Evaluation of the effect of sagging correction calibration errors in radiotherapy software on image matching

To investigate the impact of sagging correction calibration errors in radiotherapy software on image matching. Three software applications were used, with and without a polymethyl methacrylate rod supporting the ball bearings (BB). The calibration error for sagging correction across nine flex maps (FMs) was determined by shifting the BB positions along the Left–Right (LR), Gun–Target (GT), and Up–Down (UD) directions from the reference point. Lucy and pelvic phantom cone-beam computed tomography (CBCT) images underwent auto-matching after modifying each FM. Image deformation was assessed in orthogonal CBCT planes, and the correlations among BB shift magnitude, deformation vector value, and differences in auto-matching were analyzed. The average difference in analysis results among the three softwares for the Winston–Lutz test was within 0.1 mm. The determination coefficients (R2) between the BB shift amount and Lucy phantom matching error in each FM were 0.99, 0.99, and 1.00 in the LR-, GT-, and UD-directions, respectively. The pelvis phantom demonstrated no cross-correlation in the GT direction during auto-matching error evaluation using each FM. The correlation coefficient (r) between the BB shift and the deformation vector value was 0.95 on average for all image planes. Slight differences were observed among software in the evaluation of the Winston–Lutz test. The sagging correction calibration error in the radiotherapy imaging system was caused by an auto-matching error of the phantom and deformation of CBCT images

Tooth eruption in vascularized allogenic mandible of dog

We examined whether tooth eruption would occur normally in grafted allogeneic mandibular bone. Using vascularized composite tissue transplantation, we extracted portions of immature mandibles including the tooth germs from young beagle dogs and transplanted them into unrelated immature or mature beagle dogs. In addition, we prepared vascularized gingival flaps from mature dogs and grafted them onto the mandibles of unrelated immature dogs. Mandibular bone including tooth germs without covering gingiva from immature dogs was also transplanted either to immature or mature recipient dogs, and the grafted bones were covered with recipients' gingiva. Then, we examined tooth eruption in these grafted mandibular bones. Normal tooth eruption was observed only in the mandibles transplanted to the young recipient dogs. In the mature dogs, tooth eruption from the gingiva was delayed; the whole crown was covered with a cap of gingival tissue, which was not a gingival overgrowth. It is suggested that tooth eruption depends on the age of the recipient, regardless of the overlying gingival tissues transplanted.磯村 恵美子, 山本 友美, 吉富 啓一, 岡内 豊美, 東 けい, 三浦 康寛, 谷口 佳孝, 山澤 通邦, 原田 丈司, 古郷 幹彦, イヌの血管柄付下顎骨同種他家移植における歯の萌出について, 日本口腔外科学会雑誌, 2005, 51 巻, 9 号, p. 448-457, 公開日 2011/04/22, Online ISSN 2186-1579, Print ISSN 0021-5163, https://doi.org/10.5794/jjoms.51.448