阅读说明：本技术 实时x射线剂量计 (Real-time X-ray dosimeter ) 是由 J.G.梅西 M.戈登 K.罗德贝尔 于 2018-06-18 设计创作，主要内容包括：提供了一种具有光束源的辐射曝光系统。该系统还包括可变厚度降级器，该可变厚度降级器定位在光束源和待曝光的物体之间，用于向从光束源发射到物体上的辐射光束提供变化的降解度。该系统还包括一组检测器，位于可变厚度降级器与物体之间，用于接收并测量辐射光束在可变厚度降级器降解之后剩余的辐射光束的仅一部分。(A radiation exposure system having a beam source is provided. The system also includes a variable thickness degrader positioned between the beam source and the object to be exposed for providing a varying degree of degradation to a radiation beam emitted from the beam source onto the object. The system also includes a set of detectors, located between the variable thickness degrader and the object, for receiving and measuring only a portion of the radiation beam remaining after degradation of the variable thickness degrader.)

1. A radiation exposure system having a beam source, the system further comprising:

a variable thickness degrader positioned between the beam source and an object to be exposed for providing varying degrees of degradation to a radiation beam emitted from the beam source onto the object; and

at least one detector positioned between the variable thickness degrader and the object for receiving and measuring only a portion of the radiation beam remaining after degradation of the radiation beam by the variable thickness degrader.

2. The radiation exposure system of claim 1, wherein the variable thickness degrader is formed to include a plurality of segments formed of the same material, each segment of the plurality of segments having a respective one of a plurality of different thicknesses to provide a respective one of the varying degrees of degradation.

3. The radiation exposure system of claim 2, wherein each of the plurality of portions includes a respective aperture for enabling an undegraded portion of the radiation beam to pass therethrough.

4. The radiation exposure system of claim 1, wherein the variable thickness degrader is formed to include a plurality of segments, each of the plurality of segments being formed of a respective one of a plurality of different materials to provide a respective one of the varying degrees of degradation.

5. The radiation exposure system of claim 4, wherein each segment of the plurality of segments comprises a respective aperture for enabling an undegraded portion of the radiation beam to pass therethrough.

6. The radiation exposure system according to any preceding claim, wherein the variable thickness degrader is formed from one or more metals.

7. The radiation exposure system of claim 1, wherein the variable thickness downgrader is arranged to reduce the amount of radiation exposure applied to the at least one detector below a threshold amount.

8. The radiation exposure system according to any preceding claim, wherein the at least one detector comprises a set of at least one diode.

9. The radiation exposure system of any preceding claim, further comprising a processor for calculating the amount of radiation exposure emitted by the radiation beam based on the amount of current in the set of diodes.

10. A radiation exposure system according to any preceding claim wherein the at least one detector comprises a set of photomultiplier tubes.

11. The radiation exposure system according to any preceding claim, wherein the downgrader is formed to have an at least semi-circular shape.

12. The radiation exposure system according to any preceding claim, further comprising a motor for changing the position of a portion of the variable thickness downgrader exposed to the radiation beam from a set of predetermined positions corresponding to the varying degree of degradation.

13. The radiation exposure system of any preceding claim, wherein the detector is connected to a printed circuit board and arranged symmetrically around an aperture of the printed circuit board.

14. A radiation exposure system according to any preceding claim wherein the at least one detector comprises four spaced apart detectors.

15. The radiation exposure system of any preceding claim, further comprising a detection circuit comprising the set of detectors, the detection circuit being configured to detect and record the fluence of the radiation beam over time.

16. The radiation exposure system according to any preceding claim, wherein the variable thickness degrader has a step level for modulating degradation of the radiation beam by a predetermined amount.

17. The radiation exposure system according to any preceding claim, wherein the variable thickness downgrader is formed from plates of various stackable metals, such that different plate combinations formed from the various plates provide different levels of degradation to the radiation beam.

18. The radiation exposure system according to any preceding claim, further comprising a motor for controlling the position of the variable thickness degrader to obtain a particular degradation level of the different degradation levels.

19. A computer program product for radiation beam control, the computer program product comprising a non-transitory computer-readable storage medium having program instructions embodied thereon, the program instructions executable by a computer to cause the computer to perform a method, the method comprising:

providing, by a variable thickness degrader positioned between the beam source and an object to be exposed, a varying degree of degradation to a radiation beam emitted from the beam source onto the object; and

only a portion of the radiation beam remaining after degrading the radiation beam by the variable thickness degrader is received and measured by at least one detector located between the variable thickness degrader and the object.

