Fuji Photo Film Company, Limited

Philips Medical Systems, Inc.

Masamitsu Ishida

Hisatoyo Kato

Seiji Matsumoto

Shigeru Saotome

Nobuyoshi Nakajima

Kazuo Shimura

Yuuma Adachi

Takeshi Funahashi

Tokukazu Saito

Takao Komaki

Hideo Watanabe

Satoshi Arakawa

Tsutomu Kimura

Kazuo Horikawa

Shoji Hara

Kazuhiro Hishinuma

Makoto Hara

Eiichi Asai

Nobuaki Higashi

Isoji Takahashi

Tomotaka Kozeki

Kozi Shimanuki

Hisatoyc Kato

James T Karam, Jr

Nobuaki Higaski

A radiation image recording and read-out apparatus comprises a recording and read-out unit for recording a radiation image on a stimulable phosphor sheet and reading the radiation image therefrom, a shutter moveable between a masking position that prevents impingement of radiation upon a part of the stimulable phosphor sheet and a retracted position that allows impingement of radiation upon a single image recording region of the stimulable phosphor sheet, and a shutter operating device for moving the shutter between the masking position and the retracted position. The recording and read-out unit is moved by a unit movement device to move the stimulable phosphor sheet in the same plane at an image recording position in the recording and read-out unit. A system is provided for operating the shutter operating device to move the shutter to the masking position, and operating the unit movement device to move the recording and read-out unit so that the uncovered portion of the stimulable phosphor sheet at the image recording position that is not covered by the shutter changes sequentially.

Radiation image recording and read-out apparatus

A radiation image read-out method comprises the steps of exposing a stimulable phosphor sheet, on which a radiation image having a background region has been stored, to stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation, and detecting the emitted light in order to obtain an image signal representing the radiation image. The shape and location of the background region are determined in advance, and only the area outside of the background region on the stimulable phosphor sheet is exposed to stimulating rays. Light emitted from the area outside of the background region is detected and converted into an image signal. Alternatively, after the shape and location of the background region are determined, the background region is erased. Thereafter, the stimulable phosphor sheet is exposed to stimulating rays, and light emitted by the stimulable phosphor sheet is detected and converted into an image signal.

Radiation image read-out method

In an energy subtraction processing for radiation images conducted by use of stimulable phosphor sheets, a characteristic value of a difference signal obtained by a subtraction processing of digital image signals detected from the stimulable phosphor sheets carrying radiation images stored therein is calculated. When the difference signal is subjected to a gradation processing, the characteristic value is made to correspond to a predetermined density of a reproduced image by uniformly converting the difference signal or by correcting a gradation conversion table used for the gradation processing.

Density correcting method and apparatus for subtraction image

In an energy subtraction processing for radiation images, a plurality of stimulable phosphor sheets laid one upon the other are simultaneously exposed to a radiation of high energy passing through an object, and then a different stimulable phosphor sheet is exposed to a radiation of low energy passing through the same object. Digital image signals detected from the stimulable phosphor sheets exposed to the high energy radiation are weighted and subjected to arithmetic averaging. A subtraction processing is carried out between an image signal obtained by the arithmetic averaging and an image signal detected from the stimulable phosphor sheet exposed to the low energy radiation.

Energy subtraction processing method using weighted average of plural

A radiation image read-out apparatus comprises a read-out device for detecting a radiation image recorded on a recording medium and generating an electric image signal, an input device for entering information concerning the image recording portion of an object and the image recording method, and a control device for adjusting read-out conditions on the basis of the information entered by the input device and feeding the adjusted read-out conditions to the read-out device. A reproduction condition designating apparatus is constituted by the input device, the control device, a device for displaying the reproduction conditions adjusted by the control device, and a correction input device for correcting the reproduction conditions displayed by the display device.

Radiation image read-out apparatus and reproduction condition

In a method of reading out a radiation image stored in a stimulable phosphor sheet, preliminary read-out for approximately detecting the image is conducted. A cumulative histogram of the image information is created, read-out conditions in the final read-out are corrected based on a characteristic value of the cumulative histogram, then the final read-out is conducted using the corrected conditions. Alternatively, a standard image information range is determined from the characteristic value, and the read-out conditions are adjusted so that the standard range corresponds to a predetermined electronic signal range. In addition, in the read-out method where gradation processing is performed for electronic image signals obtained by photoelectrically detecting the phosphor light emitted by the sheet, histogram of the image signals is created, and a desired image signal range is determined therefrom. A cummulative histogram then is created, the desired range is corrected based on a characteristic value of the cumulative histogram, and gradation processing conditions are adjusted so that the corrected desired signal range corresponds to a predetermined electronic signal range. Alternatively, a standard signal range is determined based on the characteristic value, and gradation processing conditions are adjusted so that the standard range corresponds to a predetermined electronic signal range.

A radiation image recording and read-out apparatus comprises a recording and read-out unit provided with a case having a size nearly equal to a single image recording area on a stimulable phosphor sheet, an image recording section for recording a radiation image of an object on the stimulable phosphor sheet, an image read-out section provided in the case for reading the radiation image from the stimulable phosphor sheet, and an erasing section provided in the case. The recording and read-out unit is moved between a first position at which the stimulable phosphor sheet is disposed at an image recording position exposed to radiation passing through the object, and a second position retracted from the first position. A fluoroscopic device is provided for receiving the radiation passing through the object at the time the recording and read-out unit is present at its second position, and converting the radiation into signals for a visible image.

