ABSTRACT
UNLABELLED: The necessity of reducing the radiation dose to the patient in diagnostic radiology according to the ALARA guideline established by the ICRP has stimulated the research on additional filtration systems capable of removing the low-energy photons increasing the dose and worsening image quality. Very few literature studies deal with the effects of niobium filtration on image quality in dental radiography with the use of modulation transfer function (MTF) and square wave response function (SWRF). Only one study has considered those effects measuring dose absorption in an anthropomorphic phantom. THE AIMS OF OUR STUDY WERE: 1) to study the effects of a 30 microns additional niobium filter on image quality using the SWRF; 2) to compare the doses absorbed in vivo during a complete radiographic survey of the mouth, both with and without niobium filtration. Qualitative studies led us to conclude that niobium filtration does not significantly worsen radiographic image quality. The following doses were measured in the exposures with niobium filtration: 1678 microGy to 6000 microGy (intraoral doses) and 75 microGy to 3643 microGy (skin doses). The comparison with the doses measured during the exposures made with conventional filtration indicates that dose reduction is not significantly advantageous relative to risk reduction. In conclusion, additional niobium filtration is not advisable in dental radiology, also because of the filter cost and of the increased wear of the unit.
Subject(s)
Niobium , Radiography, Dental/methods , Adolescent , Adult , Female , Humans , Male , Middle Aged , Niobium/administration & dosageABSTRACT
The growing use of dento-maxillo-facial radiographic examinations has been accompanied by the publication of a large number of studies on dosimetry. A thorough review of the literature is presented in this article. Most studies were carried out on tissue equivalent skull phantoms, while only a few were in vivo. The aim of the present study was to evaluate in vivo absorbed doses during Orthopantomography (OPT). Full Mouth Periapical Examination (FMPE) and Intraoral Tube Panoramic Radiography (ITPR). Measurements were made on 30 patients, reproducing clinical conditions, in 46 anatomical sites, with 24 intra- and 22 extra-oral thermoluminiscent dosimeters (TLDS). The highest doses were measured, in orthopantomography, at the right mandibular angle (1899 mu Gy) in FMPE on the right naso-labial fold (5640 mu Gy and in ITPR on the palatal surface of the left second upper molar (1936 mu Gy). Intraoral doses ranged from 21 mu Gy, in orthopantomography, to 4494 mu Gy in FMPE. Standard errors ranged from 142% in ITPR to 5% in orthopantomography. The highest rate of standard errors was found in FMPE and ITPR. The data collected in this trial are in agreement with others in major literature reports. Disagreements are probably due to different exam acquisition and data collections. Such differences, presented comparison in several sites, justify lower doses in FMPE and ITPR. Advantages and disadvantages of in vivo dosimetry of the maxillary region are discussed, the former being a close resemblance to clinical conditions of examination and the latter the impossibility of collecting values in depth of tissues. Finally, both ITPR and FMPE required lower doses than expected, and can be therefore reconsidered relative to their radiation risk.
