Radiation generating apparatus and radiography system including the radiation generating apparatus

A radiation generating apparatus includes a cathode array including a plurality of electron emitting portions, and an anode array including a plurality of targets and a chained connection unit that connects the targets. The chained connection unit includes a plurality of shielding members and a thermal transfer member, the shielding members being arranged at locations corresponding to the locations of the respective targets, and the thermal transfer member having a thermal conductivity higher than a thermal conductivity of the shielding members. The thermal transfer member has a portion that is continuous in a direction in which the targets are arranged.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to radiation generating apparatuses for, in particular, diagnostic application in the field of medical equipment and nondestructive radiography in the field of industrial equipment.

2. Description of the Related Art

Radiation generating apparatuses that generate X-rays for use in medical diagnosis and industrial non-destructive imaging are required to have a high durability and maintenance efficiency to increase the operating rate thereof. Such a radiation generating apparatus may serve as a portable medical modality applicable to home medical care or emergency medical care in case of, for example, a disaster or an accident.

The thermal stability of a target that serves as a source of radiation is one of the main factors that determine the durability of the radiation generating apparatus.

In the radiation generating apparatus, which generates radiation by irradiating the target with electron beams, the “radiation generation efficiency” of the target is less than 1% because most of the energy supplied by the electron beams to the target is converted into heat. When dissipation of the heat generated by the target is not sufficient, a problem occurs in that the adhesion of the target to its support member is reduced due to thermal stress, and the thermal stability of the target is limited.

A known method for increasing the “radiation generation efficiency” of the target is to use a transmissive target including a thin-film-shaped target layer, which contains a heavy metal, and a support member, which allows the radiation to pass therethrough and supports the target layer. PCT Japanese Translation Patent Publication No. 2009-545840 discloses a rotating-anode transmissive target with which the “radiation generation efficiency” is increased to 1.5 times that of a known rotating-anode reflective target.

A known method for promoting the dissipation of heat from the target to the outside is to use diamond as the material of the support member that supports the target layer of the multilayer target. U.S. Pat. No. 6,850,598 discloses that the heat dissipation effect can be increased and the focal spot size can be reduced when the support member that supports the target layer, which is made of tungsten, is made of diamond. Diamond has high radiotransparency as well as high thermal stability and thermal conductivity, and is therefore suitable as a material of a support member of a transmissive target.

With the development of image processing technologies, such as tomography, for medical diagnosis, array-type radiation generating apparatuses that emit a plurality of X-ray beams have been developed as a modality. Such an array-type radiation generating apparatus includes radiation generating units arranged in an array, and each radiation generating unit is configured to be individually controllable.

Japanese Patent Laid-Open No. 2007-265981 discloses a structure of an array-type radiation generating apparatus in which shielding members having openings are provided on front and back sides of a plate-shaped target including a plurality of radiation generating units. The plate-shaped target is thermally in contact with the shielding members. Owing to this structure, according to Japanese Patent Laid-Open No. 2007-265981, a plurality of X-ray beams with regulated radiation angles are emitted toward the front of the radiation generating apparatus, and the heat of the target can be radiated through the shielding member on the front side of the target.

SUMMARY OF THE INVENTION

In an array-type radiation generating apparatus including a plurality of shielding members for respective targets, reduction in the stability of the radiation output has been observed. The observed reduction in stability of the radiation output, that is, radiation output variation, was more prominent in a central region than in a peripheral region of the array.

As a reference example,FIGS. 7A to 7Cshow a schematic structure of an anode array40in which a radiation output variation was observed in a central region of an array including a plurality of targets.FIG. 7Ais a plan view of the anode array viewed from an opening side from which the radiation is emitted.FIGS. 7B and 7Care sectional views of the anode array illustrated inFIG. 7Ataken along imaginary lines VIIB-VIIB and VIIC-VIIC, respectively.

In this reference example, three multilayer targets15, each target15including a target layer13and a support member14, are arranged in an arrangement direction Dat at a pitch of ½×Lat, so that the arrangement length is Lat. The anode array40is formed by connecting the targets15with a chained connection unit41including shielding members42and thermal transfer members43.

Each shielding member42is a rectangular-parallelepiped-shaped block made of tungsten, and has a columnar opening that opens at two opposing faces of the block. The inner wall of the opening in each shielding member42is connected to a side surface of the corresponding target15with a solder material (not shown) interposed therebetween. The thermal transfer members43are made of a material having a thermal conductivity higher than that of the shielding members42.

