In this paper

we calculate and evaluate the room shielding thickness of a Hi-Art tomotherapy system

which is a new type of radiotherapy facility. Due to the self-shielding of the accelerator

only scattered beam and beam leakage were considered in calculating the room shielding thickness. The radiation field of the tomotherapy system was used as the basic data to calculate the shielding thickness of every 15o solid angle. The maximum shielding thickness required of each shielding wall was at the position with the angle of 15o

and the calculated shielding thickness were 1023

975

917

1460

1147 and 1189 mm for the east wall

south wall

west wall

north wall

the roof and the floor

respectively. According to the calculation results

all shielding walls

ceiling and floor could meet the requirement of the radiation protection

but the north wall thickness of 1200 mm was a little thinner.