Abstract: In an X-ray installation comprising an X-ray source, a patient support, an X-ray detector and an electronic evaluation system, a distance is determined from an extremity of a patient which is to be imaged to the X-ray detector and is made available as an electronic data value to the electronic evaluation system. If the distance from the X-ray source to the X-ray detector as an electronic data value is also known, then a scale can be calculated for the X-ray image from the two distances on the basis of the imaging laws for the generation of the X-ray image, which scale can be faded into the X-ray image or else electronically assigned to this image for an interrogation of coordinates.

Abstract: A status indication device configured for use in an x-ray system is disclosed. The device includes an audio receiver, a processor, a tone generator, and an adjustment mechanism. The audio receiver is configured and disposed to collect audio information surrounding the x-ray system. The processor is coupled to the audio receiver and receptive of a signal representative of the collected audio information. The tone generator is coupled and responsive to the processor and is configured to generate an audio tone in response to a defined status of the x-ray system. The adjustment mechanism is coupled to the tone generator and the processor and dynamically develops a set of audio properties that cause the audio tone to be distinguishable from the collected audio information.

Abstract: A status indication device configured for use in an x-ray system is disclosed. The device includes an audio receiver, a processor, a tone generator, and an adjustment mechanism. The audio receiver is configured and disposed to collect audio information surrounding the x-ray system. The processor is coupled to the audio receiver and receptive of a signal representative of the collected audio information. The tone generator is coupled and responsive to the processor and is configured to generate an audio tone in response to a defined status of the x-ray system. The adjustment mechanism is coupled to the tone generator and the processor and dynamically develops a set of audio properties that cause the audio tone to be distinguishable from the collected audio information.

Abstract: A handswitch configured to be held by an operator of an x-ray system, configured for using handswitchable equipment to operate the x-ray system, is disclosed. The handswitch includes an exterior housing so dimensioned as to fit into a hand of the operator. An exposure switch is disposed on the exterior housing and is configured to initiate an x-ray exposure. A tactile feedback mechanism is configured to indicate, to the operator of the x-ray system, transmission of x-rays by the x-ray system.

Abstract: An x-ray system quick-connect connection is disclosed to allow an end-user to de-couple a portable x-ray detector from an x-ray scanner/host. The quick-connect connection is accessible by the end-user without removal of a service panel that exposes an interior service portion of the x-ray scanner or x-ray detector. The de-coupled x-ray detector may be stored independently from the x-ray scanner/host and may be shared among multiple x-ray scanner/host systems, when properly calibrated. De-coupling a single quick-connect connection de-couples all power and communication lines between the x-ray scanner/host and the x-ray detector.

Abstract: An X-ray analysis apparatus has information about a relationship between selection of a measurement type and a replacement work of optical parts and shows, on a screen of a display, graphical information about optical parts which should be changed, to make it easy for an operator to perform a preliminary work before measurement. When the operator selects one desired measurement type among a plurality of measurement types in a selection window, there is displayed on the display, depending on the selected measurement type, graphical information about necessary optical parts which should be newly installed and/or installed optical parts which should be removed. The operator looks at the operating instructions and then performs the replacement work. The graphical information may be: graphical indication of the installation locations of the optical parts; different pictorial expressions about the installation and the removal works; and graphical indication of the identification marks of the optical parts.

Abstract: The present invention relates to a device for supporting a radiographic cassette during the taking of an x-ray. The device as shown in FIG. 1 is especially useful to support a radiographic cassette for an x-ray of the patellofemoral joint utilizing an inferosuperior projection. The device consists of a counter balancing base unit and two straps each with attachment means to attach to the top of the radiographic cassette. When attached the device holds the cassette in position by counter balancing force.

Abstract: Certain embodiments of the present invention provide a system for coordinating a radiological imaging subsystem with a component including: a first communication device located on the radiological imaging subsystem; and a second communication device located on the component, wherein the first and second communication devices are capable of communicating to indicate a positional relationship between the radiological imaging subsystem and the component. In an embodiment, the component includes an imaging table. In an embodiment, at least one range of motion of the radiological imaging system is determinable based at least in part on the communicating to indicate a positional relationship. In an embodiment, the at least one range of motion of the radiological imaging system includes at least one range of motion of a gantry.