In this reference example, the shielding members42are disposed between the thermal transfer members43, and are arranged discontinuously in the arrangement direction Dat of the anode array40in the chained connection unit41. In this reference example, the length Ltt of each thermal transfer member43is smaller than the arrangement length Lat of the targets15, and is also smaller than the array pitch ½×Lat of the targets15. The thermal transfer members43are discretely arranged in the anode array40.

As a result of diligent studies conducted by the inventors of the present invention, it has been found that the variation in the radiation output from the array-type radiation generating apparatus according to the reference example is caused by the thermal resistance of the anode array40, which includes the plurality of targets15, in the arrangement direction Dat of the anode array40.

More specifically, the inventors of the present invention have found that the shielding members42serve as bottlenecks of heat conduction in the arrangement direction Dat of the anode array40and hinder the effective radiation of the heat generated by the target15at the center of the array.

The reduction in the radiation output stability causes nonuniform radiation output in the arrangement direction of the array, and leads to a limitation to the anode current that can be supplied to the targets and a limitation to the level to which the output of the radiation generating apparatus can be increased. Therefore, there has been a demand to suppress the reduction in the radiation output stability.

Accordingly, the present invention provides a reliable radiation generating apparatus which is an array-type radiation generating apparatus including a plurality of shielding members for respective targets and in which the radiation output variation due to the reduction in heat conduction in the arrangement direction of the array is suppressed. The present invention also provides a radiography system.

A radiation generating apparatus according to an aspect of the present invention includes a cathode array including a plurality of electron emitting portions, and an anode array including a plurality of targets and a chained connection unit that connects the targets, the targets being arranged at locations corresponding to locations of the respective electron emitting portions and generating radiation when irradiated with electrons emitted from the respective electron emitting portions. The chained connection unit includes a plurality of shielding members and a thermal transfer member, the shielding members being arranged at locations corresponding to the locations of the respective targets, the thermal transfer member having a thermal conductivity higher than a thermal conductivity of the shielding members. The thermal transfer member extends continuously in a direction in which the targets are arranged.

DESCRIPTION OF THE EMBODIMENTS

A radiation generating apparatus and a radiography system according to embodiments of the present invention will now be described with reference to the drawings. Materials, dimensions, shapes, relative arrangement, etc., of components described in the embodiments are not intended to limit the scope of the present invention unless otherwise stated.

Radiation Generating Apparatus

First, a basic structure of a radiation generating apparatus according to an embodiment of the present invention will be described with reference toFIGS. 2A,2B, and8.FIG. 2Ais a schematic sectional view of a radiation generating apparatus20including a drive circuit33.FIG. 2Bis a plan view of the radiation generating apparatus20illustrated inFIG. 2Aviewed from the side at which an anode array10is arranged.

In the present embodiment, as illustrated inFIG. 2A, the radiation generating apparatus20includes a cathode array12including a plurality of electron emitting portions11. The radiation generating apparatus20according to the present embodiment also includes an anode array10including a plurality of targets15, which are arranged at locations corresponding to the locations of the respective electron emitting portions11, and a chained connection unit1, which connects the targets15to each other.

The chained connection unit1includes shielding members2arranged at locations corresponding to the locations of the targets15and a thermal transfer member3having a thermal conductivity higher than that of the shielding members2. The thermal transfer member3is formed so as to extend continuously in an arrangement direction Dat in which the targets15are arranged. The chained connection unit1will be described in detail later.

In the present embodiment, as illustrated inFIGS. 2A and 2B, an envelope21, which is a container made of brass, is provided. The cathode array12is disposed in an inner area23of the envelope21, and the anode array10is connected to an opening22in the envelope21so that target layers13face the respective electron emitting portions11.

In the present embodiment, the cathode array12and the anode array10are connected to the drive circuit33, which defines a cathode potential and an anode potential, through a current introduction terminal34. The anode array10is connected to a ground terminal35together with the envelope21. In other words, in the radiation generating apparatus20according to the present embodiment, anodes are grounded.

The type of the electron emitting portions11is not particularly limited as long as the electron emitting portions11can be controlled by the drive circuit33. Electron sources included in the electron emitting portions11may either be cold cathodes or hot cathodes. Carbon nanotube (CNT) cathodes, impregnated electron guns, etc., may be used as the electron sources.

