Design of a flood source for calibration of gamma cameras used in nuclear medicine imaging

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Over 40 million nuclear medicine procedures are carried out daily around the world, with approximately 2 million of these in Canada. Generally, these tests produce images of the heart, lung and cancers that are used for diagnoses. These images are produced with gamma cameras that need daily calibration. It is important that the camera be calibrated to record uniformly at all points in the image so that physicians will not be confused by camera artefacts when looking for subtle changes in the images. Currently, calibration to ensure uniformity in the camera response is done with a radioactive disk-shaped 'flood source' that illuminates the entire camera field of view. These sources work well, but they must be replaced frequently, and are highly radioactive so that special procedures and shielding must be used to minimize radiation exposure to technical staff. This Engage proposal tests the feasibility of a promising new design concept for a flood source that can be turned on and off remotely. Instead of a single radioactive source as is currently used, the new design would employ three elements. The first would emit alpha particles, the second would absorb these alphas and emit neutrons, and the third would capture the neutrons and emit the gamma rays used to calibrate the cameras. The advantage of this concept is that the gammas can be turned off by simply separating the first and second elements; this can be done mechanically, hence the flood source can be turned off. The residual radioactivity in the off state is negligible, hence no special shielding or handling procedures are required. Carleton is partnering with Best Medical Canada who has experience with radiation measurement and calibration devices and access to the current US market for flood sources valued at $40M annually.