JP2001025501A - Radiation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve evenness of irradiation quality by comparing a designed irradiation does and an actual irradiation dose and controlling radiation accordance with the result thereof. SOLUTION: The density distribution of an object to be irradiated is measured by an X-ray CT unit 7 and is inputted to a designed irradiation dose calculating means 1. An irradiation dose distribution is calculated by changing an irradiation parameter in accordance with the density distribution and the designed irradiation dose is determined. An irradiation condition determining means 2 sets the actual irradiation conditions in accordance with the irradiation parameter when the irradiation dose distribution is made uniform. These conditions are sent to an irradiation control means 3. On the other hand, a judgement means 6 compares the irradiation dose distribution of the designed irradiation dose calculating means 1 and the actual irradiation dose calculated by an actual irradiation dose calculating means 5 and decides whether the irradiation is good or not. The result of the decision is sent to the irradiation control means 3 and controls the radiation means 13. The irradiation quality is thus made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation irradiating apparatus, and more particularly to the realization of reliable sterilization, sterilization, insecticidal or germination prevention by irradiation of radiation.

[0002]

2. Description of the Related Art Conventionally, there has been an apparatus for irradiating radiation for sterilization before using medical instruments such as artificial dialysers, injection needles, surgical gloves, and pharmaceutical containers. In this device, radiation is directed toward a case containing a medical instrument. In this case, since the density of the substance in the case is not uniform, it is difficult to simply calculate the radiation dose at each point in the case by calculation. Therefore, the method of actually irradiating radiation and measuring the dose at each point in the case ensures that the medical instruments housed in the case are sterilized irrespective of the arrangement in the case. Is determined in advance.

[0003] Specifically, a small radiation sensor such as a radiation-sensitive film dosimeter is placed at a plurality of positions in a case together with a medical instrument to irradiate radiation, and each point is detected by the radiation sensor. Appropriate irradiation conditions were determined based on the measured dose.

[0004] On the other hand, radiation is also used for treating diseases such as malignant tumors. This treatment involves irradiating a lesion, such as a malignant tumor, with radiation, causing the cells of the lesion to absorb radiation energy, and thereby eliminating the radiation. In this treatment, X-ray C
A T (Computer Tomography) device or an image is used. That is, a tomographic image of the inside of the patient is taken by the X-ray CT apparatus, and the position of the lesion is grasped from the tomographic image information.
While maximizing the amount of radiation energy absorbed for the lesion,
The irradiation field and irradiation conditions are determined so as to minimize the amount of radiation energy absorbed by the normal tissue.

[0005] A study to utilize the action of radiation centered on the application of radiation energy to cells has been proposed.
It is also being pursued in other industrial fields. For example, FAO (Fo
od and Agriculture Organization of the United nati
ons: United Nations Food and Agriculture Organization / WHO (World Health Org)
anization: The World Health Organization) Joint International Food Planning Commission (CAC)
Dose standards are prepared for applications such as sterilization of spoilage and pathogens, killing of pests and parasites, suppression of germination, and extension of storage period. The aim is to make food preservation safer for these uses, and to solve the world's important food problem.

Another example of recent trends is as follows.
Currently, methyl bromide, which is used to kill pests and parasites in plant quarantine treatment in Japan and other countries, has been totally abolished. Since methyl bromide is an ozone depleting substance,
Its use and production are being abolished internationally, and irradiation is promising as an alternative.
Irradiation is expected to be applied to fruits, cereals, wood, and many other varieties in the future.

[0007]

An important condition regarding the application of the radiation processing method is that irradiation is performed at a required dose uniformity. This method can be dealt with, for example, by a system / apparatus as applied for a patent in Japanese Patent Application No. 10-34244.
By applying this method, it was possible to calculate the dose uniformity with extremely high accuracy and perform irradiation under optimal conditions.

Further, another important condition regarding application of the radiation processing method is to confirm and guarantee in real time that irradiation is performed at a required dose uniformity. However, final measurements need to be taken to ensure that the dose is delivered at the planned dose uniformity. Generally, a radiation-sensitive film dosimeter or the like is used for dosimetry as described above, but it takes a considerable amount of time to obtain a measurement result.

