CN101675884B - Method for setting center parameter of image reconstruction and CT scanning device thereof - Google Patents

Abstract

The invention provides a method for setting a center parameter of image reconstruction and a CT scanning device thereof. The implementation scheme comprises the following steps: acquiring the plain scan data in the X direction, plain scan data in the Y direction or position scan data; calculating the position XC in the X direction and the position YC in the Y direction of the patients; and taking the calculated (XC, YC) as the parameter of the image reconstruction center. In the invention, the positions in the X and Y directions of the patients are calculated by acquiring the scan data of plain scan or axial scan to provide more accurate center parameters for the image reconstruction, thus avoiding undesired images due to manual setting of the doctors and unreasonable parameters probably set. The method for setting the center parameter of the image reconstruction and the CT scanning device in the invention ensures that the reconstructed image is located in the center of the DFOV, thus providing high-quality reconstructed images for doctors, avoiding the problem that the image is too small in the big DFOV or data are lost in the reconstruction of the image for the first time in the small DFOV.

Description

Method and the CT scan equipment thereof of image reconstruction Center Parameter are set

Technical field

The present invention relates to the image reconstruction of a kind of computed tomography (Computed Tomography, calls CT in the following text), particularly about a kind of method and CT scan equipment thereof that the image reconstruction Center Parameter of optimization is set when CT carries out image reconstruction.

Background technology

CT scan equipment can be rebuild patient's cross section in X ray plane, existing CT scan equipment can provide scan vision (the Scan field of view of 50cm, call SFOV in the following text), along with the development of technology, the parameter of this SFOV is also likely towards large future development.

There is different sizes in patient cross section.For example, at shoulder and buttocks, sectional dimension is maximum, but in cervical region, shank and foot, sectional dimension is minimum.So typical, patient's cross section is only likely a part of SFOV.Naturally, we wish that patient's cross section is positioned at the center of final image.In order to reach this object, existing CT scan equipment requires doctor to operate by following mode conventionally: 1) before scanning, by light beam, adjust, patient is carried out to centralization placement; Or the 2) reconstruction before scanning or after scanning; Experience based on doctor oneself arranges reconstructed center parameter, as shown in Figure 1A in the user interface of reconstructed center parameter.But for mode 1), because the bed of existing CT scan equipment all has the function of up-down adjustment, due to different patients or same patient's different scanning position, doctor needs the height of regulation bed frequently to reach centralization.And for mode 2), the experience that needs doctor to have, and can not forget setting, because if doctor forgets that before scanning the parameter that arranges or arrange is unreasonable, can in a very large reconstruction visual field (DFOV), produce undesirable image, or there is the risk of losing useful data while rebuilding image for the first time in a very little DFOV, as Figure 1B, shown in 1C, this just needs doctor to carry out secondary manually to arrange again, the mode that this dependence doctor oneself arranges, doctor's workload and the extra computation workload of CT scan equipment have not only been increased, can't guarantee the quality of image simultaneously.

Summary of the invention

The object of this invention is to provide a kind of method and CT scan equipment that obtains image reconstruction Center Parameter, it provides a kind of image reconstruction Center Parameter that obtains optimization, for doctor provides image reconstruction Center Parameter, improved and rebuild the quality of image and simplified doctor's operational ton.

Provided by the invention a kind of in CT scan device scan, arrange and rebuild picture centre parametric technique, comprise the steps:

Step 110) scan-data on directions X; And/or

Step 111), according to the scan-data on directions X, obtain patient at the position of directions X X _c;

Step 112) obtain the scan-data in Y-direction, obtain patient at the position of Y-direction Y _c; Or according to the scan-data on directions X, obtain patient's side-play amount Y _c; (the X obtaining _c, Y _c) be image reconstruction Center Parameter.

A kind of method that image reconstruction Center Parameter is set provided by the invention, comprises the steps:

Step 10) on directions X, patient is carried out to the unenhanced of 0 degree or 180 degree, obtain unenhanced data;

Step 11) in the Y direction patient is carried out the unenhanced data of 90 degree or unenhanced acquisition 90 degree of 270 degree or 270 degree, or in the direction of 90 degree or 270 degree, arbitrary position in the unenhanced scope of Z direction is scanned patient, obtains the position scan-data in Y-direction;

Step 12) according to 0 degree or the unenhanced data of 180 degree, obtain patient at the position of directions X X _c;

Step 13) according to the unenhanced data of 90 degree or 270 degree or the position scan-data in the direction of 90 degree or 270 degree, obtain patient at the position of Y-direction Y _c;

(the X obtaining _c, Y _c) be image reconstruction Center Parameter.

Image reconstruction Center Parameter X _ccan obtain by following mode:

According in 0 degree or the unenhanced data of 180 degree, obtain the projection value P of each passage on directions X _xi, according to following formula, obtain the position X of patient on directions X _c:

Wherein, i is the passage in x direction, P _xiit is the projection value on i channel position; N represents port number total in x direction.

Image reconstruction Center Parameter Y _ccan obtain by following mode: from the 90 unenhanced data of degree or the unenhanced data of 270 degree of Y-direction, obtain the projection value P of each passage in Y-direction _yi, according to following formula, obtain patient position Y in the Y direction _c:

Wherein, i is passage in the Y direction, P _yiit is the projection value on i channel position; N represents port number total in Y-direction.

In the direction at 90 degree or 270 degree, the arbitrary position in the unenhanced scope of Z direction is scanned patient, and this arbitrary position is the position of center line in the unenhanced scope of Z direction.

The invention provides another in CT scan device scan, arrange and rebuild picture centre parametric technique, comprise the steps:

Step 20): on directions X, patient is carried out to the unenhanced of 0 degree or 180 degree;

Step 21): according to the unenhanced unenhanced data of 0 degree or 180 degree, obtain the position X of patient on directions X _c;

Step 22): at the current scanning number of degrees, add that in 180 direction, the arbitrary position in the unenhanced scope of Z direction is scanned patient, obtain a position scan-data;

Step 23): according to the unenhanced unenhanced data of 0 degree or 180 degree and according to the position scan-data of the scanning of 180 degree or 0 degree, obtain respectively the total projection value P in two kinds of scanning situations _oTotal, P _180Total, and projected area value PA ₀, PA ₁₈₀, according to total projection value and projected area value, obtain patient's side-play amount Y _c, this side-play amount Y _cbe tried to achieve image reconstruction Center Parameter Y _c.

