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Sato, Tatsuhiko
no journal, ,
Precise evaluation of relative biological effectiveness (RBE) is essential in the treatment planning of ion beam and targeted alpha therapy. Various models such as microdosimetric kenetic model (MKM) and local effect model (LEM) have been proposed for evaluating the RBE of ion-beam therapy. They can consider the complicated dependences of RBE on energy and charge of ions as well as the absorbed dose. Evaluation of RBE is also needed from the viewpoint of radiological protection. In 2021, the International Commission on Radiation Units and Measurements (ICRU) and ICRP jointly proposed the use of absorbed dose instead of equivalent dose for specifying dose limits to prevent tissue reactions. However, no recommendation has yet been provided as to how to derive RBE for the mixed radiation fields. I will briefly review the recent studies on medical physics for evaluating RBE for ion-beam and targeted alpha therapy. Then, I will discuss about the possibility of applying those studies to radiological protection research by introducing our recently developed model for evaluating the RBE for tissue reactions based on MKM.
Sato, Tatsuhiko
no journal, ,
ICRU decided to publish a new report entitled "Stochastic nature of radiation interactions: microdosimetry", which not only updates Report 36 but includes descriptions, analyses, and (whenever necessary) recommendations in a variety of aspects that constitute the recent progress of the field of microdosimetry. The contents of the report will be briefly introduced at the symposium, together with the comments on the possible role of microdosimetry in the dosimetry for the next general recommendations of ICRP.
Hirouchi, Jun; Kujiraoka, Ikuo; Takahara, Shogo; Takada, Momo*; Kai, Michiaki*; Schneider, T.*; Lecomte, J.-F.*
no journal, ,
no abstracts in English
Hirouchi, Jun; Kujiraoka, Ikuo; Takahara, Shogo; Takada, Momo*; Kai, Michiaki*; Schneider, T.*; Lecomte, J.-F.*
no journal, ,
no abstracts in English
Yoshitomi, Hiroshi; Tsuji, Tomoya; Nishino, Sho; Tanimura, Yoshihiko
no journal, ,
no abstracts in English
Jin, Q.*; Sakoda, Akihiro; Iimoto, Takeshi*
no journal, ,
Radon-222, a gaseous decay product in the Uranium decay chain, has been recognized as a significant factor contributing to lung cancer and has also been widely used as a tracer for environmental monitoring. Extensive research has focused on understanding its behavior in the environment along with the measurement technique. Regarding previous research on Radon exhalation rate from the soil, various influence factors such as temperature, air pressure, humidity, soil conditions, and soil water contents have been studied extensively. For in-situ continuous measurement of Radon exhalation rate from the soil, the simplest set-up is the long-term coverage of an accumulation chamber on a soil surface to collect Radon gas from the soil. This may impact the environmental parameters such as the temperature of soil and air in the chamber, and soil conditions including soil water contents and humidity, potentially leading to differences in Radon exhalation rate measurement results between the soil surface in and around the chamber. To investigate the effects of the long-term coverage on the same soil surface on measurement results, an in-situ measurement method based on the open-loop accumulation chamber technique has been obtained for comparing the environmental parameters and the Radon exhalation rates between continuous measurement and spot measurement. This research can provide the Radon exhalation mechanism regarding the change of the environmental parameters, especially during the measurement using the accumulation chamber technique, to decrease the potential effects caused by the variation of influence factors, improving the accuracy of Radon exhalation rate measurement results.