Abstract: A low-angle self-swinging type computed tomography (CT) device is provided, having an X-ray accelerator and a plurality of rows of detectors and includes a slip ring, such that the slip ring with the accelerator and the detectors thereon is capable of performing a single-pendulum reciprocating movement while an object to be inspected passes through the slip ring, a three-dimensional CT image of the object is displayed, thereby achieving accurate inspection for large-scale objects, such as van containers.

Abstract: An electrolyte membrane thickness measurement apparatus includes a detecting medium supplying portion configured to emit a detecting medium, a detecting portion configured to detect a metal catalyst, and an analyzing unit. A thickness direction profile of a detection signal is generated by the detecting portion, and first and second inflection points are determined in the thickness direction profile based on the intensity of the detection signal by the analyzing unit. The distance between the first and second inflection points is evaluated as the thickness of the electrolyte membrane by the analyzing unit.

Abstract: The present invention makes it possible to check a target object highly accurately and quickly. Each of the electromagnetic wave reception regions includes m pieces of smaller regions which are arranged along a diameter of a circle in a plan view of a circular profile surface.

Abstract: The present invention makes it possible to check a target object highly accurately and quickly. In a sensor having an electromagnetic wave reception region, suitability of portions for capturing an image of a subject which moves fast is heightened as a distance from a center increases in a plan view of a circular profile surface.

Abstract: An image processing apparatus includes a memory unit which stores data of a first projection image and data of a second projection image, which are associated with the same object and are captured in different imaging directions, a display unit which displays the data of the first projection image and the data of the second projection image, a designation operation unit which is configured to designate a plurality of points on the displayed first and second projection images, and an operation supporting unit which generates operation supporting information for supporting an operation of designating, by the designation operation unit, the plurality of points on the second image, which anatomically correspond to the plurality of points designated on the first projection image.

Abstract: One object of this invention is to provide a radiation tomography apparatus for acquiring a tomographic image from a plurality of fluoroscopic images. The radiation tomography apparatus can acquire the tomographic image having superior visibility without being influenced by a shadow of a collimator appearing in the fluoroscopic image when radiation is applied only to a portion of an FPD through control of the collimator. In this invention, a boundary between a shadow area where the shadow of the collimator appears in the fluoroscopic image and a non-shadow area is identified, and the shadow area in the fluoroscopic image is complemented by the non-shadow area, etc., whereby a complement image is generated. Then the complement image is used for generating the tomographic image. According to this invention, an extremely dark area where the shadow of the collimator appears is removed and thereafter the tomographic image is generated.

Abstract: A method of evaluating a reservoir includes a multi-energy X-ray CT scan of a sample, obtaining bulk density and photoelectric effect index effect for the sample, estimation of at least mineral property using data obtained from at least one of a core gamma scan, a spectral gamma ray scan, an X-ray fluorescence (XRF) analysis, or an X-ray diffraction (XRD) analysis of the sample, and determination of at least one sample property by combining the bulk density, photoelectric effect index, and the at least one mineral property (e.g., total clay content). Reservoir properties, such as one or more of formation brittleness, porosity, organic material content, and permeability, can be determined by the method without need of detailed lab physical measurements or destruction of the sample. A system for evaluating a reservoir also is provided.

Abstract: An x-ray tube is described that includes components for increasing x-ray image clarity in the presence of a moving x-ray source by modifying focal spot characteristics, including focal spot size and focal spot position. In a first arrangement a static focal spot is moved in a direction contrary to the movement of the x-ray source so that an effective focal spot position is essentially fixed in space relative to one of the imaged object and/or detector during a tomosynthesis exposure. In a second arrangement, the size of the static focal spot is increased, and the resulting increase in tube current reduces the exposure time and concomitant blur effect. The methods may be used alone or in combination; for example an x-ray tube with a larger, moveable static focal spot will result in a system that fully utilizes the x-ray tube generator, provides a high quality image with reduced blur and, due to the decrease in exposure time, may scan the patient more quickly.

Abstract: A three-dimensional/four-dimensional (3D/4D) imaging apparatus and a region of interest (ROI) adjustment method and device are provided. An ROI is adjusted through an E image in a 3D/4D imaging mode, in which the E image is refreshed in real time when the ROI is adjusted and has a scan line range larger than that of the ROI.

