放射治疗高能光子束吸收剂量不同测定规程的比较

Comparison of protocols for the determination of absorbed dose for high-energy photon beams in radiotherapy

目的 :介绍美国医学物理学家协会 (AAPM)最新颁布的高能光子束吸收剂量的测定规程。 方法 :以我院实际使用的剂量仪和电离室按照第 3代规程中推荐的方法测定医用直线加速器 6 MV高能光子束的吸收剂量。 结果 :新规程与第 1代规程比较的差异在 3%左右 ,与第 2代规程相比 ,差异 <1%。 结论 :新一代规程理论严谨 ,表达简明 。

Objectives: To introduce the new protocol for clinical reference dosimetry of high energy beams published by Radiation Therapy Task Group 51, American Association of Physicists in Medicine. Methods: According to the new protocol, measuring the absorbed dose of 6MV X ray produced by the Siemens M6740 accelerator of our hospital with the help of the Capintec 192 electrometer and PR 06C chamber. Results: There is a 3% or so discrepancy between TG 51 and ICRU 14, and no more than 1% between TG 51 and TG 21 or JJG1026 91. Conclusions: The new protocol has advantages of more accuracy and the most convenience to be applied because of its precise rationale and concise formulae.