Development of a High-Energy Gamma Camera for use with NSECT Imaging of the Breast

A new imaging technique, neutron stimulated emission computed tomography (NSECT), is being developed that has potential for utilization in breast cancer imaging. NSECT is a spectroscopic imaging technique that is able to produce elemental concentration images and previous studies have identified differences in trace element concentrations between malignant and benign tissues. NSECT illuminates the body via a beam of neutrons causing elemental nuclei to become excited and emit characteristic gamma radiation. By imaging the gamma rays in a tomographic manner it is possible to reconstruct elemental composition images. This method requires high-resolution spectroscopy, thereby eliminating the use conventional scintillation gamma cameras; in this case, spectral information is obtained from high-purity germanium (HPGe) semiconductor detectors, providing only 1D spatial information. To obtain 2D elemental concentration images, we are adapting high-energy solar spectroscopy technology. A rotating modulation collimator (RMC) consisting of two parallel-slat collimators is placed in front of the detector and modulates the incoming signal in a manner predicted by its geometry. Reconstruction of 2D images is possible by counting the number incident gammas at each rotation angle. A significant challenge is presented when attempting to modify the RMC for use in the near field and a prototype camera has been constructed to verify the geometric validity of a RMC for this use. Herein we present the progress to date in the design and development of a high-energy spectroscopic gamma camera for use with NSECT imaging of the breast.