CN101458826B - Digital human body modeling method for assigning density, constituent by CT value - Google Patents

Abstract

The invention discloses a digital body modeling method for using CT values to endow density and composing components, comprising: after obtaining a colorful picture and a CT film of human body, registering and dividing the colorful picture, marking important organs or tissues of human body; converting the CT values of the CT film after colorful picture registration, to obtain the density and composing components of the organs or tissues. The inventive digital body model can actually represent the three-dimension geometric information of human body, and can actually represent the internal anatomical structure of human body, which can be used to evaluate body radiation dose in nuclear medicine and radiation protection fields.

Description

Utilize the digital human body modeling method of CT value assigning density, constituent

Technical field

The present invention relates to a kind of digital human body modeling method, especially relate to flow process and the density of digital human body modeling, the method that constituent is given.

Background technology

The digital human body model is called for short Digital human, is to utilize the manikin of medical image CT/MRI/ photochrome data through the embodiment 3 D anatomy structure of computer technology structure, is mainly used in fields such as nuclear medicine and radiation protection.The assessment of human body radiation dosage is one of nuclear medicine and radiation proof vital task.In real work, because the restriction of objective condition such as time, place, detector often can't or be inconvenient to directly measure.The exploitation of digital human body model provides brand-new means for the research of radiation protection and nuclear medicine, and in addition, the digital human body model also will be widely used in relevant field such as space flight, aviation, military and national defense and automobile, building, clothes, furniture.In the last few years, expression human body whole body or local model had obtained in fields such as radiation protection using widely.

In the process of setting up the digital human body model, giving of physical attributes such as density and constituent is to set up a very crucial step of model.Yet existing digital human body model all is average density and the constituent that report provides according to ICRP/ICRU gives each volume elements in the same organ or tissue; Because each organ or tissue all comprises a large amount of volume elements; Make like this in an organ or tissue; The density of each position, constituent are all identical, and the actual anatomical structures of this and human body obviously is not inconsistent.In addition, because human organ and the recommended value of organizing number more than the ICRP report, some organ or tissue inevitably utilizes similar structures to be similar to.Even be not similar to, the ICRP value of the report recommends also is the mean value that obtains through limited number, has certain error.

When making up the digital human body model, the view data of generally having gathered CT sheet and two kinds of forms of photochrome of human body simultaneously.Wherein, photochrome resolution is high, is easy to cut apart organ or tissue, but density information is not provided, and only has only colouring information; The CT sheet provides the density and the constituent information of organ or tissue, but its resolution is not easy to cut apart organ or tissue than low of photochrome data more.Set up the digital human body model if can use photochrome and CT sheet simultaneously; Promptly utilize photochrome to cut apart organ or tissue; Utilize the CT sheet to obtain the density and the constituent of volume elements; That can make full use of the advantage of two kinds of data, and the model of setting up like this is the anatomical structure of true embodiment human body more.

Summary of the invention

The objective of the invention is to existing digital human body modeling method; Can not react the shortcoming of the actual anatomical structures of human body really; And a kind of digital human body modeling method that utilizes CT value assigning density, constituent that proposes; The present invention is cut apart photochrome behind the CT sheet/photochrome that obtains same human body, identifies each organ or tissue of human body; The density of organ or tissue and constituent by with the photochrome registration after the CT sheet in the CT value be converted to through certain mathematical.The digital human body model that the inventive method is set up not only can reproduce the three-dimensional geometric information of human body really, also can represent the anatomical structure of inside of human body really.

A kind of digital human body modeling method that utilizes CT value assigning density, constituent is characterized in that may further comprise the steps:

(1) when obtaining the human body faultage image data, gathers the data of CT sheet and two kinds of forms of photochrome simultaneously;

(2) cut apart, identify each organ and the tissue of human body:

On photochrome, delineate out each organ of human body by hand and organize outline, fill, obtained shape, size, the geological informations such as position in human body of each organ and tissue with various colors;

(3) registration of CT sheet and photochrome:

CT sheet and photochrome are carried out registration, make the pixel of the two corresponding, behind the registration, according to the outline information of organ that on photochrome, is partitioned into and tissue, the outline information of organ and tissue on the acquisition CT sheet;

(4) obtain the density information of organ or tissue:

Because the CT value in the CT sheet is relevant with the density and the constituent of measured material, ask for the corresponding density of each organ or tissue from the CT value of each organ or tissue of human body;

(5) obtain the constituent information of organ or tissue:

Suppose that human body organ or tissue is made up of two kinds of materials of known CT value, density and constituent, be respectively (H1, ρ 1; ω 1) and (H2, ρ 2, ω 2); Wherein ω 1 representes the mass percent of certain element in two components respectively with ω 2, and H1, H2 are the CT value, and ρ 1, ρ 2 are density; Make H1≤H≤H2, then can obtain the expression formula of certain element mass percent ω in this organ or tissue:

