针对范围和设置不确定性的LETd优化的多离子疗法的稳定性:通过碳,氧和离子束进行评估和增强
Takamitsu Masuda1, Hiroaki Ikawa2, Makoto Shinoto2
1Department of Accelerator and Medical Physics, National Institutes for Quantum Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba, 263-8555, JAPAN.
Physics in medicine and biology
|January 14, 2026
概括
优化头癌的多离子疗法受到范围不确定性的挑战. 使用更重的离子,如氧气,可以提高剂量的均性和稳定性,这对于有效的癌症治疗至关重要.
科学领域:
- 医学物理 医学物理
- 辐射瘤学 辐射瘤学
- 微粒疗法是一种微粒疗法.
背景情况:
- 在优化放射治疗,平衡剂量均性,范围稳定性和高剂量平均线性能量转移 (LETd) 方面,LET三难题提出了挑战.
- 精确的光束传递在多离子疗法中至关重要,特别是在头癌中.
研究的目的:
- 评估范围和设置不确定性对LETd优化的多离子疗法计划的影响.
- 探索在头癌的I阶段LETd升级试验的背景下克服LET三难题的策略.
主要方法:
- 六名头癌患者接受了多离子治疗计划 (碳,氧,离子),目标LETd为90keV/μm.
- 由于停车功率比率的转换和每日设置变化的不确定性,计划被重新计算.
- 强度策略在一个敏感的患者身上进行了测试.
主要成果:
- 距离不确定性是导致计划质量下降的主要原因,而不是设置不确定性.
- 一个小的中央瘤显示~11%的剂量不均性和~3keV/μm的LETd变化由于不确定性.
- 在两个光束口中用氧离子取代碳氧,剂量异质性降低了>7%,同时保持了正常的组织节约.
结论:
- 在多离子疗法中更高的LETd优化增加了对范围不确定性的敏感性,在小型深层瘤中降低了剂量.
- 采用更重的离子通过提高稳定性和目标覆盖率有效解决了这一问题.
- 这些发现支持更重的离子选择,以实现强大的多离子疗法设计.
相关概念视频
01:20¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
When proton-coupled carbon-13 spectra are simplified by a broadband proton decoupling technique, structural information about the coupled protons is lost. Distortionless enhancement by polarization transfer (DEPT) is a technique that provides information on the number of hydrogens attached to each carbon in a molecule. While the DEPT experiment utilizes complex pulse sequences, the pulse delay and flip angle are specifically manipulated. The resulting signals have different phases depending on...
01:27π Electron Effects on Chemical Shift: Overview
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0, resulting in...
01:06Nuclear Overhauser Enhancement (NOE)
Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the nuclear Overhauser enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring spin-active...
01:15Insensitive Nuclei Enhanced by Polarization Transfer (INEPT)
Insensitive Nuclei Enhanced by Polarization Transfer (INEPT) is an advanced Nuclear Magnetic Resonance (NMR) technique specifically designed to detect and enhance the signals of low-abundance nuclei, such as carbon-13 and nitrogen-15, in small molecules. The fundamental principle behind INEPT is the transfer of polarization from a more abundant and highly polarizable nucleus, typically hydrogen-1, to the low-abundance nucleus of interest. This process effectively boosts the NMR signal of the...
01:12Double Resonance Techniques: Overview
Double resonance techniques in Nuclear Magnetic Resonance (NMR) spectroscopy involve the simultaneous application of two different frequencies or radiofrequency pulses to manipulate and observe two distinct nuclear spins. One important application of double resonance is spin decoupling, which selectively suppresses coupling with one type of nucleus while observing the NMR signal from another nucleus, simplifying the spectrum and enhancing resolution.
Spin decoupling is usually achieved by...
Spin decoupling is usually achieved by...