Wherein said step 23) also comprise the steps:

Establish in advance the corresponding relation of error ratio and side-play amount;

According to formula (8), obtain desirable " object central projection area value " PA;

Utilize the total projection value P obtaining _oTotalor P _180Total" object central projection area value " PA, obtains error ratio PercentError according to formula (9);

or

According to the corresponding relation of pre-set error ratio and side-play amount, find out corresponding side-play amount.

Provided by the invention another in CT scan device scan, arrange and rebuild picture centre parametric technique, comprise the steps:

Step 30): by axial scan, obtain axial scan data for the first time;

Step 31): from axial scan data for the first time, extract the position scan-data of directions X of 0 degree position or 180 degree positions and the position scan-datas of the Y-direction of 90 degree or 270 degree positions;

Step 32): according to the position scan-data of the position scan-data of directions X and Y-direction, obtain respectively the position X of patient in X and Y-direction _c, Y _c, this X _c, Y _cbe image reconstruction Center Parameter.

Provided by the invention another in CT scan device scan, arrange and rebuild picture centre parametric technique, comprise the steps:

Step 40): by axial scan, obtain axial scan data for the first time;

Step 41): from axial scan data for the first time, extract the position scan-data of the directions X of 0 degree position and 180 degree positions;

Step 42): according to the position scan-data of 0 degree position and 180 degree position directions Xs, obtain the position X of patient on directions X _c,, this X _cbe a value of image reconstruction Center Parameter;

Step 43): according to the position scan-data of 0 degree position and 180 degree position directions Xs, obtain patient's side-play amount, this side-play amount is required image reconstruction Center Parameter Y _c.

Provided by the invention another in CT scan device scan, arrange and rebuild picture centre parametric technique and comprise the steps:

Step 50): set up the various parameters of human body and image reconstruction Center Parameter Y _cfunctional relationship;

Step 51): input is scanned patient's various parameters, on directions X, patient is carried out to 0 degree or 180 degree are unenhanced, and obtain unenhanced data;

Step 52): according to unenhanced data, the value of obtaining position this position of patient on directions X is image reconstruction Center Parameter X _c;

Step 53): according to inputted patient's parameter and step 50 functional relationship), obtains image reconstruction Center Parameter Y _c.

Wherein the various parameters of human body comprise width, highly, age, sex, area, the position of scanning, the height of bed, patient's posture.

A kind of CT scan equipment of rebuilding picture centre parameter that arranges provided by the invention, comprising: the scan table scanning being scanned object; Obtain the data collection module of the scan-data that scan table sends; Scan-data is carried out to the image reconstruction unit of image reconstruction; User interface for user's operation; With for storing the memory element of data and the central control unit that scan table, data collection module, image reconstruction unit, user interface and memory element are controlled; Also comprise image reconstruction parameter calculation unit, this image reconstruction parameter calculation unit is according to scan-data, needed reconstruction parameter when calculating image reconstruction unit and rebuilding image.

This image reconstruction parameter calculation unit comprises:

Scan-data extraction unit, it obtains 0 degree of the collected directions X that is scanned object of data collection module or the unenhanced data of 180 degree, and 90 degree of Y-direction or the arbitrary position scan-data in the unenhanced scope of Z direction in the 270 unenhanced data of degree or Y-direction;

Reconstructed center parameter calculation unit; It obtains the projection value P of each passage on directions X according to the unenhanced data of the directions X extracting in scan-data extraction unit _xi, and according to the unenhanced data of Y-direction or position scan-data, obtain the projection value P of each passage in Y-direction _xi, according to following formula

Obtain patient at the position of directions X X _cwith the position Y in Y-direction _c; (the X obtaining _c, Y _c) be image reconstruction Center Parameter; Wherein, i is the passage in X or Y-direction, P _xi, P _yiit is the projection value on i channel position; N represents port number total in X or Y-direction.

Wherein said this position scan-data is the position of center line when in the unenhanced scope of Z direction.

Another program provided by the invention is the corresponding relation that described memory cell contains error ratio and side-play amount; This image reconstruction parameter calculation unit comprises: scan-data extraction unit, it obtains 0 degree or the unenhanced data of 180 degree of the collected directions X that is scanned object of data collection module, with at the current scanning number of degrees, add in 180 direction, the arbitrary position scan-data in the unenhanced scope of Z direction; With reconstructed center parameter calculation unit, it obtains the projection value P of each passage on directions X according to the unenhanced data of the directions X extracting in scan-data extraction unit _xi, and obtain patient at the position of directions X X according to following formula _c;

Reconstructed center parameter calculation unit also, according to the unenhanced unenhanced data of 0 degree or 180 degree and according to the position scan-data of the scanning of 180 degree or 0 degree, is obtained respectively the total projection value P in two kinds of scanning situations _oTotal, P _180Total, and projected area value PA ₀, PA ₁₈₀, and obtain desirable " object central projection area value " PA and error ratio PercentError according to following formula

or

Central control unit is controlled reconstructed center parameter calculation unit according to obtained error ratio and the corresponding relation of side-play amount, finds out required image reconstruction Center Parameter Y _c.

Another program provided by the invention comprises for this image reconstruction parameter calculation unit: axle scan-data extraction unit, and it extracts the axle scan-data of axial scan data for the first time from data collection module; With position scan-data extraction unit, it extracts the position scan-data of directions X of 0 degree position or 180 degree positions and the position scan-data of the Y-direction of 90 degree or 270 degree positions from axle scan-data; Reconstructed center parameter calculation unit; It is according to the X extracting in the scan-data extraction unit of position, and the position scan-data of Y-direction is obtained the projection value P of each passage on directions X _xi, and the projection value P of each passage in Y-direction _xi, according to following formula

Obtain patient at the position of directions X X _cwith the position Y in Y-direction _c; (the X obtaining _c, Y _c) be image reconstruction Center Parameter; Wherein, i is the passage in X or Y-direction, P _xi, P _yiit is the projection value on i channel position; N represents port number total in X or Y-direction.

Another program provided by the invention comprises for this image reconstruction parameter calculation unit: axle scan-data extraction unit, and it extracts the axle scan-data of axial scan data for the first time from data collection module; With position scan-data extraction unit, it extracts the position scan-data of the directions X of 0 degree position and 180 degree positions from axle scan-data; Reconstructed center parameter calculation unit; It obtains the projection value P of each passage on directions X according to the position scan-data of the directions X extracting in the scan-data extraction unit of position _xi, and according to following formula

Obtain patient at the position of directions X X _c, wherein, i is the passage on directions X, P _xi, be the projection value on i channel position; N represents port number total on directions X; And reconstructed center parameter calculation unit is according to the position scan-data of 0 degree position and 180 degree positions, obtains patient's side-play amount, this side-play amount is required image reconstruction Center Parameter Y _c.

