Software upgrading in a CT scanner: Influence on quantitative CT

Purpose: In an attempt to improve field uniformity and CT number stability, the software in a CT scanner was replaced with a new version. The purpose of the present study was to investigate the influence of the software upgrading on density measurements. Material and Methods: The upgrading influence was investigated by means of a torso phantom (European spinal). The phantom simulates a torso which contains 3 vertebrae of different densities. Results: Despite the use of a reference standard under the phantom, the software change resulted in: a) improved short-term precision; b) increased density values at 80 and 100 kVp, decreased at 130 kVp; and c) increased influence of the kVp on the values. Conclusion: The results of the present study suggest that conversion factors have to be used in density values for reference populations as well as in the values of patients undergoing follow-up studies

A beam-modification assembly for experimental neutron capture therapy of brain tumors

Recent attempts to treat intracerebral rat gliomas by boron neutron capture therapy (BNCT) have been somewhat disappointing, perhaps in part because of excessive whole-body and nasopharyngeal irradiation. Intracerebral rat gliomas were treated by BNCT with more success using a new beam-modification assembly. 3 refs., 2 figs