CN-122025156-A - Monte Carlo-based adult rat fine eye model and dose calculation method

CN122025156ACN 122025156 ACN122025156 ACN 122025156ACN-122025156-A

Abstract

The invention discloses a Monte Carlo-based adult rat fine eye model and a dose calculation method, which comprise the steps of obtaining adult rat eye structure information, comparing and integrating the structure information with literature data, carrying out experimental verification on data with differences to obtain verified structure parameters, constructing a three-dimensional adult rat eye geometric model in Monte Carlo simulation software, setting material parameters for different eye tissues in the three-dimensional geometric model, setting the type, energy, direction and spatial distribution of incident particle beams in the Monte Carlo simulation software, establishing a coordinate system by taking an eye axis of the three-dimensional geometric model as a reference direction, carrying out particle transport and interaction simulation to track the transport process of primary particles and secondary particles thereof in the three-dimensional geometric model, setting a dose sensitive unit, recording energy deposition in the volume of a crystalline lens, and normalizing the energy deposition based on the total mass of the crystalline lens to obtain the average absorbed dose of the crystalline lens.

Inventors

LI HUAN
TANG YUFU
BAI XUFANG
ZHAN JINGMING
XUE XIANGMING
GU XIAONA
YANG KAI
ZHANG TENG
WU ZHAO

Assignees

中国辐射防护研究院

Dates

Publication Date: 20260512
Application Date: 20251229

Claims (10)

1. A monte carlo-based adult rat fine eye model and dose calculation method, comprising: Acquiring eye structure information of an adult rat, wherein the structure information at least comprises size parameters, morphological characteristics and mutual position relations of cornea, sclera, choroid, retina, optic nerve, crystalline lens, vitreous body, anterior chamber and ciliary body; Comparing and integrating the structural information with literature data, and carrying out experimental verification on data with differences to obtain verified structural parameters; in Monte Carlo simulation software, constructing a three-dimensional geometrical model of the adult rat eye according to the verified structural parameters, and setting material parameters for different eye tissues in the three-dimensional geometrical model; Setting the type, energy, direction and space distribution of an incident particle beam in the Monte Carlo simulation software, establishing a coordinate system by taking an eye axis of the three-dimensional geometric model as a reference direction, and performing particle transport and interaction simulation to track the transport process of primary particles and secondary particles thereof in the three-dimensional geometric model; a dose-sensitive unit is arranged in the lens region of the three-dimensional geometric model, energy deposition in the lens volume is recorded, and the energy deposition is normalized based on the total lens mass to obtain an average absorbed dose of the lens.
2. The method of claim 1, wherein the acquiring adult rat eye structure information comprises: And obtaining eye tissues in an anatomical mode, and measuring and calculating the length, thickness, diameter and curvature radius of each eye tissue.
3. The method of claim 1, wherein the validated structural parameters include at least one or more of the following parameters: The radius of curvature of the inner wall of the cornea is 3.2mm, the radius of curvature of the outer wall of the cornea is 3.5mm, the thickness of the cornea is 0.15mm, the thickness of the sclera is 0.12mm, the thickness of the choroid is 0.08mm, the thickness of the retina and the optic nerve is 0.18mm, the diameter of the lens is 3mm, the thickness of the lens is 2.2mm, the radius of curvature of the front surface of the lens is 2.8mm, and the radius of curvature of the rear surface of the lens is 2.5mm.
4. The method of claim 1, wherein constructing the three-dimensional geometric model of an adult rat eye comprises constructing a cornea model using a hyperboloid of revolution, the cornea model satisfying: Wherein, the In the form of a transverse coordinate, the transverse coordinate, As the axial coordinate of the two-dimensional coordinate system, Is a curvature parameter and , In order to be the radius of curvature of the cornea, Is an aspherical coefficient.
5. The method of claim 1, wherein constructing the three-dimensional geometric model of the adult rat eye comprises constructing a lens model using a double-layer ellipsoid, the anterior lens surface satisfying: Wherein, the 、 In the form of a transverse coordinate, the transverse coordinate, As the axial coordinate of the two-dimensional coordinate system, 、 Is the parameter of an ellipsoid half-axis, Is offset from the center of the anterior lens surface in the axial direction, and the radius of curvature of the posterior lens surface is increased by 12% relative to the radius of curvature of the anterior lens surface.
6. The method of claim 1, wherein constructing the three-dimensional geometric model of the adult rat eye comprises constructing an iris model using an annular plane, the iris model satisfying: Wherein, the Is the radius of the inner diameter of the iris, Is the radius of the outer diameter of the iris, and the optical absorption coefficient of the iris is set as 。
7. The method of claim 1, wherein the constructing the three-dimensional geometric model of the adult rat eye comprises posterior segment tissue modeling comprising at least: The retina/choroid adopts concentric spherical shell layers and meets the requirements And adopts an exponential decay model: The glass body adopts filled spheres and is provided with a nonuniform scattering field: Wherein, the Is the outer radius of the spherical shell, In order to be a radial distance from each other, Is of depth The strength of the part is that of the part, For the initial intensity of the light to be at the same time, Is the coefficient of the exponential decay, Is radial position And a scattering coefficient.
8. The method of claim 1, wherein the setting up an incident particle beam and performing a simulation comprises: Angle of incident particle beam to eye axis Is set at least two angles of 0 °, 15 °,30 ° and 45 °, and the incident particle beam energy is set to Is set within the range of 1keV to 1 TeV.
9. The method of claim 1, further comprising constructing a lens dose response function based on the simulated data, the lens dose response function being: Wherein, the For the kinetic energy of the incident particles, For the angle between the incident particle and the eye axis, The dose is absorbed by the lens and, For coefficients obtained by least squares fitting, As the order of the energy term polynomial, Is the polynomial order of the angle term.
10. The method of claim 1, wherein the normalizing the energy deposition to obtain a lens average absorbed dose satisfies: Wherein, the For the average absorbed dose of the lens, The total deposition energy recorded for the lens dose-sensitive unit, Is the total mass of the lens.

