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Particle beam therapy (PBT), including proton and carbon ion therapy, is an emerging innovative treatment for cancer patients. Due to the high cost of and limited access to treatment, meticulous selection of patients who would benefit most from PBT, when compared with standard X-ray therapy (XRT), is necessary. Due to the cost and labor involved in randomized controlled trials, the model-based approach (MBA) is used as an alternative means of establishing scientific evidence in medicine, and it can be improved continuously. Good databases and reasonable models are crucial for the reliability of this approach. The tumor control probability and normal tissue complication probability models are good illustrations of the advantages of PBT, but pre-existing NTCP models have been derived from historical patient treatments from the XRT era. This highlights the necessity of prospectively analyzing specific treatment-related toxicities in order to develop PBT-compatible models. An international consensus has been reached at the Global Institution for Collaborative Research and Education (GI-CoRE) joint symposium, concluding that a systematically developed model is required for model accuracy and performance. Six important steps that need to be observed in these considerations include patient selection, treatment planning, beam delivery, dose verification, response assessment, and data analysis. Advanced technologies in radiotherapy and computer science can be integrated to improve the efficacy of a treatment. Model validation and appropriately defined thresholds in a cost-effectiveness centered manner, together with quality assurance in the treatment planning, have to be achieved prior to clinical implementation.

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Stretched thin films composed of a thermoplastic elastomer, a polystyrene-block-poly(ethylene butylene)-block-polystyrene triblock copolymer (SEBS), and polyolefins, poly(ethylene-co-ethylacrylate) and poly(ethylene-co-propylene), were obtained by blow-molding, uniaxial stretching, and cooling to room temperature and the gas permeability of the stretched films was investigated. When the as-blown annealed film was subjected to uniaxial stretching in the machine direction, P O2 and P N2 increased with an increase in the stretching ratio K and approached a constant value at high stretching ratios. In addition, P O2 /P N2 decreased gradually with K and approached a value of 2.95-3.0. The reason for this unique gas permeation behavior is that the molecular mobility of poly(ethylene butylene) chains in a direction normal to the film increases and reaches an equilibrium state at around K 5 4.5. The change in gas permeability of the stretched films can be explained using a deformation model for the SEBS matrix.

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