## 1 Introduction  
The MCF-10A cell line has been largely used as a model to investigate human normal breast cells [1]. These cells were obtained from benign proliferative breast tissue and spontaneously immortalized without defined factors. They show a lack of anchorage-independentgrowth and dependence on growth factors and hormones for their proliferation and survival [2], and they can form acinar structures in 3D culture [3]. These characteristics make MCF10A cells particularly suitable for studying the effects of external agents [4; 5]. They are largely used to study breast cell function and behavior, mammary gland morphogenesis, and the function of normal and malignant cells [1; 6; 7]. The MCF-10A line has also been used to test more effective radiotherapy approaches [8; 9; 10] and the effects of different radiation qualities [11]. They have also been recently employed to validate new approaches to make proton therapy more effective [12]. In fact, radiotherapy (RT) with charged particles (protons and carbon ions), known as hadrontherapy, has been rapidly establishing itself as a profitable alternative to conventional radiotherapy (CRT) because of several advantages compared to photon/electron-based CRT. These advantages are both physical and radiobiological in nature. Charged particles deposit their energy in matter following the Bragg curve. Then, charged particles release the largest part of their energy at the end of the penetration path. In this way, much better localization of the released energy inside the tumor volume is obtained compared, for example, to X-rays. This inverse dose-depth profile, in principle, permits the delivery of very high-dose gradients close to organs at risk. In this way, the high-dose area is confined to the tumor volume. Carbon ions, on the other hand, have a much higher biological effectiveness compared to the relatively low efficiency at cell killing exhibited by protons, thereby being radiobiologically eligible for radioresistant cancer treatment, but they do present a series of issues in terms of both long-term risks to normal tissue and cost-effectiveness [12; 13]. Therefore, proton therapy is a hadrontherapy approach that is rapidly expanding, totaling over 100,000 treated patients worldwide to date [14; 15]. Irrespective of the radiation used, to improve RT effectiveness strategies, it is important to take into account the wide heterogeneity in individual radiosensitivity exhibited by both cancer and healthy cells among patients [16]. To overcome such inter-individual variability, the rapid and accurate prediction of cellular radioresponse is necessary for RT tailoring. The identification of predictive markers of cancer radioresistance and normal tissue radiosensitivity is, at the moment, a fundamental task in radiobiology. The clonogenic assay is the gold standard for in vitro measurement of cellular radioresponse, having provided the most extensive database of normal and cancer tissue mean radiosensitivity values by using the alpha/beta ratios of the linear-quadratic model to interpret clonogenic dose-response curves, but it cannot be adopted routinely on an individual basis [17]. Since 2000, vibrational techniques, such as infrared and Raman spectroscopies, have been used in the study of various radiobiological endpoints [18; 19; 20]. In particular, Fourier transform infrared microspectroscopy (\(\upmu\)-FT-IR) has been employed to investigate proton-irradiated cells [21; 22; 23; 24]. Using synchrotron \(\upmu\)-FT-IR spectroscopy, it has been shown that the measurement of DNA and lipid modification in various proton-exposed cell lines can be used to monitor biochemical changes induced by particle beams in detail [21; 22; 23; 24].