Wherein said cell stores has the corresponding relation of error ratio and side-play amount; Described reconstructed center parameter calculation unit, according to the unenhanced unenhanced data of 0 degree and 180 degree and according to the position scan-data of the scanning of 180 degree and 0 degree, is obtained respectively the total projection value P in two kinds of scanning situations _oTotal, P _180Total, and projected area value PA ₀, PA ₁₈₀, and obtain desirable " object central projection area value " PA and error ratio PercentError according to following formula

or

Central control unit is controlled reconstructed center parameter calculation unit according to obtained error ratio and the corresponding relation of side-play amount, finds out required image reconstruction Center Parameter Y _c.

A kind of CT scan equipment of rebuilding picture centre parameter that arranges that the present invention provides again, comprising: the scan table scanning being scanned object; Obtain the data collection module of the scan-data that scan table sends; Scan-data is carried out to the image reconstruction unit of image reconstruction; User interface for user's operation; With for storing the memory element of data and the central control unit that scan table, data collection module, image reconstruction unit, user interface and memory element are controlled; Described cell stores has the functional relationship of human parameters and Center Parameter; And also comprising image reconstruction parameter calculation unit, this image reconstruction parameter calculation unit is according to scan-data, needed reconstruction parameter when calculating image reconstruction unit and rebuilding image; This image reconstruction parameter calculation unit comprises: scan-data extraction unit, and it obtains 0 degree of the collected directions X that is scanned object of data collection module or the unenhanced data of 180 degree; Reconstructed center parameter calculation unit; It obtains the projection value P of each passage on directions X according to the unenhanced data of the directions X extracting in scan-data extraction unit _xi, and according to following formula

Obtain patient at the position of directions X X _c; Wherein, i is the passage on directions X, P _xi, be the projection value on i channel position; N represents port number total on directions X; And reconstructed center parameter calculation unit according to user, input be scanned human parameters and human parameters and Center Parameter functional relationship, obtain required Center Parameter Y _c.

The various parameters of wherein said human body comprise width, highly, age, sex, area, the position of scanning, the height of bed, patient's posture; Its functional relationship is Y _c=f (width, highly, age, sex, area, scanning position, the height of bed, patient's posture ...).

In method in the present invention by obtaining scan-data unenhanced or that axle is swept, obtain the position of patient in X, Y-direction, as image reconstruction, provide Center Parameter more accurately, avoided because of doctor's manual setting and the unreasonable parameter that may arrange, and the undesirable image causing; The method that image reconstruction Center Parameter is set of the present invention, make image after rebuilding be positioned at the center of DFOV, for doctor provides high-quality reconstruction image, avoided or uncomfortable sensation that image is very little in large DFOV or the danger of obliterated data during image reconstruction for the first time in very little DFOV; The height that the present invention has solved especially for the bed of that CT scan equipment is the fixing situation that can not regulate, and the present invention is similarly doctor more accurate image reconstruction Center Parameter is provided.

Accompanying drawing explanation

Figure 1A is the user interface that the existing reconstruction picture centre parameter at CT scan equipment arranges;

Figure 1B, the 1C image for obtaining according to the reconstruction picture centre parameter of existing method setting;

Fig. 2 is the method flow diagram that the first embodiment that rebuilds picture centre parameter is set of the present invention;

Fig. 3 A is for carrying out the schematic diagram of the unenhanced section peace total number certificate obtaining of 0 degree or 180 degree to patient;

Fig. 3 B is for carrying out the schematic diagram of the unenhanced section peace total number certificate obtaining of 90 degree to patient;

Fig. 3 C is that the unenhanced of 90 degree or 270 degree carried out in the arbitrary position in the unenhanced scope of Z direction to patient;

Fig. 4 A is the flow chart that the second embodiment that rebuilds picture centre parametric technique is set of the present invention;

Fig. 4 B for to patient the arbitrary position in the unenhanced scope of Z direction carry out the schematic diagram of the peaceful total number certificate of the unenhanced section that obtains of 180 degree or 0 degree;

Fig. 5 is the corresponding relation figure of the side-play amount in the second embodiment and error rate in the present invention;

Fig. 6 is the flow chart that the 3rd embodiment that rebuilds picture centre parametric technique is set of the present invention;

Fig. 7 is the flow chart that the 4th embodiment that rebuilds picture centre parametric technique is set of the present invention;

Fig. 8 is the flow chart that the 5th embodiment that rebuilds picture centre parametric technique is set of the present invention;

Fig. 9, Figure 10 are the high-level schematic functional block diagram that the CT scan equipment of rebuilding picture centre parameter is set.

The specific embodiment

Below, with reference to accompanying drawing, describe example of the present invention in detail.The invention is not restricted to example.

Embodiment mono-

In actual CT scan, most of doctors when patient is scanned, only can be by 0 degree or 180 degree when to chest, heart and head scanning unenhanced, then unenhanced in conjunction with 90 degree; And even some doctor, to these positions, also only carries out the unenhanced of 0 degree or 180 degree.And for the scanning at other positions, doctor utilizes suitable dosage only to make the unenhanced of 0 degree or 180 degree.The first embodiment of the present invention is based on above-mentioned unenhanced information, proposes to arrange the method for rebuilding picture centre parameter, as shown in Figure 2.

Step 10) on directions X, patient is carried out to the unenhanced of 0 degree or 180 degree, obtain unenhanced data, as shown in Figure 3A;

Step 11) in the Y direction patient is carried out unenhancedly, obtain the unenhanced data in Y-direction; As patient carried out to the unenhanced data of unenhanced acquisition 90 degree of 90 degree, as shown in Figure 3 B; Or in the direction of 90 degree or 270 degree, the arbitrary position in the unenhanced scope of Z direction is scanned patient, best position is the position of center line in the unenhanced scope of Z direction, obtains the position scan-data in Y-direction, as shown in Figure 3 C;

Step 12) according to 0 degree or the unenhanced data of 180 degree, obtain patient at the position of directions X X _c;

Step 13) according to the unenhanced data of 90 degree or the position scan-data in the direction of 90 degree or 270 degree, obtain patient at the position of Y-direction Y _c;

(the X obtaining _c, Y _c) be image reconstruction Center Parameter.