Abstract: A configuration and an associated operating method for tomosynthetic fluoroscopy utilize an x-ray emitter and with an x-ray detector. The configuration further contains a mounting device, which is rotatably mounted about a rotational axis and about which the x-ray emitter is arranged such that the optical axis of the x-ray emitter is directed to the x-ray detector and that, in the case of a rotation of the mounting device, the focus of the x-ray emitter describes a circular path. An advantage offered by the invention lies in ensuring robust tomosynthetic fluoroscopy.

Abstract: A method of obtaining a panoramic image and an apparatus for the same are disclosed. In particular, a method of obtaining a panorama image and an apparatus for the same capable of obtaining a more clear panoramic image with reproducibility by extracting best-focused-images in case of forming images of multiple image-layer-trace images are disclosed. In accordance with the method and the device of this invention for obtaining the panoramic image, it is possible to complete the optimal image-layer-trace to be reconstructed and to obtain a clear panoramic image which vividly shows an arch of a patient by reconstructing a panoramic image for an optimal image-layer-trace most closely related to a focus-trace.

Abstract: An image processing apparatus includes a memory unit which stores data of a first projection image and data of a second projection image, which are associated with the same object and are captured in different imaging directions, a display unit which displays the data of the first projection image and the data of the second projection image, a designation operation unit which is configured to designate a plurality of points on the displayed first and second projection images, and an operation supporting unit which generates operation supporting information for supporting an operation of designating, by the designation operation unit, the plurality of points on the second image, which anatomically correspond to the plurality of points designated on the first projection image.

Abstract: The present invention relates to an imaging system for imaging a region of interest comprising an illumination unit and a detection unit. The imaging system further comprises a grouping unit for grouping the detection values, wherein each group comprises at least one alpha detection value and at least one beta detection value (103). At least one alpha aperture weighting value for the at least one alpha detection value of a group is determined by using at least one position of at least one ray within the aperture (104). Furthermore, at least one beta aperture weighting value for the at least one beta detection value of a group is approximately determined using the at least one alpha aperture weighting value of the group (105). The detection values are than aperture weighted using aperture weighting values (106). The region of interest is reconstructed by backprojecting the weighted detection values (107).

Abstract: Tomographic images in a plurality of radius places are obtained in one-time X-ray photographing, and a lot of information on the diagnose can be provided by forming a stereoscopic image with these obtained tomographic images, and thickness of radial and fineness of angular direction of tomographic image that can be obtained herein compared with prior art can be set arbitrary and can be adjusted thereby obtaining further imperceptible stereoscopic image. To this end, whole photographed images at respective divided unit angles that can be obtained in the digital dental panoramic radiography apparatus at the tomography in the circular orbit, are stored, after X-ray photographed, these photographed images are arranged substantially on the circular arc at the radius place of the tomographic image of the desired extracting part, tomographic images in radius location can be constructed by adding while shifting every photograph unit angle.

Abstract: In a method for the 3D viewing of tomosynthesis images in mammography, an algorithm is proposed for the viewing of radiology signs in series of 3D data. When the digital volume is being viewed by a practitioner, the disclosed algorithm is used to provide a dynamic indication of the position of the radiology signs on the 3D image by means of markers. The use of dynamic viewing draws the practitioner's attention to the zones of clinical interest. The disclosed algorithm thus highlights all the radiology signs in the 3D image of the breast.

Abstract: A laminography system includes a first linear guide defining a z-direction of a Cartesian coordinate system and an imaging radiation source fixable to the first linear guide and movable along the first linear guide. The radiation source is configured to form a cone of rays including a central ray defining a y-axis of the Cartesian coordinate system. A detector is disposed in a position so as to be struck at a center thereof by the central ray of the radiation source substantially in an x-direction of the Cartesian coordinate system. The system also includes a first rotation device configured to rotate the detector about a first axis of rotation that is parallel to a z-axis of the Cartesian coordinate system and that passes through an intersection of the central array and the detector. The detector is fixable to a second linear guide and is movable on the second linear guide along the first axis of rotation. An object slide is disposed between the radiation source and the detector.

Abstract: An x-ray laminography device includes at least one x-ray detector and at least one x-ray source coupled in coordinated traversal with the at least one x-ray detector. The at least one x-ray source is configured to generate and transmit x-rays. The at least one x-ray detector and the at least one x-ray source traverse an at least partially radial travel path in unison about an object such that the object is illuminated with x-rays from a plurality of oblique radial angles defined between the at least one x-ray source and the object.

