Carleton Laboratory for Radiotherapy Physics, Physics Department, Carleton University, 1125 Colonel By Dr, Ottawa, K1S 5B6, Ontario, Canada.
Phys Med Biol. 2023 Sep 15;68(18). doi: 10.1088/1361-6560/acf183.
Explore the application of Haralick textural analysis to 3D distributions of specific energy (energy imparted per unit mass) scored in cell-scale targets considering varying mean specific energy (absorbed dose), target volume, and incident spectrum.Monte Carlo simulations are used to generate specific energy distributions in cell-scale water voxels ((1m)-(15m)) irradiated by photon sources (mean energies: 0.02-2 MeV) to varying mean specific energies (10-400 mGy). Five Haralick features (homogeneity, contrast, entropy, correlation, local homogeneity) are calculated using an implementation of Haralick analysis designed to reduce sensitivity to grey level quantization and are interpreted using fundamental radiation physics.Haralick measures quantify differences in 3D specific energy distributions observed with varying voxel volume, absorbed dose magnitude, and source spectrum. For example, specific energy distributions in small (1-3m) voxels with low magnitudes of absorbed dose (10 mGy) have relatively high measures of homogeneity and local homogeneity and relatively low measures of contrast and entropy (all relative to measures for larger voxels), reflecting the many voxels with zero specific energy in an otherwise sporadic distribution. With increasing target size, energy is shared across more target voxels, and trends in Haralick measures, such as decreasing homogeneity and increasing contrast and entropy, reflect characteristics of each 3D specific energy distribution. Specific energy distributions for sources of differing mean energy are characterized by Haralick measures, e.g. contrast generally decreases with increasing source energy, correlation and homogeneity are often (not always) higher for higher energy sources.Haralick texture analysis successfully quantifies spatial trends in 3D specific energy distributions characteristic of radiation source, target size, and absorbed dose magnitude, thus offering new avenues to quantify microdosimetric data beyond first order histogram features. Promising future directions include investigations of multiscale tissue models, targeted radiation therapy techniques, and biological response to radiation.
探讨哈勒里克纹理分析在考虑不同平均比能（吸收剂量）、靶区体积和入射能谱的情况下，对细胞尺度靶区的比能（单位质量所传递的能量）三维分布的应用。使用蒙特卡罗模拟生成在细胞尺度水体素（(1m)-(15m)）中比能的分布，这些体素由光子源（平均能量：0.02-2 MeV）辐照，比能变化范围为 10-400 mGy。使用哈勒里克分析的实现计算了 5 种哈勒里克特征（同质性、对比度、熵、相关性、局部同质性），该实现旨在降低灰度量化的敏感性，并使用基本的辐射物理知识进行解释。哈勒里克度量定量描述了不同体素体积、吸收剂量大小和源能谱观察到的三维比能分布的差异。例如，具有低吸收剂量（10 mGy）的小（1-3m）体素的比能分布具有相对较高的同质性和局部同质性度量值，以及相对较低的对比度和熵度量值（相对于较大体素的度量值），反映出在一个零星分布中许多体素的比能为零。随着靶区尺寸的增加，能量在更多的靶区体素中共享，哈勒里克度量的趋势，如同质性降低和对比度和熵增加，反映了每个三维比能分布的特征。不同平均能量源的比能分布由哈勒里克度量值来描述，例如对比度通常随源能量的增加而降低，对于较高能量的源，相关性和同质性通常（并非总是）更高。哈勒里克纹理分析成功地量化了辐射源、靶区大小和吸收剂量大小特征的三维比能分布的空间趋势，从而为量化微剂量数据提供了新的途径，超越了一阶直方图特征。有前途的未来方向包括多尺度组织模型、靶向放射治疗技术和对辐射的生物学反应的研究。
