German Cancer Research Center - DKFZ, Heidelberg, Germany.
Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal.
Sci Rep. 2020 Apr 24;10(1):7007. doi: 10.1038/s41598-020-63215-0.
Proton and ion beam therapy has proven to benefit tumour control with lower side-effects, mostly in paediatrics. Here we demonstrate a feasible technique for proton and ion beam spectroscopy (PIBS) capable of determining the elemental compositions of the irradiated tissues during particle therapy. This follows the developments in prompt gamma imaging for online range verification and the inheritance from prompt gamma neutron activation analysis. Samples of water solutions were prepared to emulate varying oxygen and carbon concentrations. The irradiation of those samples and other tissue surrogate inserts by protons and ion beams under clinical conditions clearly showed a logarithmic relationship between the target elemental composition and the prompt gamma production. This finding is in line with the known logarithmic dependence of the pH with the proton molar concentration. Elemental concentration changes of 1% for calcium and 2% for oxygen in adipose, brain, breast, liver, muscle and bone-related tissue surrogates were clearly identified. Real-time in vivo measurements of oxygen, carbon and calcium concentrations will be evaluated in a pre-clinical and clinical environment. This technique should have an important impact in the assessment of tumour hypoxia over the course of several treatment fractions and the tracking of calcifications in brain metastases.
质子和离子束治疗已被证明可以在降低副作用的情况下更好地控制肿瘤，尤其是在儿科领域。在这里，我们展示了一种可行的质子和离子束光谱学（PIBS）技术，该技术能够在粒子治疗过程中确定受照组织的元素组成。这是在即时伽马成像技术用于在线射程验证以及即时伽马中子激活分析技术的基础上发展起来的。我们制备了水溶液样品来模拟不同的氧和碳浓度。在临床条件下，用质子和离子束辐照这些样品和其他组织替代物，清楚地显示出靶元素组成与瞬时伽马产生之间存在对数关系。这一发现与质子摩尔浓度与 pH 值的已知对数依赖性一致。在脂肪、脑、乳腺、肝、肌肉和骨相关组织替代物中，钙的浓度变化 1%，氧的浓度变化 2%，都得到了明确的识别。将在临床前和临床环境中评估实时体内氧、碳和钙浓度的测量。这项技术对于评估肿瘤缺氧在几次治疗过程中的变化以及跟踪脑转移中的钙化情况应该具有重要影响。