In actual irradiation, this operation is time-consuming and almost impossible to apply. Even if the application is possible, the irradiation work on the products of the same lot has been completed when the measurement result is found. Therefore, in the normal irradiation, the above-mentioned operation is performed several times in preliminary experiments for each item, and the irradiation is performed under the predetermined conditions after confirming in advance the conditions under which the dose uniformity is good. However, in this method, if the objects in the box were packed under different conditions from those in the preliminary experiment, or if the degree of overlap of the objects in the box was different from that in the preliminary experiment, Results in different results from the preliminary experiments. If the irradiation is not performed at the required dose uniformity, there is no means for detecting this problem, and this is a major problem.

Further, although the radiation irradiating means is operated with the set irradiation parameters, the irradiation parameters may slightly fluctuate in some cases. in this case,
It also affects dose uniformity. Here, a method of directly measuring the dose in the air and controlling the irradiation control unit based on the data is also employed in a medical accelerator for treating malignant tumors. However, the uniformity of irradiation is evaluated by the absorbed dose. The factors of the variation of the absorbed dose and the dose uniformity are both due to the variation of the radiation irradiating means and the fluctuation of the density distribution of the irradiation object. Even if the dispersion of the radiation irradiating means is strictly controlled, the dose uniformity alone is not sufficient. It is difficult to stabilize once.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and measures the transmitted component of the dose applied to an object to be irradiated and calculates the absorbed amount of the dose of the object. An object of the present invention is to provide an index for evaluating the dose uniformity of an object to be irradiated and to assure uniform irradiation quality.

[0012]

According to the present invention, there is provided a radiation irradiating apparatus which calculates a dose distribution of irradiation radiation to the irradiation object as an irradiation dose planning value based on a density distribution of the irradiation object. Calculation means, irradiation condition determination means for determining irradiation conditions based on the irradiation dose plan value, irradiation control means for controlling the irradiation means according to the irradiation conditions, and irradiation dose of the irradiation radiation transmitted through the irradiation object A dose detecting means for measuring, an irradiation dose actual value calculating means for calculating a dose distribution of irradiation radiation to the irradiation object from the transmitted dose measured by the dose detecting means as an actual irradiation dose value, the irradiation dose plan value and the irradiation It is characterized by including a determining means for comparing the actual dose value and controlling the radiation irradiation based on the comparison result.

[0013] The radiation irradiating apparatus according to the present invention is characterized in that it is provided with tomographic imaging means for capturing a tomographic image of an object to be irradiated in a radiation irradiation direction and acquiring a density distribution of the object to be irradiated.

[0014] A radiation irradiation apparatus according to the present invention comprises: an irradiation condition determining means for determining irradiation conditions based on an irradiation dose set as an irradiation dose plan value;
Irradiation control means for controlling the radiation irradiation means, dose detection means for measuring the dose of irradiation radiation transmitted through the irradiation object,
Irradiation dose actual measurement value calculation means for calculating the irradiation dose to the irradiation object measured by the dose detection means as the actual irradiation dose value,
The apparatus further comprises: a determination unit that compares the planned irradiation dose value and the actual irradiation dose value, and controls radiation irradiation based on the comparison result.

The radiation irradiating apparatus according to the present invention is characterized in that when the comparison result between the planned irradiation dose value and the actual irradiation dose value exceeds a predetermined value, the determining means controls to stop the irradiation.

In the radiation irradiating apparatus according to the present invention, when the comparison result between the irradiation dose plan value and the actual irradiation dose value exceeds a predetermined value, the determining means controls the radiation irradiation so that the radiation irradiation becomes equal to or less than the predetermined value. It is characterized by doing.

The radiation irradiating apparatus according to the present invention is characterized in that the radiation irradiating apparatus is provided with recording means for recording a result of comparison between the planned irradiation dose value and the actual irradiation dose value.