Description

Monte Carlo-based adult rat fine eye model and dose calculation method Technical Field The invention relates to the field of nuclear medicine, in particular to a Monte Carlo-based adult rat fine eye model and a dose calculation method. Background The ocular lens is sensitive to ionizing radiation, and in application scenes such as radiobiological research, radiation protection evaluation, space radiation risk analysis and the like, the absorbed dose of the lens in a specific radiation field is often required to be obtained as a basis for damage evaluation and threshold judgment. Since the lens is located behind the cornea, anterior chamber, iris/ciliary body, vitreous body, and other multi-tissue structures, the incident particles undergo complex physical processes such as scattering, energy deposition, and secondary particle generation during intraocular propagation, resulting in significant correlation of lens dose to particle type, energy, and direction of incidence, which is difficult to accurately characterize by simple approximation or external dose substitution alone. In the prior art, lens dose assessment typically relies on physical dosimeter measurements or computational model-based dosimetry simulations. Among them, the monte carlo method is capable of tracking particle transport and calculating energy deposition under tissue non-uniform medium and complex geometry, and is considered as an important means for high-precision dose calculation. However, the Monte Carlo calculation result is highly dependent on the fineness of the eye geometric model, the tissue material parameter setting and the authenticity of the structural dimensions, and if the model adopts a simplified sphere/ellipsoid approximation, only reference to unverified literature parameters, or insufficient description of the morphology and relative position of tissues such as the cornea, sclera, choroid, retina, lens, vitreous, anterior chamber and ciliary body, systematic errors are easily introduced, thereby affecting the credibility and repeatability of the lens dose. In addition, under the combined condition of different energies and incident angles, if Monte Carlo simulation is completely carried out each time to obtain the lens dose, the calculation cost is high, the requirements of rapid evaluation and parameterized analysis are difficult to meet, and meanwhile, the lack of a dose response relation for engineering call also limits the popularization and application of related research results. . Disclosure of Invention To achieve the above and other related objects, the present invention discloses a method for calculating a fine eye model and a dose of an adult rat based on monte carlo, comprising: Acquiring eye structure information of an adult rat, wherein the structure information at least comprises size parameters, morphological characteristics and mutual position relations of cornea, sclera, choroid, retina, optic nerve, crystalline lens, vitreous body, anterior chamber and ciliary body; Comparing and integrating the structural information with literature data, and carrying out experimental verification on data with differences to obtain verified structural parameters; in Monte Carlo simulation software, constructing a three-dimensional geometrical model of the adult rat eye according to the verified structural parameters, and setting material parameters for different eye tissues in the three-dimensional geometrical model; Setting the type, energy, direction and space distribution of an incident particle beam in the Monte Carlo simulation software, establishing a coordinate system by taking an eye axis of the three-dimensional geometric model as a reference direction, and performing particle transport and interaction simulation to track the transport process of primary particles and secondary particles thereof in the three-dimensional geometric model; a dose-sensitive unit is arranged in the lens region of the three-dimensional geometric model, energy deposition in the lens volume is recorded, and the energy deposition is normalized based on the total lens mass to obtain an average absorbed dose of the lens. Preferably, the acquiring the eye structure information of the adult rat includes: And obtaining eye tissues in an anatomical mode, and measuring and calculating the length, thickness, diameter and curvature radius of each eye tissue. Preferably, the validated structural parameters include at least one or more of the following parameters: The radius of curvature of the inner wall of the cornea is 3.2mm, the radius of curvature of the outer wall of the cornea is 3.5mm, the thickness of the cornea is 0.15mm, the thickness of the sclera is 0.12mm, the thickness of the choroid is 0.08mm, the thickness of the retina and the optic nerve is 0.18mm, the diameter of the lens is 3mm, the thickness of the lens is 2.2mm, the radius of curvature of the front surface of the lens is 2.8mm, and the radius of curvature of the rear sur