Design And Fabrication Of New ¹²⁵I Brachytherapy Source

In recent years, radiotherapy is widely used for cancer treatment by killing the tumor through the radiation emitted by the radioactive seed among body tissues. Interstitial implantation of radioactive materials known as brachytherapy can deliver most of the radiation dose to tumor while minimizing the exposure to normal tissues. Interstitial implantation of 125I brachytherapy sources has a recognized place in the radiation therapy modality.The adsorption of 125I on some matrices is the conventional method for the manufacture of 125I seeds. There are various kinds of matrices provided by some commercial manufactures such as tungsten surface, palladium wire, ceramic beads and ion exchange resins. In traditional preparation process, the adsorption efficiency of radioactive iodine is influenced by the experimental environment, such as PH of the solution, temperature and time. Moreover, the radioactive iodine cannot be uniformly adsorpted on the matrixes, it would reduce the uniformity of the radiation distribution.In this paper, a capillary-based microfluidic technique was developed as an approach for the fabrication of uniform size microspheres with core-shell structure for use as 125I brachytherapy seeds. And in order to increase the production of the micofluidic devices, some exploration has been studied. The main points of our work can be summarized as follows:1, By using a flexible two co-axial capillaries microfluidic device,125I-encapsulated seeds with core-shell structure were synthesized. I25I contained sodium iodide solution was successfully encapsulated in shell material consisted of TPGDA under ultraviolet irradiation. The core and the overall diameter (overall:～600μm) can be precisely controlled. The diameter of the encapsulation microspheres could be precisely controlled in size at a range from 100～500μm. The contents of the radioactive 125I could be precisely controlled by adjusting operating parameters and the concentration of 125I in sodium iodine solution.2, The dose distribution of the new 125I source was calculated by MCNP5, and the results showed that the nonuniformity of the dose distribution induced by the deviation of the centre core from the centre seed can be eliminated by the increasing of the core size of the seed for a size-prescribed capsule.3, Explore the design and construction of a multi-channel capillary-based microfluidic device,4-channel and 16-channel microfluidic device have been constructed respectively, the device provided useful basis data for the development of scale-up microfluidic device.