Radiation imaging system, method for taking continuous radiographic image, and radiation image detecting device

• US 9,265,467 B2
• Filed: 08/24/2012
• Issued: 02/23/2016
• Est. Priority Date: 09/27/2011
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Kamiya, Takeshi
• Primary Examiner(s): Kim, Robert
• Assistant Examiner(s): Stoffa, Wyatt
• Application Number:
  US13/593,570
• Publication Number:
  US 20130077744A1
• Time in Patent Office: 1,278 Days
• Field of Search: 378/62, 378/97, 378/98
• US Class Current: 1/1
• CPC Class Codes: A61B 6/06 Diaphragms
• CPC Class Codes: A61B 6/4233 using matrix detectors
• CPC Class Codes: A61B 6/5241 combining overlapping images of the same imaging modality, e.g. by stitching
• CPC Class Codes: A61B 6/542 involving control of exposure
• CPC Class Codes: A61B 6/544 dependent on patient size
• CPC Class Codes: A61B 6/548 Remote control of the apparatus or devices

Abstract

In continuous radiography, while a patient stands in front of an imaging support, a total image capture field is determined. The total image capture field is divided into small image capture fields. A map scaling section scales up or down a full spine irradiation area map in accordance with the size of the total image capture field. A map dividing section divides the scaled map into small maps corresponding to the small image capture fields. In each division exposure, a detection pixel selector selects one or more detection pixels belonging to an irradiation area defined by the small map, out of all detection pixels distributed in an imaging surface of an electronic cassette. If an integration value of a detection signal from the selected detection pixel reaches a threshold value, X-ray emission is stopped. Division X-ray images obtained by the division exposures are merged into a single continuous X-ray image.

Claims

1. A radiation imaging system for dividing a total image capture field into N integer number of small image capture fields, and producing a single continuous radiographic image from N number of division radiographic images obtained by division exposures of said small image capture fields, said radiation imaging system comprising:

a radiation source for emitting radiation to each of said small image capture fields;

a radiation image detecting device having a detection panel having an imaging surface having an arrangement of a plurality of pixels, said detection panel detecting said radiation that has passed through a body part of said small image capture field to produce said division radiographic image;

a plurality of dose detection sensors substantially uniformly distributed in said imaging surface, each for measuring a radiation dose;

a memory for storing an irradiation area map that defines as an irradiation area an area for measuring said radiation dose in accordance with said body part to be imaged;

a map scaling section for scaling up or down said irradiation area map so as to make said irradiation area map coincide with said total image capture field in size;

a dose detection sensor selector for selecting one or more of said dose detection sensors belonging to said irradiation area based on said irradiation area map that has been scaled up or down by said map scaling section; and

an automatic exposure controller for automatically controlling a radiation exposure in each of said division exposures, said automatic exposure controller stopping emission of said radiation from said radiation source in accordance with a measurement value obtained from a detection signal of said dose detection sensor selected by said dose detection sensor selector.

2. The radiation imaging system according to claim 1, further comprising a map dividing section for dividing said irradiation area map that has been scaled up or down by said map scaling section in accordance with said small image capture fields.

3. The radiation imaging system according to claim 1, wherein said measurement value is an integration value of said detection signal of said selected dose detection sensor;

and wherein the automatic exposure controller is arranged so that when said integration value reaches a predetermined threshold value, the emission of said radiation is stopped.

4. The radiation imaging system according to claim 3, wherein said irradiation area map includes:

a full spine irradiation area map for defining said irradiation areas corresponding to a pelvis and a spine; and

a lower limb irradiation area map for defining said irradiation areas corresponding to said pelvis, knees, and ankles.

5. The radiation imaging system according to claim 3, wherein

said irradiation area map includes a first map for defining said irradiation area of a first shape and a second map for defining said irradiation area of a second shape;

and

said dose detection sensor selector being arranged to switch between said first map and said second map in accordance with a number of said division exposures or said small image capture field.

6. The radiation imaging system according to claim 5, wherein

said first map defines said irradiation area of inverse T shape corresponding to a pelvis and a part of a spine;

and

said second map defines said irradiation area being narrow and straight corresponding to said spine.

7. The radiation imaging system according to claim 5, wherein

said first map defines said irradiation area of π

shape corresponding to a pelvis and a part of legs; and

said second map defines two of said irradiation areas being straight corresponding to said legs.

