PubMed İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/11727/4810
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Item Evaluation of maxillary trabecular microstructure as an indicator of implant stability by using 2 cone beam computed tomography systems and micro-computed tomography(2019) Kulah, Kivanc; Gulsahi, Ayse; Kamburoglu, Kivanc; Geneci, Ferhat; Ocak, Mert; Celik, H. Hamdi; Ozen, Tuncer; 30595501Objective. The aim of this study was to assess the trabecular microarchitecture of the maxilla by using cone beam computed tomography (CBCT) and micro-computed tomography (micro-CT) ex vivo. Study Design. Seventeen maxillary cadaver specimens were scanned by using micro-CT and CBCT devices. Samples were scanned with 2 CBCT devices at different voxel sizes (0.08, 0.125, and 0.160 mm for 3-D Accuitomo 170; 0.75 and 0.200 mm for Planmeca Promax 3-D Max). Morphometric parameters, such as bone volume/total volume (BV/TV) ratio, trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), and degree of anisotropy (DA) were assessed by using CTAnalyzer software. Bland-Altman limits of agreement and intraclass correlation coefficient (ICC) were performed to evaluate agreement between CBCT and micro-CT in consideration of measured morphometric parameters. Statistical significance was set at P < .05. Results. The BV/TV, Tb.Th, Tb.Sp, and DA values were higher for CBCT images compared with micro-CT images, whereas the Tb. N value was lower with CBCT images than with micro-CT images. The BV/TV and DA parameters showed the highest agreement between CBCT and micro-CT devices (ICC = 0.421 for BV/TV and ICC = 0.439 for DA; P < .01). Conclusions. The BV/TV and DA parameters measured on CBCT obtained at the smallest voxel size were found to be useful for the assessment of maxillary trabecular microstructure.Item The role of delineation education programs for improving interobserver variability in target volume delineation in gastric cancer(2017) Onal, Cem; Cengiz, Mustafa; Guler, Ozan C.; Dolek, Yemliha; Ozkok, Serdar; 0000-0002-2742-9021; 0000-0001-6908-3412; 28339289; D-5195-2014; AAC-5654-2020Objective: To assess whether delineation courses for radiation oncologists improve interobserver variability in target volume delineation for post-operative gastric cancer radiotherapy planning. Methods: 29 radiation oncologists delineated target volumes in a gastric cancer patient. An experienced radiation oncologist lectured about delineation based on contouring atlas and delineation recommendations. After the course, the radiation oncologists, blinded to the previous delineation, provided delineation for the same patient. Results: The difference between delineated volumes and reference volumes for pre-and post-course clinical target volume (CTV) were 19.8% (-42.4 to 70.6%) and 12.3% (-12.0 to 27.3%) (p = 0.26), respectively. The planning target volume (PTV) differences pre-and post-course according to the reference volume were 20.5% (-40.7 to 93.7%) and 13.1% (-10.6 to 29.5%) (p = 0.30), respectively. The concordance volumes between the pre-and post-course CTVs and PTVs were 467.1 +/- 89.2 vs 597.7 +/- 54.6cm(3) (p < 0.001) and 738.6 +/- 135.1 vs 893.2 +/- 144.6 cm(3) (p < 0.001), respectively. Minimum and maximum observer variations were seen at the cranial part and splenic hilus and at the caudal part of the CTV. The kappa indices compared with the reference contouring at pre- and post-course delineations were 0.68 and 0.82, respectively. Conclusion: The delineation course improved interobserver variability for gastric cancer. However, impact of target volume changes on toxicity and local control should be evaluated for further studies. Advances in knowledge: This study demonstrated that a delineation course based on current recommendations helped physicians delineate smaller and more homogeneous target volumes. Better target volume delineation allows proper target volume irradiation and preventing unnecessary normal tissue irradiation.