By Claudio, M. Levato, DDS
Digital Radiographic Technology
There are currently 2 different concepts of photon detection for direct digital image acquisition, the use of a solid-state image receptor or the use of a storage phosphor system. Many people think that Direct Digital Radiographic Technology means that you see an X-ray image immediately on a monitor, in fact the term direct digital refers to the direct acquisition of the image onto a receptor, like a CCD or a PSP device. Whereas the term Indirect Digital Radiographic Technology means that you take an existing X-ray film and convert it to digital after it has already been exposed and developed.
Direct Sensor Technology
To capture a radiographic image you need an X-ray generator and a solid-state image receptor or more commonly referred to as a sensor. A sensor is just a silicon chip with an electronic circuit on it. There are two solid state sensor technologies on the market today:
- CCD (charge-coupled device)
- CMOS (complementary metal oxide semiconductor)
There are a number of benefits of using direct sensor technology.
- The ability to view an image on a monitor within seconds resulting in better work flow
- Significant reduction of radiation dosage compared to D speed film (about 80%)
- Improved diagnostics, especially with electronic image processing through software tools
- Better quality control of images allowing you retake any inadequate image immediately
- Improved patient education capability by using image on large monitor instead of trying to show patient the film on a view box
- Ability to send image electronically
- Environmentally friendly, no chemicals to dispose of
- Elimination of darkroom errors and eliminating the dark room
- Better integration with electronic patient record
- Cost savings of film and chemicals Sensor barrier protection on XCP.
The disadvantages of direct sensor technology:
- Requires computer workstations
- Requires image management software
- Requires dentist and staff training
- Requires hardware and software support
Sensors can be used in virtually every application that films are used in dentistry. There are some distinct differences between the two. The sensors are rigid and usually come with a wire connection and are considerably wider than film. There is a strong misconception that sensors are more uncomfortable than film. The reality is that film was never really all that comfortable. How many times have your patient’s gums been inadvertently cut by the film and it is just as easy to gag with a film as it is with a sensor? Recently, sensors with rounded corners have become available to ensure even greater patient comfort. The issue is not the medium but the management of the technique. The best protocol still requires the use of a paralleling technique with the use of an XCP (Extension Cone Paralleling) device. You will want to make sure that the patient is always biting toward the end (away from the teeth) of the XCP bite block so that the sensor does not impinge on tissue and in most cases will be closer to the midline of the mouth, which is better because there is usually more room for the sensor.
Indirect Sensor Technology
Indirect Sensor technology is commonly referred to as Phosphor Plate Technology because the image plate consists of phosphor particles embedded in a polymer binder and coated onto a plastic base. These phosphors are called “photostimulable phosphors” (PSPs) and are used to store about 50% of the X-ray energy on the plate producing a latent image. The information contained in the plate is released by exposure to a laser scanner. The storage phosphor plates come in all the sizes of dental film and are slightly thinner.
The advantages and disadvantages of Phosphor Plate Technology over film are very similar to that of direct sensors, with the following exceptions.
- Reduction of radiation dosage compared to D speed film (about 50%)
- Unlike sensors, very little training is required for staff because it is used just like film
The disadvantages of Phosphor Plate Systems are:
- Inability to view an image on a monitor within seconds
- Cannot retake any inadequate image immediately
Images in a full-month survey on a PC
How do you use indirect sensors:
Phosphor Plates are used in very much the same way as dental film. This is both the good news and the bad news. The good news first: training of staff is very simple and direct. The placement, look, and feel are very much the same. You do have to place the plate in a barrier, then place it on the same holders you used for film, expose the plate then instead of putting it through a processor, you place it in your scanner which scans it into your patient’s digital record.
Although having fully networked computer infrastructure in place that connects all your administrative and clinical workstations is still ideal and recommended, Phosphor plate technology allows you more flexibility in integrating digital X-rays into your practice. A single scanner is sufficient for most offices and you are not limited by the number of sensors you have on hand to be able to take images throughout the office.
Extraoral Sensor Technology
CCD technology is also available for panoramic and cephlametric X-ray systems. This means that your extraoral radiographs can be directly acquired and viewed immediately on the monitor. Some of the new CCD panoramic machines are function specific robotically controlled units. The benefits are significant:
- There is no need for film, chemicals, or processor, which translates into financial savings
- There is no need for phosphor plates that require placement and scanning
- The ability to view an image on a monitor within seconds resulting in better work flow
- The beam can be collimated to the area of interest only, thereby reducing radiation dosage
- Machines can be set to open the interproximal contacts or to better visualize alveolar bone
- Improved diagnostics, especially with electronic image processing through software tools
- Better quality control of images allowing you retake any inadequate image immediately
- Improved patient education capability by using image on large monitor instead of trying to show patient the film on a view box
- Ability to send image electronically
- Elimination of darkroom errors and eliminating the dark room
- Better integration with electronic patient record
Taking a DenOptix image
CCD panoramic unit can run from $32,900 to $ 87,000, depending on the options.
Gendex Digital Pan/Ceph Orthoralix 9200DDE
The disadvantages of extraoral direct digital radiographic technologies are primarily cost factors.
- Requires an investment in a completely new system or an expensive upgrade of an existing unit.
- Most practices have a panoramic unit that still works well but has very little value for resale and dentists as a whole are reluctant to make that leap. This is where a Phosphor plate system for extraoral images makes sense until the existing equipment needs to be retired.
If you do not have an extraoral x-ray unit and are in the market for one, I would strongly encourage going with one of the CCD units first. The CCD units are the latest technology and have additional peripheral applications that greatly enhance our diagnostic applications, such as TMJ slicing or mandibular cross sections for implant placement. Most importantly, future applications will be a matter of software enhancements so your unit will continue to add value. It is my opinion that the return of investment would very quickly give you a significant return and you do not have to wrestle with the liquidation of a perfectly functioning unit.
How do you use Extraoral Sensor Technology:
These panoramic or panoramic cephlametric digital X-ray units work the same way as your conventional ones but usually have more bells and whistles and are easier to use. The main difference is that it is always ready to use with no need for loading plates or film and the images are placed directly into the database. CCD panoramic or pan-ceph combinations are more costly than conventional ones but the savings in film and chemical costs will more than compensate for that in a busy practice. The hardware is married to software that automatically performs real time corrections of technical factors to ensure optimum image contrast and balance. There are retrofit kits available for many of the existing panoramic machines out there and some of the newer analog panoramic units have kits directly from the manufacturer to convert an analog machine to a digital one. These retrofits or conversions may cost over $20,000, so you may want to consider researching the new machines to see if the new advances warrant replacing your old system. The list cost for a new
Putting it all together
Since 1895 radiology was misunderstood, so why should today’s digital radiology be spared from the same skepticism? All kidding aside, we have evolved; however, for many professionals, the change to digital is still fraught with fear. Most of the fear is from uncertainty of the reliability and of the uncertain complete financial burden to purchase, train, maintain and support this technology over the long run.
The solution to this uncertainty is to look beyond the specific technology and look at the company that is behind the product. Is the company invested in dentistry and the ongoing research, development, training and support required for you as long as you practice? I always recommend that dentists look at companies that provide solutions to help their practices, not merely sell them products.
Digital radiology today is not risky, there are over a dozen companies that manufacture, sell and support excellent digital products. Some focus on only on intraoral direct sensor solutions, whereas others provide the full gamut of digital products: intraoral, extraoral, CCD and PSP solutions. I am certain that there is a solution for any dentist and his particular practice needs, but the first step is to learn about your choices and how it can be integrated into your practice life.