This parameter can be input to automatically in CT scan equipment the corresponding position of user interface as shown in Figure 1 or input by the manual mode of doctor.

Image reconstruction Center Parameter X _ccan obtain by following mode:

According in 0 degree or the unenhanced data of 180 degree, obtain the cutaway view of an X-Z direction, shown in Fig. 3 A, at directions X, each passage has a projection value, can obtain thus the projection value P of overall channel on directions X according to formula (1) _xTotal

Wherein, i is the passage in x direction, P _xiit is the projection value on i channel position.N represents port number total in x direction; P _xTotalthe summation that represents all projection values of this cutaway view of covering

According to formula (2), obtain patient at the position of directions X X _c:

As shown in Fig. 3 B, 3C, utilize and obtain X _csame method, from the unenhanced data of Y-direction as in the 90 unenhanced data of degree or the unenhanced data of 270 degree, can obtain patient position Y in the Y direction according to formula (3) _c:

Certainly, for each Z position, can obtain independently image reconstruction Center Parameter (X of position therewith corresponding _cZ, Y _cZ); Therefore, can be by being taken at the meansigma methods (X that have image reconstruction center in related Z-direction section _average, Y _average) be used as the parameter at image reconstruction center, as formula (4):

Wherein, X _cZ, Y _cZrepresent the locational image reconstruction Center Parameter of a certain Z, Begin and End represent the starting and ending position of a certain section of Z.

The effect of optimizing can eliminate by following mode the impact that bed arranges image reconstruction Center Parameter: unenhanced and collect X, the passage projection value T of Y-direction of bed in corresponding scanning situation to bed in conjunction with 90 degree by 0 degree or 180 degree _xiand T _yi, according to formula (5), obtain patient at the position of X, Y-direction (X _c, Y _c)

Embodiment bis-

As shown in Figure 4 A, be the flow chart of the present embodiment, comprise following step:

Step 20): patient is carried out to the unenhanced of 0 degree or 180 degree;

Step 21): with the step 12 in embodiment mono-),, according to the unenhanced unenhanced data of 0 degree or 180 degree, obtain the position X of patient on directions X _c; Ask image reconstruction Center Parameter X _ccan obtain as the mode in embodiment mono-;

Step 22): at the current scanning number of degrees, add in the direction of 180 degree, the arbitrary position in the unenhanced scope of Z direction is scanned patient, best position is the position of center line in the unenhanced scope of Z direction, obtains a position scan-data, as shown in Figure 4 B; This kind only obtained to the scan mode of a certain data wire in a certain Z-direction position, be called position scanning;

Step 23): incorporated by reference to Fig. 3 A and Fig. 4 B, according to the unenhanced unenhanced data of 0 degree or 180 degree and according to the position scan-data of the scanning of 180 degree or 0 degree, obtain respectively the total projection value P in two kinds of scanning situations _oTotal, P _180Total, and projected area value PA ₀, PA ₁₈₀, according to total projection value and projected area value, obtain patient's side-play amount Y _c, side-play amount is to be scanned Ti center from the distance of CT scan device scan center of rotation, this side-play amount Y _cbe tried to achieve image reconstruction Center Parameter Y _c.

The present embodiment, by the example of the position scanning for the unenhanced of 0 degree and 180 degree, illustrates that obtaining side-play amount is image reconstruction Center Parameter Y _cmethod: by formula (7), can obtain total projection value P _oTotal; By formula (8), can obtain desirable " object central projection area value " PA.

Wherein, K represents error coefficient.

Utilize the total projection value P obtaining _oTotal" object central projection area value " PA, can obtain error ratio PercentError according to formula (9)

Mapping table or figure according to pre-set error ratio and side-play amount, as shown in Figure 5, can find out corresponding side-play amount, found out image reconstruction Center Parameter Y _c.

The X obtaining _c, Y _cas image reconstruction Center Parameter.

Embodiment tri-

The present embodiment is to obtain image reconstruction Center Parameter X based on the data of axial scan for the first time _c, Y _c, as shown in Figure 6, be the flow chart of the present embodiment:

Step 30): by axial scan, obtain axial scan data for the first time;

Step 31): from axial scan data for the first time, extract the position scan-data of directions X of 0 degree position or 180 degree positions and the position scan-datas of the Y-direction of 90 degree or 270 degree positions;

Step 32): according to the position scan-data of the position scan-data of directions X and Y-direction, obtain respectively the position X of patient in X and Y-direction _c, Y _c, this X _c, Y _cbe image reconstruction Center Parameter.

This image reconstruction Center Parameter X _c, Y _cidentical with embodiment mono-of acquisition pattern, at this, be not repeated.

Embodiment tetra-

The present embodiment is to obtain image reconstruction Center Parameter X based on the data of axial scan for the first time equally _c, Y _c, as shown in Figure 7, be the flow chart of the present embodiment:

Step 40): by axial scan, obtain axial scan data for the first time;

Step 41): from axial scan data for the first time, extract the position scan-data of the directions X of 0 degree position and 180 degree positions;

Step 42): according to the position scan-data of 0 degree position and 180 degree position directions Xs, obtain the position X of patient on directions X _c,, this X _c, be a value of image reconstruction Center Parameter; This image reconstruction Center Parameter X _cidentical with above-described embodiment of acquisition pattern, at this, be not repeated;

Step 43): according to the position scan-data of 0 degree position and 180 degree position directions Xs, obtain patient's side-play amount, this side-play amount is required image reconstruction Center Parameter Y _c, for the obtain manner of this side-play amount, can adopt the mode described in embodiment bis-to obtain.

Embodiment five

As shown in Figure 8, the present embodiment is that its method is as described below by obtaining image reconstruction Center Parameter based on scanned object as the various parameters of human body:

Step 50): set up the various parameters of human body as width, highly, age, sex, area (as Asia, the U.S. etc.), position (as head, chest, shank etc.), the height of bed, patient's parameter and the image reconstruction Center Parameter Y such as posture (if face is towards directions X or Y-direction) _cfunctional relationship;

Step 51): input is scanned patient's various parameters, 0 degree or the 180 unenhanced patients of degree, and obtain unenhanced data;

Step 52): according to unenhanced data, obtain the position of patient on directions X, the value of this position is image reconstruction Center Parameter X _c;

Step 53): according to inputted patient's parameter and step 50 functional relationship), obtains image reconstruction Center Parameter Y _c.

