by Leif Kullman
Some small hints to keep a good quality in Dental Radiography
One of the main goal with all diagnostic radiographing is to produce high quality images with a minimum of exposure to patients but also to the personnel. This means that regular routines for detecting malfunctions that affect image quality should be used in our daily work in a dentist practice. Some of the check points to perform during this work can be:
Film exposuring
Check the recommended exposure settings from the manufacturer. Compare with the kVp setting on the equipment. Check also the timer switch which is an usual cause to improper radiographs. It is an usual fault among dentists to increase the exposure time when the real reason for a bad radiograph is faulty film processing.
Remember also that the exposure settings are based on an average sized patient and to adjust for patients of different size and appearance. If not the radiographs in smaller patients can be to dark and in heavier to light.
However it has been estimated that 80-90% of radiographic pitfalls are traceable to the darkroom and film processing procedures. A correctly processed radiograph requires minimum exposure and thus minimize patient exposure to radiation. The following routines can therefore be emphasised regarding the processing.
Concerning the darkroom
The safelights should provide sufficient illumination so that all important activities can be carried out without exposing the film by mistake. The light filters should only transmit light outside the normal sensitivity range of photographic materials.
Walk into the room and close the door and turn off all lights. Look for light leaks!
Even a rather small light leak can fog film. Look for leaks under doors for example.
Check for light from sources such as clock radios and other electronic equipment.
Seal all found leaks.
A very useful and simple method to check the illumination or leaks in the darkroom is coin-on the film method. A film is unwrapped and placed on the usual working surface in the darkroom and a coin is placed on the film. After 5 minutes the film is processed in the usual manner and if there is an outline of the coin, there are leaks or not safe safelight in the room.
Some additional hints about the darkroom:
keep the working areas clean to avoid contamination and
artefacts on films.
keep both darkroom and storage rooms between
10°C and 20°C, since too high temperatures can cause
heat fog
strive for a good ventilation system by replacing inside air with
fresh outside air
Film processing
Manual Processing. Replenishment is important in processing to maintain the chemical
activity of the chemical solutions. Add recommended appropriate replenisher of the developer and fixer working solutions each day.
Under normal conditions ( about 30 intraoral films per day) it is wise that the replenished solutions are replaced with fresh working solution at least each 3 to 4 weeks.
Automatic Processing If your intraoral film processor does not have automatic replenishment, this must be made manually daily. As in manual processing fresh working solutions are prepared at least every 3 to 4 weeks under normal conditions.
Do remember that automatic processing equipment requires the same care as that used for manual processing. Daily or at least weekly periodic cleaning of roller transport racks and tanks using water and a soft brush all contribute to a radiograph with optimal image quality.
Reference radiograph
To check all the process a reference radiograph can be created.
This one is made under the proper condition from a fresh unexpired film, which has been properly stored. A bitewing is for example exposured in a skull (if available) and the film is developed with freshly mixed chemicals and when the temperatures in the different solutions are at recommended settings. New image are later on taken on the same object and are compared with this optimal reference radiograph.
Viewing
It is always advisable to use a good viewbox and a viewer when the radiographs are examined.
Next month I will tell you about a new potentiality that ODIS has started. The possibility to send digital radiographs to us to get some help in diagnosing different kinds of pathology in the image. I will report on the background and how this can be performed if you have a computer and an e-mail address.
Leif Kullman
