Grant-in-Aid for Scientific Research (B)
|Research Institution||The University of Tokyo|
NAKATSUKA Takashi University of Tokyo, associate proffesor, 医学部・付属病院, 助教授 (80198134)
SUGAWARA Yasushi University of Tokyo, staff, 医学部・付属病院, 助手 (60260494)
HIRABAYASHI Shinichi University of Tokyo, assistant proffesor, 医学部・付属病院, 講師 (60173259)
|Project Fiscal Year
1995 – 1997
Completed(Fiscal Year 1997)
|Budget Amount *help
¥6,400,000 (Direct Cost : ¥6,400,000)
Fiscal Year 1997 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1996 : ¥2,600,000 (Direct Cost : ¥2,600,000)
Fiscal Year 1995 : ¥3,400,000 (Direct Cost : ¥3,400,000)
|Keywords||simulation surgery / skull model / three-dimensional computed tomography / accuracy / 三次元CT / シミュレーションサージェリー / 精度 / 頭蓋モデル / 頭蓋顎顔面外科 / コンピューター / シミュレーション・サージェリー|
The purpose of this research were as follows.
1.Investigation of accuracy of 3D-CT image and skull replicas.
2.Investigation of the cause of bone deficits on CT image and skull replicas.
3.Search the way to reduce the false negative data.
4.Evaluation of the accuracy of the frameless three-dimensional data registration system.
Helical volume CT data of the whole head were accumulated. Using this volume data ; 0.2 mm slice data were prepared and a skull replica fabricated with a threshold CT value of 200 HU.
The skull was cut at the level of the frontonaseal suture and a photograph of the orbital floors was taken from above.
3D osseous surface images of the orbital floors then were reconstructed with the 0.2 mm slice data with threshold CT values of 200 HU and 100HU.
Slice data then were prepared with an interval of 2.0 mm and images interpolated at 0.2 mm on the workstation. From these interpolated slice data, 3D osseous surface images of the orbital floors were reconstructed with threshold CT values of 200 HU and 100HU.
The ratios of the area of bone loss to the whole orbital floors in the photograph and 3D osseous surface images were evaluated with a personal computer and then compared with each other.
We could conclude by the studies as follows.
1.The errors produced during the precess of thresholding and interpolation had play the main role in causing false bone deficits in the orbital floors of skull replicas.
2.False negative bone deficits were created on the way from accumlating data through making CAD data. The error could be reduced by taking data with a threshold CT value of 100HU.
3.Skull model have relatively high accuracy which errors are 1.96 mm maximum, 0.25 mm minimum, 0.73 mm average.
4.The average registration error was liss than one pixel (=0.39 mm)