Its functional relationship is:

Y _c=f (width, highly, age, sex, area, scanning position, the height of bed, patient's posture ...)

The image reconstruction Center Parameter X obtaining in the present invention _c, Y _ccan be input to automatically the corresponding position that the image reconstruction Center Parameter of CT scan equipment arranges, also can be input to by the mode of manual input in the corresponding frame of the user interface that image reconstruction Center Parameter arranges, as shown in Figure 1.

A kind of functional block diagram for the present invention as shown in Figure 9, with the CT scan equipment of more accurate calculating reconstructed center parameter.

CT scan equipment of the present invention, comprising: scan table 1, and it comprises that to person under inspection unenhanced, axle sweeps that spiral is swept or the position of a certain position scanning X-ray scanning; Data collection module 2, its scan-data to scan table output comprise by scan-data unenhanced, that axle is swept or spiral is swept or the scanning of the position of a certain position obtains collect, analog digital conversion; Image reconstruction unit 3, its scan-data sending according to data collection module comprises and carries out image reconstruction, and the view data that institute's reconstruct is obtained stores memory element 7 into; For the user interface 4 of user's operation, this user interface comprises the input frame of image reconstruction parameter, and the reconstruction parameter that CT scan equipment can calculate it automatically comprises that reconstructed center and DFOV are input in this input frame, and is shown to user; The reconstruction parameter that user also can calculate CT scan equipment by manual mode is input in this corresponding frame; With central control unit 5, it is connected to the outfan of described image reconstruction unit 3, and gated sweep platform 1, data collection module 2 and user interface 4; With image reconstruction parameter calculation unit 6, its scan-data that system is obtained is analyzed, is processed, and obtains more accurate reconstructed center.

Described image reconstruction parameter calculation unit 6, comprises scan-data extraction unit 60 and reconstructed center parameter calculation unit 62.

The various implementations of image reconstruction parameter calculation unit 6 computed image reconstruction parameters are described below:

Implementation one:

Scan-data extraction unit 60 is extracted on directions X patient is carried out to 0 degree or the unenhanced data of 180 degree, as shown in Figure 3A; With extracting in the Y direction, patient is carried out to the unenhanced data in the Y-direction of unenhanced acquisition, as shown in Figure 3 B; Or be extracted in the direction of 90 degree or 270 degree, the arbitrary position in the unenhanced scope of Z direction is scanned patient, and best position is the position of center line in the unenhanced scope of Z direction, obtains the position scan-data in Y-direction, as shown in Figure 3 C;

Each passage projection value P in 0 degree that reconstructed center parameter calculation unit 62 is extracted according to scan-data extraction unit 60 or the unenhanced data of 180 degree _xi; And according to each the passage projection value P in the unenhanced data of 90 degree or the position scan-data in the direction of 90 degree or 270 degree _xi, according to the formula (2) described in embodiment mono-and (3), obtain patient at the position of directions X X _cwith the position Y in Y-direction _c;

(2), wherein

(the X obtaining _c, Y _c) be image reconstruction Center Parameter.

This parameter can be input to automatically in CT scan equipment the corresponding position of user interface as shown in Figure 1 or input by the manual mode of doctor.

Certainly, for each Z position, can obtain independently image reconstruction Center Parameter (X of position therewith corresponding _cZ, Y _cZ); Therefore, can be by being taken at the meansigma methods (X that have image reconstruction center in related Z-direction section _average, Y _average) be used as the parameter at image reconstruction center, as formula (4):

Wherein, X _cZ, Y _cZrepresent the locational image reconstruction Center Parameter of a certain Z, Begin and End represent the starting and ending position of a certain section of Z.

The effect of optimizing can eliminate by following mode the impact that bed arranges image reconstruction Center Parameter: unenhanced and collect X, the passage projection value T of Y-direction of bed in corresponding scanning situation to bed in conjunction with 90 degree by 0 degree or 180 degree _xiand T _yi, therefore, reconstructed center parameter calculation unit 62 is obtained patient at the position of X, Y-direction (X according to formula (5) _c, Y _c)

Implementation two:

Scan-data extraction unit 60 extracts the unenhanced data of 0 degree or 180 degree and adds in the direction of 180 degree at the current scanning number of degrees, the position scan-data that arbitrary position in the unenhanced scope of Z direction is scanned patient, this position optimum selection is the position of center line in the unenhanced scope of Z direction;

Reconstructed center parameter calculation unit 62, according to unenhanced data, is utilized the formula (2) in implementation one, obtains the position X of patient on directions X _c

Incorporated by reference to Fig. 3 A and Fig. 4 B, reconstructed center parameter calculation unit 62, according to unenhanced data and position scan-data, obtains respectively the total projection value P in two kinds of scanning situations _oTotal, P _180Total, and projected area value PA ₀, PA ₁₈₀, according to total projection value and projected area value, obtain patient's side-play amount Y _c, side-play amount is to be scanned Ti center from the distance of CT scan device scan center of rotation, this side-play amount Y _cbe tried to achieve image reconstruction Center Parameter Y _c.

In this implementation, be by calculating projection error ratio, then according to the contrast relationship of error ratio and side-play amount, find out corresponding side-play amount Y _c.For realizing this side-play amount Y _ccalculating, its implementation is the same with the mode described in embodiment bis-, is again not repeated.The corresponding relation of this error ratio and side-play amount is stored in memory element 7.Central control unit 5 is controlled reconstructed center parameter calculation unit 62 according to obtained error ratio and the corresponding relation of side-play amount, finds out required image reconstruction Center Parameter Y _c.

Implementation three:

This implementation is to obtain image reconstruction Center Parameter X based on the data of axial scan for the first time _c, Y _cas shown in figure 10, for this implementation functional block diagram, in its image reconstruction parameter calculation unit 9 and above-mentioned two kinds of implementations, have any different: it comprises axle scan-data extraction unit 91, position scan-data extraction unit 92 and reconstructed center parameter calculation unit 93.Described axle scan-data extraction unit 91 extracts axial scan data for the first time from data collection module 2; The scan-data of position scan-data extraction unit 92 from axle scan-data extraction unit 91 extracts the position scan-data of directions X of 0 degree position or 180 degree positions and the position scan-data of the Y-direction of 90 degree or 270 degree positions; Reconstructed center parameter calculation unit 93, according to the position scan-data of the position scan-data of directions X and Y-direction, is obtained respectively the position X of patient in X and Y-direction according to formula (2) and formula (3) _c, Y _c, this X _c, Y _cbe image reconstruction Center Parameter.

