Leakage neutrons were measured around the labyrinth and the entrance of the treatment room for the 10 MV X-ray linear accelerator facility of Chiba University Hospital. A neutron rem counter and a BF3-counter surrounded by paraffin moderators were used for neutron measurements. An ionization chamber was used for scattered X-ray measurements.
Relative counting rate of leakage neutrons showed an exponential attenuation with the distance in the labyrinth and passage. Furthermore, it was found that the leakage neutrons decrease at the entrance door for shielding by about 20Dose equivalent rates for leakage radiations were 0.8 mrem/hr for neutrons and 0.5mrem/hr for scattered X-ray at the outside of the door.
These results indicate that the controlled area of our facility is satisfied the regulated value of the rule without any additional shielding for leakage neutrons.

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Dosimetric properties of Li2B407: Cu and CaSO4: Tm thermoluminescent dosimeters with thin elements were studied for 60Co and 226Ra y rays, conventional and highenergy x rays, and high-energy electrons. The thermoluminescent output of TLD was measured in a reader using the photon-counting method with optical heating.
Coefficients of variations of measured values with these TLDs were about 2 %at 0.5 R for 226Ra Y rays. The Li2B407 phosphor showed a linear response from 2mR to 1000 R, and the constant response over 20 cycles of repeated use to 300 R of 60Co y rays.
The response per exposure to conventional x rays was 10-30 % less than that to 60Co y rays. -The response per exposure of CaSO4 phosphor to226RaT rays was about 20times greater than that of Li2B407 one, and the supralinear response of Ca504phosphor was found at doses more than 100 R of 60Co y rays. The energy response of CaSO4 phosphor to x and y rays was examined. Response ratios among CaSO4 and Li2B407 phosphors, and of two CaSO4 phosphors with 280 mg/cm2 plastic and 840mg/cm2 Pb filters can be utilized to determine equivalent energy of an x and y rays.

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