Abstract: The image of an object is improved by estimating the scattered radiation that it transmits to the detectors. To achieve this, one uses the scattered radiation effectively measured through an imitation of the object, having analogous attenuation properties, and which one modifies by the weighting coefficients obtained by a transformation of the values of the total radiation received through the object (3) and the selected imitation (8). One thus manages to improve the image without subjecting the object to a double irradiation in order to measure the scattered radiation separately. The principal applications are tomography, bone densitometry and non-destructive controls.

Abstract: A method or apparatus for analyzing an object includes an X-ray prescanner that performs a prescan of the object to determine prescan information about the object. Then, a CT scanner performs a CT scan on at least one plane of the object based on the prescan information to determine CT information. In one embodiment, if the CT scan of the object includes or is in the vicinity of metal, then metal artifact correction of a reconstructed image from the CT scan is performed based on the prescan information.

Abstract: In a method for correcting for stray radiation in measured intensity values, the measured intensity values are obtained in an X-ray computed tomography scanner by means of a detector matrix that is situated in a tomography measuring field of the computer tomography scanner and has a multiplicity of detector elements arranged next to one another in a number of adjacent detector rows. At least one reference distribution of the stray radiation intensity is determined in the row direction of the detector matrix, and a stray radiation component of each measured value of intensity is determined starting from this at least one reference distribution, and the measured intensity values are corrected as a function of their respective stray radiation component. In this case, the stray radiation component of the measured values of intensity of at least a fraction of the detector rows is determined by using a recursion method on the basis of the reference distribution.

Abstract: An imaging system includes an x-ray source coupled to a gantry. The x-ray source generates an x-ray flux, wherein a portion of the x-ray flux becomes scatter radiation. A scatter detector is also coupled to the gantry to receive the scatter radiation. The scatter detector generates a scatter signal in response to the scatter radiation, and a host computer receives the scatter signal.

Abstract: A method is provided which includes scanning an object with a cone beam volumetric computed tomography (CBVCT) system with a beam pass array positioned between an x-ray source of the CBVCT system and the object to acquire scatter data, scanning the object with the CBVCT system without the beam pass array positioned between the x-ray source and the object to acquire image data, and correcting the image data using the scatter data.

Abstract: An X-ray CT apparatus includes a plurality of X-ray irradiation sources and a plurality of X-ray detection units. Timing of irradiation of X-ray is shifted by each X-ray irradiation source, the detection unit separately obtains projection data and scatter correction data. In a scatter correction unit, scatter correction is performed based on the projection data and the scatter correction data.

Abstract: In order to remove a scattered line component resulting from an object from projection data to obtain a satisfactory rearrangement image, an amount of scattered line is calculated from a region in which a first-order X-ray is shielded by an X-ray shield and a component corresponding to the scattered line is removed. Then, an image in the region in which the first-order X-ray is shielded is complemented based on an image taken from a 180-degree opposite direction.

Abstract: A method is provided which includes scanning an object with a cone beam volumetric computed tomography (CBVCT) system with a beam pass array positioned between an x-ray source of the CBVCT system and the object to acquire scatter data, scanning the object with the CBVCT system without the beam pass array positioned between the x-ray source and the object to acquire image data, and correcting the image data using the scatter data.

Abstract: A method of correcting the extrafocal radiation of an X-ray tube in image recordings with a computed tomograph, includes subjecting measured data, obtained from detector channels of at least one detector row in the computed tomography, to logarithmic manipulation and back projection in order to obtain the image recordings. The measured data, before the logarithmic manipulation and back projection, is subjected to convolution with a detector-channel-dependent convolution core EN(k), which is derived from a distribution of the extrafocal radiation on at least one detector channel of the computed tomograph or a computed tomograph of an identical type. The present method permits good correction of the extrafocal radiation without reference to the convolution cores to be used for the filtered back projection.

Abstract: A system for correcting for scatter in a computed tomography scanner includes a tunnel having a platform disposed therein for receiving an object to be scanned, an x-ray source for directing x-rays at the object to be scanned, a detector array including a plurality of primary detectors for receiving the x-rays and at least one secondary detector for receiving portion of the x-ray beam scattered within the tunnel. The system further includes processing means for reducing the effects of scatter in images of the object reconstructed from the x-rays detected by method of estimating an amount of scatter caused only by the presence of the object corrected by an amount of scattered x-ray when presence or absence of object.

