Solutions for limiting septal penetration include the use of asymmetric pinholes, 48 pinholes with channels, 47,89 loftholes, 90 clustered pinholes, 49 and very high-density materials, such as gold or uranium. High-energy applications include imaging to follow patient response to therapy or to determine doses for radionuclide therapy, real-time proton beam range verification, and high-resolution tomography of positron emitters. Xing Rong a and Eric C. In addition, dosimetry requires quantitative images, and collimators are not typically optimized for such tasks. In the second part of this paper, we give some general guidelines for selecting the best collimator type for different applications and target resolutions and in the last part, we introduce methods for sensitivity maximization and task-based collimator optimization.
Observers that have been used for lesion detection include the non-prewhitening observer, — Hotelling-trace, and CHOs, which have also been shown to correlate well with human observer performance under a variety of different experimental conditions.
A collimator optimization method for quantitative imaging: Application to Y-90 bremsstrahlung SPECT
Moreover, most commercial preclinical multiple-pinhole systems have the advantage of being stationary, which can also not be achieved with parallel-hole, fan- or cone-beam collimators. In this work, the volume sensitivity, instead of the point sensitivity in the center of the FOV, was considered, as in Ref. We seek to determine the collimator resolution and septal penetration that maximize the given task-based figure-of-merit. Each of the four columns of the system matrix was generated by arranging the corresponding projection data to form a vector. Object model The XCAT phantom code 22 was used to simulate realistic human anatomy and generate both the activity distribution and the attenuation map. Therefore, the technique is mostly used for the collimator body, in combination with pinhole inserts made from more dense materials such as tungsten, gold, platinum, uranium, or titanium. In the simulation, no activity was distributed outside the liver, as would also be typical in this application.