X-Spect Medical Physics Services
We provide Medical Physics services for Irish Dental & GP practices, Private Hospitals, Veterinary Practices, Educational Establishments, and Industrial users of Ionising Radiation Sources. All work is supervised by a registered Radiation Protection Adviser (RPA).
Digital Imaging

Advantages of Going Digital

1. Speed: Depending on the type of system that is used to digitize radiographs, x-ray images can appear on the computer screen instantaneously, or up to a few minutes later, resulting in a significant timesaving, when compared with conventional film processing

2. Image Manipulation: One of the biggest advantages of digital images is the ability to modify the image. In addition to using post-processing techniques to aid in diagnosis, the large dynamic range of digital systems means that diagnostically useful images can be produced, which might normally have been under or over exposed.

3. Quality: While one could argue that a well taken and processed analogue image cannot be beaten for quality, digital imaging produces more consistent quality and is far more reliable (because of the inconsistency and poor reliability of film processing).

4. Reduced radiation: Existing intra-oral radiography systems can be used for digital imaging, but at an exposure that is often 70-80% lower than that of traditional film x-rays. Dentists have a responsibility, under the conditions of their RPII licence, and under SI 478 of 2002, to ensure that the imaging process is optimised, and that all doses are As Low As Reasonably Achievable.

5. No chemicals: Over the long term, digital imaging saves money in chemical, film, processor maintenance, etc. It also avoids the problems associated with handling, storage, and disposal of chemicals, as well as the time and effort required to clean and maintain film processors.

6. Archiving & access to patient records: Previous patient images can be accessed almost instantaneously and the problems associated with film storage are avoided (i.e. space, degradation of images, lost films, etc.). As in many businesses, the digital office is increasing becoming the norm in dental practices, and digital imaging is a logical extension of this. Also, for large or multi-site practices, the benefits of tele-radiology allow images to be accessed from any surgery or site.


A dentist planning to incorporate digital imaging into the practice has three main options. The three systems that are currently being used are direct sensors, phosphor plates, and digital scanners.

1. Direct Sensors (commonly known as DDR or DR)
2. Phosphor Plates (commonly known as CR)
3. Direct Scanning

Use of direct sensors is the most expensive but offers the greatest number of advantages (but also has some disadvantages) from those listed above. Direct scanning offers the least advantages and is the least expensive. CR is somewhere in between. The choice will obviously be based on cost versus the various advantages/disadvantages associated with each, but also on factors such as the suitability of existing x-ray equipment.

Direct Sensors
These systems are probably the most popular digital radiography systems. They utilize CCD (Charge-Coupled Device) sensors that are hooked up directly to a video capture card on the computer. Images will appear on the computer monitor almost instantly in most cases, making DDR the fastest type of digital imaging. Most systems have their own software for image sorting and manipulation, although the dentists can also use a third-party software that does this. Available imaging software includes the Planmeca Dimaxis 4.0, Sirona SIDEXIS XG, Kodak Dental Imaging Software, and Gendex Vix Win Pro.

In the case of intra-oral systems, DR can be used with most modern x-ray units without any modification. The patient doses, and therefore exposure times, are far lower than for x-ray film. Older x-ray units may not be capable of producing exposures of sufficiently short duration to take full advantage of this, but newer units will generally have a setting, or can be pre-programmed for digital radiography. The major disadvantage is cost. The basic systems with a couple of sensors can cost upwards of €15,000 for each surgery. Additional sensors can run from about €2000 to €5000 per sensor, and they can be quite fragile. Also, the sensors are quite a bit thicker than traditional film; the average sensor is about 5 mm thick. Each sensor will have a thin cable attached to the end, which requires some practice in placing correctly in the patient’s mouth. Many patients find them to be difficult to tolerate and, of course, they cannot be used with traditional x-ray holders. Many dentists also consider them to be unsuitable for paediatrics or special needs patients (Current research in sensor technology is focusing on wireless systems which eliminate the need for the cable). Other considerations are that there must be a computer in each surgery with x-ray facilities. Examples include the Dixi3 Direct Digital System for the Planmeca Intra, the Sirona SIDEXIS system, the Kodak RVG 5000/6000 system, and the Gendex VisualiX eHD system.

OPG and OPG/Ceph. systems are available in various configurations. They generally consist of a linear array of detectors positioned where the slit would be in panoramic imaging. A similar detector is used for Ceph. imaging, where the collimated x-ray beam performs a scan across the imaging field in sync. with the detector array. This results in much longer ceph. exposures than conventional film-screen ceph. In some systems a single interchangeable detector can be used for both panoramic and Ceph. imaging. Some systems use a dedicated linear array for panoramic imaging, and a separate full field 2-dimensional array for ceph. imaging, which of course eliminates the speed disadvantage for ceph. Some conventional OPG/Ceph systems can be upgraded to digital by the addition of an array of detectors, and this might be worth considering if your existing equipment is fairly new. Examples include the Planmeca Dimax for existing ProMax products, and the Trophy Digipan Sensor Digital OPG Upgrade.

Phosphor Plates
These systems utilizes sensors that are very similar in size and thickness to x-ray film; some are even thinner than film. The individual films are taken like a traditional x-ray, and then the film is placed in a scanner and the films will be seen on the computer screen between 90 seconds and 4 minutes later. The sensors can be re-used many times and each sensor costs only €30-40 to replace. The system can be incorporated into the practice without any modification of existing conventional intra-oral or OPG/Ceph. systems. For OPG/Ceph., a modified cassette is used which has exactly the same dimensions of the film/screen cassette. As in the case of DR, exposure times are far shorter than for x-ray film, and older intra-oral x-ray units may not be capable of producing sufficiently short exposures to take full advantage of this. This system has numerous advantages over DR. Systems are available which are capable of scanning all film formats, including OPG and Ceph., and a single scanner could be used for the entire practice. Also, for intra-oral imaging, it does not suffer from the disadvantages associated with the size of the sensor and the cable etc. The disadvantage is that it is slower in producing the image, and there is a similar amount of film handling as for film processing. Examples of popular systems include the Kodak CR 7400, and the Gendex DenOptix QSD system.

Direct Scan
For the dentist on a budget, and for the dentist who wishes to digitize existing radiographs, this option offers a relatively inexpensive method of incorporating digital radiographs into the dental practice. It involves the use of a scanner with a transparency adapter. The x-rays are placed on the scanner and then scanned; the resulting images can then be seen on the computer monitor. In most cases, the process is made easier by using special software that can organize and manipulate the images. The cost savings from the other systems can be quite large; a typical scanner and transparency adapter will cost less than €1000, and the software is usually quite reasonable as well. Of course, the quality of the image will be directly related to the quality of the scanner, and in some cases, will be inferior to both the direct sensors and the phosphor plates. This system is ideal for dentists who simply want to archive their x-rays or for the office that wants to save on costs associated with duplicating x-rays.