2015 BFY II Abstract Detail Page
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||W17 - Medical Imaging: Teaching about the Gamma Camera and Ultrasound Imaging
||Instructional modules on applications of physics in medicine are being developed. The target audience consists of students who have had an introductory undergraduate physics course. This workshop will concentrate on an active learning approach to teach the principles of the gamma camera. An instructional ultrasound imaging apparatus that is being developed will also be shown.
The gamma camera (or scintillation camera) is one of the most important nuclear imaging devices used in a hospital. A radiopharmaceutical is introduced into a patient, which becomes concentrated in an organ or tumor. The gamma camera is placed over the patient. Gamma rays emitted from the radionuclide pass through an array of holes in a lead plate (called a collimator) and hit a scintillation crystal to produce flashes of light at different positions. The flashes are detected by an array of PMTs and an image based on the positions of the flashes is constructed using fast electronics. The spatial distribution of gamma emitters in the body is useful for diagnosing disease.
Since a real gamma camera is not feasible in the undergraduate physics classroom, we have developed two types of optical apparatus that teach the main principles of the device. To understand the purpose of the collimator, a set of LEDs is arranged in a pattern to mimic the distribution of gamma emitters in the body, and the light from the LEDs is passed through an array of tubes onto a screen. The distance, spacing, diameter, and length of the tubes are varied to understand the factors that affect the resolution of the image. To learn how to determine the positions of the gamma emitters, the second apparatus uses a movable green laser to represent gamma ray photons that have passed through the collimator, and orange fluorescent plastic to represent the scintillation crystal. Acrylic rods, mimicking the PMTs, collect the light, and a silicon photodetector integrates the intensity across the end face of the rod. A centroid (Anger) algorithm is used to calculate the position of the light source. Written teaching materials supplement the apparatus so that students can relate the laboratory apparatus to the real gamma camera and basic nuclear physics concepts.
For ultrasound imaging, we are working with Iowa Doppler Products. To understand how to construct a B-scan image, the students first learn how to read and interpret the echoes on a digital oscilloscope.
Loyola University Maryland