JP2012231816A - Imaging parameter determination method, x-ray ct apparatus and injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically provide an imaging parameter suitable for a subject without adding special and physical remodeling to an X-ray CT apparatus.SOLUTION: An estimation means estimates the body weight of a subject on the basis of data obtained by preliminary imaging, and a determination means determines an imaging parameter to be used for contrast imaging which is main imaging on the basis of the estimated body weight. The estimation means performs, for instance, estimation of a body mass index based on correlation between X-ray transmittance of the subject obtained by the data and the body mass index, and estimation of a body height based on a distance between anatomical feature points in the image of the subject obtained by the data, and estimates the body weight on the basis of the body mass index and the body height.

Description

  The present invention relates to a contrast parameter determination method for determining a contrast parameter used for contrast imaging by an X-ray CT apparatus, an X-ray CT (Computed Tomography) apparatus and an injector for using this method.

  Conventionally, in contrast imaging using an X-ray CT apparatus, an imaging engineer or the like obtains an injector by calculating contrast parameters used for contrast imaging based on physical data (data) such as the weight of a subject obtained in advance. It is often set manually by the control unit to be controlled.

  However, an appropriate contrast parameter cannot be obtained if there is an error in the obtained physical data of the subject, or if there is a calculation error when obtaining the contrast parameter manually.

  Therefore, there is an X-ray CT apparatus that adds a weight sensor or the like to a table on which the subject is placed, directly measures the weight of the subject, and automatically determines the amount of contrast medium based on the measured weight. It has been proposed (see Patent Document 1, Abstract, etc.).

JP 2006-325615 A

  However, if physical modifications such as adding a weight sensor to the table on which the subject is placed are added, the structure becomes complex and it becomes difficult to handle maintenance and failure. In addition, the cost of the device increases.

  Under such circumstances, it is desired to automatically obtain a contrast parameter suitable for a subject without adding any physical modification to the X-ray CT apparatus.

  According to a first aspect of the present invention, there is provided a step of estimating a weight of the subject based on data obtained by preliminary imaging of the subject by an X-ray CT apparatus, and the subject based on the estimated weight A contrast parameter determination method comprising: determining a contrast parameter used for contrast imaging.

  A second aspect of the invention is an X-ray CT apparatus that performs contrast imaging of a subject, and estimates the weight of the subject based on data obtained by preliminary imaging performed before the contrast imaging There is provided an X-ray CT apparatus comprising: an estimation unit; and a determination unit that determines a contrast parameter used for the contrast imaging based on the body weight estimated by the estimation unit.

  The invention according to a third aspect provides the X-ray CT apparatus according to the second aspect, wherein the determining means determines the contrast parameter so that the absolute amount of contrast components to be injected increases as the body weight increases.

  According to a fourth aspect of the present invention, the estimating means further estimates a body mass index (BMI) of the subject based on the data, and the determining means is based on the body mass index, The X-ray CT apparatus according to the second aspect or the third aspect for determining the contrast parameter is provided.

  The invention according to a fifth aspect is any one of the second to fourth aspects, wherein the determination means determines the contrast parameter so that the absolute amount of the contrast component to be injected decreases as the body mass index increases. An X-ray CT apparatus according to one aspect is provided.

  According to a sixth aspect of the invention, the estimating means further estimates the body fat percentage of the subject based on the data, and the determining means determines the contrast parameter based also on the body fat percentage. An X-ray CT apparatus according to any one of the second to fifth aspects is provided.

  The invention according to a seventh aspect provides the X-ray CT apparatus according to the sixth aspect, wherein the determining means determines the contrast parameter so that the absolute amount of the contrast component to be injected decreases as the body fat percentage increases. .

  According to an eighth aspect of the invention, the estimating means estimates the body mass index based on a correlation between the X-ray transmittance of the subject obtained from the data and the body mass index, and the data obtained by the data The height is estimated based on the distance between the anatomical feature points in the image of the subject, and the weight is estimated based on the body mass index and the height. An X-ray CT apparatus according to one aspect is provided.