8. The radiation imaging system according to claim 4, wherein when said small image capture field to be first exposed includes said pelvis, said dose detection sensor selector is arranged to use said first map in a first exposure, and to use said second map in a second or later exposure.

9. The radiation imaging system according to claim 3, wherein

said dose detection sensor selector includes an exposed area determination section for determining an actual exposed area based on an angle of a collimator of said radiation source and a positional relation between said radiation source and said radiation image detecting device;

and

said dose detection sensor selector is arranged to select one or more of said dose detection sensors that are present within said actual exposed area determined by said exposed area determination section and belong to said irradiation area.

10. The radiation imaging system according to claim 3, wherein said N number of small image capture fields partly overlap one another.

11. The radiation imaging system according to claim 3, wherein said plurality of pixels include:

a normal pixel for producing signal charge by an amount corresponding to said radiation dose, and accumulating said signal charge, and outputting said signal charge to a signal line through a switching element; and

a detection pixel directly connected to said signal line, for functioning as said dose detection sensor.

12. The radiation imaging system according to claim 1, wherein said radiation image detecting device is an electronic cassette having said detection panel contained in a portable housing.

13. A radiation imaging system for dividing a total image capture field into N integer number of small image capture fields, and producing a single continuous radiographic image from N number of division radiographic images obtained by division exposures of said small image capture fields, said radiation imaging system comprising:

a radiation source for emitting radiation to each of said small image capture fields;

a radiation image detecting device having a detection panel having an imaging surface having an arrangement of a plurality of pixels, said detection panel detecting said radiation that has passed through a body part of said small image capture field to produce said division radiographic image;

a plurality of dose detection sensors substantially uniformly distributed in said imaging surface, each for measuring a radiation dose;

a memory for storing an irradiation area map that defines as an irradiation area an area for measuring said radiation dose in accordance with said body part to be imaged;

a dose detection sensor selector for selecting one or more of said dose detection sensors belonging to said irradiation area based on said irradiation area map; and

an automatic exposure controller for automatically controlling a radiation exposure in each of said division exposures, said automatic exposure controller stopping emission of said radiation from said radiation source in accordance with a measurement value obtained from a detection signal of said dose detection sensor selected by said dose detection sensor selector,

wherein said measurement value is an integration value of said detection signal of said selected dose detection sensor; and

wherein the automatic exposure controller is arranged so that when said integration value reaches a predetermined threshold value, the emission of said radiation is stopped, and

wherein said dose detection sensor selector further includes;

a predicted dose calculator for calculating an instantaneous value of a predicted dose received by a directly-exposed area of said imaging surface based on an operation condition of said radiation source and a positional relation between said radiation source and said radiation image detecting device, said radiation being directly incident upon said directly-exposed area without passing through said body part; and

a body area determination section for determining a body area from a result of comparison between an instantaneous value of said detection signal of said dose detection sensor and said instantaneous value of said predicted dose,

wherein said dose detection sensor selector is arranged to select one or more of said dose detection sensors that are present within said body area and belong to said irradiation area.

14. A method for taking a continuous radiographic image comprising the steps of:

determining a total image capture field;

dividing said total image capture field into a plurality of small image capture fields in accordance with a size of a detection panel of a radiation image detecting device;

intermittently carrying out a plurality of division exposures, while relatively shifting a radiation source and said radiation image detecting device in accordance with each of said small image capture fields;

in each of said division exposures, reading out an irradiation area map corresponding to said small image capture field, said irradiation area map defining an irradiation area;

scaling up or down said irradiation area map so as to make said irradiation area map coincide with said total image capture field in size;

after the scaling step, selecting one or more dose detection sensors for use in automatic exposure control based on said irradiation area map that has been scaled up or down in said scaling step, said dose detection sensors being substantially uniformly distributed in an imaging surface of said detection panel;

stopping emission of radiation from said radiation source in accordance with a measurement value obtained by a detection signal of said selected dose detection sensor;

producing a single continuous radiographic image from a plurality of division radiographic images obtained by said division exposures.

15. The method according to claim 14, wherein

said measurement value is an integration value of said detection signal of said selected dose detection sensor;

and

when said integration value reaches a predetermined threshold value, the emission of said radiation is stopped.