This image reconstruction Center Parameter X _c, Y _cidentical with implementation one of acquisition pattern, at this, be not repeated.

Implementation four:

This implementation is to obtain image reconstruction Center Parameter X based on the data of axial scan for the first time equally _c, Y _c, equally based on shown in Figure 10: described axle scan-data extraction unit 91 extracts axial scan data for the first time from data collection module 2; The scan-data of position scan-data extraction unit 92 from axle scan-data extraction unit 91 extracts the position scan-data of the directions X of 0 degree position and 180 degree positions; Reconstructed center parameter calculation unit 93, according to the position scan-data of directions X, is obtained patient at the position of X X according to formula (1) and (2) _c, and reconstructed center parameter calculation unit 93 obtains patient's side-play amount according to 0 degree of directions X and the 180 position scan-datas of spending, this side-play amount is required image reconstruction Center Parameter Y _c.For the obtain manner of this side-play amount, can adopt in embodiment bis-or the mode described in implementation two obtains.This X _c, Y _cbe image reconstruction Center Parameter; At this, be not repeated.The corresponding relation of memory error ratio and side-play amount in memory element 7.

Implementation five:

This implementation is by obtaining image reconstruction Center Parameter based on scanned object as the various parameters of human body, shown in Fig. 9:

In memory element 7, store the various parameters of human body as width, highly, age, sex, area (as Asia, the U.S. etc.), position (as head, chest, shank etc.), the height of bed, patient's parameter and the image reconstruction Center Parameter Y such as posture (if face is towards directions X or Y-direction) _cfunctional relationship; Doctor is according to the situation that is scanned patient, and in user interface 4, input is scanned patient's various parameters, 0 degree or the 180 unenhanced patients of degree; The unenhanced data that scan-data extraction unit 60 extracts in data collection module 2;

Reconstructed center parameter calculation unit 62, according to unenhanced data, is obtained the position of patient on directions X according to formula (1) and (2), and the value of this position is image reconstruction Center Parameter X _c; And according to the human parameters in memory element 7 and image reconstruction Center Parameter Y _cfunctional relationship, calculate image reconstruction Center Parameter Y _c.Functional relationship in this implementation can participate in described in embodiment five, this no longer class state.

The image reconstruction Center Parameter X obtaining in the present invention _c, Y _ccan be input to automatically the corresponding position that the image reconstruction Center Parameter of CT scan equipment arranges, also can be input to by the mode of manual input in the corresponding frame of the user interface that image reconstruction Center Parameter arranges, as shown in Figure 1.

Image reconstruction unit 3 is carried out image reconstruction according to this reconstructed center parameter.The Center Parameter that central control unit 5 control reconstructed center parameter calculation unit 62 or 93 are calculated sends to storage in memory element 7, it can be controlled CT scan equipment and obtain automatically this reconstructed center parameter, and be input in the corresponding frame of image reconstruction operation interface in user interface 4, also can be by informing user, by manual input for family.Described reconstructed center parameter calculation unit 6 can be integrated in central control unit 5 or be integrated in image reconstruction unit 3.

Claims (17)

1. in CT scan device scan, arrange and rebuild a picture centre parametric technique, it is characterized in that, described method comprises the steps:

Step 10) on directions X, patient is carried out to the unenhanced of 0 degree or 180 degree, obtain unenhanced data;

Step 11) in the Y direction patient is carried out the unenhanced data of 90 degree or unenhanced acquisition 90 degree of 270 degree or 270 degree, or in the direction of 90 degree or 270 degree, arbitrary position in the unenhanced scope of Z direction is scanned patient, obtains the position scan-data in Y-direction;

Step 12) according to 0 degree or the unenhanced data of 180 degree, obtain patient at the position of directions X X _c;

Step 13) according to the unenhanced data of 90 degree or the position scan-data in the direction of 90 degree or 270 degree, obtain patient at the position of Y-direction Y _c;

(the X obtaining _c, Y _c) be image reconstruction Center Parameter;

Wherein, image reconstruction Center Parameter X _cby following mode, obtain:

According to 0 degree or the unenhanced data of 180 degree, obtain the projection value P of each passage on directions X _xi, according to following formula, obtain the position X of patient on directions X _c:

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

Wherein, i is the passage on directions X, P _xiit is the projection value on i channel position; N represents port number total on directions X.

2. as claimed in claim 1 setting in CT scan device scan rebuild picture centre parametric technique, it is characterized in that: image reconstruction Center Parameter Y _cby following mode, obtain: from the 90 unenhanced data of degree or the unenhanced data of 270 degree of Y-direction, obtain the projection value P of each passage in Y-direction _yi, according to following formula, obtain patient position Y in the Y direction _c:

$Y_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Yi}}\·i}{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\·\mathrm{Yi}}}$

Wherein, i is passage in the Y direction, P _yiit is the projection value on i channel position; N represents port number total in Y-direction.

3. as claimed in claim 1 setting in CT scan device scan rebuild picture centre parametric technique, it is characterized in that: in the direction at 90 degree or 270 degree, arbitrary position in the unenhanced scope of Z direction is scanned patient, and this arbitrary position is the position of center line in the unenhanced scope of Z direction.

4. in CT scan device scan, arrange and rebuild a picture centre parametric technique, it is characterized in that, described method comprises the steps:

Step 20): on directions X, patient is carried out to the unenhanced of 0 degree or 180 degree;

Step 21): according to the unenhanced unenhanced data of 0 degree or 180 degree, obtain the position X of patient on directions X _c;

Step 22): at the current scanning number of degrees, add that in 180 direction, the arbitrary position in the unenhanced scope of Z direction is scanned patient, obtain a position scan-data;

Step 23): according to the unenhanced unenhanced data of 0 degree or 180 degree and according to the position scan-data of the scanning of 180 degree or 0 degree, obtain respectively the total projection value P in two kinds of scanning situations _0Total, P _180Totalwith projected area value PA ₀, PA ₁₈₀, according to total projection value and projected area value, obtain patient's side-play amount Y _c, this side-play amount Y _cbe tried to achieve image reconstruction Center Parameter Y _c,

Wherein, image reconstruction Center Parameter X _cby following mode, obtain:

According to 0 degree or the unenhanced data of 180 degree, obtain the projection value P of each passage on directions X _xi, according to following formula, obtain the position X of patient on directions X _c:

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

Wherein, i is the passage on directions X, P _xiit is the projection value on i channel position; N represents port number total on directions X.

