Granted Patent
Utility
US 4,331,021 · App. 06/186,381
Contrast resolution tissue equivalent ultrasound test object
Inventors:
Hector Lopez, Stephen W. Smith
Patented Case
View Patent ↗
Granted: May 25, 1982
Filed: Sep 11, 1980
Inventors
Hector Lopez
Stephen W. Smith
Assignee (at issue)
The United States of America as Represented by the Secretary of the Department of Health and Human Services
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.