METHOD OF MODULATING DOSE OF X-RAY BEAM IN X-RAY CT SYSTEM

摘要

PROBLEM TO BE SOLVED: To reduce the total dose of X-rays to a patient without increasing image noise by multiplying the value read from a waveform table using a gantry angle as an index by a command value to cyclically calculate the command value controlling the dose of Xray beam to control the dose of the X-ray beam. SOLUTION: The view of one of scout data is obtained at a gantry angle of 0 deg. and the view of the other one of them is obtained at a gantry angle of 90 deg. (block 110). Next, the max. X-ray tube current (mA) to each slice is calculated (block 111) and one set of modulation indexes are calculated from the scout data (block 112). Then, a gantry angle obtaining first data with respect to a first slice from an operation parameter and the number reflecting the rotational speed of a gantry during scanning are calculated (block 114). A computer 26 sends a signal to a gantry motor controller 23 to start scanning (block 120).