[0018]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic operation flowchart of a radiation irradiation apparatus for plant quarantine, food irradiation, and the like according to an embodiment of the present invention. First, the density distribution of the irradiation object is measured by X-ray CT or the like (step 1). Next, based on the density distribution, the irradiation dose distribution to the irradiation target is calculated while changing the irradiation parameter. The irradiation dose distribution calculated in advance before irradiation is defined as an irradiation dose plan value (step 2). Next, actual irradiation conditions are set based on the irradiation parameters when the irradiation dose distribution becomes uniform (step 3). Irradiation is performed on the irradiation target based on the irradiation conditions (step 4). At this time, the actual irradiation dose distribution to the irradiation target is measured. Note that the irradiation dose distribution actually measured at the time of irradiation is defined as an actual measured irradiation dose (step 5). Calculation value of irradiation dose distribution (Step 2)
Is compared with the measured value of the irradiation dose distribution (step 5) to determine the quality of the irradiation (step 6). When uniform irradiation is performed (good case), irradiation is continuously performed under the same conditions. On the other hand, when the non-uniform irradiation is performed (in the case of failure), the irradiation condition is changed (step 7).

Next, the operation of the present invention will be described in detail using an actual configuration. FIG. 2 is a schematic block diagram of the radiation irradiation apparatus according to the embodiment of the present invention. Here, the irradiated objects 9 are imported cut flowers, spices and crude drugs, fruits, cereals, wood, and the like, and most of them are packed in boxes or bags. The shape (e.g., height, width, and depth dimensions), material, and thickness of the box vary depending on the type of product to be stored. They may be arranged. Imports and the like, which are determined to require treatment such as killing of pests by a quarantine officer's extraction inspection or the like, are carried to the apparatus as irradiated objects 9. Here, relatively simple fruit (grapefruit)
Will be described as an example.

The irradiation object 9 is placed on a belt conveyor 10 and carried to an X-ray CT unit 7 which is a tomography unit. Here, the irradiation object 9 is scanned from multiple directions with a thin X-ray beam, and a tomographic image of the irradiation object 9 is formed based on the transmission data. FIG. 3 is a reference diagram (tomographic image) of a tomographic image actually captured by the X-ray CT unit. FIG. 3 shows tomographic images of nine grapefruits, which are irradiation objects. In the figure, a white shaded portion indicates a flesh portion of grapefruit which is an object to be irradiated. Since the arrangement of each grapefruit is random, the shape of the tomographic image is also different.

FIG. 4 is an explanatory view schematically showing this tomographic image. In FIG. 4, a tomographic image 31 of six grapefruits as objects to be irradiated (black and white portions in FIG. 2 are inverted) is shown in the screen 30. In the figure, 31a
Denotes a grapefruit skin, and 31b schematically denotes grapefruit flesh. This tomographic image is constructed from CT values at each point of the cross section of the irradiation target 9 irradiated with X-rays. The CT value is a value corresponding to the density, and the tomographic image indicates the density distribution of the irradiation target 9 on the cross section. In FIG. 4, the magnitude of the density is shown as a shaded image.

FIG. 5 is an explanatory diagram of obtaining a tomographic image of the irradiation object. In the figure, x and y indicate vertical and horizontal coordinates in a cross section of the irradiation target 9, and z indicates coordinates in a moving direction of the irradiation target 9. As shown in FIG. 5, the tomographic image is transferred to the belt conveyor 10 at a plurality of positions on the irradiation object 9 while moving the irradiation object 9.
Cross section 91 perpendicular to the traveling direction 100 (coordinate z) of
92, 93... Thereby, three-dimensional density distribution information of the irradiation target 9 is obtained.

The data of the density distribution is sent to the irradiation dose plan value calculation means 1. The irradiation dose plan value calculation means 1 comprises:
A dose distribution is calculated using the data on the density distribution of the irradiation object and irradiation parameters for determining a plurality of irradiation conditions to be set for the radiation irradiation means. Irradiation parameters include radiation ray type (X-ray, electron beam, etc.), radiation energy, moving speed of belt conveyor, radiation irradiation direction,
There is the number of radiation irradiation ports. Energy is specified by international standards as bremsstrahlung X-rays using an electron beam of 10 MeV or less for electron beams and 5 MeV or less for X-rays when the irradiation target is food or the like. In the irradiation dose plan value calculation means 1,
An irradiation parameter with the most uniform and effective irradiation amount on the irradiation object is finally selected.