20. A method for radiation beam control performed by a radiation exposure system having a radiation beam source, the method comprising:

providing, by a variable thickness degrader positioned between the beam source and an object to be exposed, a varying degree of degradation to a radiation beam emitted from the beam source onto the object; and

receiving and measuring, by a set of detectors positioned between the variable thickness degrader and the object, only a portion of the radiation beam remaining after the variable thickness degrader degrades the radiation beam.

Technical Field

The present invention relates generally to radiation exposure and, in particular, to a real-time X-ray dosimeter using a diode with a variable thickness degrader.

Background

Applications requiring long-term X-ray exposure of high intensity, such as Total Ionization Dose (TID) evaluation of semiconductor components, require the ability to accurately monitor and measure exposure time and X-ray flux in real time.

If the X-ray system is off (e.g., due to external factors such as cooling water supply problems), the test system requires the ability to record the time of exposure of the end beam for accurate calculation of the total dose applied to the sample.

The test system requires the ability to monitor the X-ray flux as a function of time to measure beam stability over exposure time. The test system may extend or reduce the exposure of the sample to ensure that the desired total dose is achieved.

Today, most systems operate in "open loop," meaning that they operate at a given time and are not monitored in situ. Therefore, a real-time X-ray monitor is required.

Disclosure of Invention

According to one aspect of the present invention, there is provided a radiation exposure system having a beam source. The system also includes a variable thickness degrader positioned between the beam source and the object to be exposed for providing a varying degree of degradation to a radiation beam emitted from the beam source onto the object. The system also includes a set of detectors, located between the variable thickness degrader and the object, for receiving and measuring only a portion of the radiation beam remaining after degradation of the variable thickness degrader.

According to another aspect of the invention, a computer program product for radiation beam control is provided. The computer program product includes a non-transitory computer-readable storage medium having program instructions embodied therewith. The program instructions may be executable by a computer to cause the computer to perform a method. The method includes providing a varying degree of degradation to a radiation beam emitted from a beam source onto an object through a variable thickness degrader positioned between the beam source and the object to be exposed. The method also includes receiving and measuring, by a set of detectors located between the variable thickness degrader and the object, only a portion of the radiation beam remaining after degrading the radiation beam by the variable thickness degrader.

According to another aspect of the present invention, there is provided a method for radiation beam control performed by a radiation exposure system having a beam source. The method comprises the following steps: a radiation beam emitted from the beam source onto the object is provided with varying degrees of degradation by a variable thickness degrader positioned between the beam source and the object to be exposed. The method also includes receiving and measuring, by a set of detectors located between the variable thickness degrader and the object, only a portion of the radiation beam remaining after degrading the radiation beam by the variable thickness degrader.

These and other features and advantages will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.

Drawings

The following description will provide details of preferred embodiments with reference to the following drawings, in which:

FIG. 1 illustrates an exemplary processing system to which the present principles may be applied, in accordance with an embodiment of the present principles;

FIG. 2 illustrates an exemplary radiation exposure system to which the present principles may be applied, in accordance with an embodiment of the present principles;

FIG. 3 illustrates another exemplary radiation exposure system to which the present principles may be applied, in accordance with an embodiment of the present principles;

FIG. 4 illustrates a side view of an exemplary variable thickness downgrader formed from different materials, according to one embodiment of the present invention;

FIG. 5 illustrates a front view of the variable thickness downgrader of FIG. 4, according to an embodiment of the present invention;

FIG. 6 illustrates a side view of an exemplary variable thickness downgrader formed from different materials, according to one embodiment of the present invention;

FIG. 7 illustrates a top view of the variable thickness downgrader of FIG. 6, according to one embodiment of the present invention;

FIG. 8 illustrates a side view of another exemplary variable thickness downgrader formed from the same material, according to an embodiment of the present invention;

FIG. 9 illustrates a front view of the variable thickness downgrader of FIG. 8, according to an embodiment of the present invention;

FIG. 10 illustrates a side view of another exemplary variable thickness downgrader formed from a different material, according to an embodiment of the present invention;

FIG. 11 illustrates a front view of the variable thickness downgrader of FIG. 10, according to one embodiment of the present invention;

