## 4 Conclusions  
The skin is the first barrier against radiation exposure, and skin damage can progress several days to several years after exposure [36]. The goal of radiotherapy is to completely deliver a dose of ionizing radiation to eliminate tumor cells through ionizing radiation and reduce the damage to surrounding healthy tissues [36]. RSI is a frequent complication of radiotherapy. Severe cases can affect the patient's disease treatment and quality of life [37]. [PERSON] et al., and [PERSON] et al., regarding prevention and treatment of RSI, used zinc sulphate and synthetic superoxide dismutase/catalase mimetic EUK-207, respectively [36; 38]. This study was to evaluate the effect of EYO on rats using an RSI model, and to study its effects on the delay of radiation-induced skin injury, including impaired wound healing. The results showed that the PGC112 film displayed desirable water absorption and soft and tough mechanical properties, and also had an appropriate biodegradability. The addition of EYO will not affect the original mechanical properties of the film material and will significantly reduce the area of radiodermatitis wounds. PGC/EYO films can assist in delaying the onset of radiodermatitis. The composite film PGC112 blended with EYO has good biocompatibility and is conducive to fit with the wound. EYO microspheres coated in the substrate can be released slowly and were not diluted by body fluids, and they did not quickly degrade when in contact with tissues. Comparing the results of only smear EYO and /0.5 EYO film from in vivo tests, the researchers found that the film had a better skin repair effect and mild inflammation reaction in the initial stage. The PGC/EYO dressings were able to absorb interstitial fluid, provide a moist environment for wound repair, decrease matrix accumulation, and promote cell migration and proliferation. In addition, the EYO in the dressings can promote the re-epithelialization of radiodermatitis wounds, thus demonstrating the developmental potential of polymer PGC/0.5 EYO films. It is expected that PGC/0.5 EYO films can be applied in clinical radiotherapy for effective wound repair and wound pain alleviation.  
Figure 9: (**a**) Immunohistochemistryists of dermatitis wound using CD68 antibody (macrophage marker) after 21 days and 30 days. (**b**) The area of CD68 marker of each skin tissue. Means with different letters were significantly different (\(p\) < 0.05, mean \(\pm\) SD, \(n\) = 5).  
**Author Contributions:** Conceptualization, S.-R.H. and Y.-C.-H.; methodology, S.-R.H.; validation, J.-Y.K.; formal analysis, S.-C.H.; investigation, S.-R.H.; resources, C.-J.C.; data curation, S.-R.H.; writing--original draft preparation, Y.-C.H.; writing--review and editing, C.-M.T.; project administration, C.-J.C. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
The study was conducted according to the guidelines of the Declaration of Helsinki and approved by the animal experimentation committee at the Central Taiwan University of Science and Technology (Taichung, Taiwan) (Approve number 107-CTUST-011, 14 February 2019).  
Not applicable.  
No data to report.  
The authors declare no conflict of interest.