Abstract: In at least one embodiment, two image data records of two computed tomography pictures of the object are provided that have been recorded in the context of a different spectral distribution of the X-radiation. For voxels of at least one interesting slice, there is calculated from the two image data records a ratio r that is yielded from measured or averaged X-ray attenuation values of the respective voxel or its environment in the context of the different spectral distributions of the X-radiation and prescribed X-ray attenuation values of soft tissue in the context of the different spectral distributions of the X-radiation according to a prescribed calculation rule. Upon overshooting of a threshold value for the ratio r the respective voxel is assigned either contrast agent or calcium-containing material as a function of the magnitude of r.

Abstract: A tomographic image capturing apparatus comprises a radiation source for applying radiation to a subject at a plurality of different angles with respect to the subject, a radiation detector for detecting the radiation which has passed through the subject at each of the different angles and converting the detected radiation into image data, a tomographic image reconstructing unit for processing the image data into a reconstructed tomographic image, and an image capturing continuation determining unit for determining whether image-capturing of the subject is continued or not based on the reconstructed tomographic image.

Abstract: In time-resolved contrast-enhanced magnetic resonance angiography, a measure quantifying image quality provides a basis for generating a linear filtered composite image by facilitating selection of a mask and an arterial phase image for subtraction. Filtering of individual pixels of a temporal series of images provides enhanced contrast in a single image by allowing the temporal behavior of the pixel intensity to denote representation as an artery, vein or background tissue. Motion artifacts are suppressed by re-registering sequential images, adjusting weighting before averaging and subtraction and filtering the Fourier data to eliminate data corrupted by motion or other phenomena.

Abstract: A method is disclosed for production of computer-tomographic scans via a CT system of a patient during an intervention with an instrument. An X-ray tube is moved on a rotation plane around the patient in order to produce a beam cone, and a detector with a plurality of detector elements measuring the radiation intensity after passing through the patient. Computer-tomographic scans are reconstructed from the measured values in a computation unit. The central direction of the beams of the scanning beam cone is set at an angle to the intervention axis, and at least one slice plane which differs from the rotation plane of the beam cone is displayed on a display.

Abstract: In a method for reconstructing a 3D CT image from a number of 2D projection images each 2D projection image is divided at an arbitrarily selectable position by a substantially vertical image line and the projection image is automatically electronically analyzed to detect whether clipping occurs on the left side or on the right side, or on both sides, of the image line. For each side of the image line at which clipping is detected, a horizontal coordinate at which the clipping ends is identified. The grayscale values at the side of the horizontal coordinate opposite to the side at which the image line is located are extrapolated so that the clipping is removed. The corrected 2D projection images are then used to reconstruct a 3D image, in which capping artifacts, that would otherwise be present, or avoided or substantially minimized due to the corrections made in the 2D projections.

Abstract: There is provided a nondestructive method for inspecting ceramic structures, the method which not only easily detects the position and size of an internal defect in a ceramic structure in a short time, but also accurately identifies the position, shape, and size of the internal defect. In the method, the distribution of X-ray absorption coefficients (CT numbers) at fault planes of the ceramic structure is measured by irradiating the periphery of the ceramic structure with X rays along the periphery of the ceramic structure so that the X rays scan the entire periphery. The X rays are emitted from an X-ray tube at a tube voltage in the range of 80 to 400 kV and a tube current in the range of 2 to 400 mA.

Abstract: In a tomosynthetic image reconstruction method and diagnostic device operating with such a method, a tomosynthetic 3D x-ray image is reconstructed by a discrete filtered back projection from a number of individual digital projection data recorded from different project angles within a restricted angular range, in which at least one filtering is performed with a convolution kernel that, in the local area outside of its central value, corresponds to an exponential function.

Abstract: In time-resolved contrast-enhanced magnetic resonance angiography, a measure quantifying image quality provides a basis for generating a linear filtered composite image by facilitating selection of a mask and an arterial phase image for subtraction. Filtering of individual pixels of a temporal series of images provides enhanced contrast in a single image by allowing the temporal behavior of the pixel intensity to denote representation as an artery, vein or background tissue. Motion artifacts are suppressed by re-registering sequential images, adjusting weighting before averaging and subtraction and filtering the Fourier data to eliminate data corrupted by motion or other phenomena.

