| 摘要 |
PURPOSE:To accurately estimate drop of resolution of detector using a mixed gas of xenon and helium as the gas within a vessel of multichannel ionization chamber type radioactive ray detector and measuring gas leak rate of helium. CONSTITUTION:An ionization chamber type radioactive ray detector for the CT scanner is formed by accommodating an electrode assembly where a high voltage electrode plate and a signal electrode plate are arranged alternately and are held by the electrode holding plates within a hermetically sealed vessel and by sealing a mixed gas of xenon gas in 20atm and helium gas of 1atm within the vessel. The entire part of detector is placed within a vacuum tank, the tank is then vacuumed by a rotary pump and diffusion pump. When the tank reaches the equilibrium condition, a valve is switched and gas lead rate is measured by an He leak ditector. Therefore, estimation in drop of sensitivity of detector and gas leak check of a product condition can be realized easily. |