FIG. 12 illustrates another variable thickness downgrader having a semi-circular shape, according to an embodiment of the present invention;

FIG. 13 illustrates the collimator and monitoring circuit of FIGS. 2 and 3 according to an embodiment of the invention;

FIG. 14 shows a further embodiment of a variable thickness downgrader system using a set of variable thickness downgraders implemented as concentric rings of different materials, according to an embodiment of the present invention;

FIG. 15 shows a cross-section of the variable thickness downgrader system of FIG. 14, according to one embodiment of the present invention;

FIG. 16 illustrates another view of the variable thickness downgrader system of FIG. 14, according to one embodiment of the present invention;

FIG. 17 illustrates another embodiment of a variable thickness downgrader system using a set of variable thickness downgraders implemented as concentric rings of different materials, according to one embodiment of the present invention;

FIG. 18 illustrates a cross-section of the variable thickness downgrader system of FIG. 17, according to one embodiment of the present invention;

FIG. 19 illustrates another view of the variable thickness downgrader system of FIG. 17, according to one embodiment of the present invention; and

FIG. 20 illustrates an exemplary method for real-time X-ray dosimetry according to an embodiment of the invention.

Detailed Description

The invention relates to a real-time X-ray dosimeter using a diode with a variable thickness degrader.

It has been established that X-rays penetrate materials to generate an electrical charge. The present invention takes advantage of this fact to measure the current generated by the X-ray flux in a system using reverse biased diodes, adding material between the X-ray source and the diodes. It is to be understood that other sensor types (other than diodes) may be used in accordance with the teachings of the present invention while maintaining the spirit of the present invention. Such sensor types may include, but are not limited to, scintillators, and the like.

Furthermore, to prevent damage to the diode, a variable thickness degrader is used to attenuate the X-ray flux to which the diode is exposed. Various embodiments of a variable thickness downgrader are described herein. In one embodiment, a plurality of sensors are arranged between the variable thickness degrader and an object of interest (e.g., a Device Under Test (DUT)) such that the sensors are within the degraded beam but not within the full intensity portion of the beam. Thus, in an embodiment, the full (unattenuated) radiation beam may be used for the object of interest, while the attenuated beam may be used simultaneously for monitoring purposes. That is, in embodiments, both attenuated and collimated beams are used (e.g., for monitoring and testing, respectively). In one embodiment, the attenuated beam may be used to determine whether the flux is constant or whether the flux changes during the course of an experiment/application. In one embodiment, the attenuated beam may be used for dose calibration. It should be appreciated that the size of the variable thickness degrader is larger than the sensor used for beam intensity monitoring in order to prevent damage to the underlying sensor.

The invention is useful for high-throughput and low-throughput applications. For example, the present invention may be applied to systems using a dose rate of about 1Mrad/hr or other dose rates, as would be readily understood by one of ordinary skill in the art, while maintaining the spirit of the present invention.

Fig. 1 illustrates an exemplary processing system 100 to which the present principles may be applied, according to an embodiment of the present principles. The processing system 100 includes at least one processor (CPU)104 operatively coupled to other components via a system bus 102. Cache 106, Read Only Memory (ROM)108, Random Access Memory (RAM)110, input/output (I/O) adapter 120, sound adapter 130, network adapter 140, user interface adapter 150, and display adapter 160 are operatively coupled to system bus 102.

A first storage device 122 and a second storage device 124 are operatively coupled to system bus 102 by I/O adapter 120. The storage devices 122 and 124 may be any of disk storage devices (e.g., magnetic or optical disk storage devices), solid-state magnetic devices, or the like. Storage devices 122 and 124 may be the same type of storage device or different types of storage devices.

A speaker 132 is operatively coupled to system bus 102 by sound adapter 130. A transceiver 142 is operatively coupled to system bus 102 by network adapter 140. A display device 162 is operatively coupled to system bus 102 by display adapter 160.

A first user input device 152, a second user input device 154, and a third user input device 156 are operatively coupled to the system bus 102 by the user interface adapter 150. The user input devices 152, 154, and 156 may be any one of a keyboard, mouse, keypad, image capture device, motion sensing device, microphone, device incorporating the functionality of at least two of the foregoing devices, and the like. Of course, other types of input devices may be used while maintaining the spirit of the present principles. The user input devices 152, 154, and 156 may be the same type of user input device or different types of user input devices. User input devices 152, 154, and 156 are used to input information to system 100 and output information from system 100.

