Designing of the 14 MeV neutron moderator for BNCT

Abstract

In boron neutron capture therapy (BNCT), the ratio of the fast neutron flux to the neutron flux in the tumor (RFNT) must be less than 3%. If a D-T neutron generator is used in BNCT, the 14 MeV neutron moderator must be optimized to reduce the RFNT. Based on the neutron moderation theory and the simulation results, tungsten, lead and diamond were used to moderate the 14 MeV neutrons. Satisfying RFNT of less than 3%, the maximum neutron flux in the tumor was achieved with a three-layer moderator comprised of a 3 cm thick tungsten layer, a 14 cm thick lead layer and a 21 cm thick diamond layer.

Optimization and analysis of neutron distribution on 30 MeV cyclotron-based double layer beam shaping assembly (DLBSA)

“…The neutrons used in DLBSA are originated from reactions of 30 MeV protons with the 9 Be target. The 9 Be material is chosen for its ability to produce high flux compared to other materials, such as 7 Li and 181 Ta. Another distinctive feature of 9 Be is its melting point and boiling point which is higher than those of 7 Li [15].…”

“…10 B is highly probable to capture neutrons within the range of thermal energy (< 0.1 eV) and transforms into 11 B. Due to its instability, 11 B immediately disintegrates, emitting alpha particle and 7 Li. Li ion emits prompt gamma radiation, which is parasitic in BNCT as irradiates the normal tissue, cancer cell killing is mostly due to ions.…”

“…Some components constructed in the form of double layer show better performance. The use of a double layer moderator can increase moderation up to 19.3 % [7]. A double layer filter can produce epithermal neutron beams that range from 1.5 to 10 keV [8].…”

Photo‐Degradation of a Biopolyester Blend under UV‐C Rays

“…In particular, biopolyesters such as polycaprolactone (PCL) and polylactic acid (PLA) are used for making sutures or as scaffolds for cell growth. [ 8–11 ] These materials must be sterilized before use. One possible technique is exposure to UV‐C germicidal.…”

Neutron beam optimization based on a 7 Li(p,n) 7 Be reaction for treatment of deep-seated brain tumors by BNCT

“…The advantages of using these sources are: simple application, high safety in hospital environments, relative low cost compared with reactors, easy turning off, providing sufficient neutron flux, and less overall risk than nuclear reactors. However, the most crucial aspects for accelerator-based neutron sources are the type and energies of incident particles, and target material selection [5][6][7][8].…”