10 MV リニアックからの中性子線漏洩に対する遮蔽効果

概要

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Shielding effect is discussed for photoneutron leakage from 10 MV linear accelerator. The original shielding in existing treatmentroom was designed without neutrons in mind. The following five additional shielding methods against photoneutrons were used. (1) Opening between the treatmentroom and the maze was narrowed to 49%. (2) Additional shielding door, consisting of 3cm thick borated polyethylene and 5mm thick lead, was installed at the opening. (3) Wall thickness at the opening was increased from 45cm to 80cm. (4) Structure of the shielding door at the entrance of the maze was changed to the same one at the opening. (5) Two shielding chambers which surround the duct for air conditioning, consisting of 3cm thick borated polyethylene and 5mm thick lead, were installed above the opening. A comparison was made between the neutron dose equivalent (DE) calculated by simple manner and the DE measured with neutron rem meter. Under the condition on which we measured, the accuracy of the neutron rem meter which we used in mixed photoneutron with pulsed X-rays was ±32%. We concluded that method (2) and (4) were more effective. The calculated values were in good agreement with the measured ones.
社団法人日本放射線技術学会の論文
1991-07-01