Of course, the processing system 100 may also include other elements (not shown), as readily contemplated by those skilled in the art, and omit certain elements. For example, various other input devices and/or output devices may be included in the processing system 100, depending on the particular implementation of the processing system 100, as will be readily understood by one of ordinary skill in the art. For example, different types of wireless and/or wired input and/or output devices may be used. In addition, additional processors, controllers, memories, etc. in different configurations may also be utilized, as would be readily understood by one of ordinary skill in the art. These and other variations of the processing system 100 will be readily apparent to those of ordinary skill in the art, given the teachings of the present principles provided herein.

Further, it should be understood that the system 200 described below with reference to fig. 2 is a system for implementing a corresponding embodiment of the present principles. Some or all of processing system 100 may be implemented in one or more elements of system 200.

Moreover, it should be understood that the system 300 described below with respect to fig. 3 is a system for implementing a corresponding embodiment of the present principles. Some or all of processing system 100 may be implemented in one or more elements of system 300.

Further, it should be understood that processing system 100 may perform at least a portion of the methods described herein, including, for example, at least a portion of method 2000 of fig. 20. Similarly, part or all of system 200 may be used to perform at least a portion of method 2000 of fig. 20. Additionally, part or all of system 300 may be used to perform at least a portion of method 2000 of fig. 20.

Fig. 2 illustrates an exemplary radiation exposure system 200 to which the present principles may be applied, in accordance with an embodiment of the present principles.

The radiation exposure system 200 includes a beam source (e.g., an X-ray tube) 210, a positioning device 230, and a computer 240.

The beam source 210 provides a radiation source for emitting radiation 299 to the target structure. In an embodiment, the beam source generates X-rays.

A positioning device 230 is attached to the beam source 210 and positions the beam source 210 relative to an object of interest (e.g., a device under test in the example of fig. 2, but could also be other objects such as an object under test (e.g., a semiconductor device, a machine component, etc.)) 271 to emit radiation to one or more target structures (e.g., a semiconductor device, a machine component, etc.) in the object of interest. In general, the positioning apparatus 230 includes a structural member 231 that holds the beam source 210 for positioning and a motor 232 that positions the structural member 231 relative to one or more target structures.

Computer 240 controls the elements of system 200. For example, the computer 240 activates the beam source 210 and controls movement of the pointing device 230. The wiring for such control may be within structural member 231 or in some other arrangement. The computer 240 includes a processor 240A and a memory 240B. Processor 240A initiates control of other elements including, for example, radiation emitted by beam source 210. The memory 240B stores software for performing radiation exposure processing. The memory 240B may also store data generated during the radiation exposure process.

An X-ray source, such as beam source 210, has a large beam size, which is typically collimated to control the exposure size on the sample being tested. Accordingly, the system 200 includes a collimator 270.

The system 200 further includes a variable thickness downgrader 250 and a circuit (e.g., a diode or scintillator circuit) 260 having a set of monitors/detectors (hereinafter simply "monitors" or "detectors") 260A (e.g., a diode or scintillator circuit). The variable thickness downgrader 250 has multiple materials with different thicknesses. In the embodiment of fig. 2, variable thickness downgrader 250 is placed on movable support 290. Of course, other devices and systems may be used to position the variable thickness downgrader (see, e.g., fig. 3), while maintaining the spirit of the present invention.

The level of current generated in monitor 260A is proportional to the X-ray intensity. Thus, monitor 260A may be used to monitor the X-ray flux in real time during exposure of the sample.

However, it is well known that high intensity X-rays can cause damage in semiconductor devices (e.g., diodes) and thus can limit the lifetime of monitors (e.g., diodes). Thus, in an embodiment, the intensity of the X-ray beam is reduced for monitoring purposes without affecting the portion of the beam used for sample exposure.

It is well known that various materials (e.g., copper or aluminum) can be passed through

The X-ray intensity is reduced in relation to the thickness, where I is the intensity of the beam, t is the thickness of the material, and μ t is the linear absorption coefficient depending on the material used. Thus, the variable thickness downgrader 250 serves to reduce the exposure level of the monitor 260A.

