Microdosimetric Characteristics of Micro X-Ray Beam for Single Cell Irradiation

Abstract

A tabletop micro X-ray beam irradiation system has been developed to research radiation effects on living cells. The microbeam system is composed of a micro focus X-ray tube, a capillary for X-ray guide, an X-ray semiconductor detector for fluorescent X-ray analysis and an inverted microscope. A beam profile measurement was performed and the size of the focused beam was 10 μm in diameter (FWHM) with the divergence of 5.1 mrad. The data on the microbeam measurement was approximately agreement with a simulation of X-ray optical traces for the designed capillary. In addition, the microdosimetric characterization for the single cell irradiation was performed with the beam profile measurement and a photon-electron transport simulation. The maximum of the dose rate for the sample cells set in the system was estimated to be 0.05 Gy/s. In a preliminary experiment, single yeast cell was irradiated with the X-ray microbeam, and the data on the survival rate of the cell samples for the X-ray doses was obtained. Then, the microbeam irradiation system is useful to research the radiation effects to the living cells.

Single floating cell irradiation technique with an X-ray microbeam

“…To estimate the absorbed dose to the targeted cell, the concerned volume was considered a region including the straggling of energetic electrons caused by the X-ray interactions (Kuchimaru et al, 2006;Miller, Batdorf, Lynch, Lewis, & Wilson, 2004). The dosimetry for the cell irradiation was executed using a Monte Carlo simulation code (Particle and Heavy Ion Transport Code System) PHITS (Sato et al, 2013).…”

Monte Carlo Simulation of an X-Ray Pixel Beam Microirradiation System

“…EGS-based codes have been used for the evaluation of ion chamber response to low-energy beams (20), the design of an 192 Ir-based small animal irradiator (14), and many other kV applications (21–23). Cellular-level Monte Carlo simulation for microbeams has been studied using PENELOPE (24), PITS (25) and EGS (26, 27). The breadth of application of the Monte Carlo technique to radiotherapy in the energy range relevant to small animal studies indicates that the technique is well suited for the task of dosimetry-based system design for this microirradiation system.…”