  The invention according to a ninth aspect provides the X-ray CT apparatus according to the eighth aspect, wherein the distance between the anatomical feature points is a predetermined bone length.

  According to a tenth aspect of the present invention, in the sixth aspect or the seventh aspect, the estimating means estimates the body fat percentage based on the profile of the data or the analysis result of the image obtained by the data. An X-ray CT apparatus is provided.

  According to an eleventh aspect of the invention, from the second aspect to the tenth aspect, the determining means determines at least one of a contrast medium concentration, a contrast medium injection amount, and a contrast medium injection speed as the contrast parameter. An X-ray CT apparatus according to any one of the above aspects is provided.

  According to a twelfth aspect of the invention, from the second aspect to the eleventh aspect, the preliminary imaging is a scout scan or a helical scan using a lower dose of X-rays than the contrast imaging. An X-ray CT apparatus according to any one of the above aspects is provided.

  According to a thirteenth aspect of the invention, the preliminary imaging is a dual energy helical scan using a lower dose of X-rays than the contrast imaging, and the estimation means is the subject obtained by the dual energy helical scan. The three-dimensional image regions of the subject are classified into a plurality of substance groups based on the ratio or difference of the corresponding pixel values in the two types of three-dimensional images, and the substance is contained in the volume of the substance group for each substance group. There is provided an X-ray CT apparatus according to any one of the second to fifth aspects, wherein the sum of values obtained by multiplying specific gravity according to a group is estimated as the weight.

  The fourteenth aspect of the invention is any one of the first to thirteenth aspects, further comprising transfer means for transferring the determined contrast parameter to an injector connected to the X-ray CT apparatus. An X-ray CT apparatus according to one aspect is provided.

  According to a fifteenth aspect of the present invention, an imaging parameter obtained based on a weight estimated using data obtained by preliminary imaging of a subject by the X-ray CT apparatus is input from the X-ray CT apparatus, Provided is an injector for injecting a contrast agent into the subject using the inputted contrast parameter when performing contrast imaging of the subject.

  According to a sixteenth aspect of the present invention, an estimated body weight is input from an X-ray CT apparatus using data obtained by preliminary imaging of a subject using the X-ray CT apparatus, and the above-described weight is input based on the input body weight. An injector for determining a contrast parameter used for contrast imaging of a subject and injecting a contrast medium into the subject using the determined contrast parameter when performing contrast imaging of the subject is provided.

  According to the above aspect of the invention, without using a weight sensor or the like, it is possible to estimate the weight of a subject based on data obtained by preliminary imaging, and to determine a contrast parameter based on the estimated weight, A contrast parameter suitable for the subject can be automatically obtained without adding any physical modification to the X-ray CT apparatus.

It is a figure which shows the structure of the X-ray CT apparatus by 1st embodiment. It is a figure which shows the flow of a process in the X-ray CT apparatus which concerns on 1st embodiment. It is a figure which shows an example of the correspondence of the kind of bone, and a height estimation coefficient. It is a figure which shows an example of the correspondence of a body weight and a contrast parameter. It is a figure which shows the flow of the process by the 1st modification in 1st embodiment. It is a figure which shows an example of the correspondence of a body weight, a body mass index, and a contrast parameter. It is a figure which shows the flow of the process by the 2nd modification in 1st embodiment. It is a figure which shows an example of the correspondence of a body weight, a body fat rate, and a contrast parameter. It is a figure which shows the flow of the process by the 3rd modification in 1st embodiment. It is a figure which shows an example of the correspondence of a weight, a body mass index, a body fat rate, and a contrast parameter. It is a figure which shows the flow of a process in the X-ray CT apparatus which concerns on 2nd embodiment. It is a figure which shows the flow of the process by the 1st modification in 2nd embodiment. It is a figure which shows the flow of the process by the 2nd modification in 2nd embodiment. It is a figure which shows the flow of the process by the 3rd modification in 2nd embodiment.

  Embodiments of the invention will be described below.

