Friday, May 12, 2006

Medical Imaging -- Using RF, Ultrasonic, Nuclear and Even Holography

Medical imaging uses a variety of techniques to produce images of the human body. Radiography creates images by exposing x-rays to photographic film. Computed tomography is a series of x-rays taken from different angles and then joined together to create a cross section of the subject. Magnetic Resonance Imaging uses absorption and emission of RF energy to generate images of a subject. Ultrasonic imaging uses sound waves in the 1-15 MHz range.Virtual Instrumentation applications abound for each of these techniques. TU Delft in the Netherlands has developed a high resolution ultrasound scanning system for the detection of cervical cancer. It measures the pulse-echo traces at up to 16 revolutions per minute to create a radial image. Stanford University School of Medical developed an ultrasonic application based on micromachined transducer arrays. It uses a probe architecture for volumetric scanning. This architecture generates higher sensitivity at a lower cost.

Nuclear Medicine Imaging also called Positron Emission Tomography (PET) measures radioactive substances (injected into the subject) such as Carbon-11. PET systems use a circular shaped gamma ray detector to measure the radioactive elements, converting the gamma rays into photons. A photomultiplier tube converts the photons into electrical signals.

A number of emerging technologies are coming into play for medical imaging applications. Bio-holography or what is also called Beo-tomography places minor body parts such as the human finger into an electromagnetic field to generate holographic images of internal organs. While still in the research phase, they have tested over 8000 patients.

RF Current Density Imaging is an MRI technique that uses electromagnetic waves to measure magnitude and phase from which one can create an image of the subject.

Harris Technologies developed a technique called hyper radar (requires subscription) for medical imaging.

These emerging technologies seek to produce finer images at a lower cost by making better use of RF waves.

Best regards,
Hall T.