BEAM QUALITY SPECIFICATION FOR PHOTON-BEAM DOSIMETRY
BEAM QUALITY SPECIFICATION FOR PHOTON-BEAM DOSIMETRY
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DOI：
10.1118/1.597150
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发表时间：
1993-07-01
期刊：
影响因子：
3.8
通讯作者：
ROGERS, DWO
中科院分区：
文献类型：
--
作者：
KOSUNEN, A;ROGERS, DWO
有人认为，%dd（10），在10 × 10 cm 2的光子束在10 cm的SSD为100 cm的深度剂量的百分比，是一个更好的放射治疗束比TPR 10（20）或标称加速电位（NAP）的常用值的光束质量说明。对于辐射剂量测定目的，TPR 10（20）不是理想的束流质量说明符，因为（i）对于厚靶韧致辐射束，相同TPR 10（20）值的停止功率比可以变化高达0.7%;（ii）对于高能束，TPR 10（20）的值变得对束流质量变化不敏感;（iii）它几乎没有直观意义。相比之下，纯光子束中的%dd（10）规定所有厚靶韧致辐射束的阻止功率比在0.2%以内，保持其对高能束的灵敏度，并且具有简单的物理和临床意义。结果表明，对于所有厚靶韧致辐射束，SPR（水/空气）= 1.2676- 0.002224 [%dd（10）]，均方根偏差为0.1%。在典型的高能量临床光束中的电子污染的影响，可以使用以前发表的实验结果或通过减少电子污染使用铅散射箔进行校正。
It is argued that %dd(10), the percentage depth dose at 10 cm in a 10 X 10 cm2 photon beam at a SSD of 100 cm, is a better beam quality specifier for radiotherapy beams than the commonly used values of TPR10(20) or nominal accelerating potential (NAP). For radiation dosimetry purposes, TPR10(20) is not an ideal beam quality specifier because (i) stopping-power ratios for the same value of TPR10(20) can vary by up to 0.7% for thick-target bremsstrahlung beams; (ii) the value of TPR10(20) becomes insensitive to beam quality changes for high-energy beams; and (iii) it has little intuitive meaning. In contrast, %dd(10) in a pure photon beam specifies stopping-power ratios within 0.2% for all thick-target bremsstrahlung beams, maintains its sensitivity for high-energy beams, and has a simple physical and clinical meaning. It is shown that for all thick-target bremsstrahlung beams the spr (water/air) = 1.2676-0.002 224[%dd(10)] with a rms deviation of 0.1%. The effects of electron contamination in typical high-energy clinical beams can be corrected for using previously published experimental results or by reducing electron contamination using lead scattering foils.