Method and apparatus for acquiring image information for energy subtraction processing

• US 6,252,932 B1
• Filed: 07/22/1998
• Issued: 06/26/2001
• Est. Priority Date: 07/22/1997
• Status: Expired due to Term

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Arakawa, Satoshi
• Primary Examiner(s): Kim, Robert H.
• Assistant Examiner(s): Ho, Allen C.
• Application Number:
  US09/120,137
• Time in Patent Office: 1,070 Days
• Field of Search: 378/98.8, 378/98.9, 378/98.11, 378/98.12
• US Class Current: 378/98.9
• CPC Class Codes: A61B 6/4035 the source being combined with a filter or grating
• CPC Class Codes: A61B 6/4441 the rigid structure being a C-arm or U-arm
• CPC Class Codes: A61B 6/482 involving multiple energy imaging
• CPC Class Codes: A61B 6/585 Calibration of detector units
• CPC Class Codes: G21K 1/04 using variable diaphragms, shutters, choppers
• CPC Class Codes: H05G 1/30 Controlling

Abstract

Radiation having a high energy level, in which high energy components have been emphasized relatively to other energy components, is irradiated to an object, and high energy image information corresponding to the radiation having a high energy level, which radiation carries image information of the object, is thereby stored on a radiation detector. The radiation detector is provided with a flat surface-like scintillator, which converts radiation into visible light, and a solid-state photodetector, which is overlaid upon the scintillator and is constituted of a plurality of solid-state photo detecting devices located in a matrix-like pattern. The stored high energy image information is read from the radiation detector. Thereafter, radiation having a low energy level, in which low energy components have been emphasized relatively to other energy components, is irradiated to the object, and low energy image information corresponding to the radiation having a low energy level, which radiation carries image information of the object, is thereby stored on the radiation detector. The stored low energy image information is read from the radiation detector.

Claims

1. A method of acquiring image information for energy subtraction processing, wherein high energy image information of an object corresponding to radiation having a high energy level, in which high energy components have been emphasized relatively to other energy components, and low energy image information of the object corresponding to radiation having a low energy level, in which low energy components have been emphasized relatively to other energy components, are acquired, the method comprising the steps of:

i) irradiating the radiation having a high energy level onto the object, the high energy image information corresponding to the radiation having a high energy level, which radiation carries image information of the object, being thereby stored on a radiation detector, said radiation detector being provided with a flat surface-like scintillator, which converts radiation into visible light, and a solid-state photodetector, which is overlaid upon and in direct contact with said scintillator and is constituted of a plurality of solid-state photo detecting devices located in a matrix-like pattern,

ii) simultaneously reading the high energy image information which has been stored on said radiation detector, erasing the high energy image information from said radiation detector and preparing to irradiate the radiation having a low energy level,

iii) thereafter irradiating the radiation having a low energy level onto the object, the low energy image information corresponding to the radiation having a low energy level, which radiation carries image information of the object, being thereby stored on said radiation detector, wherein the irradiation of said radiation having a low energy level is carried out within 100 milliseconds after the irradiation of said radiation having a high energy level, and

iv) reading the low energy image information, which has been stored on said radiation detector.

2. A method as defined in claim 1 wherein predetermined radiation is employed as said radiation having a low energy level, and radiation, which is obtained by passing said predetermined radiation through a low energy component absorbing member having characteristics such that an absorptivity with respect to the low energy components is higher than an absorptivity with respect to the high energy components, is employed as said radiation having a high energy level.

3. A method as defined in claim 1 wherein said radiation having a high energy level and said radiation having a low energy level are radiated selectively out of a single radiation source, which radiates the radiation having a high energy level and the radiation having a low energy level such that they are changed over to each other.

4. An apparatus for acquiring image information for energy subtraction processing, wherein high energy image information of an object corresponding to radiation having a high energy level, in which high energy components have been emphasized relatively to other energy components, and low energy image information of the object corresponding to radiation having a low energy level, in which low energy components have been emphasized relatively to other energy components, are acquired, the apparatus comprising:

i) a radiation source, which selectively radiates the radiation having a high energy level and the radiation having a low energy level such that they are changed over to each other,

ii) a radiation detector, which is located at a position that receives the radiation having been irradiated onto the object and carrying image information of the object, said radiation detector being provided with a flat surface-like scintillator, which converts radiation into visible light, and a solid-state photodetector, which is overlaid upon and in direct contact with said scintillator and is constituted of a plurality of solid-state photo detecting devices located in a matrix-like patter, and

iii) a control means, which controls operations for;

a) radiating the radiation having a high energy level out of said radiation source, the high energy image information being thereby stored on said radiation detector,

b) simultaneously reading the high energy image information which has been stored on said radiation detector, erasing the high energy information from said radiation detector and preparing to irradiate the radiation having a low energy level,

c) thereafter radiating the radiation having a low energy level out of said radiation source, the low energy image information being thereby stored on said radiation detector, wherein the length of time occurring between the radiating of the radiation having a high energy level and the radiating of said radiation having a low energy level is set to be at most 100 milliseconds by said control means, and

d) reading the low energy image information, which has been stored on said radiation detector.

5. An apparatus as defined in claim 4 wherein said radiation source is provided with:

a radiation tube for radiating a single kind of radiation,

a low energy component absorbing member, which has characteristics such that an absorptivity with respect to the low energy components is higher than an absorptivity with respect to the high energy components of said radiation, wherein said low energy component absorbing member is moved into a position between said radiation tube and the object and thereafter retracted from said position, and

a drive means for moving said low energy component absorbing member into said position between said radiation tube and the object and retracting said low energy component absorbing member from said position in accordance with a predetermined instruction signal.

6. An apparatus as defined in claim 4 wherein said radiation source is constituted of a single radiation tube, which radiates the radiation having a high energy level and the radiation having a low energy level such that they are changed over to each other in accordance with a predetermined instruction signal.