Abstract: An imaging system includes an x-ray source coupled to a gantry. The x-ray source generates an x-ray flux, wherein a portion of the x-ray flux becomes scatter radiation. A scatter detector is also coupled to the gantry to receive the scatter radiation. The scatter detector generates a scatter signal in response to the scatter radiation, and a host computer receives the scatter signal.

Abstract: The invention relates to a method for scatter correction while forming a computed X-ray tomogram. The distribution of the scattered radiation is determined by detector cells (7′) which, because of the measuring method carried out, are shielded from direct irradiation in a two-dimensional, multi-cell detector field (3). This distribution is used to perform a scatter correction in the neighboring, directly irradiated detector cells (7). Furthermore, scatter correction can be performed by computer simulation of the scatter processes. To this end, use is preferably made of a Monte Carlo method and the effect of the geometry and the material composition of the measuring arrangement, of the patient size, of the irradiated tissue and the like, is taken into account.

Abstract: In cone-beam volume computed tomography or similar imaging techniques, the effects of x-ray scatter are reduced through using a beam compensation filter (a bow tie filter), air gap technique, and an antiscatter grid and corrected through the use of a beam stop array combined with interpolation or convolution operation. Images are taken with the beam stop array, and a larger number of images are taken without the beam stop array. The images taken with the beam stop array are spatially interpolated to derive scatter information, which is then angularly interpolated to provide as many scatter images as there are images taken without the beam stop array. The interpolations are performed through cubic spline interpolation or any other interpolation techniques or low-pass filtering operation (convolution operation with a selected kernel). Each scatter image is subtracted from a corresponding one of the images taken without the beam stop array to provide a sequence of scatter-corrected images.

Abstract: The radiography of a subject is improved by estimating the scattered radiation it transmits to the detectors. For this, one uses scattered radiation measured effectively through a simulacrum of the subject, with analogous attenuation properties, and which are modified by weighted coefficients obtained through a transformation of the values of total radiation received through the subject (3) and the simulacrum (8) selected. Thus it is also possible to improve radiographs without double irradiation of the subject to measure the scattered radiation separately.

Abstract: The invention relates to a method for scatter correction while forming a computed X-ray tomogram. The distribution of the scattered radiation is determined by means of the detector cells (7′) which, because of the measuring method carried out, are shielded from direct irradiation in a two-dimensional, multi-cell detector field (3). This distribution is used to perform a scatter correction in the neighboring, directly irradiated detector cells (7). Furthermore, scatter correction can be performed by means of a computer simulation of the scatter processes. To this end, use is preferably made of a Monte Carlo method and the effect of the geometry and the material composition of the measuring arrangement, of the patient size, of the irradiated tissue and the like, is taken into account.

Abstract: In a method for positioning a catheter that has been inserted into a vessel and a device for implementing the method, the road map technique is used, wherein as a mask image, a three-dimensional mask image of the vessel which is composed of number of individual mask images is employed. From these individual mask images, that individual mask image is selected whose exposure direction corresponds optimally to the exposure direction of an instantaneously captured individual image, in order to combine this selected individual mask image with the instantaneously captured mask image and to display the resulting combined image.

Abstract: A detector for an X-ray computed tomography apparatus has a number of detector elements separated from one another be septa forming a detector line.

Abstract: A detector for an X-ray computed tomography apparatus has a number of detector elements b1 . . . b10 separated from one another by septa. In order to fashion the detector especially universally, the widths of the detector elements are selected such that a channel occupancy combination from the following group can be realized: [20×b1 or 20×b2 or 16×b4], [16×b1 or 16×b2 or 12×b4], [8×b1 or 8×b2 or 8×b4 or 8×b6], [4×b1 or 4×b2 or 4×b4, 4×b8, 4×b12], [8×b1 or 8×b2 or 8×b5], [4×b1, 4×b2, 4×b4, 4×b10].

Abstract: The system for inspecting an object comprises a structure having a first, second and third orthogonal axes, and a source of x-ray pencil beam mounted thereto along the first axis. An incident radiation detector is mounted to the structure perpendicularly to the first axis. A first and second linear arrays of scattered radiation detectors are mounted to the structure perpendicularly to the second and third axes respectively. The source of x-ray pencil beam, the incident radiation detector and the first and second linear arrays of scattered radiation detectors are spaced apart and define therebetween an inspection zone. In use, an object to be inspected is moved inside the inspection zone relative to the x-ray pencil beam. The object is inspected voxel by voxel and the radiation measurements taken at each voxel are indicative of incident radiation attenuation, scattered radiation attenuation and electron density of that voxel.