5. as claimed in claim 4 setting in CT scan device scan rebuild picture centre parametric technique, it is characterized in that: described step 23) also comprise the steps:

Establish in advance the corresponding relation of error ratio and side-play amount;

According to following formula, obtain desirable " object central projection area value " PA;

$\mathrm{PA}=\frac{{\mathrm{PA}}_0+{\mathrm{PA}}_{180}}{2(1+0.834570-2.39029K+2.29460K^2-0.739329K^3)}$

$K=\min (\frac{{\mathrm{PA}}_0}{{\mathrm{PA}}_{180}},\frac{{\mathrm{PA}}_{180}}{{\mathrm{PA}}_0})$

Utilize the total projection value P obtaining _0Totalor P _180Total" object central projection area value " PA, obtains error ratio PercentError according to following formula;

$\mathrm{PercentError}=\frac{P_{0\mathrm{Total}}-\mathrm{PA}}{\mathrm{PA}}\×100$ Or

$\mathrm{PercentError}=\frac{P_{180\mathrm{Total}}-\mathrm{PA}}{\mathrm{PA}}\×100$

According to the corresponding relation of pre-set error ratio and side-play amount, find out corresponding side-play amount.

6. in CT scan device scan, arrange and rebuild a picture centre parametric technique, it is characterized in that, described method comprises the steps:

Step 30): by axial scan, obtain axial scan data for the first time;

Step 31): from axial scan data for the first time, extract the position scan-data of directions X of 0 degree position or 180 degree positions and the position scan-datas of the Y-direction of 90 degree or 270 degree positions;

Step 32): according to the position scan-data of the position scan-data of directions X and Y-direction, obtain respectively the position X of patient in X and Y-direction _c, Y _c, should (X _c, Y _c) be image reconstruction Center Parameter,

Wherein, image reconstruction Center Parameter X _cby following mode, obtain:

According to the position scan-data of directions X, obtain the projection value P of each passage on directions X _xi, according to following formula, obtain the position X of patient on directions X _c:

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

Wherein, i is the passage on directions X, P _xiit is the projection value on i channel position; N represents port number total on directions X.

7. in CT scan device scan, arrange and rebuild a picture centre parametric technique, it is characterized in that, described method comprises the steps:

Step 40): by axial scan, obtain axial scan data for the first time;

Step 41): from axial scan data for the first time, extract the position scan-data of the directions X of 0 degree position and 180 degree positions;

Step 42): according to the position scan-data of 0 degree position and 180 degree position directions Xs, obtain the position X of patient on directions X _c, this X _cbe a value of image reconstruction Center Parameter;

Step 43): according to the position scan-data of 0 degree position and 180 degree position directions Xs, obtain patient's side-play amount, this side-play amount is required image reconstruction Center Parameter Y _c,

Wherein, image reconstruction Center Parameter X _cby following mode, obtain:

According to the position scan-data of 0 degree position and 180 degree position directions Xs, obtain the projection value P of each passage on directions X _xi, according to following formula, obtain the position X of patient on directions X _c:

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

Wherein, i is the passage on directions X, P _xiit is the projection value on i channel position; N represents port number total on directions X.

8. in CT scan device scan, arrange and rebuild a picture centre parametric technique, it is characterized in that, described method comprises the steps:

Step 50): set up the various parameters of human body and image reconstruction Center Parameter Y _cfunctional relationship;

Step 51): input is scanned patient's various parameters, on directions X, patient is carried out to 0 degree or 180 degree are unenhanced, and obtain unenhanced data;

Step 52): according to unenhanced data, obtain the position of patient on directions X, the value of this position is image reconstruction Center Parameter X _c;

Step 53): according to inputted patient's parameter and step 50 functional relationship), obtains image reconstruction Center Parameter Y _c,

Wherein, image reconstruction Center Parameter X _cby following mode, obtain:

According to 0 degree and the unenhanced data of 180 degree, obtain the projection value P of each passage on directions X _xi, according to following formula, obtain the position X of patient on directions X _c:

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

Wherein, i is the passage on directions X, P _xiit is the projection value on i channel position; N represents port number total on directions X.

9. as claimed in claim 8 setting in CT scan device scan rebuild picture centre parametric technique, it is characterized in that the various parameters of human body comprise width, highly, age, sex, area, the position of scanning, the height of bed, patient's posture.

10. a CT scan equipment of rebuilding picture centre parameter is set, it is characterized in that, described CT scan equipment comprises: the scan table scanning being scanned object; Obtain the data collection module of the scan-data that scan table sends; Scan-data is carried out to the image reconstruction unit of image reconstruction; User interface for user's operation; With for storing the memory element of data and the central control unit that scan table, data collection module, image reconstruction unit, user interface and memory element are controlled; Described CT scan equipment also comprises image reconstruction parameter calculation unit, and this image reconstruction parameter calculation unit is according to scan-data, needed reconstruction parameter when calculating image reconstruction unit and rebuilding image;

Wherein: this image reconstruction parameter calculation unit comprises:

Scan-data extraction unit, it obtains 0 degree of the collected directions X that is scanned object of data collection module or the unenhanced data of 180 degree, and 90 degree of Y-direction or the arbitrary position scan-data in the unenhanced scope of Z direction in the 270 unenhanced data of degree or Y-direction;

Reconstructed center parameter calculation unit; It obtains the projection value P of each passage on directions X according to the unenhanced data of the directions X extracting in scan-data extraction unit _xi, and according to the unenhanced data of Y-direction or position scan-data, obtain the projection value P of each passage in Y-direction _yi, according to following formula

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

$Y_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Yi}}\·i}{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Yi}}}$

Obtain patient at the position of directions X X _cwith the position Y in Y-direction _c; (the X obtaining _c, Y _c) be image reconstruction Center Parameter; Wherein, i is the passage in X or Y-direction, P _xi, P _yiit is the projection value on i channel position; N represents port number total in X or Y-direction.

11. CT scan equipment as claimed in claim 10, is characterized in that: this position scan-data is the scan-data of the position of center line in the unenhanced scope of Z direction.