(First embodiment)
FIG. 1 is a diagram showing a configuration of an X-ray CT apparatus according to the first embodiment.

  The X-ray CT apparatus 100 includes an operation console 1, an imaging table 10, and a scanning gantry 20.

  The operation console 1 collects data acquired by the input device 2 that receives input from the operator, a central processing unit 3 that controls various parts for scanning the subject 40 and performs various calculations, and the scanning gantry 20. A data collection buffer (buffer) 5, a monitor 6 for displaying images, and a storage device 7 for storing programs and data are provided.

  The imaging table 10 includes a cradle 12 on which the subject 40 is placed and carried into and out of the opening of the scanning gantry 20. The cradle 12 is moved up and down and horizontally moved by a motor built in the imaging table 10.

The scanning gantry 20 includes a rotating unit 15 and a support unit 16 that rotatably supports the rotating unit 15. The rotating unit 15 includes an X-ray tube 21, an X-ray controller (controller) 22 that controls the X-ray tube 21, and a collimator that collimates and shapes the X-ray 81 generated from the X-ray tube 21. ) 23, an X-ray detector 24 that detects X-rays 81 irradiated from the X-ray tube 21 and transmitted through the subject 40, and a data collection device that converts and collects the output of the X-ray detector 24 into projection data (DAS; Data
Acquisition System) 25 and a rotating unit controller 26 for controlling the X-ray controller 22, the collimator 23, and the DAS 25 are mounted. The support unit 16 includes a control controller 29 that communicates control signals and the like with the operation console 1 and the imaging table 10. The rotating portion 15 and the support portion 16 are provided with a slip ring (slip
ring) 30 and is electrically connected.

  The X-ray CT apparatus 100 is connected to an injector 50 that injects a contrast medium into the subject 40. The central processing unit 3 of the X-ray CT apparatus 100 controls the injector 50 together with the imaging table 10 and the scanning gantry 20, and executes a contrast scan (contrast imaging) of the subject 50.

  Hereafter, the flow of processing in the X-ray CT apparatus according to the first embodiment will be described. In the first embodiment, a scout scan is used as preliminary photographing.

  FIG. 2 is a diagram showing a flow of processing in the X-ray CT apparatus according to the first embodiment.

  In step S1, a scout scan (preliminary imaging) of the subject 40 is performed to acquire scout data (data). In the scout scan, for example, the rotating unit 15 is fixed so that the X-ray tube 21 is positioned in the 0 ° direction, that is, directly above the subject, or in the 90 ° direction, that is, directly beside the subject, and the cradle on which the subject 40 is placed. The X-ray detector 24 detects X-rays transmitted through the X-ray detector 24 while irradiating the X-ray with a lower dose than the simple scan or contrast scan that is the main imaging.

  In step S2, the body mass index BMI of the subject 40 is estimated using the correlation between the X-ray transmittance B of the subject 40 obtained from the scout data and the body mass index BMI.

  Here, the principle of estimation of the body mass index BMI will be described.

  Non-patent literature “Japan Women's Association Journal”, reprint No. 204 (October 25, 2010), pages 2 to 3, Eisai Co., Ltd. information magazine “RT”, No. 38 (November, 2007), pages 38 to 44, etc., there is a correlation between the image noise value SD in the reconstructed image and the body mass index BMI of the subject. This is expressed by the following equation.

SD = f (BMI): f (x) is a correlation function (Formula 1)
For example, f (BMI) = α · BMI + β
Here, α and β are constants ∴BMI = F (SD): F (x ′) is an inverse function of f (x) (Equation 2)

  Further, as used in the principle of CT automatic exposure mechanism (CT-AEC), there is a gap between the X-ray transmittance B of the subject obtained from the scout data and the image noise value SD in the reconstructed image. There is a correlation. This is expressed by the following equation.

SD = g (B): g (x) is a correlation function (Formula 3)
For example, g (B) = 1 / √ (B · D · h · w ³ )
Where D is the incident dose, h is the slice thickness, and w is the pixel size (size).