Abstract: A plurality of radiation image signals, which represent radiation images of an object, are obtained by irradiating radiation from different directions to the object and detecting the radiation carrying image information of the object via a scattered radiation removing device for removing radiation having been scattered by the object. Image signal components representing a pattern of the scattered radiation removing device, which are contained in the radiation image signals, are reduced, and pattern-reduced radiation image signals, in which the image signal components representing the pattern of the scattered radiation removing device have been reduced, are thereby obtained. At least either one of a volume signal and a tomographic image signal representing an image of the object is then obtained from the pattern-reduced radiation image signals.

Abstract: A method of correcting aberrations caused by target x-ray scatter in three-dimensional images generated by a volumetric computed tomographic system is disclosed. The method uses a Monte Carlo simulation to determine the distribution of scattered radiation reaching the detector plane. The geometry for the scatter calculation is determined using the uncorrected three-dimensional tomographic image. The calculated scatter is used to correct the primary projection data which is then processed routinely to provide the corrected image.

Abstract: The present invention, in one form, is a system for reducing contribution of scatter signal to an image of an object constructed from projection data acquired during a computed tomography scan. The system includes an x-ray source which emits an x-ray beam toward a detector array. A collimator plate is movable with respect to the detector array. The system is configured to move the collimator between a first position and a second position. In the first and second positions, the collimator does not cover the detector array, i.e., the collimator does not collimate the x-ray beam impacting the detector array. When moving between the first and second positions, the collimator at least partially covers the detector array, i.e., the collimator at least partially collimates the x-ray beam impacting the detector array.

Abstract: A method of correcting aberrations caused by target x-ray scatter in three-dimensional images generated by a volumetric computed tomographic system is disclosed. The method uses a Monte Carlo simulation to determine the distribution of scattered radiation reaching the detector plane. The geometry for the scatter calculation is determined using the uncorrected three-dimensional tomographic image. The calculated scatter is used to correct the primary projection data which is then processed routinely to provide the corrected image.

Abstract: The method disclosed herein includes the steps of providing a computed tomography image having a base component, a first component of a first material, and a second component of a second material, the first and second materials causing beam hardening artifacts, segmenting the image into different sections, each section containing one of the artifact-causing components, calculating thickness of components in one of the sections, calculating a correction factor to compensate for artifacts created by the artifact-causing component in the section, and adding the correction factor to the image and additionally, the providing step may include the step of providing raw image data, which can then be converted into image data representative of the computed tomography image.

Abstract: An emission tomographic system for imaging an object of interest is described. The system, in one form, includes a gantry and a patient table. A detector including a collimator is secured to the gantry, and a computer is coupled to the gantry and to the detector to detect and control the position of the detector relative to the table. The system is configured to determine a transmission measurement and generate a scatter fraction utilizing the transmission measurement. A dual energy window data acquisition algorithm then determines non-scatter photons in a primary energy window utilizing the scatter fraction.

Abstract: A radiation image which has been recorded using an irradiation field stop and has an irradiation field is read out and an image representing the radiation image is obtained. The irradiation field is recognized and the values of the image signal components corresponding to the picture elements recognized to be outside the irradiation field out of the image signal components which make up an image signal for reproducing the radiation image as a visible image are converted according to the following formula,g(x,y)=h(t).multidot.f(x,y)+{1-h(t)}.multidot.f.sub.maxwherein f(x,y) and g(x,y) respectively represent the values of a picture element in a position (x,y) before and after the conversion, f.sub.max represents a maximum density and h(t) represents a continuous differentiable function.

Abstract: A radiographic apparatus which can improve at high speed the picture quality of an X-ray fluoroscopic image or an X-ray radiographic image is disclosed.

Abstract: The present invention, in one form, corrects any error due to varying z-axis detector cell gains represented in data obtained by a scan in a CT system. In accordance with one form of the present invention, and after correcting the image data for beam-hardening, the data is passed through a highpass filter to remove any data representing relatively slow, or low frequency, changes. Next, the filtered data is clipped and view averaged to remove high frequency data contents due to the objects being imaged. A slope estimate is then created. Using the slope estimate, an error estimate is generated. The error estimate is then subtracted from the beam-hardened corrected data, for example. As a result, errors due to z-axis gain variation of the detector cells are removed from the projection data array.

