JP2015104527A - Collimator and radiographic apparatus equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a collimator that operates normally even when a filament touch occurs in a visible light source, or a radiographic apparatus equipped with the collimator.SOLUTION: A collimator 3a is provided that operates normally even when a filament touch occurs in a visible light source 9. That is, when an occurrence of a filament touch is detected, power to be supplied to filaments is reduced so as to protect the filaments. Thereby, excessive supply of power to the filaments attributed to the filament touch is suppressed, the filaments never burn out, and an impact on other parts of the same power system can be eliminated.

Description

  The present invention relates to a collimator that limits the spread of radiation and a radiation imaging apparatus including the collimator, and more particularly to a collimator having a visible light source and a radiation imaging apparatus including the collimator.

  The present invention relates to a radiation imaging apparatus that performs radiation imaging of a subject, and more particularly to a radiation imaging apparatus that can select a radiation detector used for imaging.

  A medical institution is equipped with a radiation imaging apparatus that images a subject M by irradiating radiation (see, for example, Patent Document 1). As shown in FIG. 14, such a radiographic apparatus includes a radiation source 53 that irradiates radiation and an FPD 54 that detects the radiation. A top plate 52 on which the subject M is placed is provided between the radiation source 53 and the FPD 54.

  The radiation source 53 is provided with a collimator 53a for limiting the radiation irradiation range. The radiation emitted from the radiation source 53 passes through the collimator 53a, and the spread is limited, and the subject M is irradiated.

  The radiation emitted from the radiation source 53 cannot be visually observed. Therefore, in the conventional configuration, a visible light source 59 is provided in the collimator 53a. Since the visible light source 59 can be visually observed by the operator, the operator can visually observe a portion (irradiation region or irradiation field) where the radiation illuminates the subject M before radiography.

  This visible light source 59 is attached to the collimator 53a. The visible light source 59 obtains power from the power supply unit 60 provided in the collimator 53a. The power supply unit 60 supplies power to other components such as a motor that opens and closes the collimator provided in the collimator 53a.

JP 2007-229387 A

However, the conventional radiographic apparatus has the following problems.
That is, according to the conventional configuration, the lifetime of the visible light source is shortened.

  The visible light source 59 is a halogen lamp or the like, and a filament is used as a light emitter. This filament has a coiled structure. The filament is configured by connecting a plurality of loops (windings).

  Such a filament deteriorates with age when used over a long period of time and gradually deforms. That is, the loop constituting the filament falls into the adjacent loop, and the loops come into contact with each other. In this way, the filament is partially shorted due to aging. Such a phenomenon is called filament touch. Even if the filament touch occurs, the light quantity of the filament may decrease, but the light emission ability is not lost. When filament touch occurs, the life of the filament is significantly shortened.

  The shortening of the filament life is not caused by the filament touch itself, but by factors associated therewith. This factor will be described. The filament has a predetermined impedance, which can be considered as one resistor. The left side of FIG. 15 is a circuit diagram when the filament is regarded as a resistor. A predetermined voltage is applied to the filament from the power supply unit 60.

  The right side of FIG. 15 is a circuit diagram showing a state where filament touch has occurred. When a filament touch occurs, a short circuit occurs in a part of the filament, so the impedance of the filament itself decreases. As a result, a current easily flows through the filament as a whole, and the current passing through the filament increases. Such a decrease in impedance becomes more prominent as the filament touch progresses. If the filament is continuously used as it is, the flowing current gradually increases, and the filament eventually burns out. This is because the maximum value of the current flowing through the filament is determined by the cross-sectional area of the metal wire.

  A filament touch does not increase the rated current that can flow through the filament. Certainly, when a filament touch occurs, the effect is as if the cross-sectional area of the metal wire has increased at the contact portion between the loops, and the allowable current may increase. However, in the normal part where the loops are not in contact with each other, there is no change in the cross-sectional area of the metal wire. Since it can be considered that the contact portion and the normal portion of the filament are connected in series, the maximum value of the current in the normal portion determines the magnitude of the current that the filament can tolerate.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a collimator that operates normally even when a filament touch occurs in a visible light source and a radiation imaging apparatus including the collimator.

