Graduate School of Health Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto, Japan.
Department of Health Sciences, Faculty of Life Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto, Japan.
Phys Med. 2020 Feb;70:153-160. doi: 10.1016/j.ejmp.2020.01.022. Epub 2020 Feb 4.
We investigated the impact of transverse magnetic fields on the dose response of a nanoDot optically stimulated luminescence dosimetry (OSLD) in megavoltage photon beams.
The nanoDot OSLD response was calculated via Monte Carlo (MC) simulations. The responses R and R without and with the transverse magnetic fields of 0.35-3 T were analyzed as a function of depth at a 10 cm × 10 cm field for 4-18 MV photons in a solid water phantom. All responses were determined based on comparisons with the response under the reference conditions (depth of 10 cm and a 10 cm × 10 cm field) for 6 MV without the magnetic field. In addition, the influence of air-gaps on the nanoDot response in the magnetic field was estimated according to Burlin's general cavity theory.
The R as a function of depth for 4-18 MV ranged from 1.013 to 0.993, excepting the buildup region. The R increased from 2.8% to 1.5% at 1.5 T and decreased from 3.0% to 1.1% at 3 T in comparison with R as the photon energy increased. The depth dependence of R was less than 1%, excepting the buildup region. The top air-gap and the bottom air- gap were responsible for the response reduction and the response increase, respectively.
The response R varied depending on the magnetic field intensity, and the variation of R reduced as the photon beam energy increased. The air-gaps affected the dose deposition in the magnetic fields.
我们研究了横向磁场对纳米点光激励发光剂量计（OSLD）在兆伏光子射束中的剂量响应的影响。
通过蒙特卡罗（MC）模拟计算纳米点 OSLD 的响应。分析了在水模体中 10cm×10cm 射野处，4-18MV 光子无磁场和磁场强度为 0.35-3T 时的 R 和 R 响应，作为深度的函数。所有响应都是基于与参考条件（深度为 10cm 和无磁场时的 10cm×10cm 射野）下 6MV 条件下的响应进行比较得出的。此外，根据 Burlin 的通用空腔理论估算了磁场中空气间隙对纳米点响应的影响。
对于 4-18MV，R 作为深度的函数，除了 buildup 区外，范围从 1.013 到 0.993。与光子能量增加时的 R 相比，在 1.5T 时，R 从 2.8%增加到 1.5%，在 3T 时从 3.0%减少到 1.1%。R 的深度依赖性小于 1%，除了 buildup 区。顶空气隙和底空气隙分别导致响应减少和响应增加。
响应 R 随磁场强度而变化，随着光子束能量的增加，R 的变化减少。空气间隙影响磁场中的剂量沉积。
