Monte Carlo Simulation for the detection of intracranial hematoma using near-infrared light

Abstract

Monte Carlo simulation is a numerical method that can simulate complex physical systems and is widely used in the field of medical optics. For example, the Monte Carlo method was used to evaluate the effectiveness of near-infrared spectroscopy (NIRS) in the detection of intracranial hematoma (ICH). However, due to the relatively complex brain structure, the current simulation model is relatively simple and differs greatly from the actual physiological situation. Many important optical parameters are not selected accurately enough to reliably simulate the actual detection results of near-infrared spectroscopy in ICH, which limits the development and application of this important field.

Based on the visualization results of Monte Carlo simulation implemented by Multi-Scattering software, this project systematically optimizes and analyzes the detection process of near-infrared spectroscopy in ICH, mainly from the two aspects of multi-layer brain structure and detection fiber parameters. Specifically, this project mainly carried out the following three aspects of work:

1. This project improved the previous brain tissue models, by optimizing the optical parameters of the hematoma layer. This includes a more realistic hematoma layer, in which the hematoma occupies a part of the area, and the rest of the area is still cerebrospinal fluid. In addition, a more realistic hematoma anisotropy factor was selected, and the erroneous 0.99 anisotropy factor of the previous researchers was not used. This means that the photon propagation simulation performed by the model is more accurate to reflect the actual situation. This is making the simulation results more reliable, ensuring that the prediction of photon behavior in different tissues is closer to reality, thereby reducing the gap between simulation and actual clinical application.

2. Photon detection is operated by using optical fibers. The influence of optical fibers is simulated with different numerical apertures, as well as with different distances between the incident and the detection fibers. Thus, this study determines the optimal optical fiber configuration scheme. Those simulated results can help in improving sensitivity, stability and accuracy of photon detection.

3. For the first time, the photon path diagram in the $Multi-Scattering$ software of near-infrared intracranial hematoma detection was analyzed. This work can help to identify possible detection blind spots and to improve the accuracy of ICH diagnosis.

The more realistic model designed and simulated by the Multi-Scattering software allows to more accurately locate and quantify intracranial hematomas. This advancement improves the reliability and accuracy of NIRS technology in early intracranial hematoma detection and clinical diagnosis, which may make NIRS a more routine and accurate non-invasive detection tool for intracranial hematomas in the future.

Popular Abstract

Intracranial hematoma(ICH) refers to the accumulation of blood in the brain or between the brain and the skull when there is a head injury or rupture of a cerebral blood vessel. This can cause compression of the brain, causing headaches, vomiting, confusion, and even seizures or coma. If not treated promptly, hematomas can increase intracranial pressure, leading to brain damage or brain herniation, which can be life-threatening in severe cases. Rapid diagnosis and intervention can significantly reduce the risk, and large hematomas usually require surgery to avoid serious sequelae. Detecting hematomas is the basis for rapid diagnosis of hematomas. Through accurate and timely detection, doctors can quickly make a diagnosis and develop an appropriate treatment plan. Therefore, the detection of hematomas is very important.

Traditional CT and MRI detection methods generate a lot of radiation, which is very harmful to the human body. In addition, the equipment is relatively large and inconvenient to use. The near-infrared(NIR) detection method that uses the penetrability of NIR light and combines it with optical imaging equipment to image biological tissues can replace these traditional methods because it is radiation-free and does not require large equipment. However, due to the complex propagation process of NIR light in head tissue, the accuracy of ICH detection still faces great challenges. Scientists introduce Monte Carlo method to describe the characteristics of intracranial light propagation. Monte Carlo simulation is a process of estimating the transmission behavior of light by tracking the movement of a large number of photons after they hit a medium through a specific process. The Multi-Scattering software developed based on this idea can efficiently perform this type of simulation. However, due to the relatively complex brain structure, the current Monte Carlo simulation model is relatively simple, which is quite different from the actual physiological situation. Many important optical parameters are not selected accurately enough, and it is impossible to reliably simulate the actual results of NIR technology in ICH detection.

This project has established a new model based on the predecessors' model to simulate the detection of ICH, and has got more realistic results. In this new model, the 5-layer model is still used, but the change is that the hematoma layer is designed to be located in the middle of the cerebrospinal fluid layer, retaining the surrounding cerebrospinal fluid, rather than completely replacing the cerebrospinal fluid with the hematoma. Further, a new anisotropy factor of 0.88 that is closer to reality is used, rather than the inaccurate 0.99 used by predecessors. The influence of the numerical aperture of the optical fiber for detecting and receiving NIR light on the detection results is also studied.

In this project, ICH detection simulations were performed for different hematoma thicknesses, different skull thicknesses, different scalp absorption coefficients, and different fiber numerical apertures. Some of the simulation results of previous researchers were verified, and some new and interesting results were also found. First, even with the new model, it was still found that the thickness of the hematoma and the thickness of the skull had very little effect on the detection results of ICH, while the effect of the hair, that is, the larger scalp absorption coefficient, had a huge impact on the detection results. These are consistent with the results of previous simulations. However, for the effect of skull thickness, abnormal and interesting results were found, which are different from our general cognition. It was found that the thicker the skull, the easier it is for photons to penetrate the entire brain tissue model. There is no relevant research on the simulation of the effect of fiber numerical aperture on detection. According to these results, it is found that optical fibers with medium numerical apertures are more suitable for this type of detection.

• author: Dang, Xinze
• supervisor: Edouard Berrocal
• organization: Combustion Physics; Department of Physics
• course: PHYM03 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering; Physics and Astronomy
• keywords: Intracranial hematoma, Monte Carlo Simulation, Multi-Scattering software
• language: English
• id: 9174911
• date added to LUP: 2024-09-23 09:29:10
• date last changed: 2024-09-23 09:29:10