Abstract: A detector module, in at least one embodiment, is disclosed for x-radiation or gamma radiation that includes one or more optical waveguide sections that are arranged next to one another in order to form one or more detector rows and are optically interconnected in serial fashion. The waveguide sections include one or more converter materials for converting incident x-radiation or gamma radiation into optical radiation and are designed in such a way that optical radiation of different wavelength is generated in respectively neighboring regions along the waveguide sections upon incidence of x-radiation or gamma radiation. The present detector module, in at least one embodiment, can be implemented cost effectively with a high number of detector rows, and is of very low weight.

Abstract: An imaging technology for fuel cells is based on x-ray microscopy. A metrology system images the electrochemical interaction areas of solid-oxide fuel cells (SOFC) in-situ. This system takes advantage of both the penetrating power and elemental absorption contrast of hard x-ray radiation to image the internal interaction areas in a SOFC. The technology can further take advantage of the strong dependence of the x-ray absorption on material type and energy to distinguish the four major material types: cathode, electrolyte, air, and low-Z contaminants such as sulfur.

Abstract: A system for three-dimensional tomosynthesis imaging of a target element includes an image acquisition element and a processor. The image acquisition element obtains a plurality of images of the target element from a plurality of angles and includes a radiation source that is positionable at a plurality of angles with respect to the target element and a radiation detector. The radiation detector is positioned so as to detect radiation emitted by the radiation source passing through the target element and determine a plurality of attenuation values for radiation passing through the target element to establish a radiation absorbance projection image of the target element for a particular radiation source angle. The processor is configured to apply an iterative reconstruction algorithm to the radiation absorbance projection images of the target element obtained from a plurality of radiation source angles to generate a three-dimensional reconstruction of the target element.

Abstract: Quality of a plurality of images having a common characteristic is confirmed collectively and the images after the confirmation are transferred collectively. Images acquired by a reading apparatus are input to a workstation and stored in a recording apparatus. At the time of image confirmation, the workstation groups image data representing the images stored in the recording apparatus into image groups classified by examination. For an image group including a plurality of images, the images included therein are displayed and their quality is judged by comparison therebetween. When the images are judged to be appropriate, the images are transferred collectively as the image group to a transfer destination apparatus.

Abstract: An x-ray system for use with image-guided medical procedures is programmed to move in a first scan path to acquire cone beam attenuation data from which a three-dimensional digital subtraction angiogram of selected vasculature is reconstructed. The x-ray system is also programmed to move in a second scan path to acquire a series of tomosynthesis images during the inflow of a contrast agent into the selected vasculature. Parametric images are produced from information in the tomosynthesis images which indicate blood perfusion physiology of the tissues served by the vasculature.

Abstract: In an apparatus for radiographic projection tomography, particularly mammography, an X-ray tube is mounted at the end of a swiveling arm, with a relative movement mechanism. The relative movement mechanism is such that it enables the tube to follow a path of a cycloid. Images or exposures taken only during the time when the tube, in its path, follows cusp points such that it is possible to keep a constant speed of movement of the arm while at the same time increasing the useful duration of an image. Vibration or oscillation effects inherent in the apparatus are compensated by the positioning, if necessary, of a counterweight.

Abstract: A method for displaying a computer-generated determination of the likelihood of malignancy in a mammogram lesion. The method requires providing a digitized image of a mammogram, displaying the digitized image, and selecting a region of interest directly on the displayed digitized image. The digitized image is then processed so that classifier data of the lesion in the user-selected region of interest are generated and displayed. A system for displaying a determination of the likelihood of malignancy in a mammogram lesion. The system includes a display for presenting a digitized mammogram and an input device in communication with the display for selectably indicating a region of interest on the displayed mammogram. The system also includes a processor for generating classifier data related to a characterization feature within the region of interest. The classifier data is presented on the display.

Abstract: A method and apparatus for determining a set of functional parameters using a fluoroscopic radiography apparatus of the type comprising an X-ray source, a detector or recorder of the radiation facing the source, the source and the detector or recorder being installed on a mobile support capable of movement with respect to a table placed between the source and the detector or recorder on which a patient with a region of interest to be X-rayed will be placed. The method comprises a) movement of the support following a given movement with respect to the table, repeated during a given time; b) acquisition by the detector or recorder of a series of images of the region of interest during movement of the support with respect to the table; c) reconstitution of a series of three-dimensional models of the region of interest, starting from a series of acquired images; and d) determination of all functional parameters.

