www.ksmf.org/arhimed   arhimed@ksmf.org   [5/10/2025 4:27:18 PM] http://www.ksmf.org/arhimed/poglej.asp?id=39 Vpliv razvijalca na natancnost ocene prizadetosti celjustne kosti z metodo digitalne subtrakcijske radiografije Avtor: Aleš Fidler Mentor: prof. dr. Uroš Skaleric Somentor: mag. Boštjan Likar Izhodišca. Uporaba digitalne subtrakcijske radiografije (DSR) omogoca zaznavo majhnih razlik med rentgenogramoma, ki sta bila posneta v razmaku nekaj mesecev.Te razlike so s prostim ocesom neopazne, vendar že klinicno pomembne in jih lahko tudi kvantitativno ovrednotimo. Na natancnost DSR vplivajo napake v projekcijski geometriji ter razlike v svetlosti in kontrastu. Zadnje nastanejo tudi zaradi dotrajanosti razvijalca. V dosedaj opisanih študijah je bil uporabljen svež razvijalec ali pa so bili pogoji razvijanja standardizirani. To pa pri klinicni uporabi metode predstavlja problem. V nalogi smo želeli ugotoviti vpliv dotrajanosti razvijalca na natancnost ocene prizadetosti celjustne kosti z metodo DSR. Metode. Iz akrilata smo naredili 6 nastavkov za slikanje. Na vsakem nastavku je bila aluminjasta zagozda in del suhe cloveške mandibule. Te objekte smo slikali s petimi razlicnimi casi ekspozicije in jih razvili v razlicno dotrajanem razvijalcu. Dotrajanost razvijalca je bila posledica staranja (3 tedni) in izrabljenosti (razvitje 216 filmov). Tako smo dobili 150 rentgenogramov, ki smo jih z uporabo videokamere in vzorcevalnika prenesli v racunalnik. Ugotavljali smo vpliv dotrajnosti razvijalca na podrocjih brez sprememb ter na podrocjih z umetno povzroceno mineralizacijo in demineralizacijo. Spremembe mineraliziranosti smo vrednotili z racunanjem deleža površine, ki kaže spremembo mineraliziranosti, in z racunanjem relativnih prostorninskih sprememb mineraliziranosti. Rezultati. Ugotovili smo, da dotrajanost razvijalca ne vpliva na natancnost zaznavanja sprememb mineraliziranosti v podrocjih brez dejanskih sprememb (p<0,05). Statisticno znacilne razlike (p<0,05) smo ugotovili smo ugutovili samo pri najkrajšem casu ekspozicije. V podrocjih z umetno povzroceno mineralizacijo dotrajanost razvijalca povzroci zaznavanje prevelike mineralizacije (p<0,05). V podrocjih z umetno povzroceno demineralizacijo pa dotrajanost razvijalca povzroci zaznavanje premajhne mineralizacije (p<0,05). Zakljucki. Rezultati raziskave kažejo, da dotrajanost razvijalca vpliva na natancnost zaznavanja sprememb mineraliziranosti z metodo DSR. Ce pogoji razvijanja niso standardizirani, moramo upošteveti napake, ki nastanejo zaradi dotrajanosti «» [Abstract / English version] Influence of developer on accuracy of assessment alveolar bone mineralization changes with digital subtraction radiography Author: Aleš Fidler Mentor: prof. dr. Uroš Skaleric Co-mentor: mag. Boštjan Likar Background. Digital subtraction radiography (DSR) is a useful diagnostic tool for detecting subtle changes between sequentially obtained radiographs. Small changes in crestal alveolar bone mineralisation already clinical important, but not big enough to be perceptible by direct comparison, can be quantitized. In DSR there are two sources of error. One is nonidentical projection radiography and other is difference in brightness and contrast between two radiographs. The latter is also affected by developer exhaustion. In present articles film processing was standardized or fresh chemicals were used. The aim of our study is to test influence of developer exhaustion on accuracy of quantifying changes in alveolar bone mineralization with DSR. Methods. Six objects, made of acrylic resin, included a part of a dry human mandible and aluminium wedge, were radiographed with five different exposure times. Films were processed in increasingly exhausted developer due to depletion (developing of 216 films) and aging (three weeks). All radiographs were captured with video camera, digitized and stored in a computer. Influence of developer exhaustion was tested in regions without changes and in regions with computer simulated mineralization and demineralization. Area and volume changes in mineralization were evaluated with calculating percentage of area showing changes in mineralization and with calculating relative volume changes of mineralization. Results. Developer exhaustion showed no influence on accuracy of measuring mineralization in areas without changes (p<0.05). Statistically significant differences were found at the shortest, but they were not clinically important. In areas with computer simulated mineralization we found statistically significant overestimation of mineralization (p<0.05) and in areas with computer simulated demineralization we found statistically significant underestimation of mineralization (p<0.05) caused by developer exhaustion. Conclusions. The results of our study suggest that exhaustion of developer affects accuracy of assessing changes in mineralization of alveolar bone using DSR. If processing conditions are not standardize have to consider errors, caused by developer exhaustion.