The present invention has the following configuration in order to solve the above-described problems.
That is, the collimator according to the present invention is a collimator that limits the spread of radiation irradiated from a radiation source, a visible light source having a filament that generates visible light, and a power supply unit that supplies power to the visible light source, A detection means for detecting whether a filament touch, which is a phenomenon in which a partial short circuit occurs in a deteriorated filament, and the power supplied to the filament is reduced to protect the filament when the occurrence of the filament touch is detected. And a visible light source control means.

  [Operation and Effect] According to the present invention, a collimator that operates normally even when a filament touch occurs can be provided. That is, according to the present invention, when the occurrence of a filament touch is detected, the power supplied to the filament is reduced so as to protect the filament. As a result, the supply of excess power to the filament accompanying the filament touch is suppressed, and the filament does not burn out.

  The collimator described above includes a pair of shielding blades that block radiation and visible light, shielding blade driving means that changes the opening of the collimator by driving the shielding blades, and shielding blade control that controls the shielding blade driving means. And the power supply means can supply power to both the shielding blade driving means and the visible light source.

  Further, the collimator described above includes a holder having a plurality of additional filters that block a part of radiation, an additional filter driving means for changing the type of additional filter used by driving the holder, and an additional control for controlling the additional filter driving means. A filter control unit, and the power supply unit may supply power to both the additional filter driving unit and the visible light source.

  [Operation / Effect] The above-described configuration shows a specific configuration of the present invention. Various driving means sharing the visible light source and the power supply means are prone to torque shortage because the filament loses power due to the influence of the filament touch. According to the present invention, since the supply of excess power to the filament of the visible light source that occurs with the filament touch is suppressed, the power supplied to the various drive means is sufficient even when the filament touch occurs. Therefore, according to the present invention, it is possible to provide a collimator that operates normally even when a filament touch occurs.

  In the above collimator, the detection means can be a current measurement means for measuring a current flowing through the filament.

  [Operation / Effect] The above-described configuration shows a specific configuration of the present invention. The detection means of the present invention can be constituted by a current measurement means for measuring the current flowing through the filament.

  A radiation imaging apparatus according to the present invention is a radiation imaging apparatus that images a radiation image of a subject, and includes the above-described collimator.

  [Operation / Effect] The above-described configuration shows a specific configuration of the present invention. The collimator of the present invention can be applied to a radiation imaging apparatus.

  Further, in the above-described radiographic apparatus, it is more desirable that a warning means for warning the operator when a filament touch is detected is provided.

  [Operation / Effect] The above-described configuration shows a specific configuration of the present invention. If a warning means for warning the operator of the occurrence of the filament touch is provided, a more user-friendly radiation imaging apparatus can be provided. For example, the surgeon can prepare a replacement visible light source before the visible light source reaches the end of its life, thereby shortening the period during which the visible light source cannot be used.

  According to the present invention, a collimator that operates normally even when a filament touch occurs in a visible light source can be provided. That is, according to the present invention, when the occurrence of a filament touch is detected, the power supplied to the filament is reduced so as to protect the filament. As a result, supply of excess power to the filament accompanying the filament touch is suppressed, the filament is not burned out, and the influence on other parts of the same power supply system can be eliminated.

1 is a functional block diagram illustrating a configuration of an X-ray imaging apparatus according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a collimator according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a collimator according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a collimator according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a collimator according to Embodiment 1. FIG. 3 is a schematic diagram illustrating a collimator according to Embodiment 1. FIG. It is a schematic diagram explaining the filament touch which concerns on Example 1. FIG. FIG. 3 is a schematic diagram illustrating a problem of the collimator according to the first embodiment. FIG. 3 is a schematic diagram illustrating a problem of the collimator according to the first embodiment. FIG. 3 is a schematic diagram illustrating a problem of the collimator according to the first embodiment. 3 is a schematic diagram illustrating a characteristic configuration of a collimator according to Embodiment 1. FIG. 3 is a flowchart illustrating a characteristic configuration of the collimator according to the first embodiment. 3 is a schematic diagram illustrating a characteristic configuration of a collimator according to Embodiment 1. FIG. It is a schematic diagram explaining the radiography apparatus of a conventional structure. It is a schematic diagram explaining the problem of the collimator of a conventional structure.