Abstract: The Invention provides practical apparatus and methods for significant improvements to conventional radiography practice. It can image objects having negligible x-ray absorption contrast e.g. otherwise x-ray transparent low-Z artifacts such as human soft-tissue, by obtaining edge-enhanced contrast from an object's (BDY) x-ray refractive-index gradients. In mammography, the contrast of small micro-calcifications is increased typically 4-fold, or more. It can be "tuned" to obtain element-selective refractive-index enhanced contrast to resonantly image minute quantities of a specific element with Z.apprxeq.35-56 and only that element. With only a single brief x-ray exposure it can produce two independent images, e.g. of the object's x-ray absorption and refractive-index distributions. It virtually eliminates the blurring and contrast reducing effects of x-ray scatter, especially of very small-angle scatter.

Abstract: Only an umbra of an X-ray beam is allowed to enter a designated detecting device arrays of an X-ray detector, whereby stable and good X-ray detection signals and images are provided. Even if a focal spot in an X-ray tube shifts, occurrence of artifacts or shifts of CT numbers is prevented to improve image quality. An X-ray CT scanner comprises an X-ray tube and X-ray detector, which are opposed to each other with a patient lying down on a couchtop between them, and a pre-collimator inserted between the X-ray tube and patient for restricting the width in a slice direction of an X-ray beam irradiated by the X-ray tube. The X-ray detector consists of, for example, a two-dimensional detector in which a plurality of detecting device arrays are arranged in the slice direction, each detecting device array including a plurality of detecting channels.

Abstract: In a CT scanning system having an x-ray source, a plurality of x-ray detector modules, and a plurality of anti-scatter plate modules, signal instability and the associated introduction of artifacts into the reconstructed images are prevented by an alignment assembly which permits the anti-scatter plates to be substantially aligned with regions of substantially constant maximum sensitivity of corresponding detectors. Shadows cast by the anti-scatter plates fall entirely within these regions of substantially constant maximum sensitivity to radiation, thereby minimizing signal modulation due to thermal effects or relative movement of the source, the detectors and the anti-scatter plates between scans.

Abstract: An x-ray examination apparatus with a detector array having a number of detector elements includes a data correction computer in which the subject-scattered radiation can be numerically determined and corrected. The forward scatter intensity is determined by multiplication of the measured intensities, windowed with a window function, with the natural logarithm of the intensity normalized with the unattenuated primary intensity. The subject-scattered radiation can then be calculated and corrected through filtering of the forward scatter intensity with a convolution kernel and a suitable scaling.

Abstract: In a scattered X-ray correction method for an X-ray computerized tomograph, the quantity of X-rays passed through a phantom is measured to be converted into logarithms. Obtained from the logarithmic data is a scattered X-ray correction curve representing a relationship between the measured data in the logarithmic expression and an amount of scattered X-ray correction. For a subject, the quantity of X-rays penetrated therethrough is measured to be transformed into logarithms. From the measured data undergone the logarithmic conversion and the scattered X-ray correction curve, there is attained a scattered X-ray correction amount in a linear region which is the state before the logarithmic conversion. The measured data of the subject in the logarithmic expression is subjected to an inverse logarithmic conversion.

Abstract: Apparatus and methods for generating z-axis profiles for a CT system detector are described. In one form, the method includes the steps of directing x-ray beams having different z-axis centroids and slice thicknesses at the detector and collecting detector signals for each beam. The detector signal for a first beam is then subtracted from the detector signal for a second beam to obtain a differential, or composite, detector signal which corresponds to a third beam having yet another z-axis centroid and slice thickness. The full z-axis profile of the detector is generated from measured detector signals and composite detector signals.

Abstract: The disclosed methods for generating scatter-compensated radiation image are based on one irradiating shot of the object. By comparing the detected signal under a partially transparent body (ea. disk or strip), positioned between the x-ray source and the object being imaged, with the signal in the image near the border of the shadow of the partially transparent body, the radiation scatter signal in the location of the body is calculated. In case of a polychromatic source, calibration with two known materials allows accurate calculation of the radiation scatter. The partially transparent bodies are positioned at several locations in between object and source and, by means of interpolation technique, the radiation scatter in every location of interest can be calculated. The radiation scatter image is subtracted from the original image of the object.