The envelope21is a container that allows the electron emitting portions11and the target layers13to be arranged in the inner area23thereof or on the inner surface thereof.

To ensure sufficient mean free path of electrons and sufficient life of the electron emission characteristics of the electron emitting portions11, the inner area23of the envelope21is evacuated to vacuum. To achieve these purposes, the vacuum in the inner area23of the envelope21can be 1×10−4Pa or more and 1×10−8Pa or less.

Accordingly, the envelope21can be strong enough to withstand the atmospheric pressure. Since the anode array10according to the present embodiment constitutes a part of the envelope21, the anode array10can also be strong enough to withstand the atmospheric pressure.

In the present embodiment, since the anode array10is connected to the envelope21, the anode array10provides a function of increasing the apparatus strength due to the physical connection, an apparatus driving function due to the electrical connection, and a radiation promoting function due to the conductive connection.

Radiography System

Referring toFIG. 8, the radiation generating apparatus20according to the embodiment of the present invention may be included in a radiography system30. The radiography system30includes a radiation detection apparatus32that detects radiation17(inFIG. 2A) emitted from the radiation generating apparatus20and transmitted through an object31, and a system controller36which controls the radiation generating apparatus20and the radiation detection apparatus32in association with each other.

Anode Array

An example of the anode array10applicable to the radiation generating apparatus according to an embodiment of the present invention will now be described with reference toFIGS. 1A to 1C. The anode array10is a characteristic component according to an embodiment of the present invention.

FIG. 1Ais a plan view of the anode array10viewed from the side at which openings for emitting the radiation17(inFIG. 2A) are formed.FIGS. 1B and 1Care sectional views of the anode array10illustrated inFIG. 1Ataken along imaginary lines IB-IB and IC-IC, respectively.

Each target15of this example is a multilayer target including a target layer13and a support member14that supports the target layer13.

Each multilayer target15includes the target layer13formed on one side of the support member14. The method for forming the target layers13is not particularly limited; for example, sputtering, vapor deposition, pulse-laser deposition, or a gas-phase film forming method such as chemical vapor deposition (CVD) may be used.

The target layers13are thin films containing a target metal. The metal used as the target metal may be selected as appropriate in accordance with the required radiation quality and acceleration voltage between the anode and the cathode, and a metallic element having an atomic number of 40 or more, such as tungsten, molybdenum, or tantalum, is selected.

The target layers13are not limited to those containing the target metal as a pure metal, and the target metal may be contained in the form of a metallic alloy, nitride, carbide, or oxide.

The support members14can be made of a material that is resistant to the operating temperature of the radiation generating apparatus or the temperature during manufacture of the radiation generating apparatus. For example, beryllium, graphite, or diamond may be used. From the viewpoint of thermal stability, thermal conductivity, and self-attenuation of radiation, the support members14can be made of diamond.

When each target15has a multilayer structure as described above, the functions of radiation generation, heat dissipation, and suppression of self-attenuation of radiation17can be separately provided and the materials of the components can be optimized.

In the case where diamond is used as the material of the support members14, from the viewpoint of manufacturing process and material cost, it is not practical to form an anode array including a single plate-shaped support member as described in Japanese Patent Laid-Open No. 2007-265981. Therefore, in the case where diamond is used as the material of the support members14of the anode array, it is practical to discretely arrange the support members14made of diamond and connect the adjacent support members14made of diamond with the chained connection unit1, as illustrated inFIG. 1A to 1C.

Thus, an array-type radiation generating apparatus according to an embodiment of the present invention is a radiation generating apparatus including an anode array that includes a plurality of multilayer targets and a chained connection unit connecting the multilayer targets, the chained connection unit including shielding members that correspond to the respective targets.

Next, the chained connection unit1, which is a characteristic component of the anode array10according to the present embodiment, will be described. The chained connection unit1includes the shielding members2and the thermal transfer member3.

As illustrated inFIG. 1B, which is a sectional view taken along line IB-IB that passes through the central axis along which the targets15are arranged, the thermal transfer member3of the anode array10is divided into discontinuous portions by the shielding members2that correspond to the targets15. However, as illustrated inFIGS. 1A and 1C, the thermal transfer member3has a length Ltt and extends continuously over a range greater than the arrangement length Lat of the targets15in the arrangement direction Dat of the targets15.