Abstract: An x-ray laminography imaging system and a positioning system to be used therewith. The positioning system is configured to move the object in the X, Y and Z-directions (i.e., pitch and roll) to ensure that the object planes of the object that are being imaged are at least substantially parallel to the focal plane of the imaging system. The object is positioned so that object planes associated with the X, Y and Z-coordinates of points along the contour of the surface of the object are at least substantially parallel to the focal plane of the imaging system during imaging of the object plane. Because some objects, such as printed circuit boards, for example, are sometimes warped, by ensuring that the object plane being imaged is at least substantially parallel to the focal plane of the imaging system, precise laminographs are obtained.

Abstract: The invention provides method, system and device for determining trabecular bone structure and strength by digital topological analysis, and offers, for the first time, a demonstration of superior associations between vertebral deformity and a number of architectural indices measured in the distal radius, thus permitting reliable and noninvasive detection and determination of the pathogenesis of osteoporosis. A preferred embodiment provides imaging in three dimension of a region of trabecular bone, after which the 3D image is converted into a skeletonized surface representation. Digital topological analysis is applied to the converted image, and each image voxel is identified and classified as a curve, a surface, or a junction; and then associated with microarchitectural indices of trabecular bone to quantitatively characterize the trabecular bone network. The invention is applicable in vivo, particularly on human subjects, or ex vivo.

Abstract: An imaging system for performing tomosynthesis on a region of an object comprises an x-ray source, motion controller, an x-ray detector and a processing unit. The x-ray source is positioned at a predetermined distance from the object and continuously moves along a path relative to the object at a plurality of predetermined locations. The x-ray source transmits x-ray radiation through the region of the object. The motion controller is coupled to the x-ray source and continuously moves the x-ray source along the path relative to the object. The x-ray source minimizes vibration in the imaging system due to continuous movement. The x-ray detector is positioned at a predetermined distance from the x-ray source and detects the x-ray radiation transmitted through the region of the object, thus acquiring x-ray image data representative of the region of the object. The processing unit is coupled to the x-ray detector for processing the x-ray image data into at least one tomosynthesis image of the region of the object.

Abstract: An imaging system includes an X-ray source adapted to move in an arc shaped path and a stationary electronic X-ray detector. The system also includes a track and a mechanical driving mechanism which is adapted to move the X-ray source in the arc shaped path. A tomosynthesis X-ray imaging method includes mechanically moving an X-ray source in a stepped motion on an arc shaped path around an object using a track and irradiating the object with an X-ray dose from the X-ray source located at a plurality of steps along the arc shaped path. The method also includes detecting the X-rays transmitted through the object with an electronic X-ray detector, and constructing a three dimensional image of the object from a signal output by the electronic X-ray detector.

Abstract: Quality of a plurality of images having a common characteristic is confirmed collectively and the images after the confirmation are transferred collectively. Images acquired by a reading apparatus are input to a workstation and stored in a recording apparatus. At the time of image confirmation, the workstation groups image data representing the images stored in the recording apparatus into image groups classified by examination. For an image group including a plurality of images, the images included therein are displayed and their quality is judged by comparison therebetween. When the images are judged to be appropriate, the images are transferred collectively as the image group to a transfer destination apparatus.

Abstract: An imaging system for performing tomosynthesis on a region of an object comprises an x-ray source, motion controller, an x-ray detector and a processing unit. The x-ray source is positioned at a predetermined distance from the object and continuously moves along a path relative to the object at a plurality of predetermined locations. The x-ray source transmits x-ray radiation through the region of the object. The motion controller is coupled to the x-ray source and continuously moves the x-ray source along the path relative to the object. The x-ray source minimizes vibration in the imaging system due to continuous movement. The x-ray detector is positioned at a predetermined distance from the x-ray source and detects the x-ray radiation transmitted through the region of the object, thus acquiring x-ray image data representative of the region of the object. The processing unit is coupled to the x-ray detector for processing the x-ray image data into at least one tomosynthesis image of the region of the object.