In a method of adjusting read-out conditions for a radiation image stored on a stimulable phosphor sheet by limiting the radiation exposure field, digital image signals at respective positions on the stimulable phosphor sheet for detected on the basis of image information obtained by preliminary read-out. The digital image signals are subjected to a differentiation processing, and the radiation exposure field on the stimulable phosphor sheet is detected by use of the differentiated values obtained thereby. The read-out conditions in final read-out are adjusted on the basis of the image information obtained within the detected radiation exposure field by the preliminary read-out.

Method of adjusting radiation image read-out conditions

An apparatus for photoelectrically detecting a radiation image of an object stored on a stimulable phosphor sheet by exposure to a radiation passing through the object and storing detected image signals comprises a circuit for recognizing an irradiation field on the stimulable phosphor sheet, and an image signal selection circuit for receiving irradiation field information generated by the irradiation field recognition circuit and selecting only the image signals inside of the irradiation field from the read-out image signals. Or, the apparatus comprises a section for creating a histogram of the read-out image signals, a histogram analysis section for determining a range of the read-out image signals outside of a peak region arising in the vicinity of the maximum signal value or the minimum signal value in the histogram, and an image signal selection circuit for receiving the output of the histogram analysis section and selecting only the image signals within the range from the read-out image signals.

Radiation image read-out and image signal storing apparatus

A radiation image recording, read-out and reproducing apparatus comprises a case for housing a stimulable phosphor sheet and having an opening, a light shielding cover housed in the case for projection therefrom through the opening and having a sheet passage opening at an end on the side supported by the case at the time the light shielding cover is projected, recording section for recording a radiation image on the stimulable phosphor sheet disposed at an exposure position in the light shielding cover projected out of the case, a read-out section having a sub-scanning system for moving the stimulable phosphor sheet between the exposure position and a position in the case, and an erasing section. A reproducing section is provided for conveying a recording sheet housed in the case to feed the recording sheet out of the case through a feed-out opening of the case and, at the same time, reproducing the radiation image on the recording sheet.

Radiation image recording, read-out and reproducing apparatus

A high-speed image recording apparatus comprises a sheet changer for changing a stimulable phosphor sheet at an image recording position, a radiation source drive controller, and a filter changer for changing a radiation filter on a radiation passage between a radiation source and a stimulable phosphor sheet at each image recording step. The sheet changer, the radiation source drive controller and the filter changer are activated by signals sent from a controller to load the stimulable phosphor sheet to the image recording position, to change over the radiation filter, and then to emit radiation to the stimulable phosphor sheet via an object, thereby recording a high energy image and a low energy image of good energy discrimination in stimulable phosphor sheets.

High-speed image recording apparatus for energy subtraction processing

A radiation image recording and read-out apparatus comprises a radiation source for irradiating a radiation toward an object, a recording and read-out unit for recording a radiation image of the object on a stimulable phosphor sheet at an image recording position and reading the radiation image therefrom, and a movement system for moving the recording and read-out unit and the radiation source so that the stimulable phosphor sheet at the image recording position approximately satisfies the linear rule and the geometric rule with respect to the radiation source around an arbitrary tomographic layer. The recording and read-out unit is provided with a case having a size nearly equal to a single image recording area on the stimulable phosphor sheet, an image recording section, an image read-out section provided in the case for reading the radiation image from the stimulable phosphor sheet by exposure to stimulating rays, and an erasing section provided in the case.

In a radiation image read-out method using a stimulable phosphor sheet, read-out conditions in final read-out are adjusted based on preliminary read-out image information on a region recognized as an irradiation field. To recognize the irradiation field, sample image signals are extracted from preliminary read-out image signals at a picture element string extending from an end towards the center of the stimulable phosphor sheet. Changes between image density levels represented by the sample image signals are expressed by an approximate equation, and differences between imaginary image density levels calculated by the approximate equation and the actual image density levels are calculated. Or, the image density changes are expressed by approximate equations for picture element groups, and differences between imaginary image density levels calculated by the approximate equations in each picture element group are calculated. Or, intersections of lines represented by the approximate equations and an image density change curve higher than a predetermined density level and represented by the sample image signals are detected, and the intersection nearest to the sheet end is recognized as an edge of the irradiation field.

In a method of recognizing an irradiation field, sample image signals at a picture element string extending from an edge of a recording region towards the center thereof are extracted from image signals detected from a recording medium. Changes among image density levels represented by the sample image signals are expressed by an approximate equation, and differences between imaginary density levels calculated by the approximate equation and actual density levels are calculated to find an edge of the irradiation field. Or, intersections of lines represented by approximate equations for picture element groups and a density change curve in a range higher than a predetermined density and represented by the sample image signals are detected, and the intersection nearest to the edge of the recording region is recognized as the edge of the irradiation field. Image processing conditions are adjusted based on the image signals inside of the recognized irradiation field.

Irradiation field recognizing method, and method of adjusting image

A radiation image recording and read-out apparatus comprises a circulation transfer means for transferring a stimulable phosphor sheet along a predetermined circulation path; an image recording section which is disposed in the circulation path and in which a radiation image of an object is recorded on the stimulable phosphor sheet by exposing the stimulable phosphor sheet to radiation passing through the object; an image read-out section which is disposed in the circulation path for scanning the stimulable phosphor sheet with stimulating rays and detecting light emitted from the stimulable phosphor sheet to obtain an image signal; and an erasing section which is disposed in the circulation path and releases residual radiation energy in the stimulable phosphor sheet before the stimulable phosphor sheet is returned to the image recording section. The radiation image recording and read-out apparatus further includes a radiation quality changing filter for changing the quality of the radiation. The filter is arranged to be inserted into or retracted away from the path of the radiation in synchronization with the operation of a stimulable phosphor sheet changing mechanism for discharging one stimulable phosphor sheet from the recording position in the image recording section and positioning another sheet in the recording section.

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Kanagawa, Japan

Masamitsu Ishida