At the Saitanla Chndre1 ゴs Medical Center、 the portable type digital portal imaging device ( DPID ) , in which the detector and the treatment facility are not constructed as one body, was lntroduced . When it was apPlied to total body irradiation , the image quality under low dose conditions was examined , and its usefulness was investigated . In the investigation , 、 丶 ・ hen the source − detector distance( SDD )was changed from l m to 5 m , the input ・ output characteristics , noise and

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... t resolution in respect 三 ve mo (圭 es of standard ( 256x256)and fast ( 256× ユ 28>were measured . The pixel value of 5 m in relation tQ l m decreased to l4 % , and noise ( variation coef 石cient >increased by 4 . 5times . The pixel value of the fast mode in relation to the standard mode became 80 %