Hawthorne-based OSI Systems Inc. has been awarded a federal contract worth up to $450 million to monitor health care patients for the U.S. military. The company’s Spacelabs Healthcare division won the contract with the Defense Logistics Agency, a combat-support division of the U.S. Department of Defense. The indefinite-delivery/indefinite-quantity agreement, valued at up to $450 million, will allow Spacelabs to provide patient monitoring, related accessories and training. The OSI Systems contract is good for five years, with an optional extension of five more years. The 31-year-old company makes security systems for airport screening, as well as for radiation, explosives and narcotics detection. It also offers medical monitoring, anesthesia systems and optoelectronic devices.