In one embodiment, variable thickness downgrader 250 is implemented as a variable thickness movable plate of known material that is located between beam source 210 and monitor 260A on top of collimator 270 and has an aperture in the material above the collimator window. Thus, the full X-ray beam may pass through the collimator 270, but the monitor 260A is shielded from the full beam, thereby extending their lifetime by minimizing damage from the X-ray beam.

The desired thickness of the degrader 250 may be calculated based on the various intensities of X-rays generated in the test system in order to generate sufficient current in the monitor 260A to be reliably monitored during exposure.

To further improve the downgrader 250, multiple materials may be stacked on top of each other to achieve the desired reduced throughput for a plate with reasonable thickness (see fig. 4). In another embodiment, the degradation sheet may be of the same material, with adjacent sections of different thickness added (or subtracted) as needed (see fig. 8).

FIG. 3 illustrates another exemplary radiation exposure system 300 to which the present principles may be applied, in accordance with an embodiment of the present principles.

The radiation exposure system 300 includes a beam source 210, a positioning device 230, a computer 240, a positioning device 345, a variable thickness downgrader 250, a circuit 260 having a set of monitors 260A, and a collimator 270.

System 300 differs from system 200 by including positioning device 345 and by omitting movable support 290. The positioning device 345 is used to control the position of the variable thickness downgrader 250 (as compared to manual positioning by the movable bracket 290 in fig. 2). The positioning device 345 may include a structural member 331 that secures the variable thickness downgrader 250 for positioning and a motor 332 that positions the structural member 231 relative to one or more target structures.

Fig. 4 illustrates a side view of an exemplary variable thickness downgrader 400 formed from different materials, according to one embodiment of the present invention. Fig. 5 illustrates a front view of the variable thickness downgrader 400 of fig. 4, according to an embodiment of the present invention.

In the embodiment of fig. 4 and 5, variable thickness downgrader 400 is formed from a number of different materials (e.g., material 401, material 402, material 403, and material 404, using different hatch patterns as shown in fig. 4 and 5). The different materials enable a single degrader to reduce both the high and low intensity beams.

In the embodiment of fig. 4 and 5, variable thickness downgrader 400 is implemented, for example, by respective rectangular plates, such that each different material is on a different plate. As shown in fig. 5, each of the materials (plates) 401, 402, 403, and 404 has a hole 401A, 402A, 403A, and 404A, respectively, for light beams to pass through.

Fig. 6 illustrates a side view of an exemplary variable thickness downgrader 600 formed from different materials, according to one embodiment of the present invention. Figure 7 illustrates a top view of the variable thickness downgrader 600 of figure 6, according to one embodiment of the present invention. Variable thickness downgrader 600 depicted in fig. 6 and 7 is similar to variable thickness downgrader 400 depicted in fig. 4 and 5, except for the arrangement of holes 601A, 602A, 603A and 604A through downgraders 601, 602, 603 and 604, respectively. Furthermore, in fig. 6 and 7, one material, e.g., 601, is used for flux attenuation for a particular degrader, while in fig. 4 and 5, the beam passes through degraders made of multiple materials, except for the smallest degrader 401.

Fig. 8 illustrates a side view of another exemplary variable thickness downgrader 800 formed from the same material, according to an embodiment of the present invention. Fig. 9 illustrates a front view of the variable thickness downgrader 800 of fig. 8, according to an embodiment of the present invention.

In the embodiment of fig. 8 and 9, variable thickness downgrader 800 is formed from the same material (e.g., material 801 and 804, as shown in fig. 8 and 9 using a uniform (same) hatch pattern).

The different thicknesses serve to reduce the intensity of the X-ray beam that strikes the diode below the plate. Each segment has an aperture that will align over the collimator window but will not directly expose the diode underneath the disk. The plate may be moved to allow the segments to intersect the X-ray beam directly above the diodes. Thus, the intensity of the beam striking the monitor will be reduced, but full intensity is allowed into the collimator. The selected section will be used for a particular intensity x-ray beam to produce a measurable current in the diode without causing significant damage. If the intensity of the beam changes, the plate can be moved to another section suitable for the new intensity. This process can be automated by mounting the variable thickness downgrader 800 on a stepper motor controlled by a test system (see, e.g., fig. 3).

In the embodiment of fig. 8 and 9, the variable thickness downgrader 800 is implemented, for example, by a corresponding rectangular plate. In one embodiment, the plates may be stacked as desired. As shown in fig. 9, each of materials (plates) 801, 802, 803, and 804 has a hole 801A, 802A, 803A, and 804A, respectively, for a light beam to pass through.

