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Physics Department Colloquium," The physics of digital mammography," by Dr. Andrew Karellas, Director of Radiological Physics,UMASS Medical School

Science / Technology - Colloquium

Monday, March 18, 2013
4:00 PM-5:00 PM

Olin Hall

Digital mammography is the gold standard for the detection of non-palpable breast cancer in asymptomatic women. At his time, approximately 90% of all mammography systems in the United States are digital, and the remaining 10% are based on the old film technology which is becoming obsolete. Mammography uses a broad spectrum of x-rays with a range from about 15 to 30 keV. X-rays interact with the breast by the photoelectric, Compton or coherent effects. Ideally, all x-rays that are transmitted through the breast without interaction are detected by the digital image sensor (detector) and all scattered x-rays are rejected. However, current mammographic systems are far from ideal, and their inefficiency in x-ray detection and scatter rejection affects image quality and radiation dose to the patient. There are other intrinsic and extrinsic parameters such as spatial resolution, image noise, and breast composition that also affect image quality and dose. Image quality is critical for detecting subtle features in the breast that may be associated with breast cancer.

In mammography x-rays are generated by using a tube with a beryllium window, a molybdenum or tungsten target, and with added molybdenum, rhodium, or silver filtration. X-rays are generated from a focal spot in the x-ray tube with a size of about 0.5 mm. Digital image detectors are typically made of amorphous selenium, or amorphous silicon coupled to a solid state multi-element (pixel) detector. Other mammographic technologies use energy storage phosphors that are stimulated with a laser beam for the signal readout and final image formation. Mammography generates two-dimensional x-ray images, therefore, they lack tomographic or 3D information. However, with recent developments in digital x-ray detectors and image reconstruction techniques, x-ray imaging of the breast has been making the transition from 2D to 3D. This presentation will address the following :
• Basic concepts of image formation in mammography
• X-ray beam requirements
• Geometrical aspects of image formation
• Contrast and resolution in mammography
• Digital imaging detectors
• Image quality in mammography
• Radiation dose considerations
• The transition from 2D to 3D imaging of the breast

Refreshments will be served in Olin Hall 118 at 3;30 P.M.

Cost: Free

Suggested Audiences: College, College, College

Phone: 508-831-5258

Last Modified: March 14, 2013 at 2:49 PM

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