Presentation A Quantitation Approach for the Time Course of Mouse Leg Contracture Induced by Carbon-Ion Irradiation

Ueno, Megumi  ,  Nakanishi, Ikuo  ,  Ken-ichiro, Matsumoto

A digitalization approach of time course of radiation induced leg contracture of mouse was proposed for quantifying radiation effect on an individual living mouse. The shortening leg length of mouse can be easily measured with a caliper/ruler and can become a very simple digitalized index of radiation effect. Female C3H mice were anesthetized by i.p. injection of pentobarbital. The left hind legs of mice were irradiated with single dose of 16–45 Gy of 290 MeV carbon-ion beam using 0, 50, or 117 mm binary filter (BF). The alternative right legs of mice were used as the control. The lengths of both hind legs of the mice were measured using digital caliper before irradiation and every one week after irradiation. Degree of leg contracture, ΔSt, at the time point, t, was estimated by subtraction of left irradiated leg length from right control leg length. The Eq. 1, which is originally an equation of T1-weighted signal recovery in NMR, was fitted on the daily time course of ΔSt, then two parameters, ΔSmax and Ts, were estimated.ΔSt = ΔSmax × ( 1 – exp(t / Ts) )[1]where ΔSmax is maximum degree of leg contracture, Ts is time of leg contracture. Effect of carbon-ion irradiation given on a living mouse was quantified by the ΔSmax and the Ts of leg contracture, and then compared to that of X-ray. A single radiation dose of 16 Gy carbon-ion beam could not induce leg shortening during 220 days after irradiation. A single dose of 24, 32, or 45 Gy made starting leg shortening. By 32 Gy irradiation, ΔSmax was largest for BF117 experiment then followed by X-ray > BF50 > BF0. The Ts was shortest for X-ray experiment, then followed by BF0 < BF50 ~ BF117. In this study, an equation for quantum spin relaxation system was successfully diverted to an evaluation of radio-biological response.
1st QST International Symposium -Quantum Life Science-

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