Abstract: A unit (11) with a length (L) is utilized in a device for indicating the position of an edge (7a) of a first area (7) which is irradiated by an x-ray radiation source (2) in relation to an edge (9a) of a second area, completely or partially coinciding with the first area, which second area is illuminated by a light source. The unit is provided with a first and second parts separated by a mark (12), which parts are intended to extend inside the second area and outside the second area respectively. The unit (11) comprises x-ray radiation-indicating elements (14, 22) that assume a first indication state in the presence of x-ray radiation (6) and a second indication state in the absence of x-ray radiation. The position indication can be determined by means of the said mark and indication states. The invention also relates to an arrangement and a method for the said position indication.

Abstract: A method and a device for optimizing the image display on imaging apparatuses register whether an operator is looking at the imaging apparatus. The image display of the imaging apparatus is optimized, when it is registered that the operator is looking at the imaging apparatus and namely by dimming the room lighting and/or by increasing the contrast of the imaging apparatus.

Abstract: Apparatus includes a digital x-ray detector holder configured to hold x-ray detectors of at least two different sizes, wherein the holder is user positionable and is user lockable to maintain a user positioned relationship between the holder and an x-ray source.

Abstract: A positioning and targeting apparatus is attached to a beam emitting source having a beam central axis. The apparatus has an attachment collar enabled for securement to the emitting source. A lateral supporting member is engaged with the attachment collar and extends in an axial direction. A radial supporting member is engaged with the lateral supporting member and terminates on the beam central axis. A pointer is, in turn, engaged with the radial supporting member and positioned along the beam central axis. The pointer provides at least one axially telescoping segment and a locking nut for fixing the telescoping segment at a selected telescoping position relative to a base segment of the pointer. The radial supporting member and the pointer are made of material invisible to the source's beam.

Abstract: A cable terminal and clamp system particularly suited for use in an x-ray tube environment. The cable terminal and clamp system includes a cable socket having cable and terminal ports, each of which defines an axis. The cable terminal and clamp system includes a cable clamp that receives at least a portion of the cable socket. The cable clamp and cable socket are configured so that motion of the cable socket, relative to the cable clamp, along the axis defined by the terminal port is unimpaired, while motion of the cable socket, relative to the cable clamp, along the axis defined by the cable port is precluded. A spring interposed between the cable socket and cable clamp biases the cable socket away from the cable clamp along the axis defined by the terminal port. The cable terminal and clamp system thus accommodates thermal expansion of the terminal, while retaining the terminal in an associated receptacle and maintaining alignment of the cable clamp and cable socket.

Abstract: Laser guides for an X-ray device are disclosed in which a pair of laser projecting means are rotatably affixed to any X-ray device, either portable or stationary, such that the beams from the projecting means project toward the X-ray receptor and inward toward a line between the receptor and the X-ray device, and the laser beams cross at a particular location such that when the X-ray device is moved closer to or further from the X-ray receptor the laser beams cross when the X-ray device is at the optimum distance from the X-ray image receptor and the X-ray beam is centered upon the X-ray image receptor.

Abstract: A dielectric connector for use in high voltage devices, including x-ray tubes, is disclosed. The connector comprises a dielectric material and is pre-formed before attachment to the x-ray tube. Pre-formation of the connector creates a first cavity portion therein that conforms in shape to a corresponding segment of the tube surface. A second cavity portion is also defined for receiving a high voltage receptacle. Upon attachment to the tube, the first cavity portion receives the corresponding tube segment. The high voltage receptacle is received into the second cavity portion and electrically connects with a receptacle defined on the tube surface. The receptacle enables a high voltage signal passing through the electrode to connect with either the anode or cathode disposed within the tube. Pre-formation of the connector enables connector testing and repair to occur before it is attached to the tube, saving resources, time, and cost.

Abstract: An X-ray computed tomography apparatus wherein an X-ray is generated by a generator and an X-ray data resulting from the X-ray is detected by a detector. The apparatus includes a supporter, a driver, a body, and a converter. The supporter is configured to support the generator and the detector. The driver is configured to drive the supporter. The body is configured to incorporate the supporter and the driver. The converter is provided at a bottom of the body and is configured to convert regenerative energy caused by the driver to heat energy.

Abstract: A sterilizing drape which can be used to cover a C-arm machine in combination with a small surgical table. The invention assumes that a small surgical table has been affixed to the lower portion of a C-arm machine. The sterilizing drape covers the exposed portions of the C-arm machine as well as the small surgical table. An integrated version is disclosed which covers the C-arm machine, the small surgical table, and the patient. Other embodiments are disclosed which cover these areas using separate pieces.