$\mathrm{\ω}=\frac{{\mathrm{\ρ}}_1(H_2-H)}{{\mathrm{\ρ}}_1{H}_2-{\mathrm{\ρ}}_2{H}_1+({\mathrm{\ρ}}_2-{\mathrm{\ρ}}_1)H}({\mathrm{\ω}}_1-{\mathrm{\ω}}_2)+{\mathrm{\ω}}_2$

According to above method, the constituent that from the CT value, obtains is used to give each volume elements, and different volume elements all has corresponding constituent in same organ or tissue like this;

(6) set up the digital human body model:

According to the density and the constituent information of the above-mentioned organ or tissue that obtains, the form that requires according to the Rapid Dose Calculation method generates corresponding input file, carries out the various analog computations of human body radiation dosage.

Described digital human body modeling method; The method that it is characterized in that obtaining the density of organ or tissue is: human organ or tissue are divided between several region according to the CT value; Correspondingly the density of human body is also between zoning; After the pairing density range of known each interval CT value scope, utilize the linear relationship of CT value and density, just can utilize approach based on linear interpolation to try to achieve the corresponding density value of each volume elements of known CT value.

If CT is i, j, k are that (i, j k) locate the CT value of volume elements, and density_lower, density_upper, CT_lower, CT_upper represent density lower limit, upper density limit, CT value lower limit, the CT value upper limit in the range of linearity respectively; If M is i, j, k are the density of this volume elements, M i then, and j, k can obtain with following formula:

$M_{i,j,k}=\mathrm{density}\_\mathrm{lower}+\frac{(\mathrm{density}\_\mathrm{upper}-\mathrm{density}\_\mathrm{lower})}{\mathrm{CT}\_\mathrm{upper}-\mathrm{CT}\_\mathrm{lower}}*(\mathrm{CT}\_\mathrm{upper}-{\mathrm{CT}}_{i,j,k})$

According to said method, the density that from the CT value, obtains is used for giving each volume elements, obtains the corresponding density value of volume elements different in the same organ or tissue.

Beneficial effect of the present invention is: the digital human body model that adopts the inventive method to set up has made full use of the advantage of photochrome and CT sheet, not only can reproduce the three-dimensional geometric information of human body really, also can represent the anatomical structure of inside of human body really.

Description of drawings

Fig. 1 is a process synoptic diagram of setting up the digital human body model.

Fig. 2 is the transformational relation synoptic diagram between CT value and the density.

Embodiment

Referring to Fig. 1, Fig. 2.

Utilize the digital human body modeling method of CT value assigning density, constituent: may further comprise the steps:

(1) cuts apart, identifies each organ and the tissue of human body

When obtaining the human body faultage image data, gather the data of CT sheet and two kinds of forms of photochrome simultaneously; Because the resolution of photochrome is very high, can realize cutting apart of more accurate organ and tissue.Human body each important organ and tissue are delineated out outline by manual, and are filled with various colors on photochrome.Shape, the size of each organ and tissue have so just been obtained, geological informations such as the position in human body.

(2) registration of CT sheet and photochrome

Because the resolution of CT sheet and photochrome is different, its pixel correspondence that differs when using two kinds of data to set up the digital human body model simultaneously, must be carried out registration to both, makes both pixels corresponding.Through behind the registration, according to the profile information of the organ or tissue that is partitioned on the photochrome after cutting apart, just can obtain the profile information that the CT sheet is attend organ or tissue, be equivalent on the CT sheet, cut apart.

(3) obtain the density information of organ or tissue:

Because the CT value in the CT sheet is relevant with the density and the constituent of measured material, just can obtain the various property parameters of (volume elements) tissue in the small volume element through the certain mathematical conversion.The method of asking density of the present invention is to adopt interval method, is about to human body CT value scope and is divided between several region, accordingly also between the density zoning with human body.In same interval, density of medium and the sexual intercourse of CT value retention wire.Therefore, after knowing the pairing density range of some CT value scope, just can utilize approach based on linear interpolation to try to achieve the corresponding density of required CT value.Accompanying drawing 2 is to be example to be divided into 6 intervals to CT value scope, the graph of a relation between CT value and the density.

If CT is i, j, k are that (i, j k) locate the CT value of volume elements, and density_lower, density_upper, CT_lower, CT_upper represent density lower limit, upper density limit, CT value lower limit, the CT value upper limit in the range of linearity respectively.If M is i, j, k are the density of this volume elements, M i then, and j, k can obtain with following formula:

$M_{i,j,k}=\mathrm{density}\_\mathrm{lower}+\frac{(\mathrm{density}\_\mathrm{upper}-\mathrm{density}\_\mathrm{lower})}{\mathrm{CT}\_\mathrm{upper}-\mathrm{CT}\_\mathrm{lower}}*(\mathrm{CT}\_\mathrm{upper}-{\mathrm{CT}}_{i,j,k})$

According to said method, the density that from the CT value, obtains is used to give each volume elements, and different volume elements all has corresponding density value in same organ or tissue like this.

