Effective and organ doses from scanography and zonography:: a comparison with periapical radiography

Objectives: To compare absorbed and effective doses from scanographic and zonographic examinations performed in the Scanora(R) unit with intraoral periapical radiography. Methods: Absorbed dose measurements were made on an anthropomorphic phantom head with LiF thermoluminescent dosemeters in the regions of the pituitary gland, eye lenses, parotid glands, submandibular glands, thyroid gland and skin. Energy imparted was calculated from the measurements of air collision kerma and effective doses by using the quotient 24 mSv J(-1) between energy imparted and effective dose. The upper and lower third molar region was examined with intraoral radiographs and with ramus scanograms, dental scanograms and dental zonograms. Radiation dose measurements were also performed for Scanora(R) panoramic radiography (jaw and dental). Results: The effective doses for the ramus and dental scanograms were 0.01 mSv, similar or lower than for intraoral radiography. Zonography yielded the highest effective dose (0.03 mSv). Except for the skin doses, the salivary glands received the highest doses. Salivary gland doses were slightly higher from narrow beam than from intraoral radiography. Conclusions: Detail narrow beam radiography with the Scanora(R) is an alternative to periapical radiography and is preferred, from a radiation dose point of view, over zonography.