Algorithm soups up scanners

Algorithm soups up scanners

Defeating terrorists, locating landmines, and uncovering contraband cargo – it’s all in a day’s work for a new Australian invention.

These days, Superman isn’t the only crime-fighter with the ability to see through solid objects. Thanks to X-ray and gamma ray detectors, even mere mortals can use the penetrating powers of radiation to scan for bombs, contraband and other hidden threats to life and limb.

However, unlike the Man of Steel’s X-ray eyes, real-life radiation detectors aren’t perfect. They suffer from a problem called ‘pulse pile-up’, which reduces the speed and accuracy of the information a detector can provide.

Pulse pile-up occurs when bursts of radiation strike the detector in very quick succession. They pile on top of each other, giving the appearance of one big pulse rather than multiple smaller ones. This is a problem because the height of the pulses contains information about the elemental composition of the object being scanned, and this data is distorted as a result of pulse pile-up.

The standard technique for dealing with pulse pile-up is to identify pulses that have piled up on top of each other, then throw away that information and analyse only ‘clean’ pulses. This approach improves the accuracy of the reading but also increases the length of time a scan takes to complete.

A new Aussie innovation, however, promises to solve the pulse pile-up problem in a new way, improving accuracy and drastically speeding up the scanning process.

Developed by Mr Paul Scoullar and Professor Rob Evans at Melbourne Uni’s Department of Electrical and Electronic Engineering, the new pile-up deciphering algorithm can recover information from pulse pile-ups that would normally be discarded.

By recovering data that’s usually thrown out, Paul’s algorithm is able to retain vital information about elemental composition. In some cases this information can be a matter of life and death; for example, when using gamma spectroscopy to scan for the nitrogen-rich spectral signature of a buried landmine.

“The reason pulse pile-up spoils this technique is because you can no longer extract that information from the pulses that have piled on top of each other,” said Paul. “What we are able to do is recover that information from all of the pulses that have piled up.”

By recovering the pile-up affected information instead of discarding it and waiting for clean pulses to analyse, scans can be also be carried out much faster. In some applications over half of the pulses would normally be discarded due to pile-up: virtually 100% of this information can be recovered by the new algorithm.

While it was originally developed to improve landmine detection, the technology can be applied wherever X-ray and gamma ray detectors are used, including security scans and medical imaging. The benefits of faster scans are obvious, particularly in areas where high-volume scanning is required – such as airport baggage and shipping container screening. In the United States, for example, only about 5% of shipping containers are presently screened using gamma rays, largely due to the time constraints imposed by traditional technology.

Paul has recently formed the company Southern Innovation to commercialise the technology. Recently returned from the US, he has been demonstrating Southern Innovation’s product to some exciting potential customers.

“It’s been really encouraging to go over there and talk to the traditional giants of the radiation detection industry, and get some very strong interest from them,” Paul said.

Thanks to Southern Innovation’s pile-up beating technology, it won’t be too long before radiation detectors everywhere are faster than a speeding bullet.

Australasian Science Magazine, March 2006

About Southern Innovation:
Southern Innovation develops, markets and licenses patented pulse processing technologies for the rapid, accurate detection and measurement of radiation. The company was born out of research to review suitable technologies for the accurate and rapid detection of legacy landmines. Southern Innovation’s multi-award winning SITORO┬« technology provides a quantum leap in the efficiency of radiation detectors, with wide application in areas such as airport baggage screening, oil exploration, mineral analysis and the early detection of cancer. For more information contact