The irradiation dose plan value calculation means 1 is composed of, for example, hardware such as a computer and dedicated software. This irradiation dose plan value calculation means 1
Using the density distribution acquired by the X-ray CT unit 7, how the radiation with the set irradiation parameters is transmitted through the irradiation target is calculated and output as a deep amount percentage. Here, the deep dose percentage means the amount of radiation dose according to the depth from the surface of the irradiation object, where the value at which the amount of radiation reaches a maximum at a certain depth is defined as 100%, and the ratio is expressed as a percentage. It is. FIGS. 6 and 7 show graphs showing an X-ray deep volume percentage curve and an electron beam deep volume percentage curve as examples of the deep volume percentage. Each of these shows a plurality of curves with energy as a parameter (other parameters include SSD (distance between radiation source and object to be irradiated) shown in the figure, irradiation field (size of aperture of radiation source) ))). The horizontal axis represents the transmission distance in water, and the vertical axis represents the relative dose with the maximum value of the amount of each energy reached as 100%. In general, the energy that reaches is a position slightly entering from the irradiation object surface (1 cm to 3 c in FIGS. 6 and 7).
m (depth of m) (maximum build-up phenomenon), and thereafter it attenuates.

The uniformity of the radiation dose can be represented two-dimensionally by the depth dose percentage. FIG. 8 is a diagram for explaining an example of the dose uniformity calculated by the irradiation dose plan value calculation means 1, in which the characteristic curve of the percentage of the deep portion is displayed superimposed on the tomographic image shown in FIG. It is. Screen 30
Corresponds to a fault at an arbitrary cross section 91 in FIG.
Reference numeral 1 denotes a tomographic image of an irradiation target (here, grapefruit). The dashed lines 32a, 32b, and 32c are characteristic curves created by connecting points indicating the same depth percentage in the tomographic plane. In this example, 32a is 100%, 32b is 50%,
32c is a characteristic curve corresponding to a 20% deep amount percentage. If an arbitrary cross section is changed to 92 and 93 on the screen 30, the tomographic image 31 changes, and the depth amount percentage 3
2a, 32b, and 32c also change.

Here, since radiation has the property of being absorbed by a substance in accordance with the density, the transmitted dose is reduced in an area where a large amount of the substance is present (high density area), and finally the transmitted dose is reduced. 0%. On the other hand, the transmitted dose is 100% in a portion where no substance is present. With this property, the distribution of the transmitted dose at the bottom 33 of the tomographic plane can be calculated from the known density distribution.

FIG. 9 is a characteristic curve diagram of the transmitted dose distribution at the bottom 33 of the tomographic plane. In the figure, reference numeral 40 denotes a transmitted dose screen, and the horizontal axis in the screen indicates the position of the base 33 in the y direction.
The vertical axis represents the relative intensity of the transmitted dose. When the irradiation of the object to be irradiated is uniform, the variation in the amount of transmitted radiation between the upper part and the lower part of the object becomes small. Therefore, in this case, the characteristic curve is located at the top of the figure as indicated by 41a. On the other hand, when the radiation irradiation is non-uniform, the variation in the amount of transmitted radiation between the upper and lower parts of the irradiation object increases. Therefore, in this case, the characteristic curve is located at the bottom of the figure as indicated by 41b.

Next, the characteristic curve data at the bottom of the tomographic plane in FIG. 9 is obtained at a plurality of locations on the irradiated object. By connecting the data, a planar distribution of the transmitted dose of the irradiation object can be obtained. FIG. 10 is a distribution characteristic diagram of the two-dimensional transmitted dose on the bottom surface of the irradiation object. As described above, a plurality of sections 91, 92, 93,.
The accuracy of the distribution characteristics improves as the number of acquired data increases. Reference numeral 51 shows the distribution characteristics of the transmitted dose as contour lines.

The irradiation dose plan value calculation means 1 calculates a plurality of distribution characteristics while changing the irradiation parameters as described above, and finally calculates an irradiation parameter in the case where the variation of the distribution characteristics is minimum, from among them. Output to the irradiation condition determining means 2. Note that the distribution characteristic with the smallest variation becomes the irradiation dose plan value used in the calculation by the determination unit 6 described later, and is output to the determination unit 6.