  Therefore, there is a correlation between the X-ray transmittance B of the subject obtained from the scout data and the body mass index BMI. This is expressed by the following equation.

    BMI = F (g (B)) = J (B): J (x) is a correlation function (Formula 4)

  That is, based on this correlation, the body mass index BMI can be estimated from the X-ray transmittance B of the subject 40.

  The X-ray transmittance B of the subject 40 obtained from the scout data is, for example, X based on the transmitted X-ray signal intensity of each detection element in the channel direction of the X-ray detector 24 for each z position of the subject 40. The line transmittance B is obtained, and this is averaged in the z direction.

  The image noise value SD is, for example, a standard deviation of pixel values (CT values) per image area of a predetermined size.

  In step S3, the height H of the subject 40 is estimated based on the distance between predetermined anatomical feature points in the scout image represented by the scout data.

  For example, the distance between predetermined anatomical feature points is the bone length L of a predetermined bone, and the height H is estimated using the correlation between the bone length L and the height H. For example, the estimated height can be calculated by multiplying the bone length L of a predetermined bone by a height estimation coefficient corresponding to the type of the bone.

    Height H [m] = bone length L [m] × height estimation coefficient (Formula 5)

  FIG. 3 shows an example of the correspondence between the bone type and the height estimation coefficient.

  In scout scanning, the scanning range is often set to include the femur. Therefore, in this example, the bone length of the femur in the scout image is detected by template matching or the like, and the height H of the subject 40 is obtained by multiplying the bone length by the height estimation coefficient. The height estimation coefficient differs slightly between men and women, but there is no significant difference. Therefore, the average length of the male and female height estimation coefficients may be multiplied by the bone length regardless of the gender of the subject 40.

  In step S4, the weight W of the subject 40 is further estimated from the estimated body mass index BMI and height H of the subject 40. Since the body mass index BMI is originally an index value of obesity calculated according to the following formula, if the body mass index BMI and the height H are known, the weight W can be derived.

Body mass index BMI = weight W [kg] / (height H [m]) ² (Formula 6)

  In step S5, a contrast parameter corresponding to the estimated weight W is determined as a contrast parameter used for the contrast scan with reference to a table showing the correspondence between the weight W and the contrast parameter. A table indicating the correspondence between the weight W and the contrast parameter is stored in the storage device 7 in advance.

  FIG. 4 shows an example of the correspondence between weight and contrast parameters.

  As the contrast parameter, for example, a contrast medium concentration, a contrast medium injection amount, a contrast medium injection speed, an imaging timing, and the like can be considered. The contrast parameter is determined such that the greater the weight W of the subject 40, the greater the contrast component to be injected, that is, the absolute amount of iodine (iodine).

  The absolute amount of iodine is such that the CT value of the portion stained with the contrast agent reaches the target value, considering the balance between the contrast effect and the burden on the subject 40, and the smallest possible amount Is good. Further, when the body weight W is large, when the body fat percentage F and the body mass index BMI are the same, the substantial portion where the contrast agent is stained increases. Therefore, as described above, as the weight W increases, the contrast parameter to which a more preferable absolute amount of iodine is administered to the subject 40 can be determined by reducing the absolute amount of iodine to be injected. it can.

  In step S <b> 6, the determined contrast parameter is transferred to the injector 50 and set as a parameter relating to the control of the injector 50.

  In step S7, the imaging table 10, the scanning gantry 20, and the injector 50 are controlled to perform a simple scan before the contrast agent administration and a contrast scan after the contrast agent administration according to the set contrast parameter, which are the main imaging.

  In step S8, the simple image and the contrast image are reconstructed based on the data obtained by the simple scan and the contrast scan.

  In step S9, a simple image and a contrast image are displayed on the monitor screen.

  According to the present embodiment, it is possible to estimate the body weight of the subject based on the data obtained by preliminary imaging without using a weight sensor or the like, and to determine the contrast parameter based on the estimated body weight. In addition, it is possible to automatically obtain a contrast parameter suitable for the subject without any additional physical modification of the X-ray CT apparatus.