Abstract: An adaptive rotator including an at least partial ring mounted for rotation on a ring mount, the at least partial ring having provisions for mounting thereon accessories, a gantry coupler adapted to couple the at least partial ring to a rotatable gantry, and a mechanical compensator attached to at least one of the at least partial ring, the ring mount and the gantry coupler, the mechanical compensator yielding so that the at least partial ring rotates about a ring rotation axis generally collinear with a gantry rotation axis of the rotatable gantry without exercising significant forces on the rotatable gantry and the at least partial ring.

Abstract: A device 10 for aligning a patient for delivering a plurality of radiation beams comprising a patient support surface 12, a coarse alignment subsystem 14 connected to the patient support surface, and a fine alignment subsystem connected to the patient support surface 16. A method of aligning a patient for delivering a plurality of radiation beams from a plurality of device positions comprising compensating for flexion of a radiation beam delivery device within a gantry during movement of the radiation beam delivery device from a first device position to a second device position by using a set of predetermined data describing the flexion behavior of the radiation beam delivery device so that the target tissue within the patient is placed at the beamline center for the radiation beam delivery device at the second device position.

Abstract: An apparatus for determining a coordinate transformation for mixing an image of a first subject into an X-ray image of a second subject has an arrangement for fastening the apparatus to the second subject, markers that can be acquired by a navigation system, and X-ray-positive marks. The positions and orientations of the markers that can be acquired with the navigation system and the positions and orientations of the X-ray-positive marks relative to one another are thus known, so a coordinate transformation can be determined between a coordinate system allocated to the navigation system and a coordinate system allocated to the X-ray image. Thus an image of the first subject that can be acquired with the navigation system can be mixed into an X-ray image of the second subject.

Abstract: A device is proposed for the precision rotation of samples on a diffractometer, especially for X-ray or synchrotron radiation diffraction experiments, comprising: a centering element (26) which is held at one end of a motor-driven rotating shaft (22) and can be displaced in a plane orthogonal to the axis of rotation of the rotating shaft (22), a sample holder (30) which is fixed to the centering element (26) or integral with the latter for holding a sample (32) substantially centrally with respect to the axis of rotation in an X-ray or synchrotron radiation beam (S), at least one micrometer finger (36) which is arranged in the region of the centering element (26) and can be positioned orthogonally with respect to the axis of rotation of the rotating shaft (22) by means of a micrometer finger drive device.

Abstract: A device 10 for aligning a patient for delivering a plurality of radiation beams comprising a patient support surface 12, a coarse alignment subsystem 14 connected to the patient support surface, and a fine alignment subsystem connected to the patient support surface 16. A method of aligning a patient for delivering a plurality of radiation beams from a plurality of device positions comprising compensating for flexion of a radiation beam delivery device within a gantry during movement of the radiation beam delivery device from a first device position to a second device position by using a set of predetermined data describing the flexion behavior of the radiation beam delivery device so that the target tissue within the patient is placed at the beamline center for the radiation beam delivery device at the second device position.

Abstract: A beamblock tray for use with multiple defining heads within a medical linear accelerator is disclosed. The beamblock tray comprises a tray portion, and a plurality of coded connectors coupled to the tray portion that make the tray “intelligent” enough to identify its orientation to a user. The tray portion can be inserted into the defining head in a plurality of directions based upon the plurality of coded connectors. A system and method in accordance with the present invention utilizes a plurality of coded connectors that can be used to identify a patient. In addition, the connectors and a mounting flange are such that they permit the tray to be inserted in a plurality of directions. Finally, a coding system is provided that prevents radiation from being delivered if the tray is oriented incorrectly.

Abstract: An apparatus for stacking a predetermined number of X-ray films has a sheet member holding device disposed above a stacking position for temporarily holding at least a first X-ray film, and an actuating device for displacing the sheet member holding device from the stacking position to drop the X-ray film held by the sheet member holding device into the stacking position. The apparatus is capable of stacking a plurality of X-ray films highly accurately and efficiently in the stacking position while avoiding damage to the X-ray films.

Abstract: A sensor assembly that allows a sensor to be detachably mounted onto a fluoroscopic mount, such as a C-arm, is provided. The sensor assembly includes an electromagnetic sensor that is configured for outputting positional data relating to the fluoroscopic mount. The sensor includes a mount engaging element, and the sensor mount includes a sensor engaging element, both of which are configured to be removably mounted in an interference relationship with each other. The mount engaging element of the sensor can be a sensor housing, or alternatively, an element that is separate from the sensor housing. The sensor mount, which is composed of a non-ferromagnetic material, further includes a spacer for maintaining the sensor a prescribed distance from the ferromagnetic fluoroscopic mount, thereby minimizing any adverse ferromagnetic effects on the sensor.