  Hereinafter, examples of the present invention will be described. The X-ray imaging apparatus according to the present invention is an X-ray imaging apparatus that images an X-ray image of a subject M, and includes a collimator 3 a that limits the spread of X-rays emitted from the X-ray tube 3. X-rays in the examples correspond to the radiation of the present invention.

<Overall configuration of X-ray imaging apparatus>
First, the configuration of the X-ray imaging apparatus 1 according to the first embodiment will be described. As shown in FIG. 1, the X-ray imaging apparatus 1 includes a top plate 2 on which a subject M in a supine position is placed, and an X-ray tube 3 that emits X-rays provided on the upper side (one surface side) of the top plate 2. And an FPD 4 for detecting X-rays provided on the lower side (other surface side) of the top plate 2. The FPD 4 is a rectangle having four sides along either the body axis direction A or the body side direction S of the subject M. The X-ray tube 3 irradiates the quadrangular pyramid-shaped X-rays toward the FPD 4. The FPD 4 receives X-rays on the entire surface. The support column 5 extends from the lower side (other surface side) of the top plate 2 toward the upper side (one surface side) of the top plate 2 and supports the X-ray tube 3.

<About the collimator 3a>
The X-ray tube 3 is provided with a collimator 3a that limits the X-ray irradiation range (see FIG. 1). The collimator 3a can adjust the opening degree. As shown in FIG. 2, the collimator 3a has a pair of shielding blades 3b that move mirror-symmetrically with respect to the axis C, and another pair of shielding blades 3b that similarly move mirror-symmetrically with respect to the axis C. I have. If this collimator 3a can irradiate the entire surface of the detection surface 4a of the FPD 4 with cone-shaped X-rays B by moving the shielding blade 3b, for example, only the central portion of the detection surface 4a has a fan-shaped X-ray. The line B can also be irradiated. The axis C is an axis indicating the center of the X-ray B. One of the two pairs of shielding blades 3b adjusts the spread of the X-ray B in the body axis direction A in the shape of a quadrangular pyramid, and the other pair of shielding blades 3b is an X-ray. The spread of B in the body side direction S is adjusted. When the X-ray tube 3 is moved, the collimator 3 a is also moved along with the X-ray tube 3. The pair of shielding blades 3b blocks X-rays and visible light.

  Such opening and closing of the shielding blade 3b is realized by a collimator driving mechanism 7 as shown in FIG. That is, the collimator drive mechanism 7 changes the opening degree of the collimator 3a by driving the shielding blade 3b. Specifically, the collimator driving mechanism 7 can be configured by a stepping motor or the like. The collimator drive mechanism 7 operates under the control of the collimator control unit 8 and operates by receiving the power PW_F from the power supply unit 12. The collimator driving mechanism 7 corresponds to the shielding blade driving means of the present invention, and the collimator control unit 8 corresponds to the shielding blade control means of the present invention. The power supply unit 12 corresponds to the power supply means of the present invention.

  The X-ray tube controller 6 (see FIG. 1) is provided for the purpose of controlling the X-ray tube 3 with a predetermined tube current, tube voltage, and pulse width. When X-rays are emitted from the X-ray tube 3 under the control of the X-ray tube control unit 6, the X-rays pass through the subject M and enter the detection surface 4 a of the FPD 4. The FPD 4 includes a phosphor that is sensitive to X-rays. When the X-rays strike the phosphor, a fluoroscopic image of the subject M is printed on the phosphor, and the phosphor light is converted into an electrical signal. Converted to a digital image.

<About visible light source 9>
The visible light source 9 is provided in the collimator 3a as shown in FIG. The visible light emitted from the visible light source 9 passes through the gap between the shielding blades 3b of the collimator 3a and irradiates a part of the subject M. Similarly, the X-rays emitted from the X-ray tube 3 are also irradiated to a part of the subject M through the gap between the shielding blades 3b of the collimator 3a. The portions of the subject M illuminated by the X-ray beam output from the X-ray tube 3 coincide with each other. Since the visible light source 9 can be visually observed by the operator, the operator can visually observe the portion (irradiation region or irradiation field) where the X-ray illuminates the subject M before X-ray imaging. .

