Digital radiography, or radiovisiography (RVG), is a method of recording, displaying and processing radiographs using electronic data processing. It differs from conventional radiographs, which use film for recording, in that a sensor or sensor film is positioned in the mouth in place of the conventional dental film. The radiation image is visualized with a digital image receiving system. The use of such systems reduces the radiation dose.
Indications (areas of application)
The diagnostic issues that require the acquisition of a digital radiograph coincide with the indications for a conventional radiograph. I. Intraoral single-tooth radiographs, in which the sensor or sensor film is placed intraorally (in the oral cavity), are needed, for example
- For the diagnosis of approximal caries (interdental caries) in the form of bite wing exposures.
- For the diagnosis of secondary caries (re-occurring caries at filling and crown margins).
- For the assessment of the periodontium (periodontium) of individual teeth or the entire dentition (dental status).
- In the course of root canal treatments
- Before the extraction (removal) of individual teeth
- For control after extraction or apicoectomy (surgical removal of the root tip of a root-filled tooth).
II. orthopantomograms (OPG, panoramic tomograms, PSA) provide a two-dimensional overview of all teeth as well as the adjacent bone structures, maxillary sinuses and temporomandibular joints. This results in the following indications, among others:
- For overview during initial examination
- Dentition control (for the progress control of the change of teeth so as in the case of suspicion of non-attached teeth).
- Before extraction of individual teeth to assess the neighboring structures such as the proximity to the maxillary sinus.
Contraindications
Before taking any X-ray, in principle, there must be a justifying indication. If this is missing, the use of X-rays is contraindicated. These include elective procedures during pregnancy that require radiography.
Before the examination
Because digital radiography is a radiologic procedure, appropriate precautions must be taken to protect the patient and the treating team from x-ray radiation:
- Questioning women of childbearing age about possible pregnancy.
- Inquiring about recently taken radiographs
- Protecting parts of the body not to be examined with a lead apron or shield
- Correct adjustment technique on the patient to avoid repeat exposures.
- Correct setting of all technical parameters to avoid repeat exposures.
The procedures
Digital X-ray technology, like the conventional X-ray method, is based on the application of X-rays. A homogeneous X-ray beam is generated in a special X-ray tube, which is directed via a tube onto the object to be examined. The X-ray beam is modified (altered) by the tissue lying in the beam path. For intraoral exposures, a rectangular tube limits the beam path for radiation protection reasons to an area whose diagonal is max. 1 cm larger than the sensor or sensor foil placed in the mouth. I. Systems with semiconductor sensors (CCD sensor technology):
While in conventional X-ray the radiation exposes a highly sensitive film positioned behind the tissue, in a digital sensor the radiation reaches a crystal with electronic detectors, amplifying the incident radiation. The crystal, called a scintillator, is brought to an energetically excited state by the X-rays and emits flashes of light when it returns to its lower initial state. This physical process is called scintillation. The light flashes are collected by a detector consisting of numerous photodiodes and fed directly to the computer via an amplifier system. The computer processes the information. The resulting image is immediately available. II. sensor foil system (digital luminescence radiography; DLR):
Alternatively, digital radiography can use an imaging plate instead of the wired sensor.This imaging plate stores the energy of the X-rays in the form of charge states of electrons. After exposure, the foil must first be read out by a system working with a laser scanner, which records the information about the different gray levels and digitizes it. Reading out a single tooth image takes about one to two minutes. Afterwards, the image is transferred to the computer, after which it is available. Advantages of digital X-ray:
- 3-D images can be made, which lead to a diagnosis preciseness.
- Post-processing capabilities: Gray levels can be changed for better diagnosis and pathological (pathological) changes can be measured.
- Computerized data storage and archiving.
- Fast availability at the treatment site
- Buffer zone against overexposure and underexposure
- Due to the higher sensitivity of digital image receiving systems, the radiation dose can be reduced by approximately 30% compared to conventional dental film.
Disadvantages of digital radiography include:
- Sensors are wired, rigid and uncomfortable in the mouth.
- Cable breakage on sensors
- Sensor foils scratch quite easily, which affects the image quality
- From the EDP-based data processing can also be disadvantages such as data loss or the question of long-term access security over 10 to 20 years arise
