Multislice CT apparatus and method for data preprocessing
View Patent ↗A multislice CT apparatus includes a setting unit, a correcting unit, a filtering unit and a reconstructing unit. The setting unit sets a weighting coefficient in such a way that data on a middle column is weighted high while data on columns on both sides of the middle column is weighted low on a middle channel in a multislice detector, and that a weight given to data on a middle column falls while a weight given to data on both side columns rises as shifting from the middle channel to an end channel. The correcting unit corrects the weighting coefficient in such a way that a weight rises as shifting from a central column to an end column. The filtering unit filters data on the basis of the corrected weighting coefficient in a column direction. The reconstructing unit reconstructs an image on the basis of the filtered data.
1. A multislice CT apparatus comprising:
an X-ray source configured to produce X-rays;
a multislice detector having a plurality of columns of detecting elements each being configured to detect the X-rays;
a scan performing unit configured to perform a conventional scan by rotating the X-ray source and the multislice detector around an object;
a weighting coefficient setting unit configured to set a weighting coefficient in such a way that data before reconstruction on a middle column is weighted high while data before reconstruction on columns on both sides of the middle column is weighted low on a middle channel in the multislice detector, and that a weight given to data before reconstruction on a middle column falls while a weight given to data before reconstruction on both side columns rises as shifting from the middle channel to an end channel;
a correcting unit configured to correct the weighting coefficient in such a way that a weight rises as shifting from a central column to an end column in the multislice detector;
a column direction filtering unit configured to filter data before reconstruction collected by the scan on the basis of the corrected weighting coefficient in a column direction; and
an image reconstructing unit configured to reconstruct an image on the basis of the filtered data before reconstruction.
2. The multislice CT apparatus according to claim 1 , wherein:
the weighting coefficient setting unit sets the weighting coefficient as a first weighting coefficient; and
the correcting unit sets a second weighting coefficient in such a way that the weight rises as shifting from the central column to the end column in the multislice detector, the correcting unit being configured to set a third weighting coefficient as the corrected weighting coefficient on the basis of the first weighting coefficient and the second weighting coefficient.
3. The multislice CT apparatus according to claim 2 , wherein
the correcting unit sets the weight rising linearly or in a curvilinear manner as shifting from the central column to the end column in the multislice detector.
4. The multislice CT apparatus according to claim 1 , wherein:
the column direction filtering unit filters raw data being the data before reconstruction on the basis of the corrected weighting coefficient in the column direction so as to produce projection data; and
the image reconstructing unit reconstructs an image on the basis of the projection data.
5. The multislice CT apparatus according to claim 1 , wherein
the correcting unit corrects the weighting coefficient in such a way that the weight is zero on the middle column in the multislice detector.
6. A method for preprocessing data comprising:
setting a weighting coefficient in such a way that data before reconstruction on a middle column is weighted high while data before reconstruction on columns on both sides of the middle column is weighted low on a middle channel in a multislice detector, and that a weight given to data before reconstruction on a middle column falls while a weight given to data before reconstruction on both side columns rises as shifting from the middle channel to an end channel;
correcting the weighting coefficient in such a way that a weight rises as shifting from a central column to an end column in the multislice detector; and
filtering data before reconstruction collected by a conventional scan on the basis of the corrected weighting coefficient in a column direction.
7. The method for preprocessing data according to claim 6 , wherein:
the weighting coefficient is set as a first weighting coefficient at a step for setting the weighting coefficient; and
a second weighting coefficient is set in such a way that the weight rises as shifting from the central column to the end column in the multislice detector, and a third weighting coefficient is set as the corrected weighting coefficient on the basis of the first weighting coefficient and the second weighting coefficient at a step for correcting the weighting coefficient.
8. The method for preprocessing data according to claim 7 , wherein
the second weighting coefficient is set in such a way that the weight rises linearly or in a curvilinear manner as shifting from the central column to the end column in the multislice detector at a step for correcting the weighting coefficient.
9. The method for preprocessing data according to claim 6 , wherein
raw data being the data before reconstruction is filtered on the basis of the corrected weighting coefficient in the column direction so that projection data is produced at a step for filtering in the column direction.
10. The method for preprocessing data according to claim 6 , wherein
the weighting coefficient is corrected in such a way that the weight is zero on the middle column in the multislice detector at a step for correcting the weighting coefficient.