Robotics and Imaging Laboratory

Research

Research Overview

Onboard imaging is essential in radiation therapy. Currently it is predominantly cone-beam CT, which has limited potential for molecular and functional imaging. Yet cancer is distinguished from surrounding healthy tissue largely by molecular and functional characteristics such as hypoxia, angiogenesis, cell proliferation, metabolism, apoptosis, multi-drug resistance, and HER2 expression. The purpose of this work is to develop single-photon emission computed tomography (SPECT) methods for functional and molecular imaging onboard radiation therapy machines. These methods may also improve imaging for other tasks in which only a limited region of the full patient cross-section is of primary interest, such as cardiac imaging.

Typical SPECT scans last 20 minutes or more and yield images that are noisy and have poor spatial resolution. Yet onboard imaging should be performed within 4 minutes and provide accurate tumor localization. Also, a conventional SPECT gantry could not scan a patient in position for radiation therapy. To address these concerns, we have designed a novel robotic multi-pinhole SPECT imaging system.

 

Fig. 1: The robotic SPECT laboratory (Left). CAD simulation of robotic multi-pinhole SPECT onboard a radiation therapy machine (Right).

Fig. 2: First, intermediate, and final stops of a 49-pinhole trajectory for imaging the red spherical region.

Fig. 3: Computer simulation study on imaging the red spherical region in Fig. 2. Center slice of the phantom (left) and images reconstructed from computer-simulated 4-minute acquisitions by a characteristic parallel-hole system (middle) and the 49-pinhole system (right).