Integrated endoscope for real-time 3D ultrasound imaging and hyperthermia: A feasibility study
The goal of this research is to determine the feasibility of using a single endoscopic probe for the combined purpose of real-time 3D (RT3D) ultrasound imaging of a target organ and the delivery of ultrasound hyperthermia to facilitate the absorption of compounds for cancer treatment. The ability to combine ultrasound hyperthermia and 3D imaging could improve visualization and targeting. In this study, numerical modeling and experimental measurements were developed to determine the feasibility of combined therapy and imaging with a 5 MHz, 1cm diameter endoscopic RT3D probe with 504 active channels. A finite element mesh was constructed with over 128,000 elements in LS-DYNA to simulate the induced temperature rise from our transducer with a 3cm deep focus in tissue. Based on intensity values calculated in Field II using the transducer's array geometry, a minimum ISPTA of 3.43 W/cm2 is required in order to induce a temperature rise of 4°C within 5 minutes. It was determined through dosimetry measurements that the probe can presently maintain intensity values up to 2.4 W/cm2 over indefinite times for therapeutic applications combined with intermittent 3D scanning to maintain targeting. In vitro heating experiments of excised pork tissue yielded a maximum temperature rise of 2.3°C over 5 minutes of ultrasound exposure with an average rise of 1.8 ± 0.2°C over 5 trials. Modifications to the power supply and transducer array may enable us to reach the higher intensities required to facilitate drug delivery therapy. © 2006 IEEE.
