Bench Press

A few weeks ago I wrote a post about the development of the Standoff Patient Triage Tool, an impressive use of lasers in order to make health critical readings of patients from a distance. Well one of the best things about science is that many people can utilize the same tools to come up with unique methods and solutions for any given problem. In this case, researchers have used lasers to develop a technology that could someday revolutionize imaging procedures in medicine.

Photoacoustic imaging of melanoma in vivo.

Photoacoustic tomography is the basis behind a new imaging technology being developed in hopes of providing more flexible and cost effective devices for physicians. The technique takes advantage of ultrasonic emissions produced when a non-ionizing laser pulse is directed towards a tissue. The emissions, resulting from transient thermoelastic expansion of the target tissue due to absorption of the laser energy, are detected and analyzed with various algorithms to construct an image (2D or 3D) of the targeted area. This differs from the reliance on the doppler shift produced by the reflected laser beam in the SPTT.

Images of vasculature like the one seen on the right can be produced by using photoacoustic tomography without the injection of contrast as differences between the molecular composition of the target can be used instead. In the example to the right, the difference between oxygenated and deoxygenated blood is an effective natural contrast. Photoacoustic tomography also presents other benefits over traditional imaging techniques as explained by The Economist:

CT scans also involve potentially harmful ionising radiation. And MRI and CT scans are very expensive, using machines that cost millions of dollars and require dedicated staff to operate them. Photoacoustic tomography, by contrast, could eventually be performed using portable hand-held devices, similar to those used for ultrasound scanning. This would allow doctors to diagnose and monitor patients in clinics, and reduce the need to refer them to consultants.

The adaptability of this nascent technology is also impressive as researchers are already looking at using it to detect specific ailments such as brain lesions and cancer. In the case of cancer, the ability to accurately image vasculature could allow doctors to monitor patients for the development of new blood vessels (angiogenesis) a hallmark of cancer development.

While there are some issues to work out with this new technique, such as the lack of imaging depth (ultrasound signal emitted is reduced the deeper the tissue lies) and ultrasound distortion from varying tissue types within the human body (e.g. bone vs muscle), photoacoustic imaging is a very promising new technology.

(Source)

We’ve posted a couple of times before about revolutions in scanning and probing technology allowing scientists to study and detect intricate molecular detail (e.g lab-on-a-chip, nanoscale MRI, and imaging mass spectrometry).

But what if you’re trying to study something much larger? Say a Mayan temple? Or a cave? Good luck running a imaging mass spec on that!

Seismic imaging techniques might give you some clues, but they run the risk of damaging what you’re trying to study and are generally not precise enough to necessarily be able to detect hidden rooms. What you want is to be able to X-ray the temple – without the hassle of an X-ray. Well, researchers at the University of Texas in Austin are using just such a method: muons.

For those of you who aren’t particle physicists, muons are negatively charged subatomic particles that are about 200 times larger than electrons and are very good at penetrating substances, a property which makes muon tomography possible. Much as X-rays can be used to image the insides of a person because of their ability to penetrate the skin, muons can be used to image Mayan pyramids because of their ability to penetrate the rock which makes up the walls of the pyramid. And, instead of being absorbed by bone like X-rays are, muons are deflected, and the amount of deflection is dependent on the density of the substance that they encounter.

So, the method sounds great on paper, but where do you get these muons? Does one need to carry a giant muon machine analogous to the large X-ray devices that you may find at the doctor’s or dentist’s? Well, that would be one approach, except the energy necessary to create muons is only achieved inside a high energy particle accelerator. Unless someone is intending to move the Large Hadron Collider to Central America, that approach hardly seems viable.

Luckily, there is a readily accessible source of muons that is far more powerful than CERN’s famed Large Hadron Collider: the universe.

Every moment, thanks to cosmic rays, we are being bombarded by muons, and since they pretty much come from everywhere in the cosmo’s, that gives a decent “baseline” from which to measure muon deflection.

All that’s needed is to plant a couple muon detectors (pictured on the left) in strategic locations, some detection techniques borrowed from particle physics, and sophisticated computer-aided tomography technology, the self-dubbed UT Maya Muon group is able to image at meter-resolution at a radius of almost 100 meters from the detector – enabling the researchers to create a 3D model of the pyramid.

And, I bet if you listen carefully, you’ll hear someone say “my muon generator is bigger than your muon generator!”

(Image Credit – Mayan temple) (Image Credit – Muon detector)