The heat transfer mechanism of this structure is represented by an equivalent circuit in which three heat sources are connected in parallel to a serial heat transfer path of the thermal transfer member3via thermal resistances of the support members14at locations separated from each other by intervals of ½×Lat.

In this example, no shielding members having a large thermal resistance are arranged so as to impede the heat transfer in the arrangement direction Dat of the targets15and the direction opposite to the arrangement direction Dat. Therefore, the heat emitted from the target15at the center of the arrangement is effectively transferred to the ends of the arrangement. This is the difference between the anode array10of this example and the anode array40illustrated inFIGS. 7A to 7Cin which a radiation output variation was observed.

Each shielding member2may be composed of a back shielding portion2barranged on a side of the corresponding target layer13that faces the corresponding electron emitting portion11, and a front shielding portion2farranged on a side of the target layer13that is opposite to the side facing the electron emitting portion11.

With regard to the material of the shielding members2, a material having a high specific gravity may be selected as appropriate in consideration of the quality and intensity of the radiation generated by the target layers13. To achieve a good balance between the radiation shielding performance and cost, the material can contain tungsten (specific gravity is 19000 kg/m3and thermal conductivity is 115 W/m/K at 1200K) as a main component.

In the case where each shielding member2includes the back shielding portion2b, the target metal contained in the target layers13may be used as the material of the shielding members2. In such a case, the influence of degradation of radiation quality caused by electrons reflected by the target layers13can be reduced.

According to an embodiment of the present invention, the shielding members2are made of a material having a specific gravity higher than that of the thermal transfer member3. Accordingly, the radiation shielding performance can be provided separately from the heat dissipation performance provided by the thermal transfer member3. This contributes to increasing the thermal resistance of the anode array10and reducing the size of the anode array10.

The thermal transfer member3is made of a material having a thermal conductivity higher than that of the shielding members2. To achieve a good balance between the thermal conductivity and cost, the material can contain copper (specific gravity is 8460 kg/m3and thermal conductivity is 342 W/m/K at 1200 K), silver (specific gravity is 9824 kg/m3and thermal conductivity is 358 W/m/K at 1200 K), or an alloy thereof as a main component.

FIG. 6Ais an enlarged view of a connecting portion between each support member14and the chained connection unit1illustrated inFIG. 1A.FIG. 6Ashows a solder material26that is not illustrated inFIG. 1A. As illustrated inFIG. 6A, the anode array10of this example includes a connecting portion25which couples the thermal transfer member3to the side surface of the support member14with the solder material26interposed therebetween.

When the solder material26is made of silver solder, the thermal conductivity thereof can be made higher than that of the shielding members2(about 150 to 200 W/m/K). Unlike the shielding members2, the solder material26occupies very small spaces in the chained connection unit1, so that the continuity of the thermal transfer member3is not reduced even when the solder material26is arranged as illustrated inFIG. 6A.

OTHER EXAMPLES

Other examples of the anode array10applicable to a radiation generating apparatus according to an embodiment of the present invention will be described with reference toFIGS. 3A to 3C,4A to4C,5,6A, and6B.

In an anode array10illustrated inFIGS. 3A to 3C, the manner in which a support member14of each target15is coupled to a chained connection unit1differs from that in the anode array10illustrated inFIGS. 1A to 1C.FIG. 6Bis an enlarged view of a connecting portion between each support member14and the chained connection unit1illustrated inFIG. 3B.FIG. 6Bshows a solder material26that is not illustrated inFIG. 3A.

As illustrated inFIG. 6B, the anode array10of this example includes a connecting portion25which couples the thermal transfer member3to the side surface of the support member14with the solder material26and the shielding member2interposed therebetween. This connecting portion25differs from the connecting portion25illustrated inFIG. 6Ain that the shielding member2is interposed between the thermal transfer member3and the side surface of the support member14.

FIGS. 3B and 3Care sectional views of the anode array10illustrated in a plan view ofFIG. 3A, taken along imaginary lines IIIB-IIIB and IIIC-IIIC, respectively.

The heat transfer mechanism of this structure is represented by an equivalent circuit in which three heat sources are connected in parallel to a serial heat transfer path of the thermal transfer member3via serial thermal resistances of the support members14and the shielding member2at locations separated from each other by intervals of ½×Lat.

