天然采光计算新法──光束计算法(英文)

本法是以“达尼留克图表”为基础，用简单的计算方法求取投光口的基本光束量。实践表明本法有助于设计人员较好地掌握计算精度、节约时间。 根据“立体角投影定律”的概念，将立体角ω分解为δ和η，分别代表窗洞高度ａ及宽度ｂ与幅射距离ｒ的比值。算出δ和η，立即可换算成ｅ１和ｅ２，那么ｅ１×ｅ２×ｃｏｓθ即窗洞的基本光束量。 考虑到投射角度的变化和墙厚的影响，按下列公式计算δ和η： １．对垂直安装的窗： δ＝（ａｓｉｎθ-ｔｃｏｓθ）ｃｏｓθ／ｈ ① η＝（ｂｓｉｎβ-ｔｃｏｓβ）ｃｏｓθ／ｈ ② ２．对水平安装的窗： δ＝（ａｃｏｓθ-ｔｓｉｎθ）ｃｏｓθ／ｈ ③ η＝（ａｓｉｎβ-ｔｃｏｓβ）ｃｏｓθ／ｈ ３．对大厅式多 窗（垂直安装）： δ＝（ａｃｏｓθ-ｔｃｏｓθ）ｃｏｓθ／ｈ η＝Ｎ（ｂｓｉｎβ-ｔｃｏｓβ）ｃｏｓθ／ｈ ④ ４．对任意倾角安装的窗先用“外切角换面法”换成水平窗，再用③式和②式求得δ、η。 式中：ｈ——窗中点至工作面的高度（Ｍ） Ｎ——多樘窗的樘数。 ｂ——多樘窗的平均宽（Ｍ） ｔ——墙厚（Ｍ） θ——垂直投射倾角， β——水平投射倾角。 算得δ和η成换成ｅ１ｅ２后，按下式计算出采光系数Ｃ。

激光跟踪仪的现场测量精度评定

根据激光跟踪测量系统的特点,用一种评定激光跟踪仪现场测量误差的方法,即布设一个小型实验控制网,从各个测站对所有的固定目标点分别进行测量,对所测的数据进行光束法平差,然后对平差之后水平角、垂直角、斜距的残差进行统计计算,得出跟踪仪在现场的测量精度,这种方法把现场的测量环境,仪器的自身性能,操作人员的水平等因素包括在内。

Evaluation of photon beam dose calculation accuracy of treatment planning systems using in vivo dosimetry

Objective The treatment planning system currently represents one of the basics of radiation therapy,because it is the only method to estimate patient dose delivery fast forward and accurately represent estimated tumor location of the tumor with the possibility of estimating densities in the tissue surrounding the tumor to overcome dose calculation defects but radial estimated the patient.Despite the flaws associated with the systems and calculates the dose of your programs in all programs currently existing in the world.Than necessary,to the existence of a review of the accuracy of accounts and how to confirm the radiation dose to the patient programs.Methods A total of 35 cancer patients were considered for this study,with 245 field measurements made with low-and high-energy diode detectors for brain and prostate cases.The treatments for all patients were planned using Eclipse Treatment Planning System version 13.6.Results Of the 105 field measurements made for the prostate cancer patients,16 included discrepancies outside the ±5% action level.Of the 145 measurements taken of the brain cases,there were four outside the ±5% action level.The results indicated a higher degree of accuracy.The study revealed that,for the prostate measurements,the higher discrepancy in the doses for the particular fields(exceeding the action level) may have been due to the isocenter being very close to the jaws and multi-leaf collimator of the linear accelerator machine.As a result,scatter from the jaws and the multi-leaf collimator could have contributed to the high dose delivered to the diode;hence,a probable higher discrepancy of the dose in more brain cases due highest quality of VMAT technique and fixation system.Conclusion A greater percentage of the observed discrepancies were well within the set tolerance level.However,it is recommended that the positioning of the diode on the patient's skin and the angular sensitivity of the diodes be reconsidered.It is also recommended that a more accurate calculation of expected diode values be performed,especially for fields that pass through the table.These efforts would achieve action levels of ±5%.

空三加密软件PBBA在生产中常见问题的处理方法

本文对使用空三加密过程中易出现的问题进行了技术方面的探讨,并针对这些问题提出解决方法。