1. Anthropomorphic Liver Phantom for CT and Ultrasound Katelyn Herbert Advisor: Dr. Robert Galloway (BME) Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee ABSTRACT CONCLUSION THE MODEL and METHODS RESULTS RESULTS INTRODUCTION. FUTURE DIRECTION We were able to create a phantom that had tumors that were visible using both CT imaging and Ultrasound imaging, and were able to accurately locate them in the physical space of the phantom. We embedded proximity detectors in the tumors to give a range of distances the ablation tool (magnet) was away from the tumor by using the reed switches that close the circuit when a magnetic field is present. However, this is a binary result (the reed switch closes when the magnet is at least 32 mm away). Therefore we are not able to get the exact distance of the ablation tool to the tumor and further work would need to be done to achieve that result. Attempt to use a different method in which the actual distance of the ablation tool to the tumor could be found May be implemented with an antenna and signal source 20,000 people are diagnosed with liver cancer every year. A very invasive and difficult type of liver tumor to treat is the Hepatocellular Carcinomas (HCCs), but the removal of these tumors is very difficult. Surgical resection only available for 20% of patients RF ablation is the alternative method for tumor removal RF Ablation Needle-like ablation tool is placed inside the tumor High frequency RF signal heats the surrounding tissue, killing it. Surgery is tomographically guided using CT or ultrasound imaging. Success is dependent on being accurately guided imaging modality to correctly place the ablation tool in the center of a tumor. 44 percent of all liver tumors are indistinguishable from healthy tissue using CT and Ultrasound Finding the center of the three-dimensional object (the tumor) in a two-dimensional view of CT or US images is difficult. Objective The purpose of this project is to create an anthropomorphic liver phantom that will allow the investigation of whether CT and Ultrasound imaging guidance are comparable for finding liver tumors. Be able to determine whether the methods currently used to locate tumors are the accurate enough for actual surgeries. Anthropomorphic phantom of the liver “Liver Tissue”- 1:1 ratio of Ecoflex® Silicone mixture. “Liver Tumors”-1:1 ratio of Ecoflex® Silicone mixture. -Small amount of barium powder added- makes visible in CT -introduced air bubbles in to the mixture-makes visible to US Proximity Detectors 4.7 mm reed switch (GR200) from Standex Electronics is embedded inside the tumor, tumor embedded in liver -activated by the presence of a magnetic field Small magnet from K&J Magnetics (D11SH) placed in tip of ablation tool. As magnet nears the tumor, the reed switch closes the circuit and turns on an LED. Imaging Imaged the phantom using CT (120kV,79mAs,slice thickness- 2mm) Imaged the phantom using Ultrasound Tested the distance the magnet needed to be away from the reed switch in order to make it close while approaching it from several different angles Found that depending on the angle, the magnet needed to be about 32mm-10mm away from the reed switch in order to make it close. Locating the Tumor Using Images The phantom was imaged using CT and Ultrasound. Able to locate the tumor using both modalities. Imaging method was able to guide us to the actual physical space in which the tumor was located. Proximity detectors were effective in guiding us to the location of the tumor. The purpose of this project is to create an anthropomorphic liver phantom in which liver tumors can be imaged using both CT (Computed Tomography) and Ultrasound to investigate whether imaging liver tumors with CT and Ultrasound is comparable. We tested the different imaging modalities by locating the tumors in the images, and then finding the actual physical space of the tumor using proximity detectors embedded in the tumors in the liver. We found that the tumors were observable in CT and Ultrasound images, and the proximity detectors worked in a range of 32 mm or less. Table 1. Tested at what the distance the magnet was when it caused the reed switch to close (caused LED to turn on). Approached the reed switch from several different angles. Figure 1. CT image of the liver phantom and tumor. The “Liver tissue” appears grey in the image, and the “tumor” appears white in the image. Figure 2. US Image of phantom. Red circle=location of tumor Angle of Approach (degrees) Distance From Reed Switch (mm) 90 from front10 90 from back10 45 from left30.1 45 from right30.1 90 from top32.2 DISCUSSION REFERENCES 1. Schöber et al, “Guidance and monitoring of radiofrequency liver tumor ablation with contrast-enhanced ultrasound.”, European Journal of Radiology [0720-048X]yr. 2004 vol. 51 pg. 19 2. Meloni et al, “Hepatocellular Carcinoma Treated with Radiofrequency Ablation.” American Journal of Roentgenology 2001 vol. 177 pg. 375 3. Gazelle et al. “Tumor Ablation with Radiofrequency Energy”. Radiology 2000 vol. 217 633-646 4. http://www.hopkins-gi.org