This heat transfer mechanism differs from that of the anode array10illustrated inFIGS. 1A to 1Cin that thermal resistances of the shielding members2are provided in heat transfer paths that connect the heat sources in parallel to the serial heat transfer path of the thermal transfer member3at three locations. Accordingly, the heat dissipation performance of the anode array10of this example is relatively low. However, also in the anode array10of this example, as illustrated inFIGS. 3A and 3C, the thermal transfer member3has a length Ltt and extends continuously over a range greater than the arrangement length Lat of the targets15in the arrangement direction Dat of the targets15. Thus, this anode array10also has the characteristic feature according to an embodiment of the present invention.

In an anode array10illustrated inFIGS. 4A to 4C, a region in which each shielding member2is formed differs from that in the anode array10illustrated inFIGS. 1A to 1C.FIGS. 4B and 4Care sectional views of the anode array10illustrated in a plan view ofFIG. 4A, taken along imaginary lines IVB-IVB and IVC-IVC, respectively.

The heat transfer mechanism of this structure is represented by an equivalent circuit in which three heat sources are connected in parallel to a serial heat transfer path of the thermal transfer member3via thermal resistances of the support members14at locations separated from each other by intervals of ½×Lat. The anode array10of this example has a heat dissipation performance equivalent to that of the anode array10illustrated inFIGS. 1A to 1C.

FIG. 5illustrates an anode array10whose array pattern differs from that of the anode array10illustrated inFIGS. 1A to 1C. The anode array10illustrated inFIGS. 1A to 1Chas a one-dimensional arrangement pattern, while the anode array10of this example illustrated inFIG. 5has a two-dimensional arrangement pattern. Also in this example, the thermal transfer member3has lengths Ltr and Ltc and extends continuously over ranges greater than the arrangement lengths Lar and Lac in the arrangement directions Dar (row direction) and Dac (column direction).

Thus, the arrangement pattern of the targets included in the anode array applied to a radiation generating apparatus according to an embodiment of the present invention is not limited to a one-dimensional arrangement pattern. In addition, with regard to the arrangement direction, the targets are not necessarily arranged along orthogonal lines of a matrix or along a straight line, and the present invention may be applied to anode arrays having other arbitrary arrangement patterns.

An anode array10having the structure illustrated inFIGS. 1A to 1Cwas manufactured by the following processes.

That is, first, disc-shaped support members14having a thickness of 1 mm and a diameter of 6 mm and made of diamond were prepared. Next, the support members14were subjected to degreasing using an organic solvent, and residual organic substances were removed by using an ozone asher device. The thermal conductivity of the support members14was 1950 W/m/K at 25° C.

Next, a target layer13having a thickness of 8 μm and a diameter of 3.5 mm was formed on one circular surface of each support member14by sputtering using argon as a carrier gas. An annular electrode (not shown) made of chromium was also formed on each support member14in a region from the periphery of the target layer13to the rim of the support member14. It was confirmed that the chromium electrode extended to the side surface of the support member14. Three multilayer targets15were produced by these processes.

Next, three shielding members2having openings formed by a mechanical process were prepared. The shielding members2were arranged at a pitch of 12 mm, and were integrally molded by pouring molten copper into a space around the three shielding members2. Lastly, surfaces corresponding to the outer peripheral surfaces of the chained connection unit were mechanically ground so that the shapes thereof are adjusted. Thus, the chained connection unit1, which is structured as illustrated inFIGS. 1A to 1Cand includes the thermal transfer member3made of copper and the shielding members2made of tungsten, was prepared. The thermal conductivities of the thermal transfer member3and the shielding members2at 25° C. were 397 W/m/K and 177 W/m/K, respectively. Each shielding member2had a cylindrical shape and included a front shielding portion2fand a back shielding portion2b, each of which had a wall thickness of 2 mm.

Next, the targets15were coupled to the chained connection unit1in areas where the thermal transfer member3were exposed in the openings of the shielding members2by using the solder material26(not shown), as illustrated inFIG. 1B. Thus, the anode array10having an arrangement pitch of 12 mm was produced. The thermal conductivity of the solder material was 170 W/m/K at 25° C.

FIG. 6Ais an enlarged view of a region around the connecting portion25between the chained connection unit1and each target15in the anode array10according to Example 1. As illustrated inFIG. 6A, the gap between the support member14and the thermal transfer member3, which is 90 to 100 μm, is filled with the solder material26in a thermally conductive manner.