The irradiation condition determining means 2 calculates an actual optimum irradiation condition based on the optimum irradiation parameters determined as described above, and outputs it to the irradiation control means 3. The irradiation control unit 3 controls a radiation irradiation unit 13 described later using the optimum irradiation conditions.

On the other hand, after the tomographic data is acquired by the X-ray CT unit 7, the irradiation object 9 is carried to the radiation irradiation means 13 by the belt conveyor 11. The radiation irradiation means 13 is housed in a radiation shield room 14 for shielding radiation. The belt conveyor 11 has a structure in which the entrance and exit of the radiation shield room 14 pass through a maze-shaped portion from the viewpoint of radiation shielding.
While the object to be irradiated is moving on the belt conveyor 11, optimal irradiation is performed under irradiation conditions based on the irradiation parameters set as described above. At the same time, the dose transmitted through the irradiation object 9 is measured by the dose detection means 4.

Generally, an ionization chamber method is often used for the dose detecting means 4. However, when a high intensity dose is detected, the dose is immediately saturated and it is difficult to perform accurate measurement. Therefore, a sensor corresponding to a high intensity dose is used, such as an ionization chamber specially provided with a measure for suppressing the saturation state, a semiconductor type radiation detector, a detector using light such as scintillation and Cherenkov.

Here, a semiconductor type radiation detector and a sensor corresponding to a high intensity dose using light such as scintillation and Cherenkov are used. The structure of the dose detection means 4 is such that a plurality of sensors are arranged in a direction (y-direction) perpendicular to the direction of travel of the irradiation object and housed in a radiation shield case. The length has a dimension at least as large as the width of the belt conveyor 11. FIG. 11 shows an example of the structure of the dose detection means 4. Here, 61 indicates a sensor, 62 indicates a shield case, and 11a indicates a traveling direction (z direction) of the belt conveyor 11. As a result, the transmitted dose of the irradiation object that has passed through the dose detection means 4 can be measured at a plurality of points. The measurement speed is a very short time as compared with the speed at which the irradiation object moves. Therefore, it is possible to measure a plurality of locations while the irradiation object box passes through the dose detection means 4.

Further, a position detecting means 8 is installed near the belt conveyor 11 in order to detect at which position of the irradiation object the transmitted dose data is measured. As a method of the position detecting means 8, any method such as a mechanical switch method, a non-contact optical method, and a detection method using an industrial camera can be applied. As will be described later, this position detection is performed in conjunction with the dose detection by the dose detector 4.

The positional relationship between the measured data and the irradiated object is as follows:
The moving speed of the belt conveyer 11 and the dose detecting means 4 start when the one end of the irradiation object 9 passes through the position detecting means 8.
From the data measurement time interval. For example, the length of the box of the irradiation target 9 is 1 m, and the belt conveyor 11 is
Is 10 cm / sec, and the data measurement interval of the dose detection means 4 is 1 time / sec, the measurement points are 11 in total. As described above, as the number of data measurement points increases, the calculation accuracy of the distribution characteristic diagram of the transmitted dose based on the actually measured data described later improves. Further, when the length of the irradiation target is unknown, the positional relationship can be similarly specified by measuring the points at both ends of the irradiation target by the position detecting means. For example, the time of position detection at both ends is measured, the length of the irradiation object is determined from the moving speed of the belt conveyor, and the measurement point can be specified in the same manner as described above. The position information calculated by the position detecting means is sent to the irradiation dose actual measurement value calculating means 5 described later, and is used for obtaining the measured dose transmission distribution.

