Let’s go digital............................. Instant diagnosis.....................

Digital radiography is a form of X-ray imaging, where digital X-ray sensors are used instead of traditional photographic film. Advantages include time efficiency through bypassing chemical processing and the ability to digitally transfer and enhance images. Also less radiation can be used to produce an image of similar contrast to conventional radiography.

Digital dental radiography comes in two forms: direct, that connect directly to the computer via USB and provides immediate images, and indirect (photostimulable phosphor plates, or PSP) which uses plates that are radiated and then digitally scanned.

Direct digital sensors represent a significant initial investment, but in addition to the convenience of digital images, provide instant images that can reduce the time the patient spends in the dental chair. They also reduce the need for the constant purchase of film and the necessary development chemicals. Early systems used CCD sensor technology, but changed to CMOS sensors following their introduction in early 1998-9.

Indirect digital imaging (also termed Computed Radiography) utilizes a reusable plate in place of the film. After X-ray exposure the plate (sheet) is placed in a special scanner where the latent formed image is retrieved point by point and digitized, using laser light scanning. The digitized images are stored and displayed on the computer screen. This method is halfway between old film-based technology and current direct digital imaging technology. It is similar to the film process because it involves the same image support handling but differs in that the chemical development process is replaced by scanning. This is not much faster than film processing and the resolution and sensitivity performances are contested. PSP has been described as having an advantage of fitting within any pre-existing equipment without modification because it replaces the existing film; however, it includes extra costs for the scanner and replacement of scratched plates.

Historical milestones for digital intraoral sensors

• 1987 – RVG (radiovisiography), Trophy Radiology (France) introduced the world's first intraoral X-rays imaging sensor. Trophy Radiology patented it under the restricted name radiovisiography (other companies use the phrase digital radiography) and continues to produce intraoral sensors today under the Kodak name, which is used under license by Carestream (Canada). Trophy has released a wireless version of their RVG intraoral sensor named the RVG 6500.
• 1992 – Sens-a-Ray of Regam Medical System AB (Sundsvall, Sweden) is introduced. The company went out of business and their technology was purchased by Dent-X, recently renamed to ImageWorks (USA).
• 1993 – VisualX of Gendex-Italy (subsidiary of USA company).
• 1994 – CDR of Schick Technologies, USA. Schick were the first company to offer three film-like sizes of sensor, as well providing the significant breakthroughs of CMOS-APS technology (1998), USB connectivity (1999), the first sensors without cables (2003) and the first sensors with replaceable cables (2008). They launched their second generation of CMOS-APS chips in 2009. Schick merged with Sirona (Germany) in 2006 and is now part of Sirona Dental Systems, LLC.
• 1995 – SIDEXIS of Sirona, DEXIS of ProVison Dental Systems, Inc. (renamed DEXIS, LLC following its acquisition by Danaher Corp.), DIGORA (PSP solution) of Soredex (Finland)

Today there are many other products available under a lot of different names (rebranding is quite usual for this type of product).

Historical milestones for digital panoramic systems

• 1995 – DXIS, the first dental digital panoramic X-rays system was introduced by Signet (France). DXIS targets to retrofit all the panoramic models.
• 1997 – SIDEXIS, of Siemens (currently Sirona, Germany) offered for Ortophos Plus panoramic unit, DigiPan of Trophy Radiology (France) offered for the OP100 panoramic made by Instrumentarium (Finland).
• 1998–2004 – many panoramic manufacturers offered their own digital system.
• 2005 – SCAN300FP, of 'Ajat' (Finland) is the latest innovation offered. It shows the feature to acquire many hundreds of mega bytes of image information at high frame rate and to reconstruct the panoramic layer by intensive post acquisition computing like a computed tomography. The main advantage is the ability to reconstruct focused differently. The drawback is the low signal/noise ratio of primary information which involves much software work for correction. Also the ability to reconstruct various layers raises the importance of the geometrical distortions already high in dental panoramic radiography. Since 2008 the SCAN300FP system is available in Ajat ART PLUS and ART PLUS C system.

Conclusion-

1.      Digital is convenient.

2.      Digital is time saving and instant.

3.      Digital requires less inventory.

4.       Digital can be used to convince and educate patient.

        (By Dr. Ajay pandey :BDS-Army Dental college, MBA, General management-IIM-L)