(First modification)
FIG. 5 is a diagram illustrating a flow of processing according to the first modification example of the first embodiment.

  In the first modification of the first embodiment, step S5A is executed instead of step S5.

  In step S5A, a contrast parameter corresponding to the estimated weight W and body mass index BMI is determined as a contrast parameter used for the contrast scan with reference to a table showing the correspondence between the weight W and body mass index BMI and the contrast parameter. A table showing the correspondence between the weight W and the body mass index BMI and the contrast parameter is stored in the storage device 7 in advance.

  FIG. 6 shows an example of the correspondence relationship between the body weight and body mass index and the contrast parameter.

  The contrast parameter is determined so that the absolute amount of iodine to be injected increases as the weight W increases, and the absolute amount of iodine to be injected decreases as the body mass index BMI increases.

  The absolute amount of iodine is such an amount that the CT value of the portion stained with the contrast agent reaches the target value and should be as small as possible. In addition, when the body mass index BMI is large, a subject having the same body weight has a large amount of fat, and a substantial portion where the contrast agent is stained decreases. Therefore, as described above, the contrast parameter more suitable for the subject 40 can be determined by reducing the absolute amount of iodine to be injected as the body mass index BMI increases.

(Second modification)
FIG. 7 is a diagram illustrating a flow of processing according to the second modification example of the first embodiment.

  In the second modification of the first embodiment, steps S51B and S52B are executed instead of step S5.

  In step S51B, the body fat percentage F of the subject 40 is estimated based on the profile shape of the scout data.

  For example, both ends of the data profile in the channel direction at a predetermined z position of the subject 40 (for example, the navel of the subject) are detected as the positions of the left and right body surfaces of the subject 40. Further, the first peak from one body surface toward the center is detected as the position of one bone group. Further, the fat region width is defined from the position of the one body surface to the position of the one bone group. Then, the body fat percentage F is estimated based on the ratio between the distance between the left and right body surfaces and the width of the fat region.

  For example, the body fat percentage F can also be estimated by a dual energy X-ray absorption method (DXA method). The DXA method is a method for obtaining the body fat percentage F by using the fact that the subject 40 is irradiated with two types of X-rays having different energies and there is a difference in the X-ray transmittance of each tissue. Specifically, for example, fat mass, bone mineral content, lean mass and the like are obtained from the difference in X-ray transmittance of the subject 40 when two types of X-rays are irradiated, and the body fat percentage = fat mass / Calculate as the total amount. Therefore, when this method is used, when performing a scout scan of the subject 40, it is necessary to scout the subject 40 with two types of X-ray tube voltages.

  In step S52B, a contrast parameter corresponding to the estimated weight W and body fat rate F is determined as a contrast parameter used for the contrast scan with reference to a table showing the correspondence between the weight W and body fat rate F and the contrast parameter. . A table showing the correspondence between the weight W and the body fat percentage F and the contrast parameter is stored in the storage device 7 in advance.

  FIG. 8 shows an example of the correspondence relationship between body weight and body fat percentage and contrast parameters.

  The contrast parameter is determined so that the absolute amount of iodine to be injected increases as the weight W increases, and the absolute amount of iodine to be injected decreases as the body fat percentage F increases.

  The absolute amount of iodine is the amount by which the CT value of the portion stained with the contrast agent reaches the target value, and it is better that it is as small as possible. Further, when the body fat percentage F is large, when the weight W is the same, the fat is more and the substantial portion where the contrast agent is stained is smaller. Therefore, as described above, the contrast parameter to which a more preferable absolute amount of iodine is administered to the subject 40 is determined by reducing the absolute amount of iodine to be injected as the body fat percentage F increases. Can do.

(Third modification)
FIG. 9 is a diagram illustrating a flow of processing according to the third modification example of the first embodiment.

  In the third modified example of the first embodiment, step S52C is executed instead of step S52B based on the second modified example of the first embodiment.

