Task-driven Monte Carlo scattered photon simulation method
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A task-driven, simulation-based technology, applied in radiological diagnostic instruments, 2D image generation, image data processing, etc., can solve problems such as poor result change and difficulty in importance distribution, and achieve the effect of improving simulation efficiency
Inactive Publication Date: 2018-10-09
SOUTHERN MEDICAL UNIVERSITY
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Furthermore, the skill of reducing variance can improve the calculation efficiency only if the user gives a suitable importance distribution of particle interaction points, otherwise the result will be worse, and it is usually the most difficult to give a s...
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Embodiment 1
[0066] Such as Figure 1-5 As shown, a task-driven Monte Carlo scattering photon simulation method, the specific steps are as follows:
[0067] Step 1: Preset and initialize photon scattering parameters to generate an original photon path.
[0068] Among them, the parameters of photon scattering include photon scattering energy, type, order, path probability and number of photon paths, and the total probability of photon scattering path is the product of each fragment probability in all fragments.
[0069] The second step: use the uniform sampling algorithm and the random walk sampling algorithm to sample the positions of the scattering points to generate a simulated photon path.
[0070] In the second step, according to the different positions of the scattering points, the corresponding sampling algorithm is selected for random sampling operation, as follows:
[0071] P1. Determine the position of the scattering point.
[0072] If it is a first-order scatter point, a unifo...
Embodiment 2
[0115] A kind of Monte Carlo scattering photon simulation method based on task-driven, other features are identical with embodiment 1, and difference is: as Image 6 As shown, this embodiment is an actual simulation operation, and the data adopted and acquired below are all obtained from actual operations and are authentic.
[0116] The platform of the simulation operation is the ubuntu-12.04.4 system GPU architecture, the graphics card device is NVIDIAGeForce GTX TITAN Z, the energy of the X-ray source is 60kVp, and the uniform phantom size used is 10×10×2.8cm 3 , the size of the matrix is 250×250×280, the size of the detector is 40cm×30cm, the size of the matrix is 512×384, the distance from the ray source to the rotation center and the distance from the rotation center to the detector are 15.59cm and 49.41cm respectively, the following is Specific simulation steps:
[0117] The first step is to preset and initialize photon scattering energy, type, order, path probabili...
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Abstract
The invention discloses a task-driven Monte Carlo scattered photon simulation method. Specifically, the method comprises the following steps: presetting and initializing photon scattering parameters,so that original photon paths are generated; conducting position sampling on scattering points via a uniform sampling algorithm and a random walk sampling algorithm, so that simulation photon paths are generated; comparing probabilities of the original photon paths and the simulation photon paths; automatically sampling the simulation photon paths via a path sampling algorithm, and judging whetherthe quantity of photon paths of deposition satisfies a preset photon path quantity; if so, ending operations; otherwise, returning to the second step. According to the method, the efficiency of photon scattering simulation is improved from the level of a sampling principle, and a simulation task demand is actively included into a controllable path variable space; the photon paths are subjected variation sampling via an automatic sampling model, then the importance of front and rear sampling paths is taken into comparison and paths, which are relatively important to a simulation task, are selected as current energy deposition paths, so that automatic importance sampling of the photon paths is achieved.
Description
technical field [0001] The invention relates to the technical field of scattered photon simulation, in particular to a task-driven Monte Carlo simulation method for scattered photons. Background technique [0002] Cone-beam computed tomography (CBCT) system is widely used in many clinical departments of hospitals due to its small size, light weight and fast scanning speed, especially in dental CT, breast CT and image-guided radiotherapy . Since the detector used in the CBCT system is a flat-panel detector, the collimator technology cannot be used to shield the scattered rays, so there are serious scattering artifacts in the reconstructed CBCT image. [0003] In order to make CBCT images deeply applied in clinical practice, researchers at home and abroad have carried out a lot of research on the correction of scattering artifacts. Boone J M summarized it into two types of scattering correction technology based on hardware and software. Among them, hardware-based scatter co...
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