Exposure in Dental Radiology: A Comparison Between Intra-oral, Panoramic and Tomographic Examinations

The purpose of this paper is to present a comparison of doses delivered to the patients when dealing with intra-oral, panoramic and CT dental examinations. The technology progress will be discussed from a dose and an image quality point of view. DAP values were measured for two intra-oral systems using speed D and E/F dental films, and a digital system in two different acquisition modes (CCD technology). For each system the DQE was also assessed. DWP and DAP were measured on three panoramic systems of various generations of units. Finally, CTDIw and DLP were measured using a standard CT (Dentascan) and a new tomographic system (NewTom) in order to assess the dose delivered when planning dental implants. The use of an E/F system instead of the D system allowed to reduce the DAP by a factor of 2 (respectively 56 and 24 mGy⋅cm) without significant loss of image quality. A further dose reduction by a factor of four was possible with digital systems but with a significant loss of spatial resolution. The DAP measured on OPG systems showed that the oldest system (20 years old) delivered a higher dose than a more recent system (respectively 0.2 and 0.07 Gy⋅cm). Finally, DLP values of 224 mGy⋅cm and 55 mGy⋅cm were obtained with respectively the standard CT acquisition and a new tomographic system designed specifically for dental radiology. The introduction of digital detectors has a significant potential in dose reduction. Nevertheless, this will impose to use intra-oral units that handle short exposure times. The new tomographic technology enables to reduce the dose delivered to the patient by a factor of 4 when compared with Dentascan.