[Neutron Dosimetry System Using CR-39 for High-energy X-ray Radiation Therapy].
Neutrons are produced during radiation treatment by megavolt X-ray energies. However, it is difficult to measure neutron dose especially just during the irradiation. Therefore, we have developed a system for measuring neutrons with the solid state track detector CR-39, which is free from the influence of the X-ray beams. The energy spectrum of the neutrons was estimated by a Monte Carlo simulation method, and the estimated neutron dose was corrected by the contribution ratio of each energy. Pit formation rates of CR-39 ranged from 2.3 x 10(-3) to 8.2 x 10(-3) for each detector studied. According to the estimated neutron energy spectrum, the energy values for calibration were 144 keV and 515keV, and the contribution ratios were approximately 40:60 for 10 MV photons and 20:70 for photons over 15 MV. Neutron doses measured in the center of a high-energy X-ray field were 0.045 mSv/Gy for a 10 MV linear accelerator and 0.85 mSv/Gy for a 20 MV linear accelerator. We successfully developed the new neutron dose measurement system using the solid track detector, CR-39. This on-time neutron measurement system allows users to measure neutron doses produced in the radiation treatment room more easily.
Kazutoshi
K
Yabuta
Hajime
H
Monzen
Masaya
M
Tamura
Takao
T
Tsuruta
Tetsuo
T
Itou
Akihiro
A
Nohtomi
Yasumasa
Y
Nishimura
D002138:Calibration; D006801:Humans; D009010:Monte Carlo Method; D009502:Neutrons / Q000009:adverse effects; D010315:Particle Accelerators / Q000295:instrumentation; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods; D011882:Radiotherapy, High-Energy / Q000295:instrumentation* / Q000379:methods