FLASH radiotherapy is a novel technique that has been shown in numerous preclinical in vivo studies to have the potential to be the next important improvement in cancer treatment. However, the biological mechanisms responsible for the selective FLASH sparing effect of normal tissues are not yet known. An optimal translation of FLASH radiotherapy into the clinic would require a good understanding of the specific beam parameters that induces a FLASH effect, environmental conditions affecting the response, and the radiobiological mechanisms involved. Even though the FLASH effect has generally been considered as an in vivo effect, studies finding these answers would be difficult and ethically challenging to carry out solely in animals. Hence, suitable in vitro studies aimed towards finding these answers are needed. In this review, we describe and summarise several in vitro assays that have been used or could be used to finally elucidate the mechanisms behind the FLASH effect.
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http://dx.doi.org/10.1017/erm.2022.5 | DOI Listing |
Nanoscale Adv
December 2024
Department of Pharmacy, The First Affiliated Hospital of Wannan Medical College, Yijishan Hospital of Wannan Medical College Wuhu China
Ultra-high dose-rate (FLASH) radiotherapy serves as an ideal procedure to treat tumors efficiently without harming normal tissues and has demonstrated satisfactory antitumor effects in multiple animal tumor models. However, the biological mechanisms of FLASH radiotherapy have not yet been fully elucidated, and the small number of devices delivering FLASH dose rate has limited its wide application. This review summarizes the possible biological mechanisms and antitumor effects of FLASH radiotherapy, its application in nanotherapeutic strategy, as well as its challenges and future development.
View Article and Find Full Text PDFPhys Med Biol
January 2025
RaySearch Laboratories AB, Eugeniavägen 18C, Stockholm, 113 68, SWEDEN.
The advent of ultra-high dose rate irradiation, known as FLASH radiation therapy, has shown promising potential in reducing toxicity while maintaining tumor control. However, the clinical translation of these benefits necessitates efficient treatment planning strategies. This study introduces a novel approach to optimize proton therapy for FLASH effects using traveling salesperson problem (TSP) heuristics.
View Article and Find Full Text PDFPhys Med Biol
January 2025
Department of Oncology Radiation, University of California San Francisco, 1600 Divisadero Street, Suite HM006, San Francisco, California, 94143, UNITED STATES.
To study the effect of dose-rate in the time evolution of chemical yields produced in pure water versus a cellular-like environment for FLASH radiotherapy research. A version of TOPAS-nBio with Tau-Leaping algorithm was used to simulate the homogenous chemistry stage of water radiolysis using three chemical models: 1) liquid water model that considered scavenging of eaq-, H● by dissolved oxygen; 2) Michaels & Hunt model that considered scavenging of ●OH, eaq-, and H● by biomolecules existing in cellular environment; 3) Wardman model that considered model 2) and the chemical repair enzyme glutathione (GHS). H2O2 concentrations at conventional and FLASH dose-rates were compared with published measurements.
View Article and Find Full Text PDFPhys Med Biol
January 2025
Physics, The University of Western Australia, 35 Stirling Highway, Mailbag M013, WA 6009, Perth, 6009, AUSTRALIA.
FLASH radiotherapy employs ultra-high dose rates of >40 Gy/s, which may reduce normal tissue complication as compared to conventional dose rate treatments, while still ensuring the same level of tumour control. The potential benefit this can offer to patients has been the cause of great interest within the radiation oncology community, but this has not translated to a direct understanding of the FLASH effect. The oxygen depletion and inter-track interaction hypotheses are currently the leading explanations as to the mechanisms behind FLASH, but these are still not well understood, with many questions remaining about the exact underpinnings of FLASH and the treatment parameters required to optimally induce it.
View Article and Find Full Text PDFMol Cancer Ther
December 2024
National Center for Tumor Diseases, Heidelberg, Germany.
Ultra-high dose rate radiotherapy with electrons and protons has shown potential for cancer treatment by effectively targeting tumors while sparing healthy tissues (FLASH effect). This study aimed to investigate the potential FLASH sparing effect of ultra-high-dose rate helium ion irradiation, focusing on acute brain injury and subcutaneous tumor response in a preclinical in vivo setting. Raster-scanned helium ion beams were used to compare the effects of standard dose rate (SDR at 0.
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