Abstract: In a method and CT apparatus for producing CT images of a body region periodically moving with resting or motion phases, data corresponding to a number of projections serving the purpose of imaging are analyzed to determine whether each projection was acquired during a resting or motion phase, and only those data that were acquired during a resting phase are employed for image reconstruction.

Abstract: A method for determining the properties of a log, in which a moving log is radiographed by at least more than one X-radiation source, and the radiographic information is received by a detector array measuring radiation. Stemwood and knots of the log are calculated by a principle which is based on a known geometry and density of stemwood and knots. After measurement, the effect of stemwood in radiographic projections, and hence the analysis for locating knots, is eliminated by filtering. The knot mass is then converted from radiographic projections into volumetric elements of a cylindrical coordinate system and, from the value of each volumetric element, an evidence value representative of the presence of a knot in the element is derived. The evidence values of mutually associated elements are then combined, thus producing an aggregate evidence value which permits the knots to be located.

Abstract: In a method for image reconstruction in imaging technology for the implementation of a fast convolution with the transformation length M while allowing slight over-convolution errors, each of p or 2p out of n measured projections of the length N are convolved with a modified filter kernel h (k) using Fast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT) simultaneously in one step.

Abstract: In a method for producing a tomosynthesis exposure a reference object is used which is formed by a region of the examination subject. It is thus possible to determine the distance of the beam transmitter to the beam receiver and to the examination subject, the irradiation angle, and the direction of irradiation, on the basis of the signals that can be derived from the beam receiver during the transillumination of the reference object, without the reference object causing any disturbance in the region of the subject of examination.

Abstract: A radiation image recording apparatus comprises a radiation source for emitting a radiation to an object, a device for moving the radiation source to change the irradiation angle, a sheet changer for feeding a stimulable phosphor sheet to an image recording position exposed to the radiation passing through the object to have a radiation image of the object stored on the stimulable phosphor sheet and then receiving a drive signal to remove the stimulable phosphor sheet from the image recording position and feed a next stimulable phosphor sheet thereto, and a device for moving the sheet changer so that the stimulable phosphor sheet at the image recording position and the radiation source satisfy the linear rule and the geometric rule with respect to a point within the object or in the vicinity thereof.

Abstract: Apparatus for making sectional radiographs which allows for the operator to preset the scanning patterns to be followed by the apparatus during the making of a sectional radiograph. The operator positions the source or the image detector in at least one point on the path defining the desired scanning pattern. This position is measured and applied to an arithmetic device which derives therefrom reference values for driving the source and the image detector.

Abstract: In an exemplary embodiment, an x-ray tube is mounted on a tube support arm carried on a separate tube stand. A layer rod releasably couples with the tube support arm for the purpose of aligning the x-ray tube relative to a displaceable radiographic installation on the underside of the patient support platform. The tube need not always be aligned relative to such radiographic installation, but may be aligned, according to requirements, relative to a second radiographic installation. In order to facilitate such change of alignment, the disclosure provides that the layer rod may be placed in a loosely coupled state relative to the tube support arm, and that it bears coupling surfaces which are capable of being brought into positive locking engagement with the tube support arm to effect automatic reorientation of the x-ray tube (without prior manual alignment of the x-ray tube to the radiographic installation) during recoupling operation.

Abstract: In the exemplary embodiments the path of movement of the photographic exposure unit comprised of an x-ray tube and image layer (or film) carrier can be selected. For determination of the photographic exposure time, either an mAs-relay or an automatic exposure timer with a radiation detector may be placed in control of the energization of the x-ray tube. The x-ray tube current or the current of the radiation detector are integrated and the integrator contents are sampled at a predetermined time following commencement of the photographic exposure. The sampled value is compared with a reference value and the running speed of the photographic exposure unit is influenced in such a fashion that the photographic exposure time determined by the switching of the mAs-relay or by the automatic exposure timer approximately corresponds to the running time of the photographic exposure unit.

Abstract: A tomographic x-ray machine has camera and film-plane sections which move about a primary axis for imaging a selected cross-section of an anatomical member onto a film. A "scout image" of the member is obtained at right angles to the plane of the desired cross-section to indicate the cross-section's orientation with respect to the primary axis. The anatomical member is then moved to place it on the primary axis and a second film is located at the same angle that the selected cross-section makes with the primary axis. The second film and the cross-section are then maintained in parallel planes throughout motion of the camera and the second film during tomographic radiography.