A commonly used, and relatively inexpensive, imaging technology depends on acoustic or ultrasonic waves sent into the body where they are both refracted and reflected (this is an example of medical remote sensing that does not draw upon EM radiation). The result is a sonogram or echogram which to the layman appears fuzzy and limited in definition but is informative to the physician and trained technicians. A transducer that both generates acoustic waves and receives their reflections (echos) can be placed directly near the specific organ being investigated. The acoustic signal that passes through the body is between 1 and 10 MHz (3.5 to 7.0 MHz most frequently used). A brief summary of Ultrasonic imaging is found at the HowStuffWorks site. Once there additional information can be sought by clicking on “Lots More Information” and then on “Basic Concepts of Ultrasound” that gets you to “Diagnostic Ultrasound” by Beverly Stern of Yale University (putting on a direct link on this page fails to work). Both the text and the references on the HowStuffWorks site touch upon Doppler sonography and 3-D sonography.
A team of experts at the Yale University has recently announced that it has developed a new series of nanosensors, a class of devices that is able to analyze whole blood samples, and detect the presence of cancer biomarkers in them. The latter are chemical agents that tumors and cancer cells produce, and their existence in the body can only mean one thing. The amazing achievement could soon enable physicians to cut the cancer-detection process short, leaving more time for the actual treatments.