Fig. 10 illustrates a side view of another exemplary variable thickness downgrader 1000, formed of a different material, according to one embodiment of the present invention. Figure 11 illustrates a front view of the variable thickness downgrader 1000 of figure 10, according to one embodiment of the present invention.

In the embodiment of fig. 10 and 11, variable thickness downgrader 1000 is formed from a number of different materials (e.g., material 1001, material 1002, material 1003, and material 1004, as shown in fig. 10 and 11, using different shading patterns). In contrast to the examples of fig. 10-11, the different materials do not overlap, but are continuous. As will be readily appreciated by one of ordinary skill in the art, any connection mechanism or method may be used to connect the different materials at the adjacent boundaries and is therefore not limited to any particular connection mechanism or method.

In the embodiments of fig. 10 and 11, for example, the variable thickness downgrader 1000 is implemented by a respective rectangular plate, such that each different material is on a different plate. As shown in fig. 11, each of materials (plates) 1001, 1002, 1003, and 1004 has a hole 1001A, 1002A, 1003A, and 1004A, respectively, for a light beam to pass through.

While fig. 4-11 illustrate a variable thickness downgrader formed substantially from a rectangular plate, other shapes may be used in accordance with the teachings of the present invention while maintaining the spirit of the present invention. For example, square, circular, oval, and other shapes may also be used (see, e.g., fig. 12 and 14-19). Further, while four plates have been shown, any number of plates or materials or sections may be used in other embodiments while maintaining the spirit of the present invention. Given the teachings of the present invention provided herein, one of ordinary skill in the related art will readily contemplate these and other variations of a variable thickness downgrader, while maintaining the spirit of the present invention.

Fig. 12 illustrates another variable thickness downgrader 1200 having a semi-circular shape, according to an embodiment of the present invention. Variable thickness downgrader 1200 has various sections 1201-1206, shown in fig. 12 using different shading patterns, made of a number of different materials or made of the same material (e.g., copper, aluminum, etc.) with a number of different thicknesses. As shown in fig. 12, each of the individual segments 1201, 1202, 1203, 1204, 1205 and 1206 has an aperture 1201A, 1202A, 1203A, 1204A, 1205A and 1206A, respectively, for the light beam to pass through. The variable thickness downgrader 1200 may have its position changed relative to the central axis 1299 so that different portions are exposed to the radiation beam.

The following is a general exemplary discussion of how the variable thickness downgrader described in fig. 12 may be used to implement the present invention. Other variable thickness downgrader orientations may also be implemented in a similar manner, while maintaining the spirit of the present invention, as will be appreciated by those of ordinary skill in the art given the teachings of the present invention provided herein.

Different materials or different thicknesses are used to reduce the intensity of the X-ray beam striking the monitor below the variable thickness downgrader 1200. Each segment has an opening that will align over the collimator window but will not directly expose the monitor below the variable thickness degrader, again noting that the variable thickness degrader is larger than the monitor below. The variable thickness degrader 1200 is rotatable to allow the segments to intersect the X-ray beam over the monitor. Thus, the intensity of the beam striking the monitor will be reduced, but the full intensity is allowed to pass through the collimator. The selected segments will be used for a particular intensity of X-ray beam to produce a measurable current in the monitor without causing significant damage. If the intensity of the light beam changes, the variable thickness downgrader 1200 may rotate to another section appropriate for the new intensity. This process may be automated by mounting variable thickness downgrader 1200 on a stepper motor controlled by a test system.

In fig. 13, the collimator 270 and the monitoring circuit 1360 of fig. 2 and 3 are shown, according to an embodiment of the present invention.

