Radiographic apparatus and method for switching a grid

• US 7,110,502 B2
• Filed: 05/12/2004
• Issued: 09/19/2006
• Est. Priority Date: 05/12/2003
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tsuji, Osamu
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): KAO, CHIH CHENG G
• Application Number:
  US10/844,982
• Publication Number:
  US 20040228439A1
• Time in Patent Office: 860 Days
• Field of Search: 378/114, 378/115, 378/116, 378/154, 378/155
• US Class Current: 378/116
• CPC Class Codes: A61B 6/06 Diaphragms
• CPC Class Codes: A61B 6/4291 the detector being combined with a grid or grating
• CPC Class Codes: A61B 6/5235 combining images from the same or different ionising radiation imaging techniques, e.g. PET and CT
• CPC Class Codes: A61B 6/5252 removing objects from field of view, e.g. removing patient table from a CT image

Abstract

This invention provides a radiographic apparatus and method, which can suitably set a grid in radiography or fluoroscopy and execute fluoroscopy or radiography of an object under optimum imaging conditions. The radiographic apparatus includes an X-ray unit (102) which irradiates an object with radiation (X-rays), a two-dimensional detector (106) which detects, through a grid, the radiation which has passed through the object, and a read control unit (107) which acquires an image of the object from the detected X-rays. The apparatus further includes a user interface (113) capable of setting imaging conditions such as an X-ray condition, grid condition, and read condition, a grid switching unit (105) which selects one of a plurality of grids on the basis of the set imaging conditions, and a grid stripe reduction unit (109) which reduces grid stripes generated on the image by the grid.

Claims

1. A radiographic apparatus comprising:

mode selection means for selecting either a first mode for imaging a still image or a second mode for imaging a moving image;

a plurality of grids for removing scattered radiation from radiation which has passed through an object;

grid selection means for selecting one of the plurality of grids in accordance with the selected mode;

a two-dimensional detector for converting the radiation from which the scattered radiation has been removed by the selected grid into electrical signals;

setting means for setting a read condition on a basis of the selected mode, which includes read pixel pitch and an amplification degree;

acquisition means for acquiring an image of the object from the electrical signals on a basis of the read condition set by the setting means; and

grid stripe reduction means for reducing grid stripes on the image on a basis of parameters corresponding to the read pixel pitch;

wherein in the read condition, the read pixel pitch of the two-dimensional detector and the amplification degree of the second mode are larger than in the first mode.

2. The apparatus according to claim 1, wherein a grid for the second mode and a grid for the first mode are connected in the same plane, and said grid selection means switches one of the grid for the second mode and the grid for the first mode by shifting the grid for the second mode and the grid for the first mode.

3. The apparatus according to claim 2, wherein the grid for the second mode and the grid for the first mode have different grid ratios or different grid frequencies.

4. The apparatus according to claim 1, further comprising irradiation means for irradiating the object with radiation, wherein

tube voltage of the irradiation means in the case of the second mode is lower than that in the case of the first mode.

5. The apparatus according to claim 1, further comprising irradiation means for irradiating the object with radiation, wherein

tube current of the radiation means in the case of the second mode is smaller than that in the case of the first mode.

6. A radiographic method comprising:

a mode selection step for selecting either a first mode for imaging related to a still image or a second mode for imaging related to a moving image;

an irradiation step of irradiating an object with radiation;

a removing step of removing scattered radiation from radiation which has passed through the object;

a grid selection step for selecting one of a plurality of grids in accordance with the selected mode;

a two-dimensional converting step for converting the radiation from which the scattered radiation has been removed by the selected grid into electrical signals;

a setting step for setting a read condition on a basis of the selected mode selected in said mode selection step, which includes read pixel pitch and an amplification degree;

an acquisition step of acquiring an image of the object from the electrical signals on a basis of the read condition set in the setting step for setting a read condition;

a setting step of setting imaging conditions; and

a grid stripe reduction step of reducing grid stripes on the image on a basis of parameters corresponding to read pixel pitch, wherein in the setting step for setting the read condition, the read pixel pitch and the amplification degree of the second mode are larger than in the first mode.

7. A computer-readable medium encoded with a computer program which causes a computer to execute:

a mode selection step for selecting either a first mode for imaging related to a still image or a second mode for imaging related to a moving image;

an irradiation step of irradiating an object with radiation;

a removing step of removing scattered radiation from radiation which has passed through the object;

a grid selection step for selecting one of a plurality of grids in accordance with the selected mode;

a two-dimensional converting step for converting the radiation from which the scattered radiation has been removed by the selected grid into electrical signals;

a setting step for setting a read condition on a basis of the selected mode selected in said mode selection step, which includes read pixel pitch and an amplification degree;

an acquisition step of acquiring an image of the object from the electrical signals on a basis of the read condition set in the setting step for setting a read condition;

a setting step of setting imaging conditions; and

a grid stripe reduction step of reducing grid stripes on the image on a basis of parameters corresponding to read pixel pitch,

wherein in the setting step for setting the read condition, the read pixel pitch and the amplification degree of the second mode are larger than in the first mode.