Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Ismaninger Str. 22, 81675 München, Germany.
Phys Med Biol. 2012 Mar 7;57(5):N47-53. doi: 10.1088/0031-9155/57/5/N47. Epub 2012 Feb 14.
Laser-driven particle acceleration is a potentially cost-efficient and compact new technology that might replace synchrotrons or cyclotrons for future proton or heavy-ion radiation therapy. Since the energy spectrum of laser-accelerated particles is rather wide, compared to the monoenergetic beams of conventional machines, studies have proposed the usage of broader spectra for the treatment of at least certain parts of the target volume to make the process more efficient. The thereby introduced additional uncertainty in the applied energy spectrum is analysed in this note. It is shown that the uncertainty can be categorized into a change of the total number of particles, and a change in the energy distribution of the particles. The former one can be monitored by a simple fluence detector and cancels for a high number of statistically fluctuating shots. The latter one, the redistribution of a fixed number of particles to different energy bins in the window of transmitted energies of the energy selection system, only introduces smaller changes to the resulting depth dose curve. Therefore, it might not be necessary to monitor this uncertainty for all applied shots. These findings might enable an easier uncertainty management for particle therapy with broad energy spectra.
激光驱动粒子加速是一种潜在的高效、紧凑的新技术，可能会取代同步加速器或回旋加速器，用于未来的质子或重离子放射治疗。由于激光加速粒子的能谱比传统机器的单能束要宽得多，因此研究人员提出了使用更宽的能谱来治疗靶区的至少某些部分，以提高治疗效率。本研究分析了在此过程中引入的附加能谱不确定性。结果表明，不确定性可以分为粒子总数的变化和粒子能量分布的变化。前者可以通过简单的剂量计进行监测，并且在大量统计波动的射束中会相互抵消。后者，即固定数量的粒子在能谱选择系统的透射能窗内重新分配到不同的能量bins 中，只会对最终的深度剂量曲线产生较小的影响。因此，对于所有应用的射束，可能没有必要监测这种不确定性。这些发现可能会使具有宽能谱的粒子治疗的不确定性管理更加容易。