  In step S52C, with reference to a table showing the correspondence between the body weight W, the body mass index BMI and the body fat percentage F and the contrast parameter, the contrast parameters corresponding to the estimated weight W, the body mass index BMI and the body fat percentage F are contrast-enhanced. It is determined as a contrast parameter used for scanning. A table showing the correspondence between the weight W, the body mass index BMI, and the body fat percentage F and the contrast parameter is stored in the storage device 7 in advance.

  FIG. 10 shows an example of the correspondence relationship between the body weight, body mass index, body fat percentage, and contrast parameter.

  The contrast parameter is such that the absolute amount of iodine to be injected increases as the weight W increases, the absolute amount of iodine to be injected decreases as the body mass index BMI increases, and the body fat percentage F increases. The absolute amount of iodine to be injected is determined to be small.

  The absolute amount of iodine is such an amount that the CT value of the portion stained with the contrast agent reaches the target value and should be as small as possible. Further, when the body mass index and the body fat percentage are large, the subject 40 having the same body weight has a large amount of fat, and the substantial portion where the contrast agent is stained decreases. Therefore, as described above, the contrast parameter more suitable for the subject 40 can be determined by decreasing the absolute amount of iodine to be injected as the body mass index BMI and the body fat percentage F increase.

(Second embodiment)
FIG. 11 is a diagram showing a flow of processing in the X-ray CT apparatus according to the second embodiment. In the second embodiment, a low-dose helical scan is used as preliminary imaging.

  In step T1, the subject 40 is helically scanned with low-dose X-rays to acquire helical data. In this helical scan, for example, the cradle 12 on which the subject 40 is placed is moved horizontally while the rotating unit 15 on which the X-ray tube 21 is mounted is rotated around the subject 40. The X-ray detector 24 emits a lower dose of X-rays than the simple scan or contrast scan, which is radiography, and the X-ray detector 24 detects the transmitted X-ray.

  In step T2, the body mass index BMI of the subject 40 is estimated based on the correlation between the X-ray transmittance B of the subject 40 obtained from the helical data and the body mass index BMI. The principle of estimation of the body mass index BMI is the same as that of the first embodiment.

  The X-ray transmittance B of the subject 40 obtained from the helical data is obtained, for example, from the transmitted X-ray signal intensity of each detection element in the channel direction of the X-ray detector 24 for each view. This is the value averaged over all views.

  In step T3, the height H of the subject 40 is estimated based on a predetermined bone length in the tomographic image or MPR image reconstructed based on the helical data. The principle of estimating the height H is the same as in the first embodiment.

  Since step T4 and subsequent steps are the same as step S4 and subsequent steps of the first embodiment, description thereof is omitted.

  Even in such a second embodiment, the same effects as in the first embodiment can be obtained.

(First modification)
FIG. 12 is a diagram showing a flow of processing according to the first modification in the second embodiment.

  In the first modification of the second embodiment, step T5A is executed instead of step T5.

  In step T5A, with reference to a table showing the correspondence between the weight W and the body mass index BMI and the contrast parameter, the contrast parameter corresponding to the estimated weight W and the body mass index BMI is determined as a contrast parameter used for the contrast scan.

  As the body mass index BMI here, for example, one obtained in the process of estimating the height H is used. For example, the correspondence shown in FIG. 6 is used as the correspondence between the weight W and the body mass index BMI and the contrast parameter.

(Second modification)
FIG. 13 is a diagram illustrating a flow of processing according to the second modification example of the second embodiment.

  In the second modification of the second embodiment, steps T51B and T52B are executed instead of step T5.

  In step T51B, the body fat percentage F of the subject 40 is estimated from the analysis result of the image reconstructed based on the helical data.

  For example, by using a known fat region extraction method such as the method disclosed in Japanese Patent No. 4437333, a region indicating fat in the reconstructed tomographic image is extracted, and the region indicating fat and other regions are extracted. The ratio of the area is obtained, and the body fat percentage F is estimated.