Abstract: A device 10 for aligning a patient for delivering a plurality of radiation beams comprising a patient support surface 12, a coarse alignment subsystem 14 connected to the patient support surface, and a fine alignment subsystem connected to the patient support surface 16. A method of aligning a patient for delivering a plurality of radiation beams from a plurality of device positions comprising compensating for flexion of a radiation beam delivery device within a gantry during movement of the radiation beam delivery device from a first device position to a second device position by using a set of predetermined data describing the flexion behavior of the radiation beam delivery device so that the target tissue within the patient is placed at the beamline center for the radiation beam delivery device at the second device position.

Abstract: The present invention provides devices for improved radiation attenuation in devices which generate x-ray radiation. A high voltage receptacle is disclosed, the receptacle being adapted to accommodate a high voltage connector to supply power to an x-ray tube and being formed of a mixture of a dielectric material and an x-ray attenuating material, such as an x-ray attenuating metal compound. X-ray radiation impinging upon the high voltage receptacle that would otherwise pass through the unshielded receptacle is absorbed or scattered by the x-ray attenuating material without the need for additional x-ray shielding. Also disclosed is an x-ray housing assembly including an x-ray housing adapted to contain an x-ray tube, and a high voltage receptacle, wherein the high-voltage receptacle and optionally a portion of the x-ray housing is formed of a mixture of a dielectric material and an x-ray attenuating material.

Abstract: An x-ray shielding device for use with an examination table. The x-ray shielding device includes a rectangularly shaped drape positioned on the tabletop and sized to extend over the width of the top. At least a portion of the drape extending over the width is configured for connecting to and supporting x-ray shielding panels.

Abstract: A phantom for use in measuring parameters in a digital radiography image system comprising a substantially rectangular member of an x-ray attenuating material; a first rectangular array of landmarks associated with the member for use in geometry measurements; a set of regions associated with the central position of the member for exposure linearity and accuracy measurement and a set of sharp angular edges part of one of the regions for modulation transfer function measurements.

Abstract: A stage system includes a first stage movable along a reference plane, containing a vertical direction, and in the vertical direction or in a first direction close to the vertical direction, a second stage movable in a second direction intersecting with the first direction and relative to the first stage, a first driving mechanism for moving the first stage in the first direction, a second driving mechanism for moving the second stage in the second direction, a countermass movable in the first direction, and a third driving mechanism for moving the countermass in a direction opposite to the first direction.

Abstract: A thermotherapy apparatus has a reclining surface (3) and an X-ray drawer (6) that can be retracted from the apparatus together when needed. A carrier (12) is located at the X-ray drawer (6) and can be connected to the reclining surface (3) in a preferred position.

Abstract: The present invention relates to a system and method for calibrating a radiation therapy device, such as a collimator. A method for calibrating a collimator according to an embodiment of the present invention is presented. The method comprises moving a leaf of a collimator; determining whether a distance between the leaf and a line approximately equals a predetermined measurement; and associating the predetermined measurement with a collimator specific count if the distance between the leaf and the line approximately equals the predetermined measurement.

Abstract: A monitoring apparatus analyzes detector data from a CT system to detect a signature of a bad detector. The apparatus generates a plurality of Helgason-Ludwig condition values from the detector data. The generated values are processed to generate a comparison value, which is compared to a predetermined threshold value. A warning message may be generated when the comparison value exceeds the predetermined threshold value, the warning message alerting an operator to the likely presence of a bad detector. In one embodiment, the generated values are further analyzed to generate an estimate of the position of the bad detector. In a preferred embodiment, the comparison value is a matrix norm of a matrix generated from the Helgason-Ludwig condition values.

Abstract: According to an embodiment of the present invention, an isocenter of an image may be found by using a multi-leaf collimator. According to this embodiment, a center leaf is projected into the center of the x-ray field with all other leaves retracted. An image is acquired. A line through the center of the center leaf is identified. This line is also a line through isocenter. Another method according to an embodiment of the present invention for finding isocenter uses an accessory. The accessory according to an embodiment of the present invention includes a metal marker in the center of the accessory with metal markers interspersed away from the center at a predetermined interval. An image may be acquired through the accessory, with the patient on the table. The resulting image may be analyzed to identify the position of the metal markers to determine isocenter.

