Medical Imaging with Filters and Quantum Dots

Feb 11, 2011

Stephan Briggs, Edmund Optics

The onset of nanotechnology and targeted therapy methods for a number of pathologies has made it increasingly more difficult to image effectively in the medical field. With that being said, the inception of quantum dots and the improvements to optical filters has made this once daunting task a common practice. The appealing nature of quantum dots in conjunction with optical filters is the ability of quantum dots to be tagged to specific biological agents for long durations of time and then imaged via the fluorescent energy they emit. This fluorescent energy that is emitted is selectively filtered resulting in a crisp and pristine image that can easily differentiate between a normal, healthy cell and a deadly, malignant cell. One prime example is the imaging of Reed-Sternberg cells that are common in cases of Hodgkin's lymphoma. Typically an easy cell to identify, but in the case of Hodgkin's lymphoma are surrounded by a plethora of healthy white blood cells and a deep bed of other lively tissues (1).

Through spectroscopy one can effectively quantify the interaction between light energy and matter. There are many types of spectroscopy which include absorption, X-ray, visible, ultraviolet, infrared, fluorescence, and many more. As mentioned above, fluorescent spectroscopy can be utilized in medical imaging systems efficiently as photons excite the sample of interest. In this case, the sample of interest is a quantum dot actively targeted for a cancerous region which then emits a low level of energy that can be detected with a spectrometer. In the detection of Reed-Sternberg cells, it is crucial to understand which wavelength is being emitted at which region. One must differentiate between a metastatic region and a healthy tissue bed without error otherwise there will be unnecessary cell death and tissue damage. To do this best and most effectively spectroscopy is put into action.