The transmitted dose data measured here is sent to the irradiation dose measured value calculation means 5. The irradiation dose actual measurement value calculation means 5 is constituted by hardware such as a computer and dedicated software. By associating the dose detected by the dose detecting means 4 with the position of the box of the irradiation target by the position detection means 8, it can be drawn as a dose transmission distribution of the irradiation target in a plane. FIG. 12 shows a calculation example of the dose transmission distribution. FIG. 12 is basically the same as that shown in FIG. FIG. 12 is a pattern diagram obtained by actually measuring the transmission intensity of the dose at the same point as the tomographic images 91, 92, 93,. Reference numeral 71 denotes the pattern as contour lines. As can be seen from the figure, reference numeral 71 denotes the dose transmitted through the irradiation object 9 and the box bottom surface 33 of the irradiation object (actually measured transmitted dose screen 70 in the figure).
FIG. 7 is a pattern diagram of actual measurement values projected on a graph. In other words,
It is an actually measured version of the pattern diagram 51 in FIG. 10 obtained by calculation. This actually measured value is output to the determination means 6 described later as the actually measured irradiation dose.

The pattern diagram 71 is calculated as a relative value. The reference value for obtaining the relative value is a measured value of the transmitted dose detected by the sensor 61 at the end of the dose detecting means 4. Used. That is, as described above, since the dose detection unit is configured to be longer than the width of the irradiation target, the sensor at the end of the dose detection unit does not pass through the irradiation target and reaches the sensor directly. Therefore, the transmitted dose detected by the sensor at the end is substantially equal to the input dose (known amount) from the irradiation source to the irradiation target. Further, the known amount is corrected for an increase due to the phenomenon due to the build-up shown in FIGS. 6 and 7, and a final reference value can be obtained. The relative value can be calculated by the ratio to the reference value.

Next, the transmitted dose distribution pattern result calculated by the irradiation dose plan value calculation means 1 and the actual dose calculated by the irradiation dose calculation means 5 are determined by the judgment means 6 for comparing the calculated value of the transmitted dose distribution with the actually measured value. Enter the measured transmitted dose distribution pattern result. The configuration of the judging means 6 is composed of, for example, hardware such as a computer and dedicated software. The comparison / judgment method is performed, for example, by subtracting the two-dimensional measurement result from the two-dimensional calculation result. When the result becomes 0, it can be considered that the calculation result and the actual measurement result match. Actually, there is a possibility that they do not completely match due to calculation errors and measurement errors.

Therefore, in actual actual operation, an allowable range is provided for determining the calculation result. Here, when the determination means 6 determines that the result is within the allowable range and is good,
The irradiated object is carried out of the radiation shield room 14 by the belt conveyor 11.

Next, when the judgment means 6 judges a defect, the irradiation result does not satisfy the request. In this case, the irradiation is stopped. Further, in the present apparatus, when the irradiation result does not satisfy the request,
It is possible to calculate how much the irradiation parameter should be changed from the calculation process regarded as irradiation failure in.
By sending the result to the irradiation control means 3, irradiation can be performed while changing the irradiation parameters so as to satisfy the request. For example, if the dose uniformity is poor, changing the energy to a higher direction improves the uniformity.

Although the present embodiment mainly focuses on the means for obtaining the dose uniformity, the dose detection means 4 can also measure the irradiation dose (absolute dose). For that purpose, it is necessary to first calibrate the dose detecting means 4 with a standard dosimeter. If the calibration method is performed in accordance with, for example, the standard measurement method of absorbed dose (physical subcommittee of the Japanese Society of Medical Radiology), the measured value of the dose detecting means 4 which has been dose-calibrated indicates the irradiation dose (absolute dose). Become. This result is naturally used as basic data used in the irradiation dose plan value calculation means 1.

The irradiation dose (absolute dose) in addition to the dose uniformity can be sent to the irradiation control means 3 in the same manner as described above to optimize the irradiation parameters of the radiation irradiation means 13. That is, an irradiation dose (absolute dose) preset for a specific position of the irradiation target is used as the irradiation dose plan value, and the actual irradiation dose value is used as the irradiation dose actual value by the above-configured dose detection means. By using the irradiation dose (absolute dose value) measured at the position (1), it is possible to make the same determination as when using the pattern (dose uniformity). As an example of optimization, when the measured irradiation dose (absolute dose) is too large than the planned irradiation dose (absolute dose), the speed of the belt conveyor 11 is increased, and the object 9 is irradiated with the radiation irradiating means 13. That is, it is only necessary to shorten the time required to pass through. On the other hand, if the measured irradiation dose (absolute dose) is smaller than the planned irradiation dose (absolute dose), the speed of the belt conveyor 11 is reduced, and the irradiation target 9 passes through the irradiation unit 13. You have to extend the time you do.

