Selecting scanning voltages for dual energy CT scanning
View Patent ↗A method and apparatus for selecting high and low energy scanning voltages for a dual energy CT scanner are provided. The method may comprise: setting a criterion of selection for selecting high and low energy scanning voltages; generating combinations of high and low energy scanning voltages according to all scanning voltages supported by a dual energy CT scanner, wherein each of the combinations may comprise a high energy scanning voltage and a low energy scanning voltage; and selecting a combination of high and low energy scanning voltages from the generated combinations of high and low energy scanning voltages based on the criterion of selection.
1. A method for selecting high and low energy scanning voltages for a dual energy CT scanner, the method comprising:
setting a criterion of selection for selecting the high and low energy scanning voltages based on a degree of contrast of a to-be-scanned material;
wherein the degree of contrast of the to-be-scanned material, DE contrast , is calculated as follows:
DE
contrast
=
DE
ratio_material
1
-
DE
ratio_material
2
;
DE
ratio
=
CT
highKV
-
CT
highKV_ref
CT
lowKV
-
CT
lowKV_ref
;
wherein
DE ratio represents a ratio of CT values of high and low energy scanning voltages of the to-be-scanned material (“a high/low ratio”),
DE ratio _ material1 represents a high/low ratio of a first to-be-scanned material,
DE ratio _ material2 represents a high/low ratio of a second to-be-scanned material,
CT lowKV and CT highKV represent a CT value of the to-be-scanned material under a low energy scanning voltage and a CT value of the to-be-scanned material under a high energy scanning voltage,
CT lowKV _ ref represents a CT value of a preset reference material under a low energy scanning voltage,
CT highKV _ ref represents a CT value of the preset reference material under a high energy scanning voltage, and
DE ratio is acquired through experiments or calculations in advance;
generating combinations of high and low energy scanning voltages according to all scanning voltages supported by the dual energy CT scanner, wherein each of the combinations comprises a high energy scanning voltage and a low energy scanning voltage; and
selecting a combination of high and low energy scanning voltages from the generated combinations of high and low energy scanning voltages based on the criterion of selection.
2. The method of claim 1 , wherein selecting the combination of high and low energy scanning voltages comprises:
selecting a combination corresponding to the greatest absolute value of the degree of contrast of the to-be-scanned material DE contrast .
3. The method of claim 1 , wherein the degree of contrast of the to-be-scanned material has constraint of noise index, and selecting the combination of high and low energy scanning voltages comprises:
selecting a combination of high and low energy scanning voltages corresponding to the greatest absolute value of the degree of contrast of the to-be-scanned material having constraint of noise index DE CNR ;
wherein the degree of contrast of the to-be-scanned material having constraint of noise index DE CNR is calculated as follows:
DE
CNR
=
DE
contrast
Noise
;
wherein
Noise is a known quantity, which is a preset noise index, and
DE contrast represents the degree of contrast of the to-be-scanned material.
4. The method of claim 1 , wherein the degree of contrast of the to-be-scanned material has constraint of noise and dose, and selecting the combination of high and low energy scanning voltages comprises:
selecting a combination of high and low energy scanning voltages corresponding to the greatest absolute value of the degree of contrast of the to-be-scanned material having constraint of noise and dose DE CNRD ;
wherein the degree of contrast of the to-be-scanned material having constraint of noise and index DE CNRD is calculated as follows:
DE
CNRD
=
DE
contrast
Noise
*
CTDI
;
wherein
CTDI represents a sum of a scanning dose corresponding to a high energy scanning voltage and a scanning dose corresponding to a low energy scanning voltage, which is calculated in advance,
Noise is a known quantity, which is a preset noise index, and
DE contrast represents the degree of contrast of the to-be-scanned material.
5. The method of claim 1 , wherein generating the combinations of high and low energy scanning voltages according to all scanning voltages supported by the dual energy CT scanner comprises:
dividing all scanning voltages supported by the dual energy CT scanner and satisfying an image quality into a set of low energy scanning voltages and a set of high energy scanning voltages; and
selecting a low energy scanning voltage and a high energy scanning voltage from the set of low energy scanning voltages and the set of high energy scanning voltages respectively to form a combination of high and low energy scanning voltages.
6. The method of claim 5 , wherein the image quality is determined based on a relative value of noise or an absolute value of noise.
7. The method of claim 1 , wherein the method is performed by an apparatus for selecting high and low energy scanning voltages for the dual energy CT scanner, the apparatus comprising:
a processor which invokes machine readable instructions corresponding to a control logic for selecting high and low energy scanning voltages stored on a non-transitory storage medium and executes the machine readable instructions to:
perform the method for selecting the high and low energy scanning voltages for the dual energy CT scanner.
8. A method for selecting high and low energy scanning voltages for a dual energy CT scanner, the method comprising:
setting a criterion of selection based on a degree of contrast of spectrums of high and low energy scanning voltages;
generating combinations of high and low energy scanning voltages according to all scanning voltages supported by the dual energy CT scanner, wherein each of the combinations of high and low energy scanning voltages comprises a high energy scanning voltage and a low energy scanning voltage; and
selecting a combination of high and low energy scanning voltages by:
acquiring an overlapping area DE Area of a spectrum corresponding to a low energy scanning voltage and a spectrum corresponding to a high energy scanning voltage in each of the combinations of high and low energy scanning voltages;
selecting all combinations of high and low energy scanning voltages each of which has an overlapping area less than a preset value to form a candidate set; and
selecting a combination of high and low energy scanning voltages corresponding to a minimum overlapping area from the candidate set.
9. The method of claim 8 , where the method is performed by an apparatus for selecting high and low energy scanning voltages for the dual energy CT scanner, the apparatus comprising:
a processor which invokes machine readable instructions corresponding to a control logic for selecting high and low energy scanning voltages stored on a non-transitory storage medium and executes the machine readable instructions to perform the method for selecting the high and low energy scanning voltages for the dual energy CT scanner.
10. A method for selecting high and low energy scanning voltages for a dual energy CT scanner, the method comprising:
setting a criterion of selection based on a degree of contrast of spectrums of high and low energy scanning voltages having constraint of dose;
generating combinations of high and low energy scanning voltages according to all scanning voltages supported by the dual energy CT scanner, wherein each of the combinations of high and low energy scanning voltages comprises a high energy scanning voltage and a low energy scanning voltage; and
selecting a combination of high and low energy scanning voltages by:
acquiring an overlapping area DE Area of a spectrum corresponding to a low energy scanning voltage and a spectrum corresponding to a high energy scanning voltage in each of the combinations of high and low energy scanning voltages;
selecting all combinations of high and low energy scanning voltages each of which has an overlapping area less than a preset value to form a candidate set; and
selecting a combination of high and low energy scanning voltages corresponding to a minimum scanning dose from the candidate set.
11. The method of claim 10 , where the method is performed by an apparatus for selecting high and low energy scanning voltages for the dual energy CT scanner, the apparatus comprising:
a processor which invokes machine readable instructions corresponding to a control logic for selecting high and low energy scanning voltages stored on a non-transitory storage medium and executes the machine readable instructions to perform the method for the selecting high and low energy scanning voltages for the dual energy CT scanner.