Archive for the ‘CT’ tag
Lasers, not just for ray guns
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)