Design Process

Problem Statement

Today, as the technology in 4D flow CT advances, it is able to obtain blood flow patterns in vessels of interest, measure velocity vectors, display streamlines and trace particles. In fact, a quantitative approach for blood flow measurement is not available even though X-ray CT imaging is widely used to evaluate cardiovascular anatomy and function. Therefore, there is a desire for an accurate X-ray based method to quantitatively evaluate blood flow fields in CHD diagnosing treatment. The main purpose of this study is to design a 4D flow phantom designed for vitro experiments in cardiovascular flow imaging research by using a neural network based approach to estimate the spatiotemporal blood flow fields from the reconstructed CT images and the CT sinograms.

Goals

Develop an in-vitro model for use in 4D flow CT imaging research.
Validate a neural network framework for measuring blood flow noninvasively.
Contribute to the diagnostics and treatment of coronary heart disease

Constraints

Hardware and System Dimensions

The flow system’s dimensions have to be compatible with the physical restraints of the Jacobs Medical Center CT scanning equipment.

Safety of Participants and Equipment

To avoid overexposure of participants to X-ray radiation, the system must be automated or remote-controlled, to allow for operation of the flow system from behind the CT scanning window.
In addition, to safeguard against iodine and water spillage in the CT scanning room, flow system parts must be fabricated to be leak-proof, and materials must be water-resistant.

Designing the Modular Imaging Box

To meet the constraints imposed by CT scanners in terms of dimensions and materials, our team designed a modular imaging box that was safe to use in CT scanners and fit the imaging zone Dr. Contijoch and Rick targeted. We achieved this by using Inkscape software to design the box CAD. We implemented inlet/outlet holes in various locations to accommodate the present and future mixing chamber designs. We incorporated finger joints along the edges of the box and taped them to avoid gluing the walls together so that the walls could be replaced in the future if needed. Lastly, we laser cut acrylic sheets using an epilog laser cutter and assembled the modular imaing box.

Fabricating the Mixing Chamber

Inspiration

The coiled design was inspired by the original mixing chamber Rick used prior to the start of our project. The coils effectively slow down the flow in the system in the target imaging zone so that the user has more time to capture a CT movie of the contrast agent flow.

CAD Model

Our team used the Solidworks software to create a computer-aided design (CAD) model of the mixing chamber.

Resin Printed Model

The final model was resin printed in photopolymer resin material using a FormLabs 3+ printer.

Design History

Although our final mixing chamber was printed using resin material, we experimented using PLA and PETG material prior to that. With the 3D printing resources available to us at UCSD, we were able to test several iterations of this design before finalizing the model.

Flow System Design

The hydraulic circuit drafted for this flow system encompasses components that would be widely applicable for a range of hemodynamics experiments. The end product of this system engineering consists of a reservoir unit for storage of iodine contrast, an automatic syringe pump for injecting contrast into fluid flow via remote LabVIEW control, a fluid pump located outside of the CT bore, and the modular box containing the mixing chamber(s).

Schematic of Hydraulic Circuit Drafted for Flow System

Complete Integration of Hydraulic System Components in Clinical CT Scanner

Leader: Esmeralda Lopez

Page updated

Report abuse