Dose-Rate Variations for Patient Treatments in Flash and conventional radiation therapy

放射治疗是癌症治疗的一个重要组成部分，已经有几十年了。而 肿瘤控制的参数已经被相对较好地理解，正常组织并发症可能， 在治疗方案的设计中，NTCP通常仅被认为是限制因素。 然而，随着原发性病变治疗方法的不断改进，NTCP及其对 生活质量已经成为研究的焦点。 据报道，保护健康组织的最突出的方法之一是FLASH放射疗法，即ul-fuse放射疗法。 超快（>40戈伊/s）辐照，据报道，这会产生令人难以置信的组织保留效果，而不会出现并发症。 有希望的肿瘤治疗效果。相反，也有报道称， 以提供保护功能。总之，这些实验表明，目前的临床常规，治疗 中等剂量率约2戈伊/min的患者，实际上可能是最不利的， 健康组织的副作用 在临床实践中，患者采用各种放射治疗方式进行治疗。结果- 在不同的治疗方式中，靶向剂量相似，输送到正常组织的剂量和时间结构相似。 递送的真实性可以显著变化。尽管治疗计划的剂量率范围不同， 生物效应仅根据接受的总剂量进行估计。 我们假设剂量率在放射治疗的结果中起着重要的作用， 用于特定的治疗方案。对于极端情况，如FLASH治疗，平均剂量- 费率没有充分反映相关的时间结构。我们将应用蒙特卡罗模拟， 确定从分钟（点扫描/机架旋转时间）到NA的临床标度的时间结构， noseconds（点内输送时间），并评估对健康组织保护的潜在影响， 证明放射治疗患者的生活质量。

Radiation therapy has been an important component in the treatment of cancer for many decades. While the parameters of tumor control have been relatively well understood, normal tissue complication proba- bilities (NTCPs) are often only thought of as constraining factors in the design of a treatment regimen. However, with continuously improving treatments of primary lesions, NTCP and their impact on the quality of life have moved into the focus of research. One of the most prominent methods reported to spare healthy tissue is FLASH radiation therapy, i.e. ul- trafast (>40 Gy/s) irradiations, which reportedly results in incredible tissue sparing effects without com- promising efficacy for tumor cure. Conversely, very low dose-rate irradiations have also been reported to offer protective features. Together, these experiments suggest that the current clinical routine, treating patients with a medium dose-rate of ~2 Gy/min, could in fact be the least favorable when considering healthy tissue side effects. In clinical practice, patients are treated with a variety of radiation treatment modalities. While the result- ing target doses are similar across modalities, the dose delivered to the normal tissue and the time struc- ture of the delivery can vary significantly. Despite the range of dose-rates across treatment plans, the biological effect is estimated only based on the total dose received. We hypothesize that dose-rate plays an important role in the outcome of radiation therapy that can be exploited for specific treatment scenarios. For extreme cases such as FLASH therapy, averaged dose- rates do not capture the relevant time structures adequately. We will apply Monte Carlo simulations to determine time structures from the clinical scale of minutes (spot scanning / gantry rotation time) to na- noseconds (intra-spot delivery time) and assess potential effects on healthy tissue sparing that would im- prove the quality of life for radiation therapy patients.