Next, a cathode array12including three electron emitting portions11arranged at the same pitch as the arrangement pitch of the anode array10was formed by fixing impregnated thermionic guns to a holder (not shown).

Next, the cathode array12was secured by using a jig (not shown) in an inner area23of an envelope21, which was made of SUS304, and the anode array10was connected to an opening22in the envelope21by using silver solder (not shown). Next, the cathode array12and the anode array10were electrically connected to a current introduction terminal34that had been arranged in the envelope21in advance. The anode array10and the envelope21were electrically connected to a ground terminal35.

Next, the inner area23of the envelope21was evacuated to vacuum by using an exhaust pipe, a vacuum pump, and a getter, all of which are not illustrated. The vacuum pressure of the envelope21was 2×10−6Pa.

Then, the current introduction terminal34was connected to a drive circuit33. Thus, a radiation generating apparatus20structured as illustrated inFIG. 2Awas manufactured.

Next, the driving stability of the radiation generating apparatus20was evaluated. The evaluation of the driving stability was performed by driving the drive circuit33under the following conditions. That is, the acceleration voltage was set to +100 kV, and the density of the electron current applied to the target layers13was set to 3 mA/mm2. Pulse driving was performed by repeating an electron irradiation time of 2 seconds and a non-irradiation time of 198 seconds. The cathode array12was dot-sequentially driven so that the three targets15arranged in the arrangement direction Dat were sequentially subjected to pulse driving.

In the evaluation of stability of the radiation output intensity, the current that flows from the target layers13to the ground terminal35was measured, and control was performed using a negative feedback circuit (not shown) so that the variation in the anode current was within 1%.

The radiation output intensity was determined as the average of values obtained over a detection period of 1 second by using a radiation dosimeter placed 1 m in front of each target15of the anode array with a pinhole arranged therebetween. The stability was evaluated on the basis of a variation rate obtained by standardizing the radiation output intensity after 100 hours with the original radiation output intensity.

In the radiation generating apparatus20according to Example 1, variations in the radiation output of the targets15included in the anode array10illustrated inFIGS. 1A to 1Cwere 0.98, 0.99, and 0.99 in that order from the target15at the left.

According to the radiation generating apparatus20including the transmissive targets15of Example 1, even when the radiation generating apparatus20was driven for a long time, no prominent radiation output variation occurred in the arrangement direction of the array. Thus, it was confirmed that stable radiation output intensity can be obtained.

According to the anode array10of Example 1, the radiation output variation is suppressed because the thermal transfer member3is shaped so as to extend continuously in the arrangement direction Dat, and the shielding members2and the targets15are arranged discretely in the arrangement direction Dat, as illustrated inFIGS. 1A to 1C.

It was also confirmed that the radiation generating apparatus20was stably driven without causing a discharge in the period in which the driving stability was being evaluated.

A radiation generating apparatus20of Example 2 was manufactured by a method similar to that in Example 1 except that an anode array10structured as illustrated inFIGS. 4A to 4Cwas used.

In the radiation generating apparatus20according to Example 2, variations in the radiation output of the targets15included in the anode array10illustrated inFIGS. 4A to 4Cwere 0.98, 0.98, and 0.99 in that order from the target15at the left.

Also in Example 2, similar to Example 1, no prominent radiation output variation occurred in the arrangement direction of the array, and it was confirmed that the radiation generating apparatus20was highly reliable.

In Example 3, a radiography system30structured as illustrated inFIG. 8was manufactured by using the radiation generating apparatus20according to Example 1.

Since the radiography system of Example 3 includes the radiation generating apparatus20in which the radiation output variation in the arrangement direction of the array is suppressed, X-ray images with high SN ratios were obtained.

A radiation generating apparatus according to an embodiment of the present invention includes an anode array including a plurality of shielding members for respective targets. However, the “reduction in thermal conductivity in the arrangement direction of the targets” due to the shielding members is suppressed. Thus, a high-reliability radiation generating apparatus in which the radiation output variation is suppressed and a radiography system including the radiation generating apparatus can be provided.

This application claims the benefit of Japanese Patent Application No. 2013-025729, filed Feb. 13, 2013, which is hereby incorporated by reference herein in their entirety.