APPLICATIONS OF TECHNOLOGY:
- Models the human torso, heart, and lungs for improving SPECT and PET imaging
- Develops and validates algorithms to correct for cardiac and respiratory motion in nuclear imaging
- Intermodality image registration
- Simultaneous modality imaging
- Validates and co-registers data using multimodality imaging systems
- Helps correct mismatch in data in hybrid SPECT/PET and CT systems with intermodality image registration using simultaneous and multimodality data input and processing.
- Can stop both cardiac and respiratory motion for independent imaging
- Can be used to generate a database of different types and rates of respiratory motion
- Simulates both respiratory motion and cardiac deformation and realistically replicates twisting motion in left ventricle during expansion of the heart
Most physical phantoms do not model respiratory motion, which contributes significantly to image degradation in SPECT (single photon emission computed tomography) and PET (positron emission tomography) scans. Grant Gullberg, Rostyslav Boutchko, Karthikayan Balakrishnan, and colleagues at Lawrence Berkeley National Laboratory have designed a phantom that mimics respiratory and cardiac cycles in a human subject. This permits the collection of nuclear medicine data simulating cardiac and respiratory motion. The phantom is used to evaluate algorithms that correct for these physiological motions, which often result in a mismatch between SPECT/PET and CT data in hybrid systems.
To make the phantom, liquid silicone rubber is used to coat the cast of a life-sized model. When the cast is removed, this flexible coating forms the lungs of the phantom. These are inflated and deflated by a tank of compressed air, and the inflation/deflation cycle is controlled by computer-operated solenoid valves. The heart phantom, adapted from the Jaszczak dynamic phantom, rests between the inflatable rubber lungs. Two sealable rubber sacs filled with fluid independently model the liver and the rest of the abdomen. Changes in the volume of the lung cause non-linear deformation of the lung and, to a lesser extent, the heart and the internal organs of the body. Fluid is pumped in and out of the innermost chamber of the heart by an independent pump.
The cavities of the heart and the internal organs can be filled with radioactive fluid of controllable concentrations, allowing modeling of different uptake levels of each organ independently. The parts are elastic, interconnected, and enclosed in a non-rigid container filled with water. Position markers placed on the outer surface of the phantom and the surface of the “heart” allow tracking of respiratory motion with external optical devices. A limit switch on the pump provides an R-wave trigger that simulates the human ECG signals needed for the acquisition of cardiac gated data.
Data can be collected either in snapshot or dynamic mode, with the phantom “breathing” and “beating” continuously. The snapshot mode can be used to create a database of SPECT/PET sinograms and attenuation maps for different cardiac and respiratory phases, so that datasets of different types and rates of motion can be generated. The system can be tailored to multimodality input and processing. The modalities can be registered and run simultaneously.
Published PCT Patent Application WO2008/151202 available at www.wipo.int. Available for licensing or collaborative research.
To learn more about licensing a technology from LBNL see http://www.lbl.gov/Tech-Transfer/licensing/index.html.
FOR MORE INFORMATION:
Balakrishnan, K., Boutchko, R. Reutter B., Sitek A., and Gullberg G.T., “An anthropomorphic phantom for simulating cardiac and respiratory motion in SPECT/CT and PET/CT,” Journal of Nuclear Medicine 2007, 48 (Supplement 2):42P.
REFERENCE NUMBER: IB-2358
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