Abstract: Modular interchangeable phantoms for multiple x-ray systems are provided. A variety of x-ray phantoms may be interchangeably inserted into a modular phantom carrier. Once a phantom has been inserted into the carrier, the phantom is locked to the carrier by either at least one rotating fastener or a plastic ring with at least one fastening pin. The carrier is then inserted into an x-ray system and x-rays are transmitted through the phantom. The phantom carrier also includes an interior mesh allowing measurement of the resolution non-uniformity of the x-ray system. Three phantoms for use with the modular phantom carrier are presented. Each phantom includes a number of sub-phantoms useful in the determination of various parameters of the x-ray system.

Abstract: An apparatus for medical diagnosis and/or therapy includes an electromagnetic obstacle sensor in order to prevent collisions with, for example a patient to be examined. The sensor is constructed so as to include a radiation transmitter and a radiation receiver in the form of capacitive electrodes 16 and 18, respectively, whereto electronic circuits 26 and 28 for signal processing are connected. In order to enable the electrodes 16 and 18 and the electronic circuits 26 and 28 to be checked for correct operation, a test electrode 14 is connected between the transmitter electrode 16 and the detection electrode 18, which test electrode can be connected, if desired, to a point 32 of fixed voltage via a controllable switch 34. The presence of an obstacle is thus simulated. The output signal of the electronic circuits 26 and 28 can be checked to determine whether this output signal corresponds to the situation in which an obstacle is present.

Abstract: An image quality test phantom tool is provided for use in the calibration and standardization of digital x-ray fluoroscopy and radiography systems. A composite phantom has a base for providing mechanical stability, a mesh with a central cut-out overlaid on the base, inserts positioned in the cut-out, and a carrier for housing the composite phantom. A digital image of the phantom is processed to compute x-ray system image quality measurements.

Abstract: A process for therapeutic treatment of changes in human or animal bones which cause a boundary surface gap with a width of less than 5 millimeters to form between the bone and an acoustically reflective body such as an implant, a tooth or a bone fragment. The process include a first step of locating the desired boundary surface gap by means of a locating device; next the body of the patient is exposed to acoustical shock waves through the surface of the skin after focusing the shock waves on the boundary surface gap. Vibrations are generated in the bone surfaces, the surfaces of the acoustically reflecting body, and at the gap by multiple reflections of the generated shock waves. The preferred device for carrying out the process uses a therapy head to generate and focus acoustic shock waves in a predetermined direction. The shock waves are conducted through the surface of the skin into the body of the patient by a coupling unit.

Abstract: A portable battery powered tool for aligning equipment in an X-ray room includes two spaced apart channel engaging connectors carried by a reference surface of the tool for engaging the usual recessed channels in the ceiling of the X-ray room, a laser carried by the tool for projecting a line in a projection plane parallel to the reference surface and an electronic sensor and indicator carried by the tool for indicating with an array of LEDs whether the projection plane deviates from level along each of two orthogonal axes. The tool also includes adjustment screws for finely adjusting the orientation of the reference surface relative to the ceiling. When mounted to the ceiling and leveled, the tool projects a line on a surface of the rail which projected line is used as a reference for leveling the rail. A stand is provided for the tool to establish a vertical projection plane so as to produce corresponding projected lines on the floor and ceiling.

Abstract: In storage phosphor radiography a latent x-ray image of a patient is stored in a storage phosphor. A storage phosphor reader converts the latent image into an x-ray image signal. A patient identifying and exam collection bar code system provides patient identification and x-ray exam data at the time of the exam which is matched with the x-ray image signal in the reader.

Abstract: Repeat fixation for medical procedures is accomplished using a non-invasive locator, specifically a bite plate. The bite plate has at least three fiducial markers on it. The fiducial markers may be LEDs, radiopaque markers for angiography or computerized tomography (CT) imaging or magnetic resonance markers for magnetic resonance (MR) imaging. By detecting the position of the markers, the position of features within the patient (such as a brain tumor or other intracranial target to which radiation is to be applied) can be determined with great precision. Since the bite plate has been molded to uniquely fit to the patient's teeth, it may be removed after an initial imaging of the patient. The bite plate may then be re-attached one or more times to the teeth and the location of the features will be in a known position relative to the sensed markers.

