Measurement of absorbed dose rate in water phantom maintained at body temperature by 60Co irradiator – comparison of experimental results and Monte Carlo simulation

Abstract

To analyze the biological effects of radiation, it is important that the conditions of in vitro experiments match closely with those of in vivo experiments. In this study, we constructed an irradiation system to conduct irradiation experiments under conditions similar to those of in vivo experiments. The Dongnam Institute of Radiological and Medial Sciences has a gamma irradiator including 60Co radioisotope for research purposes and accreditation for standard calibration of the ion chamber. The temperature of the water phantom was maintained the same as that of the normal human body, and the physical dosimetry was carried out accurately using the ion chamber with traceability. We report the measurement of lateral profiles, depth profiles, and absorbed dose rate in water, Dw, at the irradiation location of the blood samples using a farmer-type ion chamber. We simulated the source, collimator, irradiator, phantom, and extra structure of the gamma irradiation system using the Monte Carlo code and compared the simulated and the experimental results. The experimentally and theoretically evaluated dose rates were 0.2975 ± 0.0055 Gymin–1 (at coverage factor k = 2) and 0.2978 ± 0.0052 Gymin–1 (at coverage factor k = 2) at source-to-surface distance of 100 cm and 5 gcm–2 depth in the water phantom, respectively. Blood irradiation will be conducted in vitro, under conditions similar to in vivo conditions, to provide the dose-response curve based on dosimetry with traceability.

Keywords

• absorbed dose
• water phantom
• blood irradiation
• standard calibration
• mcnpx code