Radiation imaging method, radiation imaging apparatus, computer program and computer-readable recording medium
The present invention prevents useless defect correction from being effected on pixels for obtaining a radiation image, to thereby improve the reliability of the radiation image provided for diagnosis. An initial defect map 1 in which a defective pixel extracted during shipment from a factory is registered, a QC defect map 2 in which a defective pixel extracted during periodical inspection in the market is registered, and a pseudo-defect map 3 in which a pseudo-defective pixel of abnormal sensitivity extracted during the shipment from the factory is registered are prepared to thereby enable the pseudo-defective pixel registered in the pseudo-defect map 3 to be eliminated from the object of defect correction so that useless defect correction can be curtailed.
1. A radiation imaging method using a radiation detector having a plurality of pixel groups, comprising:
a first map producing step for producing a first defect map for registering therein positions of defective pixels not functioning as pixels from the plurality of pixel groups;
a second map producing step for producing a second defect map for registering therein positions of pseudodefective pixels, a pseudodefective pixel differing from an ordinary pixel in at least one of sensitivity, a dark current and stability; and
a combined defect map producing step for producing a combined defect map in which a pixel group for effecting defect correction is registered, on the basis of the first defect map and the second defect map, wherein the positions of the pseudodefective pixels are excepted from the positions of the defective pixels to thereby produce the combined defect map.
2. A radiation imaging method according to claim 1 , wherein the first map producing step has a step of detecting the defective pixels at least two points of time or/and by at least two methods, and the positions of the defective pixels detected at each step are registered as the first defect map.
3. A radiation imaging method according to claim 1 , further comprising a defect correcting step of effecting defect correction by use of the combined defect map.
4. A radiation imaging method according to claim 3 , wherein the defect correcting process comprises a levelling process.
5. A radiation imaging method according to claim 4 , wherein the levelling process substitutes the output of a marked pixel for a numerical value calculated by the use of both of the output of the marked pixel and the outputs of ambient pixels surrounding the marked pixel.
6. A radiation imaging method according to claim 1 , wherein the pseudodefective pixels are defect-corrected when they reach saturation.
7. A radiation imaging apparatus provided with a radiation detector having a plurality of pixels, a recording unit for storing therein a defective pixel map and program of the radiation detector, and a controller for effecting control including an operation of executing the program,
wherein the defective pixel map is a first defect map in which the position of an initial defective pixel is registered, a second defect map in which the position of a pseudodefective pixel is registered the pseudodefective pixel differing from an ordinary pixel in at least one of sensitivity, a dark current and stability, and a third defect map in which the position of a defective pixel discovered by periodical inspection is registered, and
the controller produces a combined defect map in which a pixel for effecting defect correction is registered, by the use of the first defect map, the second defect map and the third defect map, and stores it in the recording unit, wherein the controller is arranged to produce the combined defect map by excepting the position of the pseudodefective pixel from the position of a defective pixel.
8. A radiation imaging apparatus according to claim 7 , wherein the controller effects defect correction by the use of the combined defect map.
9. A computer-readable recording medium that stores a computer program for causing a computer to execute:
a first map producing step for producing a first defect map for registering therein the position of defective pixels not functioning as the pixels of a radiation detector having a plurality of pixel groups;
a second map producing step for producing a second defect map for registering therein the position of pseudodefective pixels, a pseudodefective pixel differing from an ordinary pixel in at least one of sensitivity, a dark current and stability; and
a combined defect map producing step for producing a combined defect map in which a pixel group for effecting defect correction is registered, on the basis of the first defect map and the second defect map, wherein the positions of the pseudodefective pixels are excepted from the positions of the defective pixels to thereby produce the combined defect map.