¹H、⁴He、⁶Li、⁸Be、¹⁰B、¹²C、¹⁴N 和 ¹⁶O 离子形成扩展布拉格峰的剂量和剂量平均 LET 比较。

Dose and dose averaged LET comparison of ¹H, ⁴He, ⁶Li, ⁸Be, ¹⁰B, ¹²C, ¹⁴N, and ¹⁶O ion beams forming a spread-out Bragg peak.

机构信息

Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilissia, 157 71 Athens, Greece.

出版信息

Med Phys. 2011 Dec;38(12):6585-91. doi: 10.1118/1.3662911.

DOI:10.1118/1.3662911

PMID:22149840

Abstract

PURPOSE

Modern clinical accelerators are capable of producing ion beams from protons up to neon. This work compares the depth dose distribution and corresponding dose averaged linear energy transfer (LET) distribution, which is related to the biological effectiveness, for different ion beams (¹H, ⁴He, ⁶Li, ⁸Be, ¹⁰B, ¹²C, ¹⁴N, and ¹⁶O) using multi-energetic spectra in order to configure spread-out Bragg peaks (SOBP).

METHODS

Monte Carlo simulations were performed in order to configure a 5 cm SOBP at 8 cm depth in water for all the different ion beams. Physical dose and dose averaged LET distributions as a function of depth were then calculated and compared. The superposition of dose distribution of all ions is also presented for a two opposing fields configuration. Additional simulations were performed for (12)C beams to investigate the dependence of dose and dose averaged LET distributions on target depth and size, as well as beam configuration. These included simulations for a 3 cm SOBP at 7, 10, and 13 cm depth in water, a 6 cm SOBP at 7 depth in water, and two opposing fields of 6 cm SOBP.

RESULTS

Alpha particles and protons present superior physical depth dose distributions relative to the rest of the beams studied. Dose averaged LET distributions results suggest higher biological effectiveness in the target volume for carbon, nitrogen and oxygen ions. This is coupled, however, with relatively high LET values-especially for the last two ion species-outside the SOBP where healthy tissue would be located. Dose averaged LET distributions for ⁸Be and ¹⁰B beams show that they could be attractive alternatives to ¹²C for the treatment of small, not deeply seated lesions. The potential therapeutic effect of different ion beams studied in this work depends on target volume and position, as well as the number of beams used.

CONCLUSIONS

The optimization of beam modality for specific tumor cites remains an open question that warrants further investigation and clinically relevant results.

摘要

目的

现代临床加速器能够产生从质子到氖的离子束。本研究比较了不同离子束（¹H、⁴He、⁶Li、⁸Be、¹⁰B、¹²C、¹⁴N 和 ¹⁶O）在多能谱下形成扩展布拉格峰（SOBP）的深度剂量分布和相应的平均线性能量传递（LET）分布，后者与生物学效应有关。

方法

为了在水中 8 cm 深度处配置 5 cm 的 SOBP，我们进行了蒙特卡罗模拟，以配置所有不同离子束的 SOBP。然后计算并比较了物理剂量和剂量平均 LET 分布随深度的变化。还呈现了所有离子的剂量分布叠加，用于两个相对场的配置。还针对（12）C 束进行了额外的模拟，以研究剂量和剂量平均 LET 分布对靶深度和大小以及束配置的依赖性。这些模拟包括在水中 7、10 和 13 cm 深度处配置 3 cm 的 SOBP，在水中 7 cm 深度处配置 6 cm 的 SOBP，以及两个 6 cm 的 SOBP 相对场。

结果

与研究的其他束相比，α粒子和质子具有优越的物理深度剂量分布。剂量平均 LET 分布结果表明，在靶区中，碳、氮和氧离子的生物学效应更高。然而，在 SOBP 之外，健康组织所在的位置，相对较高的 LET 值（尤其是对于后两种离子）会导致这种情况。⁸Be 和 ¹⁰B 束的剂量平均 LET 分布表明，它们可能是¹²C 治疗小而不深的病变的有吸引力的替代品。本研究中研究的不同离子束的潜在治疗效果取决于靶区体积和位置以及使用的束数。