Fundamental Study of Three Dimensional Fine Structure Analysis of Jaw Bone

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 15592006
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Pathobiological dentistry/Dental radiology
• Research Institution: Tsurumi University
• Principal Investigator: MORITA Yasuhiko Tsurumi University, School of Dental Medicine, Associate Professor, 歯学部, 助教授 (10182255)
• Co-Investigator(Kenkyū-buntansha): KURABAYASHI Touru Tokyo Medical and Dental University, Professor, 大学院・医歯学総合研究科, 教授 (60178093) ; IZUMI Yuichi Kagoshima University, graduate school, Professor, 大学院・医歯学総合研究科, 教授 (60159803) ; BANN Seiji Kagoshima University, graduate school, Professor, 大学院・医歯学総合研究科, 教授 (10159105) ; MAJIMA Hideyuki Kagoshima University, graduate school, Professor, 大学院・医歯学総合研究科, 教授 (60165701) ; INDOU Hiroko Kagoshima University, graduate school, Professor, 大学院・医歯学総合研究科, 助手 (00301391)
• Project Period (FY): 2003 – 2005
• Keywords: CT designed for the dentistry / phantom / CT value / apatite / digital tomography / spaceal resolution / rapid prototyping / three dimensional structure

Research Abstract

CT values of the same bone specimen can not be measured as the same value at small field of view CT (CT designed for the dentistry) scans in different conditions. This phenomenon depended on the contour and size of the specimen greatly, and occured even if subjects were covered within limited view. The un-stability of the CT value at the CT designed for the dentistry was believed to happened by so-called the imcomplete projection data that caused by limited views. However, this explanation may not be true, because the un-stability of the CT value occurs even if objects size were enough small that could be covered within the field of views in our result. Also some special viewing image processing like slices sum methods improve the image quality like S/N but loose the special resolution for view-axis.
By using both the whole body CT and CT designed for the dentistry, an uniform aluminum + copper (5%) alloy cone (CT value beyond the upper limit of 3000H.U.) were measured. The the non-unif orm CT values at CT designed for the dentistry indicated the non-linear characters of the pixel density of the CT.
Also it was proved that CT designed for the dentistry was very close to Digital-Tomography with this point.
The CT designed for the dentistry was not especially excellent in visible test of spaceal resolution using W-wires at the comparison between MD-CT for the whole body and CT designed for the dentistry, though it wasn't clear because MTF wasn't being taken into consideration because of the non-linear character of the CT designed for the dentistry.
Small HA phantoms were designed so that small hole and line can be measured without aritifacts.
Holes with the size of 300μm could not be detected by MD-CT, while it could be detected by the CT designed for the dentistry. The predominance of the CT for the dentistry for the endodontics was shown in the point.
It seemed to be not easy to analyze the three dimensional structure by small field of view CT (CT designed for the dentistry) using pixel value like CT. The result of our study show the importance of small CT phantom that similar to bone at contents.