  The visible light source 9 has a filament that generates visible light. This filament has a coil shape and is configured to generate visible light when an electric current is passed therethrough.

  Such lighting control of the visible light source 9 is realized by the visible light source control unit 13 as shown in FIG. Specifically, the visible light source control unit 13 can be configured by a switching regulator, a series regulator, or the like. The visible light source 9 receives the power PW_L from the power supply unit 12 and operates. The visible light source control unit 13 adjusts how much power PW_L supplied through the power supply unit 12 is supplied to the visible light source 9 to turn off or turn on the visible light source 9 or adjust the light amount of the visible light source 9. It has a configuration to do. The visible light source control unit 13 corresponds to the visible light source control means of the present invention.

  Next, the positional relationship between the X-ray tube 3 and the collimator 3a will be described. FIG. 3 is a schematic diagram illustrating the positional relationship between the members. The X-ray tube 3 is provided with an irradiation port 3p that emits X-rays. The collimator 3a is provided with a mirror 19 that is inclined with respect to the irradiation port 3p. The collimator 3 a is provided with a visible light source 9 so as to be at the same position as the mirror image of the focal position of the X-ray tube 3 by the mirror 19 when viewed from the subject M.

  When the visible light source 9 is turned on to emit visible light, the visible light is reflected by the mirror 19 and travels toward the collimator 3a. The spread of the visible light is limited by the collimator 3a to form a cone-shaped visible light beam, which is output to the subject M side.

  When the visible light source 9 is turned off and X-rays are irradiated from the X-ray tube 3, the X-rays pass through the mirror 19 and travel toward the collimator 3a. Then, the spread of the X-ray is limited by the collimator 3a to form a cone-shaped X-ray beam and output to the subject M side. As long as the shielding blade 3b of the collimator 3a is not moved, the visible light beam and the X-ray beam travel toward the subject M in the same spreading manner.

<Additional filter 25f>
FIG. 4 illustrates the configuration of the holder 25 according to the configuration of the additional filter 25f attached to the collimator 3a. The holder 25 holds an additional filter that transmits X-rays. The holder 25 is a disk-shaped member that spreads on a plane orthogonal to the direction in which the X-rays B are emitted. As shown in FIG. 1, the holder 25 is disposed at a position between the X-ray tube 3 and the collimator 3a. Therefore, the X-ray beam emitted from the X-ray tube 3 passes through the holder 25 and reaches the collimator 3a.

  The holder 25 can rotate with respect to the X-ray tube 3. That is, a center axis 25a extending in the X-ray beam emission direction is provided at the center of the holder 25, and the holder 25 is rotatable about the center axis 25a. The additional filter drive mechanism 17 executes the rotational drive of the holder 25. The additional filter control unit 18 is provided for the purpose of controlling the additional filter driving mechanism 17.

  The holder 25 includes a plurality of additional filters 25f that block a part of the X-rays. The holder 25 is provided with a plurality of rectangular holes 25b, and the holes 25b penetrate the holder 25 in the X-ray beam emission direction. Therefore, the hole 25b penetrates the holder 25 in the central axis C direction. The hole 25b is provided so as to surround the central axis 25a of the holder. In FIG. 4, four holes 25b are provided, but the number of holes 25b can be freely changed. The hole 25b is a through hole provided in the holder 25 through which the X-ray beam passes. Different types of additional filter 25f can be set in the hole 25b, or the additional filter 25f can be prevented from being set.

  The manner in which the holder 25 holds the additional filter 25f will be described. The additional filter 25f is fixed to the holder 25 so as to close the hole 25b. FIG. 4 shows a state where the additional filter 25f fixed to the holder 25 is removed. The additional filter 25f is a thin plate-like member in the X-ray beam emission direction. The additional filter 25f is provided for the purpose of changing the quality of the X-ray beam to a desired one. That is, when the X-ray beam emitted from the X-ray tube 3 passes through the additional filter 25f, a part of the X-ray beam is absorbed by the additional filter 25f and does not reach the subject M.

  By rotating the holder 25, the type of the additional filter 25f through which the X-ray beam passes can be changed. The position at which the X-ray beam emitted from the X-ray tube 3 passes through the holder 25 can be changed by rotating the holder 25. By such an operation, the quality of the X-ray beam irradiated to the subject M can be made desired. This is because the additional filter 25f accommodated in the holder 25 also follows and rotates. Further, by rotating the holder 25, the X-ray beam can be prevented from passing through any of the additional filters 25f.