In particular, fig. 13 shows a cross section of the collimator 270 and the circuit 1360, as well as the X-ray beam 1301 incident on the collimator 270. The viewpoint of fig. 13 is along the path of an incident X-ray beam 299 (shown in fig. 2 and 3) and after the variable thickness downgrader 1200. The dashed line 1301 in fig. 13 represents the cross-sectional area of the incident X-ray beam 299 (shown in fig. 2 and 3) at the top of the collimator. The cross-sectional area 1301 is represented in fig. 13 as a rectangular shape, but those skilled in the art will recognize that different X-ray beam sources 210 may produce incident X-ray beams 299 of various cross-sectional shapes. The circuit 1360 includes a PC board 1310 having an opening 1312 above and concentric with the collimator opening 1320. PC board 1310 also includes a set of monitors 1311. Monitor 1311 may be a diode or a scintillator, as non-limiting examples. For accurate measurements, the monitor 1311 of the monitoring circuit 260 should be within the cross-section 1301 of the incident X-ray beam 299. Cross-section 1301 represents (1) a high intensity portion of incident X-ray beam 299 at the center of the region that travels through the PC board 1312 and the concentric holes in collimator opening 1320, and (2) a reduced intensity portion of incident X-ray beam 299 covering the portion of PC board 1310 that contains monitor 1311.

In the embodiment of fig. 13, the monitors 1311 may be arranged on the PC board 1310 at 0, 90, 180, and 270 degrees (in this example, rectangular, but not limited to any shape) around the openings 1312 on the collimator window 1320. The monitors 1311 may be equally spaced in a configuration as shown in fig. 13, where four monitors 1311 are shown for illustration purposes. PC board 1310 may be connected to a monitor/test system (e.g., computer 240) via bus/interface 1330 for real-time dose measurement.

Thus, the plurality of monitors 1311 are distributed around a collimator window 1320 between the beam source 210 and the collimator 270. Multiple monitors 1311 may be used to calculate the average X-ray intensity across the beam area, monitor the intensity of the beam over time, and the like. PC board 1310 provides the ability to monitor the response of each monitor to the incident x-ray beam (e.g., by measuring the resulting current) to monitor beam uniformity.

Fig. 14 shows an additional embodiment of a variable thickness downgrader system 1400 using a set of variable thickness downgraders 1410 implemented as concentric rings of different materials, according to an embodiment of the present invention. For illustrative purposes, the set of variable thickness downgraders 1410 includes variable thickness downgraders 1411 to 1414, noting that other numbers of downgraders may be used. FIG. 15 shows a cross-section 1500 of the variable thickness downgrader system 1400 of FIG. 14, according to one embodiment of the present invention. Figure 16 illustrates another view 1600 of the variable thickness downgrader system 1400 of figure 14, according to one embodiment of the present invention. As an example, in one embodiment, four rings of different diameters are used, with the larger diameter rings being thicker than the smaller diameter rings. Each concentric ring has an aperture (generally designated by reference numeral 1420) in the center that will align with an aperture in the collimator so that the fully unattenuated beam passes through the center of the collimator. The one or more monitors may be arranged circumferentially under the one or more rings.

If the response of the monitor changes during the exposure test, the incident X-ray beam is accidentally changed or turned off. Thus, the exposure time may be shortened or lengthened by the test system to achieve the desired total dose based on the dose rate measured in real time, or in the case of a shutdown, the test system may record the elapsed exposure time for an accurate measurement of the total absorbed dose, and the system may run longer (when X-rays are resumed) to compensate for the shutdown, etc.

Although four monitors are shown in the example of fig. 14 and 15 for illustrative purposes, other numbers and geometric arrangements of monitors may be used while maintaining the spirit of the present invention.

Fig. 17 illustrates another embodiment of a variable thickness downgrader system 1700, according to one embodiment of the present invention, which uses a set of variable thickness downgraders 1710 implemented as concentric rings of the same material. For illustrative purposes, the set of variable thickness downgraders 1710 includes variable thickness downgraders 1711 to 1714, noting that other numbers of downgraders may be used. Figure 18 shows a cross section 1800 of the variable thickness downgrader system 1700 of figure 17, according to one embodiment of the present invention. Fig. 19 illustrates another view 1900 of the variable thickness downgrader system 1700 of fig. 17, according to one embodiment of the present invention. Thus, the variable thickness downgrader system 1700 of fig. 17-19 differs from the variable thickness downgrader system 1400 of fig. 14-16 in that 1700 uses rings formed of the same material, while 1400 uses rings formed of (at least two) different materials.

FIG. 20 illustrates an exemplary method 2000 for real-time X-ray dosimetry according to embodiments of the invention. The method is performed with respect to a radiation exposure system (e.g., the radiation exposure system 200 of fig. 2 or the radiation exposure system 300 of fig. 3). It will be appreciated that for brevity and clarity, some steps of the radiation exposure process may be omitted from FIG. 20, with method 2000 involving various aspects of the present invention.