In the above description, the irradiation dose (absolute value) at a specific position of the irradiation object is used. However, the irradiation dose to the entire irradiation object (measured at each position) is specified without specifying the position. The sum of the irradiation doses (integrated value)) or the average irradiation dose to the irradiation target may be used.

Next, the data storage means 15 will be described. The configuration of the data storage means is composed of, for example, hardware such as a computer, dedicated software, and a recording device. Any recording device such as a magnetic tape or a magnetic disk can be used as long as it has a function of storing data. Even if the calculation result of the irradiation dose plan value calculation means 1 and the calculation result of the irradiation dose actual value calculation means 5 sent to the determination means 6 are basically not stored, there is no problem as a system of the irradiation apparatus. However, in order to guarantee the quality of irradiation to the customer, it is preferable to ship the irradiation data attached to the product. In order to make this possible, a data storage unit 15 is provided, and the calculation result of the irradiation dose plan value calculation unit 1 and the calculation result of the irradiation dose actual measurement value calculation unit 5 sent to the determination unit 6 are used. Enter and save all items related to irradiation such as name. As a result, a guarantee of irradiation quality can be created at any time. If necessary, irradiation parameters,
Arbitrary data such as an irradiation plan value and an irradiation result value can be called and printed.

Although this embodiment has been described by taking fruit as an example, the present invention can be applied to artificial organs and artificial dialysers (dialyzers) that are currently sterilized as medical instruments and have complicated structures and shapes. Needless to say, it is very effective.

The above description is based on the operation flow of FIG. 1 and is based on the premise that irradiation parameters with optimum uniformity can be obtained in the dose distribution calculation process in step 2. However, depending on the size and density of the irradiation object, it may be determined that the predetermined uniformity cannot be achieved. In this case, it is necessary to provide a check function between step 2 and step 3 in FIG. 1, and if the uniformity cannot be achieved, it is necessary to rearrange the irradiated object so as to achieve the uniformity. The operation flow in this case is shown in FIG. Steps 2a and 2b correspond to the check function.

[0048]

According to the radiation irradiating apparatus of the present invention, since the dose distribution and the transmitted dose can be calculated in advance and the transmitted dose of the irradiated object can be detected in real time, the irradiation can be performed appropriately and reliably as planned. An effect is obtained that the irradiance can be managed in a form in which the variation of the irradiation device and the variation of the irradiation target are combined. In addition, uniform radiation irradiation can be easily realized over the entire irradiation target, so that the work of determining irradiation conditions can be saved, and radiation irradiation processing on the irradiation target is appropriately and reliably performed.
For example, the effect that the safety of the irradiated object such as food is ensured is obtained.

According to the radiation irradiation apparatus of the present invention, since the tomography means represented by the X-ray CT scanner is used to measure the density distribution of the irradiation object, the dose distribution of the irradiation radiation can be easily and accurately measured. The effect of being able to calculate well is obtained.

According to the radiation irradiating apparatus of the present invention, since the irradiation dose to the object to be irradiated can be detected in real time, it is determined whether the irradiation is performed properly and reliably according to the plan and the variation of the irradiation object. An effect is obtained in that management can be performed in a form in which variations are combined. In addition, uniform radiation irradiation can be easily realized over the entire irradiation target, so that the task of determining irradiation conditions can be saved, and radiation irradiation processing on the irradiation target is appropriately and reliably performed. And the like, the effect of ensuring the safety of the irradiated object is obtained.

According to the radiation irradiating apparatus of the present invention, when irradiation is not performed as planned, it is possible to control the radiation irradiating apparatus to be stopped, so that it is possible to select an irradiation defective product.

According to the radiation irradiating apparatus of the present invention, when irradiation is not performed as planned, control can be performed so as to change the radiation irradiating condition, so that an effect of improving irradiation failure can be obtained.

According to the radiation irradiating apparatus of the present invention, since all the data related to the irradiation is stored, it is possible to utilize the data by printing a document for guaranteeing the irradiation. Can be

[Brief description of the drawings]

FIG. 1 is a schematic operation flowchart of a radiation irradiation apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic block diagram of a radiation irradiation apparatus according to an embodiment of the present invention.