  Such rotation of the holder 25 is realized by the additional filter driving mechanism 17 as shown in FIG. The additional filter driving mechanism 17 changes the type of the additional filter 25 f used by driving the holder 25. Specifically, the additional filter drive mechanism 17 can be configured by a stepping motor or the like. The additional filter driving mechanism 17 operates under the control of the additional filter control unit 18 and operates by receiving the power PW_A from the power supply unit 12. The additional filter driving mechanism 17 corresponds to the additional filter driving means of the present invention, and the additional filter control unit 18 corresponds to the additional filter control means of the present invention.

<Commonality of power supply>
In the configuration of the present invention, as shown in FIG. 6, the collimator driving mechanism 7, the visible light source 9, and the additional filter driving mechanism 17 all operate by receiving power PW_F, PW_L, and PW_A from the same power supply unit 12. As described above, the power supply unit 12 supplies power to all of the visible light source 9, the collimator driving mechanism 7, and the additional filter driving mechanism 17. Specifically, it can be considered that the collimator driving mechanism 7, the visible light source 9, and the additional filter driving mechanism 17 are electrically connected in parallel as shown in the lower side of FIG. Such a configuration normally causes no problem in operation, but becomes a problem when the visible light source 9 deteriorates and a filament touch occurs.

<About filament touch of visible light source>
FIG. 7 illustrates filament touch. The left side of FIG. 7 represents a state when the filament of the visible light source 9 is new. The filament is a coil in which loops (windings) are arranged at a predetermined pitch. When such a visible light source 9 is used for a long time, the loop is deformed. The right side of FIG. 7 represents a state in which the filament has deteriorated. Due to aging deterioration, adjacent loops of the filament are deformed so as to lean against each other. Such a phenomenon that the loop comes into contact is called a filament touch. Filament touch causes deterioration of the visible light source 9 itself, such as a decrease in light amount and a decrease in life.

<Effect of filament touch on visible light source 9>
FIG. 8 is a circuit diagram showing a state in which a filament touch is generated in the filament of the visible light source 9. As shown in FIG. 8, in the filament touch, when the filament itself is considered as a resistor, it can be considered that the resistor is short-circuited inside. That is, the filament touch acts to decrease the resistance value of the filament and increase the current I_L flowing through the filament of the visible light source 9.

  When the filament touch proceeds and the resistance value of the filament continues to decrease, the current I_L flowing through the filament continues to increase, and finally the filament cannot withstand the excess current and burns out. At this time, the resistance of the filament does not change even if the resistance value is lowered by the filament touch. The rated current of the filament (the maximum current that can be safely passed) is determined by the cross-sectional area of the loop. Certainly, the filament touch generation portion in the filament is in a state where two loops are attached as shown on the left side of FIG. 9, and it can be understood that the cross-sectional area of this portion has doubled. However, since the filament touch is an event that occurs at a part of the filament, the filament after the filament touch has a portion where adjacent loops do not stick to each other as shown on the right side of FIG. Such a normal portion has no change in the cross-sectional area of the loop just because the filament touch occurs. Therefore, there is no change in the rated current of the filament before and after the occurrence of the filament touch.

  That is, the filament touch is a cause of shortening the lifetime of the visible light source 9. In addition, the filament touch acts to reduce the light amount of the visible light source 9 based on the same principle as that of reducing the number of turns of the loop constituting the filament.

