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The Radiation Protection and Shielding Division is developing and promoting radiation protection and shielding aspects of nuclear science and technology — including interaction of nuclear radiation with materials and biological systems, instruments and techniques for the measurement of nuclear radiation fields, and radiation shield design and evaluation.
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Latest News
Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
B. Juste, R. Miró, G. Verdú, S. Díez, J. M. Campayo
Nuclear Technology | Volume 175 | Number 1 | July 2011 | Pages 175-181
Technical Paper | Special Issue on the 16th Biennial Topical Meeting of the Radiation Protection and Shielding Division / Radiation Transport and Protection | doi.org/10.13182/NT11-A12287
Articles are hosted by Taylor and Francis Online.
Megavoltage sources are commonly used in radiotherapy treatments, and the determination of the spectral distribution of a photon beam is extremely important for exact dosimetry and for the calculation of therapeutic dose distributions. Since direct measurements of the spectrum are very difficult, we present a technique to accurately calculate the bremsstrahlung spectra based on a numerical reconstruction upon central-axis depth dose data measured in a water tank using inverse methods.The basic idea of this technique is that the measured depth dose curve can be expressed as a weighted superposition of monoenergetic depth dose curves. While traditional approaches directly use the measured depth dose data, we show the improvement of using the gradient of these data for reconstruction. The inverse problem in terms of gradients is shown to be markedly less ill-conditioned than the usual inverse problem. In each case, a Tikhonov regularization is introduced to minimize the effects of noise due to measurement and computation. We illustrate this theory to calculate a 6-MeV photon beam from an Elekta Precise radiotherapy unit utilizing the gradient of depth dose measurements in a water tank.