  In step T52B, a contrast parameter corresponding to the estimated weight W and body fat rate F is determined as a contrast parameter used for the contrast scan with reference to a table showing the correspondence between the weight W and body fat rate F and the contrast parameter. . For example, the correspondence shown in FIG. 8 is used as the correspondence between the weight W and the body fat percentage F and the contrast parameter.

(Third modification)
FIG. 14 is a diagram illustrating a flow of processing according to the third modification example of the second embodiment.

  In the third modification of the second embodiment, Step T52C is executed instead of Step T52B based on the second modification of the second embodiment.

  In step T52C, a table showing the correspondence between the body weight W, the body mass index BMI and the body fat percentage F and the contrast parameter is referred to, and the contrast parameters corresponding to the estimated weight W, the body mass index BMI and the body fat percentage F are contrast-enhanced. It is determined as a contrast parameter used for scanning. For example, the correspondence shown in FIG. 10 is used as the correspondence between the weight W, the body mass index BMI, the body fat percentage F, and the contrast parameter.

  As mentioned above, although embodiment of invention was described, embodiment of invention is not limited to said thing, In the range which does not deviate from the meaning of invention, various forms can be taken.

  For example, the determined contrast parameter may be displayed on the screen of the monitor 6 without being transferred to the injector 50. In this case, the operator operates the operation unit of the injector 50 and manually sets the displayed contrast parameter as the control parameter of the injector 50.

  Further, for example, the X-ray CT apparatus 100 obtains one or a plurality of patterns of contrast parameter candidates based on the estimated weight W or the like (that is, without performing the final determination), and transfers and inputs these to the injector 50, The injector 50 may determine (set) one of the input contrast parameter candidates as a contrast parameter used for actual contrast imaging.

  Further, for example, the X-ray CT apparatus 100 performs estimation up to the body weight W, the body mass index BMI, the body fat percentage F, etc. based on the scout data, and transfers and inputs them to the injector 50. The contrast parameter may be determined based on the input weight W or the like. In this case, the correspondence relationship (correspondence table or function) between the weight W or the like and the contrast parameter may be stored and referred to by the injector 50 itself, or the correspondence relationship may be stored by the X-ray CT apparatus 100. 50 may read and refer to the correspondence.

  Also, for example, the distance between anatomical feature points used for height estimation is the width of a predetermined internal organ such as the lung, the distance between the cervical spine and the diaphragm, in addition to the bone length of a predetermined bone. May be.

  Further, for example, regarding the contrast parameter, individual parameters may be determined collectively, but individual parameters may be determined separately. The contrast parameter may be determined using not only a correspondence table based on the weight W of the subject, the body mass index BMI, the body fat percentage F, etc., but also a predetermined calculation formula.

  Further, for example, as preliminary imaging, low-dose dual energy helical scan using X-rays having a lower dose than contrast imaging may be used, and the weight W of the subject may be estimated from the obtained data. For example, first, as preliminary imaging, low-dose dual energy helical scan of the entire subject is performed, and helical scan data HD1 based on the first X-ray tube voltage E1 and helical scan data HD2 based on the second X-ray tube voltage E2 And collect. Next, the first three-dimensional image V1 of the subject based on the helical scan data HD1 and the second three-dimensional image V2 of the subject based on the helical scan data HD2 are reconstructed. Next, the substance represented by each voxel is roughly specified from the ratio or difference between the CT value of the voxel (pixel) in the first three-dimensional image V1 and the CT value of the corresponding voxel in the second three-dimensional image V2, The three-dimensional image area of the subject is classified into a plurality of substance groups. The substance group is, for example, fat, soft part, bone part or the like. Then, a volume is obtained for each substance group, and the total sum of values obtained by multiplying the volume by the specific gravity corresponding to the substance group is estimated as the weight W of the subject.