12. CT scan equipment as claimed in claim 10, is characterized in that: described memory cell contains the corresponding relation of error ratio and side-play amount;

This image reconstruction parameter calculation unit comprises:

Scan-data extraction unit, it obtains 0 degree or the unenhanced data of 180 degree of the collected directions X that is scanned object of data collection module, and at the current scanning number of degrees, adds in 180 direction the arbitrary position scan-data in the unenhanced scope of Z direction;

Reconstructed center parameter calculation unit; It obtains the projection value P of each passage on directions X according to the unenhanced data of the directions X extracting in scan-data extraction unit _xi, and obtain patient at the position of directions X X according to following formula _c;

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

Reconstructed center parameter calculation unit also, according to the unenhanced unenhanced data of 0 degree or 180 degree and according to the position scan-data of the scanning of 180 degree or 0 degree, is obtained respectively the total projection value P in two kinds of scanning situations _0Total, P _180Total, and projected area value PA ₀, PA ₁₈₀, and obtain desirable " object central projection area value " PA and error ratio PercentError according to following formula

$\mathrm{PA}=\frac{{\mathrm{PA}}_0+{\mathrm{PA}}_{180}}{2(1+0.834570-2.39029K+2.29460K^2-0.739329K^3)}$

$K=\min (\frac{{\mathrm{PA}}_0}{{\mathrm{PA}}_{180}},\frac{{\mathrm{PA}}_{180}}{{\mathrm{PA}}_0})$

$\mathrm{PercentError}=\frac{P_{0\mathrm{Total}}-\mathrm{PA}}{\mathrm{PA}}\×100$ Or

$\mathrm{PercentError}=\frac{P_{180\mathrm{Total}}-\mathrm{PA}}{\mathrm{PA}}\×100;$

Central control unit is controlled reconstructed center parameter calculation unit according to obtained error ratio and the corresponding relation of side-play amount, finds out required image reconstruction Center Parameter Y _c.

13. CT scan equipment as claimed in claim 10, is characterized in that: this image reconstruction parameter calculation unit comprises:

Axle scan-data extraction unit, it extracts the axle scan-data of axial scan data for the first time from data collection module;

Position scan-data extraction unit, it extracts the position scan-data of directions X of 0 degree position or 180 degree positions and the position scan-data of the Y-direction of 90 degree or 270 degree positions from axle scan-data;

Reconstructed center parameter calculation unit, it is according to the X extracting in the scan-data extraction unit of position, and the position scan-data of Y-direction is obtained the projection value P of each passage on directions X _xi, and the projection value P of each passage in Y-direction _yi, according to following formula

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

$Y_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Yi}}\·i}{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Yi}}}$

Obtain patient at the position of directions X X _cwith the position Y in Y-direction _c; (the X obtaining _c, Y _c) be image reconstruction Center Parameter; Wherein, i is the passage in X or Y-direction, P _xi, P _yiit is the projection value on i channel position; N represents port number total in X or Y-direction.

14. CT scan equipment as claimed in claim 10, is characterized in that, this image reconstruction parameter calculation unit comprises:

Axle scan-data extraction unit, it extracts the axle scan-data of axial scan data for the first time from data collection module;

Position scan-data extraction unit, it extracts the position scan-data of the directions X of 0 degree position and 180 degree positions from axle scan-data;

Reconstructed center parameter calculation unit; It obtains the projection value P of each passage on directions X according to the position scan-data of the directions X extracting in the scan-data extraction unit of position _xi, and according to following formula

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

Obtain patient at the position of directions X X _c, wherein, i is the passage on directions X, P _xiit is the projection value on i channel position; N represents port number total on directions X;

And reconstructed center parameter calculation unit is according to the position scan-data of 0 degree position and 180 degree positions, obtains patient's side-play amount, this side-play amount is required image reconstruction Center Parameter Y _c.

15. arrange the CT scan equipment of rebuilding picture centre parameter as described in claim 14, it is characterized in that; Described cell stores has the corresponding relation of error ratio and side-play amount; Described reconstructed center parameter calculation unit, according to the unenhanced unenhanced data of 0 degree and 180 degree and according to the position scan-data of the scanning of 180 degree and 0 degree, is obtained respectively the total projection value P in two kinds of scanning situations _0Total, P _180Total, and projected area value PA ₀, PA ₁₈₀, and obtain desirable " object central projection area value " PA and error ratio PercentError according to following formula

$\mathrm{PA}=\frac{{\mathrm{PA}}_0+{\mathrm{PA}}_{180}}{2(1+0.834570-2.39029K+2.29460K^2-0.739329K^3)}$

$K=\min (\frac{{\mathrm{PA}}_0}{{\mathrm{PA}}_{180}},\frac{{\mathrm{PA}}_{180}}{{\mathrm{PA}}_0})$

$\mathrm{PercentError}=\frac{P_{0\mathrm{Total}}-\mathrm{PA}}{\mathrm{PA}}\×100$ Or

$\mathrm{PercentError}=\frac{P_{180\mathrm{Total}}-\mathrm{PA}}{\mathrm{PA}}\×100;$

Central control unit is controlled reconstructed center parameter calculation unit according to obtained error ratio and the corresponding relation of side-play amount, finds out required image reconstruction Center Parameter Y _c.

16. CT scan equipment as claimed in claim 10, is characterized in that: described cell stores has the functional relationship of human parameters and Center Parameter; This image reconstruction parameter calculation unit comprises:

Scan-data extraction unit, it obtains 0 degree of the collected directions X that is scanned object of data collection module or the unenhanced data of 180 degree;

Reconstructed center parameter calculation unit; It obtains the projection value P of each passage on directions X according to the unenhanced data of the directions X extracting in scan-data extraction unit _xi, and according to following formula

$X_C=\frac{\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}\·i}{\underset{i=1}{\overset{i=N}{\mathrm{\Σ}}}{P}_{\mathrm{Xi}}}$

Obtain patient at the position of directions X X _c; Wherein, i is the passage on directions X, P _xiit is the projection value on i channel position; N represents port number total on directions X;

And reconstructed center parameter calculation unit according to user, input be scanned human parameters and human parameters and Center Parameter functional relationship, obtain required Center Parameter Y _c.

The 17. CT scan equipment of rebuilding picture centre parameter that arrange as claimed in claim 16, it is characterized in that described human parameters comprise width, highly, age, sex, area, the position of scanning, the height of bed, patient's posture; Its functional relationship is Y _c=f (width, highly, age, sex, area, scanning position, the height of bed, patient's posture).