JP2006116137A5

JP2006116137A5 -

Info

Publication number: JP2006116137A5
Application number: JP2004308364A
Authority: JP
Filing date: 2004-10-22
Publication date: 2007-12-06
Anticipated expiration: 2024-10-22

Claims

An X-ray tube current determining method for an X-ray CT apparatus for determining an X-ray tube current to be passed through an X-ray tube of an X-ray CT apparatus,
Scanning the subject only in one direction without rotating the X-ray tube and the X-ray detector, and obtaining a subject cross-sectional model from the scanogram data obtained from the X-ray detector at the time of scanning;
Determining an X-ray tube current standard modulation curve of an X-ray tube current to be changed for each view based on the subject cross-sectional model;
The image of the reconstructed image based on the image noise variance contribution value of each view when the X-ray tube current on the X-ray tube current standard modulation curve is used and the view direction weight applied to each view Estimating a noise variance value;
Correcting the X-ray tube current on the X-ray tube current standard modulation curve based on a ratio between a target image noise variance value determined from an image noise target value set by an operator and the estimated image noise variance value When,
A method for determining an X-ray tube current of an X-ray CT apparatus.

The reference CTDIvol value in (Equation 1) for each usable tube voltage and for each phantom that is the reference for CTDI
(Formula 1) Tube current 1 mA, irradiation time 1 s, movement pitch (top plate z movement amount per scanner rotation / X-ray beam thickness) = 1
Is stored in advance,
Calculating and displaying a predicted value of the exposure dose based on the reference CTDIvol value and the X-ray tube current on the modified X-ray tube current standard modulation curve;
The X-ray tube current determination method for an X-ray CT apparatus according to claim 1.

An X-ray source comprising: an X-ray tube that emits X-rays; and an X-ray tube control device that controls the X-ray tube;
An X-ray detector facing the X-ray source across the subject, detecting X-rays and outputting imaging data;
A rotating plate mounted with the X-ray source and the X-ray detector and capable of rotating at predetermined angles;
An image processing device that performs reconstruction calculation processing based on the imaging data;
An X-ray CT apparatus comprising:
Means for scanning the subject only in one direction without rotating the X-ray tube and the X-ray detector, and obtaining a subject cross-sectional model from the scanogram data obtained from the X-ray detector at the time of scanning;
Means for determining an X-ray tube current standard modulation curve of an X-ray tube current to be changed for each view based on the subject cross-sectional model;
Means for estimating an image noise variance contribution value of each view when using an X-ray tube current on the X-ray tube current standard modulation curve;
Means for estimating the image noise variance value of the reconstructed image based on the estimated image noise variance contribution value of each view and the view direction weight applied to each view;
Means for correcting an X-ray tube current on the X-ray tube current standard modulation curve based on a ratio between a target image noise variance value determined from an image noise target value set by an operator and the estimated image noise variance value When,
An X-ray CT apparatus comprising:

Reference CTDIvol value in (Equation 2) for each usable tube voltage and for each phantom that is the reference for CTDI
(Formula 2) Tube current 1 mA, irradiation time 1 s, movement pitch (top plate z movement amount per scanner rotation / X-ray beam thickness) = 1
Means for storing
Means for calculating and displaying a predicted value of the exposure dose based on the reference CTDIvol value and the X-ray tube current on the modified X-ray tube current standard modulation curve;
The X-ray CT apparatus according to claim 3.