals, you’ll pay for this system in a year! There are two sides to this coin, money saved and money spent. In 1999, the last year we used film, I checked out the cost of this approach including the cost of film, chemicals, processor maintenance and film scanning time and was surprised that the annual cost was only $2,132. If this comparison is important to you, you need to determine how many radiographs you will be taking and whether or not you charge for them.

I will finish with three more questions that will perhaps complicate the decision making process for you and I apologize for that.

When will the direct sensor become available? If you were to get a chest X-ray at a hospital today, you probably would have it taken with a direct sensor that has replaced the film and the cassette and cost the hospital a good deal. The direct sensor is a device that you would use in your existing machine and would immediately acquire the image without scanning. These devices are expensive and there is such a direct sensor for a panograph machine called the Digipan and it sells for 22 K. There is not yet an equivalent sensor for the ceph so I guess the question is, Will there ever be one, when will it happen and how much will it cost? If the direct pan and ceph sensor do become available soon at a reasonable cost, I suspect the existing 2D scanning devices will be in very low demand. I have heard much speculation on this issue, but no definite information is at hand as of today.

The newest rage in our specialty is the introduction of the volumetric scanning devices, better known as the cone beam machines. The first one appeared about 3 ½ years ago on the West Coast and there are some 200 installations reported today. This technology directs a cone at a flat sensor as both revolve around the patient’s head collecting some 360 plus or minus 2D images. The software then assembles these images into a 3D model of the skin, muscles, bones and teeth which can be manipulated on screen in many ways. Various cuts can be imaged giving the operator much more information than what is available for 2D images. Today, this imaging is being used by orthodontists for impacted teeth problems, supernumeraries and missing teeth to better aid in their diagnosis and treatment planning. The major use of cone beam data is by implantologists to better plan precise placement of their implants. There is no doubt many of us will be using this technology much more in the future but as of now, we don’t know for what. Much research needs to be done in this area to determine just how cone beam data will assist us in orthodontics. The current available systems today are:

New Tom $350,000
iCat $150,000
Hitachi $300,000
Morita 2-3 teeth only so it's not a consideration for orthodontics

Currently, a patient referred to a cone beam facility is imaged by a technician and the referring doctor's prescription is read so the proper cuts can be determined and returned on paper. In this process, a radiologist is involved so any existing pathology can be ruled out. Soon, much of this will be done electronically so that a referred patient is imaged and the images are returned via the internet. And the day is coming when the software will be so user friendly, a referring doctor will be able to manipulate the 3D data and determine and make his/her own cuts for diagnostic purposes. A major question that arises out of this model is the role of the radiologist or who will rule out any pathology.

It is interesting to note what universities are doing with cone beam technology. Loma Linda and USC are getting cone beam data on all their orthodontic patients while UCSF, UNC and Case are imaging only selected patients. As time goes on, I suspect we will have more information on just who we should cone beam and more research will have been accomplished.

Cone beam data represents a technology leapfrog effect in many ways if it turns out to be as effective as we think it is today. It in theory will be substituting for everything we now use for beginning, progress and final records on an orthodontic patient. There will be no more impressions, 2D radiographs and it is the beginning of Invisalign, Orametrix, Insignia and Lingualcare. Current technology will even allow the fabrication of a Hawley retainer from cone beam data.

And finally the newest 3D effort is Trigem, a company based in France. Andre Horn, orthodontist and Jacques Triel, radiologist are the leaders of this company which is unique in many ways. They claim they are able to use an existing cat scan machine, alter its exposure to produce 3D data equivalent or better than that of cone beam data at a cost of $140 and radiation exposure equal to that of a panorex. They also claim to have over twelve years of research and experience with the trigeminal foramina analysis which is growth predictable. I think we will be hearing more from Trigem in the years to come.