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Knowledge sharing of radiotherapy risk contributes to keep the safety practice between the oncologists, medical physicists, and therapists. But the mechanisms of risks tend to complex because of its diversities. Recently, an ontological analysis is tried to share knowledge in the various domains. Therefore, the aim of this study is to construct Radiotherapy Risk Ontology (RRO) and clarify the implicit structures of risks towards knowledge sharing. The method of this study is below. First, the classes and relations were extracted from the risk categorization of the publications. Second, these classes and relationships were connecting and mapping by the ontology editor. Third, the total relationships of classes were verified using paired comparison chart. This paper distinguishes between publication-oriented relationships and the other relationships. And these relationships was defined the explicit and implicit relationships. RRO was constructed 789 classes and 14 types of the explicit relationships. The 22 types of the implicit relationships were clarified using paired comparison. RRO provided the conceptual mapping and the implicit knowledge. The result of this study assisted the knowledge sharing.

Ionizing radiation is frequently used for cancers with a curative intent for many patients. The total dose delivered on the tumour plays a major factor for locoregional control. Increasing the dose to the tumour volume is generally correlated with an increased dose to normal tissue. Dose constraints to organs at risk must be taken into account for the planning of external beam radiation. A high dose will generate more acute and late side effects. Medical doctors should record these toxicities prospectively. Registration and grading should be simple, reproducible and sensitive in order to obtain an accurate and appropriate evaluation for each organ. Several scales have been published in the literature (WHO, EORTC/RTOG, LENT-SOMA, NCI CTCAE) but none have a satisfactory level. The National Cancer Institute has proposed several version of the CTCAE and its latest version 4.0, currently appears to be the most adapted. The advantage of using only this common and universal classification will be to harmonize practices and have a common language., (Copyright (c) 2010 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.)

Radiation tolerance of normal tissues remains the limiting factor for delivering crucial tumoridical dose. The late toxicity of normal tissues is the most element of an irradiation: somatic, functional and structural alterations occur during the actual treatment itself, but late effects manifest months to years after acute effects heal, and may progress with time. The optimal therapeutic ratio ultimately requires not only complete tumor clearance, but also minimal residual injury to surrounding vital normal tissues. The disparity between the intensity of acute and late effects and the inability to predict the eventual manifestations of late normal tissue injury has made radiation oncologists recognize the importance of careful patient follow-up. There is so far no uniform toxicity scoring system to compare several clinical studies in the absence of a "common toxicity language". This justifies the need to establish a precise evaluation system for the analysis of late effects of radiation on normal tissues. The current proposed scales are not yet validated, and should be used cautiously. The present toxicity scale for acute and late radiation complications is not complete. It bases on analyses and additions of existent system as CTC (Common Toxicity Criteria) and SOMALENT by EORTC/RTOG. Current classification can be used for quantitative definition of complications' grade and for treatment planning.

Deficiency of one or more anterior pituitary hormones may follow treatment with external irradiation when the hypothalamic-pituitary axis falls within the fields of irradiation. Hypopituitarism occurs in patients who receive radiation therapy for pituitary tumours, nasopharyngeal cancer and primary brain tumours, as well as in children who undergo prophylactic cranial irradiation for acute lymphoblastic leukaemia, or total body irradiation for a variety of tumours and other diseases. The degree of pituitary hormonal deficit is related to the radiation dose received by the hypothalamic-pituitary axis. Thus, after lower radiation doses isolated growth hormone deficiency ensues, whilst higher doses may produce hypopituitarism. The timing of onset of the radiation-induced pituitary hormone deficit is also dose-dependent. The main site of radiation damage is the hypothalamus rather than the pituitary, although the latter may be affected directly., (Copyright 2003 S. Karger AG, Basel)

A classification system in German language is proposed for scoring of acute and chronic treatment sequelae after radiotherapy. It includes all important organs and organ systems. The proposed grading corresponds to the four-scale-system of the WHO and UICC. The system is also compatible to the RTOG and EORTC acute and late radiation morbidity scoring criteria. This facilitates the data transfer for retrospective and prospective analysis of monomodal and multimodal radiotherapy treatment regimens. We recommend to use this scoring system in all German speaking countries for multicentric prospective studies. It is possible, that organ-specific sophistication of the toxicity grading will be developed in the future. These additions should conform with (inter)national standards and apply the same four-scale grading of this classification system.