Friday, February 17, 2006
Designing X-ray Detectors
for Medical Imaging
Hologic, Inc., Advance Technology Division
The x-ray interaction with matter allows us to visualize different parts of the human body. The large variation in photoelectric absorption between bone, tissue, air, water, etc. is related to the variation of the density and the thickness of different body parts. The conventional and cheaper way to get analog x-ray images is to use film cassettes that utilize phosphor material and film that has to be developed after x-ray screening. Digital x-ray detectors create high resolution, high contrast, digital image that can be reviewed on the computer right after the screening. Every digital detector is made of a TFT matrix panel + an x-ray detection medium. There are two approaches in designing a digital x-ray detector based on the x-ray photon conversion into electrical charge. Indirect conversion typically utilizes a scintillator, material that absorbs x-rays and converts them into the visible light, which then get converted into the charge in a silicon diode. This signal is integrated, amplified and digitized for the digital display. Direct conversion utilizes a semiconducting material with the high x-ray absorption that directly converts x-rays into electrical charge. Different detector designs and their applications in medical imaging will be discussed.
Refreshments at 4:00 PM. Seminar begins at 4:10 PM.
Building 8 (Science Bldg.) - Room 241
For further information, please call (909) 869-4014