JP2005073765A5 - - Google Patents

Claims (5)

A rotating disk driven to rotate around the subject, first, second and third X-ray sources arranged and held around the rotating disk at equal intervals in the rotation direction of the rotating disk, the first First, second, and third X-ray detections that are arranged opposite to the second and third X-ray sources and detect X-rays irradiated from the respective X-ray sources and transmitted through the subject. , A table for holding the subject movably along the body axis, and image reconstruction means for reconstructing a tomographic image of the subject based on the intensity of the X-ray detected by each X-ray detector The multi-tube X-ray CT apparatus has a transmitted X-ray dose calculation unit that calculates an average transmitted X-ray dose at each angular position with respect to the subject of each X-ray source from the detection signal of each X-ray detector,
The irradiation X-ray dose at a certain rotation angle position of the first X-ray source is controlled based on the average transmitted X-ray dose calculated when the second X-ray source was immediately before the rotation angle position. The irradiation X-ray dose at a certain rotation angle position of the second X-ray source is based on the average transmitted X-ray dose calculated when the third X-ray source was immediately before the rotation angle position. The irradiation X-ray dose at a certain rotational angle position of the third X-ray source is the average transmission calculated when the first X-ray source was immediately before the rotational angle position. A multi-tube X-ray CT apparatus controlled based on an X-ray dose. The irradiation X-ray dose at a rotation angle position of the first X-ray source is further calculated as an average transmission calculated when the third X-ray source was immediately before the rotation angle position of the first X-ray source. Based on the X-ray dose, the irradiation X-ray dose at the rotation angle position where the second X-ray source is located is further determined so that the first X-ray source is located immediately before the rotation angle position where the second X-ray source is located. The irradiation X-ray dose based on the average transmitted X-ray dose calculated at the time and at the rotation angle position of the third X-ray source is further determined by the second X-ray source immediately before the third X-ray source. 2. The multi-tube X-ray CT apparatus according to claim 1, wherein the multi-tube X-ray CT apparatus is controlled based on an average transmitted X-ray dose calculated at a certain rotation angle position. The irradiation X-ray dose at a rotation angle position of the first X-ray source is further based on the average transmitted X-ray dose calculated at the time of the projection measurement immediately before or near the first X-ray source. The irradiation X-ray dose at a certain rotational angle position of the X-ray source is further based on the average transmitted X-ray dose calculated at the time of the projection measurement immediately before or near by the second X-ray source and the third X-ray source. The irradiation X-ray dose at a rotation angle position of the source is further controlled based on an average transmitted X-ray dose calculated at the time of the projection measurement immediately before or near to the third X-ray source. 2. A multi-tube X-ray CT apparatus according to 2. The multi-tube X-ray CT apparatus according to claim 1, wherein the first, second, and third X-ray detectors are held on the rotating disk. A rotating disk driven to rotate around the subject, a plurality of X-ray sources arranged and held around the rotating disk at equal intervals in the rotation direction of the rotating disk, and facing the plurality of X-ray sources The same number of X-ray detectors that are disposed, detect each X-ray irradiated from each X-ray source and transmitted through the subject, a table for holding the subject movably along the body axis, and each X-ray In a multitubular X-ray CT apparatus provided with image reconstruction means for reconstructing a tomographic image of a subject based on the intensity of X-rays detected by a detector, each detection signal from each X-ray detector A transmitted X-ray dose calculation unit for calculating an average transmitted X-ray dose at each angular position with respect to the subject of the X-ray source, and an irradiation X-ray dose at a rotation angle position of one X-ray source among the plurality of X-ray sources; Is another X-ray source of the plurality of X-ray sources immediately before the rotational angle position. The multi-tube X-ray CT apparatus is controlled based on the average transmitted X-ray dose calculated at the time.