Renovation of epithermal neutron beam for BNCT at THOR

• Published in: Applied radiation and isotopes 2004-11, Vol.61 (5), p.1039-1043
• Main Authors: Liu, Y.-W.H, Huang, T.T, Jiang, S.H, Liu, H.M
• Format: Article
• Language: English
• Subjects: Boron Neutron Capture Therapy - instrumentation; Boron Neutron Capture Therapy - statistics & numerical data; Epithermal neutron beam design; Facility Design and Construction; Fast Neutrons - therapeutic use; Humans; Phantoms, Imaging; Renovation; Taiwan; THOR
• ISSN: 0969-8043; 1872-9800
• DOI: 10.1016/j.apradiso.2004.05.042

Heading for possible use for clinical trial, THOR (Tsing Hua Open-pool Reactor) at Taiwan was shutdown for renovation of a new epithermal neutron beam in January 2003. In November 2003, concrete cutting was finished for closer distance from core and larger treatment room. This article presents the design base that the construction of the new beam is based on. The filter/moderator design along the beam is Cd(0.1 cm)+Al(10 cm)+FLUENTAL™(16 cm)+Al(10 cm)+FLUENTAL(24 cm)+Void(18 cm)+Cd(0.1 cm)+Bi(10 cm) with 6 cm Pb as reflector. Following the filter/moderator is an 88 cm long, 6 cm thick Bi-lined collimator with Li 2CO 3-PE at the end. The collimator is surrounded by Li 2CO 3-PE and Pb. The calculated beam parameters under 2 MW at the beam exit is φ epi=3.4×10 9 n/cm 2/s, D f/ φ epi=2.8×10 −11 cGy cm 2/n, D γ / φ epi=1.3×10 −11 cGy cm 2/n, and J +/ φ= 0.8. For a phantom placed 10 cm from beam exit, MCNP calculation shows that the advantage depth is 8.9 cm, and advantage ratio is 5.6 if boron concentration in tumor and normal tissue are assumed to be 65 and 18 ppm. The maximum dose rate for normal tissue is 50 cGy/min. The maximum therapeutic ratio is 6. The construction of the beam is scheduled to be finished by the end of April 2004.