<Effect of filament touch on the drive>
The filament touch also adversely affects the collimator driving mechanism 7 and the additional filter driving unit 17 connected in parallel with the visible light source 9. When the filament touch occurs and the current I_L flowing through the filament increases, the power supplied by the power supply unit 12 is deprived by the visible light source 9 accordingly. Since there is a limit to the power that can be supplied by the power supply unit 12, the influence of the increase in the current I_L appears as a decrease in the voltage V_PW generated by the power supply unit 12 as shown in FIG. The collimator driving mechanism 7 and the additional filter driving mechanism 17 must operate by receiving the reduced voltage V_PW. Even if the collimator driving mechanism 7 tries to drive the shielding blade 3b in such a state, there is a possibility that a sufficient driving force cannot be obtained. The opening and closing of the shielding blade 3b of the collimator 3a involves a certain amount of friction. If the driving force of the collimator driving mechanism 7 is too weak, it may happen that the shielding blade 3b cannot be fully opened or closed or cannot be opened and closed itself. Similarly, even if the additional filter drive mechanism 17 tries to rotate the holder 25 in a state where the voltage V_PW is lowered, there is a possibility that sufficient rotational force cannot be obtained. The rotation of the holder 25 involves a certain amount of friction. If the rotational force of the additional filter drive mechanism 17 is too weak, the holder 25 may not be sufficiently rotated or may not be able to rotate itself.

<Characteristic configuration of the present invention>
The present invention is devised so that the filament touch does not have the adverse effects described above. That is, the visible light source 9 according to the present invention includes a filament touch detection unit 14 that detects a filament touch as shown in FIGS. It is devised so that does not increase. The filament touch detection unit 14 has a function of detecting whether a filament touch, which is a phenomenon in which a partial short circuit occurs in a deteriorated filament, has occurred. The filament touch detection unit 14 corresponds to detection means of the present invention.

  FIG. 11 is a circuit diagram showing a characteristic part of the present invention. The visible light source control unit 13 operates so that the current generated from the power supply unit 12 is converted into a pulse wave and sent to the visible light source 9. The visible light source control unit 13 outputs the pulse wave only to the visible light source 9 and does not output it to the collimator driving mechanism 7 and the additional filter driving unit 17. A current flows directly from the power supply unit 12 to the collimator driving mechanism 7 and the additional filter driving unit 17.

  As shown in FIG. 11, the filament touch detection unit 14 can be specifically configured with an ammeter that measures the current flowing through the visible light source 9. This ammeter can monitor the current I_L flowing through the visible light source 9. Thus, the filament touch detection unit 14 can be a current measuring unit that measures the current flowing through the filament.

  FIG. 12 illustrates operations of the visible light source control unit 13 and the filament touch detection unit 14 that accompany the occurrence of a filament touch. The filament touch detection unit 14 always monitors the current flowing through the visible light source 9 while the visible light source 9 is turned on. When a filament touch occurs (step S1), the filament touch detection unit 14 detects an increase in the current I_L (step S2). When the increase in the current I_L exceeds a certain threshold, the filament touch detection unit 14 notifies the visible light source control unit 13 to that effect, and the pulse light wave that the visible light source control unit 13 sends to the visible light source 9 as shown in FIG. The waveform is changed so that more current is thinned out. As the threshold value at this time, for example, a value representing 10.5 A can be adopted for the visible light source 9 having a rated current of 10 A. In addition, the operation of changing the waveform of the pulse wave so as to thin out the current is also referred to as the operation of reducing the DUTY ratio.

  In this way, the visible light source control unit 13 reduces the effective voltage applied to the visible light source 9 (step S3). As described above, when the occurrence of filament touch is detected, the visible light source control unit 13 reduces the power supplied to the filament so as to protect the filament. Then, the current I_L flowing through the visible light source 9 is reduced (step S4), and the current exceeding the rating is prevented from flowing through the visible light source 9. Furthermore, the voltage V_PW supplied by the power supply unit 12 is also prevented from decreasing, and the collimator driving mechanism 7 and the additional filter driving mechanism 17 can drive each driving unit with sufficient torque.

<Other configuration of the apparatus according to the present invention>
The console 26 (see FIG. 1) is provided for the purpose of inputting an instruction such as start of X-ray irradiation by the operator. The main control unit 27 (see FIG. 1) is provided for the purpose of comprehensively controlling each control unit. The main control unit 27 is constituted by a CPU, and realizes the X-ray tube control unit 6 and the units 8, 11, and 18 by executing various programs. Further, each of the above-described units may be divided and executed by an arithmetic device that takes charge of them. The storage unit 28 (see FIG. 1) stores all parameters relating to device control such as threshold values. The image generation unit 11 generates an X-ray image in which a fluoroscopic image of the subject M is reflected based on an X-ray detection signal output from the FPD 4. The display unit 20 is provided for the purpose of displaying the X-ray image generated by the image generation unit 11.

