Siddon R L
Phys Med Biol. 1985 Aug;30(8):817-24. doi: 10.1088/0031-9155/30/8/005.
Computing the intersection of a line with a volume, or 'ray tracing' as it is commonly known, is an integral component of three-dimensional radiotherapy dose calculation algorithms. Examples of ray tracing include the intersection of a ray from the radiation source with the patient, with heterogeneous volumes within the patient and with beam-modifying devices, such as a wedge or compensator. Ray tracing is also of primary importance in the field of three-dimensional computer graphics. Through the process of ray tracing, various display features, such as hidden surfaces, shadows, reflection and refraction, can be rendered simply and with startling realism. Advances have recently been made in three-dimensional ray-tracing methods in computer graphics. Due to the similarity of ray tracing in three-dimensional computer graphics and radiotherapy, these new techniques have an immediate application to the ray-tracing problems in three-dimensional radiotherapy dose calculations. The purpose of this paper is to present these advances and illustrate their use in radiation therapy.
计算直线与体积的相交情况，即通常所说的“光线追踪”，是三维放射治疗剂量计算算法的一个不可或缺的组成部分。光线追踪的例子包括从辐射源发出的射线与患者的相交、与患者体内异质体积的相交以及与束流修正装置（如楔形板或补偿器）的相交。光线追踪在三维计算机图形学领域也至关重要。通过光线追踪过程，可以简单地渲染各种显示特征，如隐藏表面、阴影、反射和折射，且具有惊人的真实感。计算机图形学中的三维光线追踪方法最近取得了进展。由于三维计算机图形学中的光线追踪与放射治疗有相似性，这些新技术可直接应用于三维放射治疗剂量计算中的光线追踪问题。本文的目的是介绍这些进展并说明它们在放射治疗中的应用。
