Fifteen symposia on microdosimetry: implications for modern particle-beam cancer radiotherapy

The objective of microdosimetry was, and still is, to identify physical descriptions of the initial physical processes of ionising radiation interacting with biological matter which correlate with observed radiobiological effects with a view to improve the understanding of radiobiological mechanisms and effects. The introduction of therapy with particles starting with fast neutrons followed by negative pions, protons and light ions necessitated the application of biological weighting factors for absorbed dose in order to account for differences of the relative biological effectiveness (RBE). Dedicated radiobiological experiments in therapy beams with mammalian cells and with laboratory animals provided sets of RBE values which are used to evaluate empirical ‘clinical RBE values'. The combination of such experiments with microdosimetric measurements in identical conditions offered the possibility to establish semi-empirical relationships between microdosimetric parameters and results of RBE studie

シェアビジネスにおけるSNSの信頼性に関する研究-シェアビジネスの先端事例ケーススタディとSNSの信頼性の影響に関する実証分析

Otaru University of Commerce（小樽商科大学）博士（商学）doctoralcours

The Effects of Marital Separation and Divorce on Children

This study will examine the effects of parental separation and divorce on the children involved as seen through the indicators of sense of self-esteem, social interactions, and academic performance/cognitive development while controlling for the time lapsed since the divorce. The review of literature closely examines the correlation between divorce and these indicators . Following the collection of the literature, the general conclusion of this document is that parental separation and divorce negatively affect the children involved as seen through the specified indicators. To further explore the relationship of parental separation and divorce on the development of the child, several theories were applied, including a through examination of the broad Theory of Symbolic Interactionism. In addition, the sub-theories of the looking glass self, Systems Levels theory, and the Frustration and Aggression theory were also discussed. For completion of the Senior Independent Thesis, two-hundred College of Wooster students were randomly administered surveys. The Statistical Package for the Social Sciences edition Ten was applied to analyze the data. The results of the collected data show that although the patterns of self-esteem, social interaction, and academic performance/ cognitive development of children of divorce were consistently lower than those of children from intact families, the percentage of difference was not statistically significant. However, this study was not able to allow for several intervening variables: social desirability, age, and sample size

Radiobiological Characterization of Clinical Proton and Carbon-Ion Beams

Electromagnetic radiation (photons) or particle beam (protons or heavy ions) have similar biological effects, i.e. damage to human cell DNA that eventually leads to cell death if not correctly repaired. The biological effects at the level of organs or organisms are explained by a progressive depletion of constitutive cells; below a given threshold, cell division is no longer sufficient to compensate for cell loss, up to a point where the entire organism (or organ) breaks down. The quantitative aspects of the biological effects are modulated by the microscopic distribution of energy deposits along the beam or particle tracks. In particular, the ionization density, i.e. the amount of energy deposited by unit path length (measured in keV/{\mu}m), has an influence on the biological effectiveness, i.e. the amount of damage per energy unit deposited (measured in gray or Gy, equivalent to 1 joule/kg). The ionization density is usually represented by the Linear Energy Transfer or LET, also expressed in keV/{\mu}m. Photon beams (X-rays, g-rays) are low-LET radiation, with a sparsely ionising characteristic. Particle beams have a higher LET, with a more dense distribution of energy deposits along the particle tracks. Protons are intermediary, with a LET larger than the photon one, but still belong to the 'radiobiological' group of low LET. The higher the ionization density, the higher the biological effectiveness per unit of dose

Comparison of the Methods of Specifying Carbon Ion Doses at NIRS and GSI.

Due to the RBE variations, the carbon-ion doses (in Gy) are no longer sufficient to monitor adequately the biological effect of these radiations. Therefore, "RBE dose weighting factors" - W(RBE) - allowing for the RBE variations with energy, dose and biological system have to be introduced in the treatment plans in order to provide the physician with interpretable information. This paper compares the methods employed for this purpose at NIRS and GSI, which are specific of the beam delivery system of these institutions. NIRS has a "passive" beam delivery system where the dose distribution in the SOBP is determined by a Ridge filter. The dose distribution - and thus, the shaping of the filter - is chosen according to the clinical situation and determined with respect to W(RBE) factors in order to yield a biologically iso-effective SOBP. W(RBE )factors in the SOBP are at first derived from a RBE/LET function for HSG cells, then normalized to 3 at a LET of 80 keV/mum. The latter value of 3 corresponds to the clinical RBE of NIRS-neutrons, which were found to exhibit the same radiobiological properties as 80 keV/mum carbon-ions. GSI has a "dynamic" beam delivery system ("spot" or "voxel" scanning) making it possible to irradiate irregular volumes and to modulate the radiation intensity according to the radiosensitivity of different tissues and/or different sub-volumes. Due to the "power" and the resulting complexity of the system, W(RBE )factors are determined through an integrated calculation code allowing iterative interaction of both physical and radiobiological parameters. The "Local Effect Model" (LEM) was developed in this view with the aim of deriving carbon-ion W(RBE )factors from the parameters determining the response to photons. Advantages and weaknesses of the respective methods will be discussed

Thérapie anticancéreuse par rayonnements à TEL élevé

L'application en radiothérapie des rayonnements à TEL (Transfert Linéique d'Énergie) élevé est basée sur des arguments d'ordre radiobiologique : efficacité spécifique vis-àvis des cellules cancéreuses hypoxiques, des cellules se trouvant dans une phase du cycle mitotique résistante aux rayons-X ou quiescentes. Toutefois, d'un point de vue clinique, le problème de la sélection des malades susceptibles de bénéficier des rayonnements à TEL élevé n'est pas résolu. L'observation clinique a montré que les rayonnements à TEL élevé apportent un bénéfice pour certains types de tumeurs : glandes salivaires, sinus maxillaires, prostates, sarcomes, etc. Ces tumeurs sont, dans l'ensemble, à croissance lente, bien différenciées et résistantes aux rayons-X classiques, comme d'ailleurs à la chimiothérapie. Parmi les rayonnements à TEL élevé, les neutrons rapides ont été le plus largement utilisés. Aujourd'hui, ils peuvent être appliqués dans des conditions techniques et de sélectivité physique comparables à celles de la radiothérapie classique. Les ions lourds présentent l'avantage d'une sélectivité physique élevée et permettent d'appliquer les rayonnements à TEL élevé dans des conditions optimales. Malheureusement, la complexité de l'équipement et surtout son coût ont freiné leur développement