Background & Aim: The use of panoramic radiograph is increasing, due to its numerous advantages. Radiographic films used in this techniques are of double emulsion kind which are used with intensifying screens. Single emulsion or video films can also be used for this purpose. The aim of this investigation was to determine the exposure parameters to achieve an appropriateoptical density in these two types of film, and also to evaluate the radiation doses under such parameters.
Methods & Materials: This study was performed through a tissue equivalent phantom (RANDO phantom). First, with various tube voltages (KVp) and tube currents (mA). A total of 128 radiographs were taken from the phantom with these two types of film. The exposure parameters were determined under which both films showed the same density after examining the optical densities. Then, phantom was again exposed to the radiation and the absorb doses were measured, using TLDs.
Results: It was demonstrated that:
1. SE films, require two times radiation in comparison to the double emulsion film in order to provide appropriate optical density.
2. Using SE films increases absorbing does, of MBM up to 2-2.5 times, thyroid gland to 1.7-2 times and parotid gland does up to 1.3 times, in comparison to the DE films.
3. In DE films, under lower exposure parameters and desirable processing, absorbing does of the MBM will increase to 3.5 times, thyroid gland to 1.5 times and parotid gland to 2.5 times normal dose.
Conclusion: Considering the increased risk of radiation induced cancers following the repeated radiations, the use of SE film should strongly be avoided.