  As described above, according to the present invention, it is possible to provide a collimator 3a that operates normally even when a filament touch occurs. That is, according to the present invention, when the occurrence of a filament touch is detected, the power supplied to the filament is reduced so as to protect the filament. As a result, supply of excess power to the filament accompanying the filament touch is suppressed, the filament is not burned out, and the influence on other parts of the same power supply system can be eliminated.

  In addition, various driving means sharing the visible light source 9 and the power supply unit 12 are liable to run out of torque because the filament is deprived of power by the influence of the filament touch. According to the present invention, the supply of excess power to the filament of the visible light source 9 that occurs with the filament touch is suppressed, so that the power supplied to the various drive means is sufficient even when the filament touch occurs. Therefore, according to the present invention, it is possible to provide a collimator 3a that operates normally even when a filament touch occurs.

  The present invention is not limited to the configuration described above, and can be modified as follows.

  (1) In the above configuration, the filament touch detection unit 14 is an ammeter that measures the current flowing through the visible light source 9, but the present invention is not limited to this configuration. The filament touch detection unit 14 may be a camera that captures the filament of the visible light source 9 or may be a voltmeter that measures the voltage V_PW of the power supply unit 12. Further, the filament touch detection unit 14 may be an illuminometer that captures the light amount of the visible light source 9.

  (2) When the filament touch detection unit 14 is configured as an ammeter, various specific ammeter configurations are conceivable. For example, the filament touch detection unit 14 may be an ammeter having a shunt resistance or a clamp meter.

  (3) In addition to the above-described configuration, a configuration for notifying an operator of the occurrence of a filament touch may be provided. That is, when the increase in the current I_L flowing through the filament exceeds a certain threshold value, the filament touch detection unit 14 may send a message to that effect to the display unit 20 so that the display unit 20 displays the occurrence of the filament touch. At this time, the amount of light displayed on the display unit 20 is limited by notifying the abnormality of the visible light source 9, prompting the user to replace the visible light source 9, or changing the pulse wave waveform of the visible light source control unit 13. Various aspects are conceivable, such as notifying the effect. In this way, when the occurrence of the filament touch is detected, the display unit 20 warns the operator to that effect. The display unit 20 corresponds to warning means of the present invention.

3a Shielding blade 7 Collimator driving mechanism (shielding blade driving means)
8 Collimator control unit (shielding blade control means)
9 Visible light source 12 Power supply unit (power supply means)
13 Visible light source control unit (visible light source control means)
14 Filament touch detector (detection means)
17 Additional filter drive mechanism (additional filter drive means)
18 Additional filter control unit (additional filter control means)
20 Display (Warning means)
25 Holder 25f Additional filter

Claims (6)

A collimator for limiting the spread of radiation emitted from a radiation source,
A visible light source having a filament that generates visible light;
Power supply means for supplying power to the visible light source;
Detection means for detecting whether a filament touch, which is a phenomenon in which a partial short circuit occurs in a deteriorated filament,
A collimator comprising: a visible light source control unit that reduces power supplied to the filament to protect the filament when occurrence of the filament touch is detected. The collimator according to claim 1, wherein
A pair of shielding blades that block radiation and visible light;
Shielding blade driving means for changing the opening of the collimator by driving the shielding blade;
Shielding blade control means for controlling the shielding blade drive means,
The collimator characterized in that the power supply means supplies power to both the shielding blade driving means and the visible light source. The collimator according to claim 1 or 2,
A holder with a plurality of additional filters that block some of the radiation;
An additional filter driving means for changing the type of the additional filter used by driving the holder;
Additional filter control means for controlling the additional filter drive means,
The collimator characterized in that the power supply means supplies power to both the additional filter driving means and the visible light source. The collimator according to any one of claims 1 to 3,
The collimator characterized in that the detecting means is a current measuring means for measuring a current flowing through the filament. A radiographic apparatus for imaging a radiographic image of a subject,
A radiation imaging apparatus comprising the collimator according to claim 1. The radiographic apparatus according to claim 5,
A radiation imaging apparatus comprising warning means for warning an operator of the occurrence of occurrence of filament touch.

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