(4) obtain the constituent information of organ or tissue:

Suppose that certain organ or tissue is made up of two kinds of materials of known CT value, density and constituent, be respectively (H1, ρ 1, ω 1) and (H2, ρ 2, ω 2), wherein ω 1 representes the mass percent of certain element in two components respectively with ω 2.Make H1≤H≤H2, then can obtain the expression formula that this tissue element is formed situation ω:

$\mathrm{\ω}=\frac{{\mathrm{\ρ}}_1(H_2-H)}{{\mathrm{\ρ}}_1{H}_2-{\mathrm{\ρ}}_2{H}_1+({\mathrm{\ρ}}_2-{\mathrm{\ρ}}_1)H}({\mathrm{\ω}}_1-{\mathrm{\ω}}_2)+{\mathrm{\ω}}_2$

According to above method, the constituent that from the CT value, obtains is used to give each volume elements, and different volume elements all has corresponding constituent in same organ or tissue like this.

(5) set up the digital human body model

According to the density and the constituent of the above-mentioned organ or tissue that obtains, the form that requires according to the Rapid Dose Calculation method generates corresponding input file, just can carry out the various analog computations of human body radiation dosage.

Claims (1)

1. digital human body modeling method that utilizes CT value assigning density, constituent is characterized in that may further comprise the steps:

(1) when obtaining the human body faultage image data, gathers the data of CT sheet and two kinds of forms of photochrome simultaneously;

(2) cut apart, identify each organ and the tissue of human body:

On photochrome, delineate out each organ of human body by hand and organize outline, fill, obtained three kinds of geological informations in shape, size, the position in human body of each organ and tissue with various colors;

(3) registration of CT sheet and photochrome:

CT sheet and photochrome are carried out registration, make the pixel of the two corresponding, behind the registration, according to the outline information of organ that on photochrome, is partitioned into and tissue, the outline information of organ and tissue on the acquisition CT sheet;

(4) obtain the density information of organ or tissue:

Because the CT value in the CT sheet is relevant with the density and the constituent of measured material, ask for the corresponding density of each organ or tissue from the CT value of each organ or tissue of human body;

(5) obtain the constituent information of organ or tissue:

Suppose that human body organ or tissue is made up of two kinds of materials of known CT value, density and constituent, be respectively (H1, ρ 1; ω 1) and (H2, ρ 2, ω 2); Wherein ω 1 representes the mass percent of certain element in two components respectively with ω 2, and H1, H2 are the CT value, and ρ 1, ρ 2 are density; Make H1≤H≤H2, then can obtain the expression formula of this kind element mass percent ω in this organ or tissue:

$\mathrm{\ω}=\frac{{\mathrm{\ρ}}_1(H_2-H)}{{\mathrm{\ρ}}_1{H}_2-{\mathrm{\ρ}}_2{H}_1+({\mathrm{\ρ}}_2-{\mathrm{\ρ}}_1)H}({\mathrm{\ω}}_1-{\mathrm{\ω}}_2)+{\mathrm{\ω}}_2$

The constituent that from the CT value, obtains is used to give each volume elements, and different volume elements all has corresponding constituent in same organ or tissue like this;

(6) set up the digital human body model:

According to the density and the constituent information of the organ or tissue that obtains, the form that requires according to the Rapid Dose Calculation method generates corresponding input file, carries out the various analog computations of human body radiation dosage;

The method of asking for the corresponding density of each organ or tissue from the CT value of each organ or tissue of human body in the said step (4) is: human organ or tissue are divided between several region according to the CT value; Correspondingly the density of human body is also between zoning; After the pairing density range of known each interval CT value scope; Utilize the linear relationship of CT value and density, just can utilize approach based on linear interpolation to try to achieve the corresponding density value of each volume elements of known CT value;

If CT _{I, j, k}For (i, j k) locate the CT value of volume elements, and density_lower, density_upper, CT_lower, CT_upper represent density lower limit, upper density limit, CT value lower limit, the CT value upper limit in the range of linearity respectively; If M _{I, j, k}Be the density of this volume elements, then M _{I, j, k}Can obtain with following formula:

$M_{i,j,k}=\mathrm{density}\_\mathrm{lower}+\frac{(\mathrm{density}\_\mathrm{upper}-\mathrm{density}\_\mathrm{lower})}{\mathrm{CT}\_\mathrm{upper}-\mathrm{CT}\_\mathrm{lower}}*(\mathrm{CT}\_\mathrm{upper}-{\mathrm{CT}}_{i,j,k})$

The density that from the CT value, obtains is used for giving each volume elements, obtains the corresponding density value of volume elements different in the same organ or tissue.

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