Avtor/Urednik		Fidler, Aleš
Naslov		Vpliv kompresije rentgenskih slik na natančnost meritev sprememb mineraliziranosti alveolarne kosti
Tip		monografija
Kraj izdaje		Ljubljana
Založnik		Medicinska fakulteta
Leto izdaje		2002
Obseg		str. 37
Jezik		slo
Abstrakt		The aim of the study was to evaluate the impact of JPEG lossy image compression on the determination of alveolar bone gain by quantitative digital subtraction radiography (DSR). Nine dry domestic pig mandible sections were radiographed three times ("Baseline", "No change", and "Gain") with standardized projection geometry. Bone gain was simulated by adding artificial bone chips (1, 4, and 15mg). Images were registred either before or after compression at four compression levels (1:7, 1:16, 1:22, and 1:31). No change areas in compressed and subtracted "No change - Baseline" images and bone gain volumes in compressed and subtracted "Gain - Baseline" images were calculated and compared to the corresponding measurements performed in original subtracted images. Measurements of no change areas ("No change - Baseline") were only slightly affected by compressions of down to 1:22, applied either before or after registration. Simulated gain of alveolar bone ("Gain - Baseline") was underestimated when compression was performed before registration. The underestimation was bigger when small bone chips (1 mg) were measured and when higher compression rates were used. Bone chips of 4 and 15 mg were only slightly underestimated at compressions of 1:7, 1:16, and 1:22, applied before registration. Lossy JPEG commpression does not affect the measurements of no change areas by DSR. Images undergoing substraction should be registered before compression and if so, J90 compression with compression ratio of 1:7 can be used to detect and measure 4mg and larger bone gain.
Deskriptorji		ALVEOLAR BONE LOSS RADIOGRAPHIC IMAGE ENHANCEMENT SWINE