Since Favaudon's paper of 2014, there has been an increasing interest in FLASH radiotherapy. The FLASH modality could represent a breakthrough in radiation oncology; nevertheless, it brings new scientific and technological challenges. Currently, one of the main limits the scientific community has to cope with is the lack of a common technological platform to experiment with. Considering this framework, the possibility of readapting existing linac platforms to produce a FLASH beam is particularly attractive and different attempts have been already made. The purpose of this article is to illustrate how it is possible to transform a dedicated Intra Operative Radio Therapy (IORT) mobile linac into a FLASH research machine. Compared to the modification required by a standard medical linac, such transformation is easier, does not affect the machine settings and can be rapidly performed by the final user. NOVAC 7 is an IORT linac which can reach a maximum dose-per-pulse up to 13 cGy/pulse (average dose rate 39 Gy/min); such dose rate can be significantly increased by modifying the collimation system.

Four different Source Surface Distance (SSD) can be obtained:

- Clinical reference configuration;

The fourth configuration allows reaching values of dose-per-pulse up to around 18 Gy/pulse and dose rates up to around 500 Gy/s, at a Pulse Repetition Frequency (PRF) of 30 Hz. The other three configurations can be obtained without using any tool and without changing NOVAC settings, until reaching a FLASH dose rate in the third configuration. For FLASH configurations, relative and absolute dosimetric characterization of the beam were performed using radiochromic films EBT3. NOVAC7 transformed in FLASH mode can be used both for dosimetric testing and characterization of detectors and for radiobiological studies on cells and organoids, offering a wide range of dose-per-pulse, from 3 cGy/pulse up to 18 Gy/pulse; dose rates correspondingly change from 3 cGy/s up to 540 Gy/s.

自Favaudon在2014年发表论文以来，人们对FLASH放射疗法的兴趣日益增加。FLASH模式可能代表放射肿瘤学的突破；但是，它带来了新的科学技术挑战。当前，科学界必须应对的主要限制之一是缺乏通用的实验技术平台。考虑到该框架，重新配置现有的直线加速器平台以产生FLASH光束的可能性特别有吸引力，并且已经进行了不同的尝试。本文的目的是说明如何将专用的手术中放射治疗（IORT）移动直线加速器转变为FLASH研究机器。与标准医疗直线加速器所需的修改相比，这种转换更加容易，不会影响机器设置，并且可以由最终用户快速执行。NOVAC 7是一种IORT直线加速器，可以达到最高每脉冲13 cGy /脉冲的最大剂量（平均剂量率39 Gy / min）；通过修改准直系统，可以显着提高这种剂量率。

可以获得四种不同的源表面距离（SSD）：

-临床参考配置；

第四种配置允许在30 Hz的脉冲重复频率（PRF）时达到高达约18 Gy /脉冲的每脉冲剂量值和高达约500 Gy / s的剂量率。无需使用任何工具，也无需更改NOVAC设置即可获得其他三种配置，直到在第三种配置中达到FLASH剂量率为止。对于FLASH配置，使用放射色膜EBT3进行光束的相对和绝对剂量表征。转换为FLASH模式的NOVAC7可用于剂量测定测试和检测器表征，以及用于细胞和类器官的放射生物学研究，可提供从3 cGy /脉冲到18 Gy /脉冲的大范围每脉冲剂量；剂量率相应地从3 cGy / s变化到540 Gy / s。