Efficacy and toxicity of FLASH radiotherapy: A systematic review.

In recent times, research on the use of ultrahigh-dose rates delivered in super-fast times in cancer treatment has been garnering interest. This has brought about the term "FLASH" radiotherapy (RT). Thus, in the present study, we systematically review these recent studies on FLASH RT with regard to its efficacy and safety. The reporting of this systematic review was done in line with the statement of Preferred Reporting Items for Systematic reviews and Meta-Analyses. Electronic search of the databases such as PubMed, Scopus, and Embase was conducted to retrieve relevant studies investigating the FLASH effect. From an initial search of 216 potential articles, 16 articles (in vivo, in vitro , and clinical studies) were finally included in this systematic review. Results showed that FLASH RT dose rates had protective effects on normal tissues in addition to antitumor effect. Although still in its early research stages, FLASH RT has the potential to rival present RT regimens in terms of safety and antitumor effect. However, further studies are needed to address the aspects such as optimal dose rate, effect on deep tumors, tumor recurrence, longer follow-up time, and mechanism of action.

Monte Carlo simulation and analytical calculation methods to investigate the potential of nanoparticles for INTRABEAM® IORT machine.

In the present study, Monte Carlo (MC) simulation and analytical calculation methods were used to investigate the potential of cancer treatment for the combination of IORT with nanoparticles (NPs). The Geant4 MC toolkit was used to simulate ZEISS INTRABEAM® IORT machine and its smallest applicator with 1.5 cm diameter. The dose enhancement effects (DEFs) were obtained for silver (Ag), gold (Au), bismuth (Bi), copper (Cu) and iron (Fe) spherical NPs considering different concentrations. In addition, analytical calculations were performed based on attenuation coefficient formula for sample NPs. Our MC results showed that the use of different NPs led to an increase in DEF up to 40%. Among different NPs, Au had the maximum DEF. In addition, analytical calculations revealed a significant increase, using NPs as well. Our study has suggested that the use of NPs in combination with IORT has the potential to enhance treatment outcomes.

Dosimetric characteristics of the INTRABEAM ® system with spherical applicators in the presence of air gaps and tissue heterogeneities.

The main aim of this study was to investigate the dosimetric characteristics of the INTRABEAM ® system in the presence of air gaps between the surface of applicators (APs) and tumor bed. Additionally, the effect of tissue heterogeneities was another focus. Investigating the dosimetric characteristics of the INTRABEAM® system is essential to deliver the required dose to the tumor bed correctly and reduce the delivered dose to the ribs and lung. Choosing the correct AP size and fitting it to the lumpectomy cavity is essential to remove the effect of air gaps and avoid inaccurate dose delivery. Consequently, the Geant4 toolkit was used to simulate the INTRABEAM ® system with spherical APs of various sizes. The wall effect of the ion chamber (IC) PTW 34013 used in the present study was checked. The simulations were validated in comparison with measurements, and then used to calculate any inaccuracies in dose delivery in the presence of 4- and 10-mm air gaps between the surface of the APs and the tumor bed. Also, the doses received due to tissue heterogeneities were characterized. It turned out that measurements and simulations were approximately in agreement (± 2%) for all sizes of APs. The perturbation factor introduced by the IC due to differences in graphite-coated polyethylene and air as compared to the phantom material was approximately equal to one for all AP. The greatest relative dose delivery difference was observed for an AP with a diameter of 1.5 cm, i.e., 44% and 70% in the presence of 4- and 10-mm air gaps, respectively. In contrast, the lowest relative dose delivery difference was observed for an AP with a diameter of 5 cm, i.e., 24% and 42% in the presence of 4- and 10-mm air gaps, respectively. Increasing APs size showed a decrease in relative dose delivery difference due to the presence of air gaps. In addition, the undesired dose received by the ribs turned out to be higher when a treatment site closer to the ribs was assumed. The undesired dose received by the ribs increased as the AP size increased. The lung dose turned out to be decreased due to the shielding effect of the ribs, small lung density, and long separation distance from the AP surface.

Radioprotective Effect of Hesperidin: A Systematic Review.

Background and objectives: Ionizing radiation (IR) has been of immense benefit to man, especially for medical purposes (diagnostic imaging and radiotherapy). However, the risks of toxicity in healthy normal cells, leading to cellular damage as well as early and late side effects, have been major drawbacks. The aim of this study was to evaluate the radioprotective effect of hesperidin against IR-induced damage. Materials and Methods: The preferred reporting items for systematic reviews and meta-analyses (PRISMA) were applied in reporting this study. A search was conducted using the electronic databases PubMed, Scopus, Embase, Google Scholar, and www.ClinicalTrials.gov for information about completed or ongoing clinical trials. Results: From our search results, 24 studies involving rats, mice, and cultured human and animal cells were included. An experimental case-control design was used in all studies. The studies showed that the administration of hesperidin reduced oxidative stress and inflammation in all investigated tissues. Furthermore, it increased 30-day and 60-day survival rates and protected against DNA damage. The best radioprotection was obtained when hesperidin was administered before irradiation. Conclusions: The results of the included studies support the antioxidant, anti-inflammatory, and antiapoptotic abilities of hesperidin as a potential radioprotective agent against IR-induced damage. We recommend future clinical trials for more insights.