Abstract: A system for distribution of near-video-on-demand (NVOD) program information featuring use of ADSL telephone links. In NVOD, video program material is divided into segments which are spooled from a server into threads which contain the program information, but at times offset from each other. Telco central offices or other nodes are linked to each other by a publicly accessible network, such as the Internet, with either the telco central offices or Internet nodes providing thread replication so that service requests from a plurality of users may be met. At the telco central offices or nodes the threads may be multiplexed together for transmission over wideband channels, such as T1, OC3 or the like, while incoming threads are demultiplexed and routed to subscribers on ADSL channels. Each ADSL channel has a wideband portion operating in one direction and a narrow band portion operating in the opposite direction.

Abstract: A scanning radiographic system having reduced scatter and improved tube loading employs a pre-patient slit to form the x-ray beam into a fan beam and a post-patient slot to eliminate scattered rays from the fan beam. A grid incorporated into the slot permits a further reduction of scatter sufficient to employ a wider slot without detrimental increase in scatter but with significant improvement in tube loading. The lamellae of the grid proceed diagonally across the width of the slot to reduce grid lines and are tipped to focus on the focal spot of the x-ray source.

Abstract: A method and apparatus to calibrate and correct magnetic and geometrical distortions in an imaging system, specifically a computer tomography (CT) system, includes a calibration object which is placed on the surface of an image intensifier. An image frame of the calibration object is generated, and a vertical correction table is generated corresponding to the amount of image distortion caused to the image frame of the calibration object. The image frame is corrected using the vertical correction table, and the corrected image frame data is summed or averaged and either stored for further transformation into a slice image or used to generate a horizontal correction table to correct distortions in the horizontal direction. Once the vertical and horizontal correction tables have been generated using the calibration object, subsequent image frames are corrected using the correction values in the correction tables.

Abstract: There is disclosed an assembly for slit radiography with image equalization, comprising an X-ray source which can scan a body for examination via a slit of a slit diaphragm with a flat, fan-shaped X-ray beam over a scanning path in a direction transverse to the lengthwise direction of the slit for forming an X-ray shadowgraph on an X-ray detector; an absorption device which under the control of control signals can influence the fan-shaped X-ray beam per sector thereof, in order to permit control of the X-ray radiation falling in each sector on the body to be examined; and detection assembly which is designed to detect the quantity of X-ray radiation transmitted by the body instantaneously per sector during a scanning movement of the X-ray beam and to convert it into corresponding signals.

Abstract: In X-ray photography by an X-ray equipment, grid images based on only a grid are acquired by a grid image generating circuit under various photograph conditions, and are stored in image memories. A subject image based on a subject to be examined is acquired under a predetermined photograph condition. A grid image which is acquired under the same photograph condition as that of the subject image or under a condition similar thereto is read out from a corresponding image memory. The subject image and the readout grid image are regulated by gain regulators to have the same gain. The subject image is then divided by the grid image in the divider. As a result, the subject image without the grid image can be obtained.

Abstract: A computer tomography apparatus has an x-ray source which emits a fan-shaped x-ray beam which irradiates a slice of an examination subject. The x-ray source is rotatable around the examination subject to irradiate the slice from different angular directions in the plane of the slice. A row of detector elements is disposed to receive radiation attenuated by the examination subject as the x-ray source rotates around the patient. The radiation detector is disposed on a ring which is rotatable around the examination subject separately from the x-ray source. This permits to meet the conditions of the sampling theorem, applied to the projections with the focus as projection center, without increasing the number of defectors.

Abstract: The invention concerns an X-ray tomograph device.This device makes it possible to obtain the image (1) of a plane cutting (2) of an object (3). In particular, it comprises an X-ray source (4) which supplies high energy pulses which traverse the object. At least one measurement detector small bar (10) receives the attenuated energy pulses which have traversed the object. A display and processing means connected to the detectors supplies the image of the cutting. These processing means include amplifier-integrator circuits (13) connected to the detectors (10) and to a computer (15) controlling the integration period of the detection pulses suplied by the detectors (10). The computer corrects the value of the amplitude of each detection pulse by talking account of an intermediate integration value so as to take account of the drag of each pulse and the stray current of each detector.

