Computer simulation analysis of image and patient dosage in Rotational Panoramic Radiography

旋转全景摄影的成像质量和病人剂量受各种机械因素的影响。例如X射线束的垂直角、束宽和束运动模式。为了分别评估各个因素对图像和剂量的影响，我们引入了一种计算机仿真方法。首先，构建用于仿真的头部模型，用数值表示组织和器官。目的组织器官包括空气、软组织、海绵骨、皮质骨、牙齿组织、唾液腺、甲状旁腺和眼晶状体。其次，开发了用于在计算机中再现实际成像过程的模拟程序。利用该程序可以同时模拟多种力学因素下的图像和剂量分布。1.头模体的结构与人类的结构不够忠实。2.应更准确地确定头部体模中各元素的X射线衰减系数。3.根本不考虑散射辐射。这些问题将在不久的将来得到解决。

The image quality and the patient dosage in rotational panoramic radiography are affected by various mechanical factors. such as the vertical angle of x-ray beam, beam width, and beam movement pattern. In order to evaluate separately the effect of each factor on the image and the dosage, we introduced a computer simulation method.At first, the head phantom for simulation, which represented tissues and organs by numerical values, was constructed. Objective tissues and organs were air, soft tissue, spongy bone, cortical bone, tooth tissue, salivary grand, thyroid grand and eye lens. Next, the simulation program for reproducing the actual image formation process in the computer was developed. With this program, the image and the dosage distribution could be simultaneously simulated under several mechanical factors.The present simulation program has the problems as follows. 1. The structure of the head phantom is not sufficiently faithful to that of the human. 2. X-ray attenuation coefficients of each element in the head phantom should be decided more accurately. 3. The scatter radiation is not considered at all.These problems will be resolved in near future.