WASHINGTON (AP) — The government needs to develop a better way to evaluate the effectiveness of technology to detect nuclear and radiological material at U.S. ports, according to a report commissioned by the Homeland Security Department.

Congress and its investigative arm, the Government Accountability Office, have been skeptical about the department's testing of such systems. As a result, the department called for an independent audit into its testing.

The report by the Homeland Security Institute did not find that the testing has been biased or results manipulated. It did say the department should devise a better process to test and evaluate how effective the machines are.

The Associated Press obtained the executive summary of the report.