Abstract: A platform which is mounted over the fluoroscopic table in a catheterization procedure. The platform contains compartments for diagnostic or therapeutic catheterization procedure dependent devices, supplies, wastes, or fluids. The platform is mounted on a vertical support structure and utilizes removable inserts that fit within the compartments.

Abstract: An operating mechanism for an X-ray system has a carrier for a number of operating elements which is connected to the patient table so as to be pivotable around an axis extending parallel to the longitudinal axis of the patient table. The carrier has two generally U-shaped sides, with one leg of each U-shaped sides being connected to the patient support table in a pivotable manner, and the other leg of each U-shaped side being connected to a generally longitudinally extending connector section. The operating elements are removably mounted on the connector section. The carrier is connected at one side of the patient support table, and feed and control lines for the operating elements can be conducted inside the carrier to the operating elements. The carrier may have a touch-sensitive patch strip embedded therein so that, when the carrier is gripped by an attendant, a control element for assisting in the positional adjustment of the patient support table is activated.

Abstract: A collision-free control system comprising a multi-axially controllable manipulator having interconnected supporting arms which are movable by way of actuators in such a way that a free end of the manipulator can be positioned spatially and moved into various positions. The actuators are controlled via a miniature model of the manipulator which is operated manually and is equipped with a series of position transducers which are capable of delivering control signals for commanding the actuators in such a way that the manipulator and the miniature model thereof always assume identical positions.

Abstract: An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

Abstract: A one-piece C-arm for use with X-ray diagnostic equipment included in cross-section two generally vertical sidewalls extending generally parallel to one another, an inner support wall connecting the sidewalls, and an outer support wall spaced-apart from the inner support wall and connecting the sidewalls. A pair of flanges extend outwardly from respective sidewalls, and toward one another to form at least one channel along an outer portion of the C-arm frame for receiving wheels or bearings to allow moveable mounting of the C-arm on diagnostic equipment.

Abstract: An apparatus for positioning a human foot for X-ray examination on an apparatus support surface, the human foot having a foot bottom surface, a foot rear surface and two foot side surfaces, includes structure for retaining the foot including a foot retaining bottom portion extending over the foot bottom surface, a foot retaining rear portion extending over the foot rear surface and a foot retaining side portion extending over at least one of the foot side surfaces, and structure for propping and orienting the foot including a substantially horizontal base member for resting on the apparatus support surface and for supporting the foot and the structure for retaining, the base member having laterally distributed contact activated fasteners for engaging the foot retaining rear portion at any of several laterally distributed points along the base member for securing left and right feet, and including a substantially vertical upright member for positioning the foot and the structure for retaining, the upright memb

Abstract: An x-ray apparatus includes an x-ray tube having a focus, the x-ray tube being contained in a housing and the housing having a mechanical distance-measuring device attache thereto. The mechanical distance-measuring device is suitable for obtaining a measured value which exactly corresponds to the focus-to-skin distance for all types of examinations. The mechanical distance-measuring device, which may be a tape measure, is connected to an electrical signal generator which converts the mechanically measured value into a corresponding electrical signal.

Abstract: Disclosed is a device for determining an angle of incident light or a shift in incident light based on the output value of a detector. In a predetermined angle detection range, a beam of light incident on a detector for detecting the intensity of light incident thereon is restricted such that the amount of light continuously increases or decreases in accordance with the angle between an optical axis of the incident light and a referential axis of an exposure apparatus. Outside of the predetermined angle detection range, the amount of light is restricted depending on the direction in which the optical axis of the light is shifted from the angle detection range. The amount of light incident on the detector continuously increases or decreases in accordance with the angle between the optical axis of the incident light and the referential axis when the light is made incident within the angle detection range by means of the light restriction means.

Abstract: A marker for forming identifying indicia on X-ray film is comprised of two overlapping layers of material which define a predetermined shape, with a first layer of material having first predetermined X-ray absorbing characteristics, and-a second layer of material having second X-ray absorbing characteristics complementary to the X-ray absorbing characteristics of the first material, such that the combination of the two layers block a sufficient portion of the X-rays imparted to the X-ray film to form an identifying indicia on the X-ray film having good contrast. The combination of the two layers of material block a substantially greater portion of the X-rays than that blocked by either of the two materials alone. A plurality of indicia-defining layers of material are encapsulated within a clear encapsulating material having magnetic engaging means, whereby a single marker having a plurality of identifying indicia may be easily picked up and engaged with the platen containing the X-ray film.