Method of adjusting radiation image read-out conditions

Claim 1

A method of adjusting radiation image read-out conditions in which preliminary read-out conducted by exposing a stimulable phosphor sheet carrying a radiation image of an object stored thereon by limitation of an irradiation field in a rectangular form to stimulating rays of a level lower than the level of stimulating rays used in final read-out and detecting the radiation image stored on the stimulable phosphor sheet is carried out prior to the final read-out wherein the stimulable phosphor sheet is exposed to stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy and the emitted light is photoelectrically detected to obtain electric image signals used for reproducing a visible image, and read-out conditions in the final read-out are adjusted on the basis of the image information obtained by the preliminary read-out, wherein the improvement comprises the steps of: (i) detecting digital image signals at respective positions on said stimulable phosphor sheet on the basis of the image information obtained by said preliminary read-out, (ii) setting an X axis and a Y axis along two adjacent sides of a contour of said rectangular irradiation field on said stimulable phosphor sheet, (iii) adding up said digital image signals in said X axis direction and in said Y axis direction, detecting positions on said Y axis at which the levels of the added-up signals in said X axis direction are equal to a predetermined threshold value Th, and detecting positions on said X axis at which the levels of the added-up signals in said Y axis direction are equal to the predetermined threshold value Th, (iv) determining a region, which is surrounded by straight lines in said X axis direction at said positions on said Y axis and straight lines in said Y axis direction at said positions on said X axis on said stimulable phosphor sheet, as the irradiation field, and (v) adjusting said read-out conditions in said final read-out on the basis of the image information obtained within said irradiation field by said preliminary read-out.

Claim 2

A method of adjusting radiation image read-out conditions in which preliminary read-out conducted by exposing a stimulable phosphor sheet carrying a radiation image of an object stored thereon by limitation of an irradiation field in a rectangular form to stimulating rays of a level lower than the level of stimulating rays used in final read-out and detecting the radiation image stored on the stimulable phosphor sheet is carried out prior to the final read-out wherein the stimulable phosphor sheet is exposed to stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy and the emitted light is photoelectrically detected to obtain electric image signals used for reproducing a visible image, and read-out conditions in the final read-out are adjusted on the basis of the image information obtained by the preliminary read-out, wherein the improvement comprises the steps of: (i) detecting digital image signals at respective positions on said stimulable phosphor sheet on the basis of the image information obtained by said preliminary read-out, (ii) setting an X axis and a Y axis along two adjacent sides of a contour of said rectangular irradiation field on said stimulable phosphor sheet, (iii) adding up said digital image signals in said X axis direction and in said Y axis direction, detecting positions on said Y axis at which the levels of the added-up signals in said X axis direction are equal to a predetermined threshold value Th, and detecting positions on said X axis at which the levels of the added-up signals in said Y axis direction are equal to the predetermined threshold value Th, (iv) determining a region, which is surrounded by straight lines in said X axis direction at said positions on said Y axis and straight lines in said Y axis direction at said positions on said X axis on said stimulable phosphor sheet, as the irradiation field, and (v) adjusting said read-out conditions in said final read-out on the basis of the image information obtained within said irradiation field by said preliminary read-out.