[Relationship between the gray level of X-ray photograph and the cortical thickness].
OBJECTIVE
In order to get three dimensional measurements simply an plain X-ray photographs.


METHODS
The multi-layers of bone pieces were made by use of bone saw, and piled up to spiral ladder, which was used as a calibrating module for to living bone in clinics. The relationship between the cortical thickness and gray level of the X-ray photographs was obtained.


RESULTS
The correlation can be described with a cubic regression curve, and it can be simplified to a linear regression equation when cortical thickness is small than 3.8 mm.


CONCLUSIONS
It can be realized to get three dimensional measures of the bone on plain X-ray photographs, by use of the bony spiral ladder described here.
Zhong
Hong-gang
HG
College of Life Science & Bioengineering, Beijing University of Technology, Beijing 100022, China.
Bu
Hai-bin
HB
Dong
Fu-hui
FH
D000328:Adult; D001842:Bone and Bones / Q000737:chemistry* / Q000000981:diagnostic imaging*; D006801:Humans; D011859:Radiography; D014965:X-Rays