1 operation console 2 input device 3 central processing unit (estimating means, determining means)
DESCRIPTION OF SYMBOLS 5 Data collection buffer 6 Monitor 7 Memory | storage device 10 Imaging table 12 Cradle 15 Rotation part 16 Support part 20 Scanning gantry 21 X-ray tube 22 X-ray tube controller 23 Collimator 24 X-ray detector 25 Data collection device 26 Rotation part controller 29 Control controller 30 slip ring 40 subject 50 injector 81 X-ray

Claims (16)

Estimating the weight of the subject based on data obtained by preliminary imaging of the subject by an X-ray CT apparatus;
A contrast parameter determining method comprising: determining a contrast parameter used for contrast imaging of the subject based on the estimated weight. An X-ray CT apparatus for performing contrast imaging of a subject,
An estimation means for estimating the weight of the subject based on data obtained by preliminary imaging performed before the contrast imaging;
An X-ray CT apparatus comprising: a determination unit that determines a contrast parameter used for the contrast imaging based on the body weight estimated by the estimation unit.   The X-ray CT apparatus according to claim 2, wherein the determination unit determines the contrast parameter so that the absolute amount of the contrast component to be injected increases as the body weight increases. The estimation means further estimates a body mass index (BMI) of the subject based on the data,
The X-ray CT apparatus according to claim 2, wherein the determination unit determines the contrast parameter based on the body mass index.   The X-ray CT apparatus according to any one of claims 1 to 3, wherein the determination unit determines the contrast parameter so that an absolute amount of a contrast component to be injected decreases as a body mass index increases. The estimation means further estimates the body fat percentage of the subject based on the data,
The X-ray CT apparatus according to claim 2, wherein the determination unit determines the contrast parameter based on the body fat percentage.   The X-ray CT apparatus according to claim 6, wherein the determination unit determines the contrast parameter so that an absolute amount of a contrast component to be injected becomes smaller as a body fat percentage increases.   The estimation means estimates the body mass index based on the correlation between the X-ray transmittance of the subject obtained from the data and the body mass index, and anatomical images in the subject image obtained from the data The X-ray CT apparatus according to any one of claims 2 to 5, wherein the height is estimated based on a distance between feature points, and the weight is estimated based on the body mass index and the height.   The X-ray CT apparatus according to claim 8, wherein the distance between the anatomical feature points is a predetermined bone length.   The X-ray CT apparatus according to claim 6 or 7, wherein the estimation unit estimates the body fat percentage based on a profile of the data or an analysis result of an image obtained from the data.   The X-ray CT according to any one of claims 2 to 10, wherein the determining unit determines at least one of a contrast medium concentration, a contrast medium injection amount, and a contrast medium injection speed as the contrast parameter. apparatus.   The X-ray CT apparatus according to any one of claims 2 to 11, wherein the preliminary imaging is a scout scan or a helical scan using X-rays having a lower dose than the contrast imaging. The preliminary imaging is a dual energy helical scan using a lower dose of X-ray than the contrast imaging,
The estimation means determines a three-dimensional image region of the subject as a plurality of substances based on a ratio or difference between corresponding pixel values in two types of three-dimensional images of the subject obtained by the dual energy helical scan. 6. The method according to any one of claims 2 to 5, wherein the body weight is estimated as a sum of values obtained by classifying into groups and multiplying the volume of the substance group by a specific gravity corresponding to the substance group for each substance group. X-ray CT apparatus described in 1.   The X-ray CT apparatus according to any one of claims 2 to 13, further comprising a transfer unit that transfers the determined contrast parameter to an injector connected to the X-ray CT apparatus.   When the contrast parameter obtained based on the body weight estimated using the data obtained by the preliminary imaging of the subject by the X-ray CT apparatus is input from the X-ray CT apparatus and the imaging of the subject is performed And an injector for injecting a contrast agent into the subject using the inputted contrast parameter.   The body weight estimated using the data obtained by preliminary imaging of the subject by the X-ray CT apparatus is input from the X-ray CT apparatus, and the contrast used for contrast imaging of the subject based on the input body weight An injector for determining a parameter and injecting a contrast agent into the subject using the determined contrast parameter when performing contrast imaging of the subject.

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