Exploration of parameters affecting jet injection using a high-speed X-ray imaging system

Abstract

This thesis explores the effects of two parameters, contact force and jet shape, on jet injection using a high-speed X-ray imaging system. The scope of the thesis is twofold. The first part describes the process of optimization of the high-speed imaging system for better stress distribution and deformation of the porcine tissue block used in the jet injection experiment. The parameters for the high-speed X-ray imaging system, namely the voltage and the current of the X-ray source and the exposure time of the high-speed camera, were optimized for tissue blocks with different width by evaluating the signal to noise ratio (SNR) of X-ray images. High-speed X-ray images of jet injection into tissue with dimension of 80 mm x 65 mm (Lx W) x 40 mm (H) suggested that the image quality of the current system was susceptible to varying X-ray absorptions associated dependent on the width of the imaged tissue. As an alternative solution, a jet injection experiment on a porcine tissue with asymmetric dimension of 80 mm x 30 mm (LxW) x 30 mm (H) was conducted. Based on the results from the experiment, it was concluded that asymmetric dimension will improve the stress distribution and the deformation of tissue of porcine tissue in jet injection, with reasonable image quality while possibly introducing a defect of an asymmetric dispersion pattern. The second part of this thesis examines the effects of contact force and jet shape on the jet injection using the newly optimized parameters for the imaging system. The presence of 1 N contact force in jet injection reduced the required jet pressure to breach the tissue by at most 8 MPa as the contact force pretensioned the tissue surface. Also the dispersion patterns jet injections with presence and absence of the contact force showed that the pre-tensioning can possibly improve the delivery of injectate into the tissue. In addition, jet injections into tissue analog and ex vivo porcine tissue suggested that jet injection with a collimated jet shape can result in a deeper penetration than that with a dispersed jet shape.