サブトラクションフィルムを用いた口内法フィルム現像の Quality Assurance の研究

抄録

Since the frequency of intraoral reontgenography has increased, the levels of exposure to patients by a radiation dose should be taken into consideration. The dose given to the whole body by one single dental radiography is low, when compared to radiography to other organs. As to calculation of risk, however, a rather high frequency of radiography should be taken into account. Statistical data show that approximately one hundred million radiographs are taken yearly in Japan. The use of high sensitive dental films and being careful not to commit techical failure are important in reducing the radiation dose given to patients. There are many reasons why the radiographic quality can not be constantly well-kept. The use of an old developer is one of them. It is very important to know the quality of the developer in use. In this study, the subtraction masking film method was attempted to evaluate the quality of radiographs and the developer. A wedge made of Mix D (10 mm wide, 30 mm long, 0~40 mm in height) was radiographed and developed with a new solution. A subtraction masking radiograph was prepared from the radiograph of the wedge. Dental films of the wedge were also developed using weakened developing solutions. Each dental film was superimposed on the masking film prepared at first to measure the density. If the developer is effective, then the superposed films have the same transmission density at any area. If the film is developed with a weakened developer, the density is reduced. The density is decreased with an increase in the number of films developed, because the developing solution becomes weakned and undergoes chemical changes during the course of development. In this study, a decrease in transmission density was detected after development of approximately 100 films. This method is simple and useful for the evaluation of the activity level of the developer at any time after preparation.