Boots – shoes – and leggings
Patent
1985-10-29
1988-04-19
Fleming, Michael R.
Boots, shoes, and leggings
250367, G01N 2302
Patent
active
047394811
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention concerns X-ray CT image processing apparatus adapted to eliminate the bone-induced beam hardening artifact resulted in X-ray CT images (CT is an abbreviation for computed tomography) at high speed by the correcting computation using only the reconstructed image data.
BACKGROUND ART
Correction for the bone-induced beam hardening to X-ray CT images has usually been made as found in Joseph, et al. literatures (Joseph, et al. A Method for Correcting Bone Induced Artifacts in Computed Tomography Scanners, Journal of Computer Assisted Tomography vol. 2, p 100-108, Jan. 1978) by scanning the reconstructed image elements, calculating the correction amount from the pass length of the soft tissue portion and bone (separated with CT values) contained therein, correcting the same with the actual scan data and, thereafter, reconstructing them again.
However, the method has the following problems.
(1) Since twice reconstructing and once scanning of the image elements are required, the computing amount is enormous and no high speed processing can be expected
(2) While it is customary to erase the actual scan data after once reconstructing the image to prepare for the next scanning, the actual scan data have to be preserved after the image reconstruction till the correction of the actual scan data and the second image reconstruction have been completed.
DISCLOSURE OF INVENTION
The object of this invention is to provide an X-ray CT image processing apparatus capable of conducting correction for bone induced beam hardening only based on the reconstructed image data at high speed and simply.
In order to attain the above object, this invention is adapted to judge the bone region in the reconstructed image based on the reconstructed image data, form the correcting image through mask addition or convolution of a 2-dimensional weight function using the judged bone region as a mask and add the correcting image to the reconstructed image.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a block diagram for one embodiment of an X-ray CT image processing apparatus for practicing this invention,
FIG. 2 is a flow chart showing the function of the binarizing digitizer in FIG. 1,
FIG. 3 is a graph showing a weight function utilized by the masked adder in FIG. 1,
FIG. 4 is a flow chart showing the function of the masked adder in FIG. 1,
FIG. 5 is a flow chart showing the function of the image adder in FIG. 1,
FIG. 6 is a block diagram showing another embodiment of the X-ray CT image processing apparatus practicing this invention,
FIG. 7 is a flow chart showing the function of another embodiment of the masked adder in FIG. 1 and FIG. 2,
FIG. 8 is a block diagram for the device judging the bone region more precisely,
FIG. 9 is a flow chart showing the function of the labeller in FIG. 8,
FIG. 10 is a flow chart showing the function of the characteristics calculator in FIG. 8,
FIG. 11 is a flow chart showing the function of the discriminator,
FIG. 12 is a graph showing the distribution of the characteristics amount as the object to be scanned,
FIG. 13 is a block diagram showing one embodiment of the X-ray CT image processing apparatus practicing this invention by using the device in FIG. 8 for the discrimination of the bone region,
FIG. 14 is a block diagram for one embodiment of the X-ray CT image processing apparatus according to this invention, in which the processing time is shortened,
FIG. l5 is a flow chart showing the function of the image reduction device in FIG. 4, and
FIG. l6 is a flow chart showing the function of the image magnifier in FIG. 14.
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of this invention will now be described more specifically referring to drawings. FIG. 1 is a constitutional block diagram showing one embodiment of the X-ray CT image processing apparatus according to this invention. In the drawing, are shown a first image memory 1 for storing the reconstructed image, a binary digitizer 2, a second image memory 3, a weight function memory 4, a masked adder 5, a third im
REFERENCES:
patent: 4223384 (1980-09-01), Hounsfield
patent: 4247774 (1981-01-01), Brooks
patent: 4272820 (1981-06-01), Lux
patent: 4654796 (1987-03-01), Takagi
patent: 4654797 (1987-03-01), Fujita
Fleming Michael R.
Kojima Moonray
Yokogawa Medical Systems Limited
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