Abstract: A computer tomography apparatus includes an x-ray source which irradiates an examination subject, thereby producing attenuated primary radiation, and scatter radiation. A row of detector elements for the attenuated primary radiation is, during normal operation, disposed behind the examination subject in registry with the x-ray beam. During an examination, the x-ray source and the detector row are rotated around an axis to irradiate the examination subject from different directions. A second row of detector elements, for detecting the scatter radiation, is, during normal operation, disposed next to the primary radiation detector row in the direction of the axis of rotation. During calibration using a standardized scatter element as the examination subject, the primary radiation detector row can be axially displaced to occupy the position normally occupied by the scatter radiation detector row.

Abstract: A dynamic focusing device is provided for an X-ray scanner, the device comprising at least one detector module located in a position to receive, be illuminated by, and respond to X-rays. A source of X-rays is movable toward or away from the detector module. The module comprising a plurality of crystals each having a scintillation surface located in a common plane, with a plurality of septa separating the crystals. The septa have a height which is upstanding above the surfaces of the crystals far enough to reduce lateral X-ray scatter and to cast a shadow upon the surfaces of the crystals responsive to an illumination thereof from said X-ray source. The invention dynamically positions the detector module relative to the distance between the detector module and the source of X-rays in order to reduce substantially to a minimum any shadow in the X-rays cast by the septa upon the surfaces of the crystals.

Abstract: A dynamic focusing device is provided for an X-ray scanner, the device comprising at least one detector module located in a position to receive, be illuminated by, and respond to X-rays. A source of X-rays is movable toward or away from the detector module. The module comprises a plurality of crystals each having a scintillation surface located in a common plane, with a plurality of septa separating the crystals. The septa have a height which is upstanding above the surfaces of the crystals far enough to reduce lateral X-ray scatter and to cast a shadow upon the surfaces of the crystals responsive to an illumination thereof from said X-ray source. The invention dynamically positions the detector module relative to the distance between the detector module and the source of X-rays in order to reduce substantially to a minimum any shadow in the X-rays cast by the septa upon the surfaces of the crystals.

Abstract: The radiation image in a radiation imaging system is improved by extracting a scatter distribution and subtracting the scatter distribution from the radiation image. The scatter distribution is extracted from the radiation image by an adaptive filter using a scatter-glare point spread function. The scatter-glare point spread function is obtained by measurements of the radiation system.

Abstract: A computed tomograph apparatus for obtaining tomograms of a subject under examination comprises a supporting table for supporting the subject, and on which a tomogram image pick-up area is defined. The apparatus further comprises an X-ray source for radiating X-rays onto the image pick-up area. X-rays emitted from the X-ray source proceed along a slice plane intersecting with the image pick-up area. A principal detector is provided within the slice plane, and detects X-rays transmitted linearly.

Abstract: A scattering beam eliminating member is located between an X-ray tube and an X-ray gas detector such that it is intimately bonded to the window of the X-ray detector. The scattering beam eliminating member is of such a type that plates and X-ray transmission areas are alternately arranged in a slice direction to permit any scattering beam to be absorbed in the slice direction and never to be incident to the X-ray detector.

Abstract: An X-ray generator projects X-rays into an object under examination. An X-ray detector detects the X-ray image data transmitted through the object. The transmitted X-ray image data is digitized by an A/D converter and visually displayed by a monitor. For effecting such display, an X-ray shield member having an X-ray shield section configured in a predetermined pattern is set in an X-ray projection area. The transmitted X-ray image data containing the X-ray shield section data obtained under this condition is supplied to a scattered X-ray intensity computing circuit through first and second switching circuits and a memory. The computing circuit computes the scattered X-ray component. Then, the X-ray shield member is retracted from the X-ray projection area. Under this condition, the transmitted X-ray image data is supplied through the first and second switching circuits to a subtracting circuit.

Abstract: An X-ray computed tomography apparatus is disclosed which includes an X-ray source for irradiating an X-ray, a main detector section for detecting the X-ray passed through a subject and a scattering ray detector for detecting its scattered component. An X-ray shield member is detachably mounted between the X-ray source and the main detector section to shield the main X-ray. The apparatus thus manufactured evaluates a ratio between an amount of scattered component incident on the main detector section when the main X-ray is shielded from the X-ray shield member and an amount of scattered component which is detected by the scattering ray detector. With this ratio placed as K, an amount of X-ray, m, to be measured is found fromm=b-a/Kwhere a denotes the scattered component detected by the scattering ray detector and b denotes an output level of the main detector section when the X-ray is not shielded.