At step 2010, different degrees of reduction in the intensity of the radiation beam emitted from the beam source onto the object are provided by a variable thickness degrader positioned between the beam source and the object to be exposed. In this way, the set of detectors may be exposed to a lower amount of radiation than can cause damage to the detectors.

At step 2020, only a portion of the radiation beam remaining after the intensity of the radiation beam is reduced by the variable thickness degrader is received and measured by a set of detectors located between the variable thickness degrader and the object. In an embodiment, step 2020 involves monitoring the stability of the radiation beam (in terms of dose) and providing feedback (e.g., for Total Ionized Dose (TID) experiments, etc.).

At step 2030, the measure of the flux of decreasing intensity is correlated to the flux of the impacting object. In one embodiment, step 2030 is performed with a similar detector using a variable thickness downgrader under a collimator.

At step 2040, the flux is determined from the known attenuation of the beam and the associated measurements of step 2030.

In step 2050, the operation of the radiation exposure system or another system is controlled based on the result (flux) determined by step 2040. For example, such control may involve, but is not limited to, outputting an amount of radiation to which the object has been exposed, restarting the system to resume radiation exposure, moving the object (e.g., by a robot or other automated device) to a next station for processing (e.g., testing, further manufacturing, etc.), and so forth. Step 2050 may be performed, for example, by the radiation exposure system itself or by a computer processing machine configured to control the radiation exposure system.

The present invention may be a system, method and/or computer program product that integrates levels of technology detail where possible. The computer program product may include a computer-readable storage medium (or media) having computer-readable program instructions thereon for causing a processor to perform various aspects of the present invention.

The computer readable storage medium may be a tangible device that can hold and store the instructions for use by the instruction execution device. The computer-readable storage medium may be, for example^--But are not limited to^--An electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a Static Random Access Memory (SRAM), a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), a memory stick, a floppy disk, a mechanical coding device, such as punch cards or in-groove projection structures having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media as used herein is not to be construed as a transitory signal per se, such as a radio wave or other freely propagating electromagnetic wave, through a waveguide, orElectromagnetic waves (e.g., light pulses through fiber optic cables) propagated by other transmission media, or electrical signals transmitted through electrical wires.

The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to a respective computing/processing device, or to an external computer or external storage device via a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. The network adapter card or network interface in each computing/processing device receives computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in the respective computing/processing device.

The computer-readable program instructions for carrying out operations of the present invention may be assembler instructions, Instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as SMALLTALK, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, an electronic circuit comprising, for example, a programmable logic circuit, a Field Programmable Gate Array (FPGA), or a Programmable Logic Array (PLA), can execute computer-readable program instructions by personalizing the electronic circuit with state information of the computer-readable program instructions in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.

These computer-readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer-readable program instructions may also be stored in a computer-readable storage medium that can direct a computer, programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer-readable medium storing the instructions comprises an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer, other programmable apparatus or other devices implement the functions/acts specified in the flowchart and/or block diagram block or blocks.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Reference in the specification to "one embodiment" or "an embodiment," as well as other variations of the invention, means that a particular feature, structure, characteristic, etc. described in connection with the embodiment is included in at least one embodiment of the invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in addition to any other variations that may appear in various places throughout this specification are not necessarily all referring to the same embodiment.

It is to be understood that, for example, in the case of "a/B", "a and/or B" and "at least one of a and B", the use of "/", "and/or" and "at least one of" below is intended to encompass the selection of only the first listed option (a), or the selection of only the second listed option (B), or the selection of both options (a and B). As another example, in the case of "a", B, and/or C "and" at least one of a, B, and C ", this phrase is intended to include selecting only the first listed option (a), or only the second listed option (B), or only the third listed option (C), or only the first and second listed options (a and B), or only the first and third listed options (a and C), or only the second and third listed options (B and C), or all three options (a and B and C). This can extend up to the listed items as would be readily apparent to one of ordinary skill in the art and the relevant art.

Having described preferred embodiments for systems and methods (which are intended to be illustrative and not limiting), it is noted that modifications and variations can be made by persons skilled in the art in light of the above teachings. It is therefore to be understood that changes may be made in the particular embodiments disclosed which are within the scope of the invention as outlined by the appended claims. Having thus described aspects of the invention, with the details and particularity required by the patent laws, what is claimed and desired protected by letters patent is set forth in the appended claims.