Malusek Alexandr, Sandborg Michael, Carlsson Gudrun Alm
Linköping University, Department of Radiation Physics, 581 85 Linköping, Sweden.
Comput Methods Programs Biomed. 2008 May;90(2):167-78. doi: 10.1016/j.cmpb.2007.12.005. Epub 2008 Feb 13.
The CTmod toolkit is a set of C++ class libraries based on the CERN's application development framework ROOT. It uses the Monte Carlo method to simulate energy imparted to a CT-scanner detector array. Photons with a given angle-energy distribution are emitted from the X-ray tube approximated by a point source, transported through a phantom, and their contribution to the energy imparted per unit surface area of each detector element is scored. Alternatively, the scored quantity may be the fluence, energy fluence, plane fluence, plane energy fluence, or kerma to air in the center of each detector element. Phantoms are constructed from homogenous solids or voxel arrays via overlapping. Implemented photon interactions (photoelectric effect, coherent scattering, and incoherent scattering) are restricted to the energy range from 10 to 200keV. Variance reduction techniques include the collision density estimator and survival biasing combined with the Russian roulette. The toolkit has been used to estimate the amount of scatter in cone beam computed tomography and planar radiography.
CTmod工具包是一组基于欧洲核子研究组织（CERN）的应用开发框架ROOT的C++类库。它使用蒙特卡罗方法来模拟传递给CT扫描仪探测器阵列的能量。具有给定角度-能量分布的光子从由点源近似的X射线管发射，穿过体模传输，并对每个探测器元件单位表面积上传递的能量贡献进行计分。或者，计分的量可以是每个探测器元件中心处的注量、能量注量、平面注量、平面能量注量或空气中的比释动能。体模通过重叠由均匀固体或体素阵列构建而成。实现的光子相互作用（光电效应、相干散射和非相干散射）限于10至200keV的能量范围。方差缩减技术包括碰撞密度估计器和与俄罗斯轮盘赌相结合的存活偏倚。该工具包已用于估计锥束计算机断层扫描和平面放射摄影中的散射量。