FIG. 3 is a reference diagram (tomographic image) of a tomographic image taken by an X-ray CT unit.

FIG. 4 is an explanatory diagram schematically showing a tomographic image taken by an X-ray CT unit.

FIG. 5 is an explanatory diagram of acquiring a tomographic image of an irradiation target.

FIG. 6 is a graph showing an X-ray deep dose percentage curve.

FIG. 7 is a graph showing an electron beam deep amount percentage curve.

FIG. 8 is a calculated characteristic curve diagram of the percentage of the depth in the fault plane.

FIG. 9 is a characteristic curve diagram of a calculated transmitted dose distribution at the bottom of the tomographic plane.

FIG. 10 is a calculated distribution characteristic diagram (contour diagram) of the transmitted dose at the bottom surface of the irradiation object.

FIG. 11 is a configuration diagram of a dose detection unit.

FIG. 12 is a distribution characteristic diagram (contour diagram) of an actually measured transmitted dose at the bottom surface of the irradiation object.

FIG. 13 is a schematic operation flowchart of a radiation irradiation apparatus according to another embodiment of the present invention.

[Explanation of symbols]

1 means for calculating irradiation dose plan values, 2 means for determining irradiation conditions,
3 irradiation control means, 4 dose detection means, 5 irradiation dose actual measurement value calculation means, 6 determination means, 7 X-ray CT unit, 8
Position detecting means, 9 irradiation object, 10, 11 belt conveyor, 11a belt conveyor moving direction, 13 radiation irradiation means, 14 radiation shield room, 15 data storage means, 30 tomographic image screen, 31 irradiation object tomographic image, 31a object Irradiated object tomographic image (grapefruit skin), 31b Irradiated object tomographic image (grapefruit flesh), 32a, 32b, 32c Depth amount percentage characteristic curve, 33 Irradiated object bottom, 40 Transmitted dose screen, 41
a, 41b transmitted dose distribution characteristic curve, 51 transmitted dose distribution contour, 61 sensor, 62 shield case, 70
Measured transmitted dose screen, 71 Transmitted dose distribution contour, 91,
92,93 Irradiated object tomographic plane, 100 Belt conveyor moving direction

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4B021 LA01 LP10 LT03 LT06 LW02 LW07 LW09 4C058 AA16 AA21 BB06 DD12 KK03 KK32 4C082 AC02 AC06 AG02 AP02 AP03

Claims (6)

[Claims] 1. A radiation irradiating apparatus for irradiating an object with radiation from a radiation irradiating unit and performing a process, wherein a dose distribution of the irradiation radiation to the object is determined based on a density distribution of the object. Irradiation dose plan value calculation means for calculating as a value; irradiation condition determination means for determining irradiation conditions based on the irradiation dose plan value; irradiation control means for controlling the irradiation means in accordance with the irradiation conditions; A dose detecting means for measuring a dose of irradiation radiation transmitted through the radiation source; an irradiation dose actual value calculating means for calculating a dose distribution of the irradiation radiation to the irradiation target from the transmitted dose measured by the dose detecting means as an actual irradiation dose value; A radiation irradiating apparatus comprising: a radiation dose irradiator comprising: a radiation dose control unit that compares the radiation dose planned value with the radiation dose actual value, and controls radiation radiation based on the comparison result. 2. The radiation irradiating apparatus according to claim 1, further comprising tomographic imaging means for photographing a tomographic image of the irradiated object in a radiation irradiation direction and acquiring a density distribution of the irradiated object. 3. A radiation irradiator that irradiates an object with radiation from a radiation irradiator and performs a process, comprising: an irradiation condition determining unit that determines an irradiation condition based on an irradiation dose set as a planned irradiation dose; An irradiation control unit that controls the irradiation unit according to the irradiation condition; a dose detection unit that measures a dose of the irradiation radiation transmitted through the irradiation target; and an irradiation dose to the irradiation target measured by the dose detection unit. An irradiation dose actual measurement value calculating means for calculating as an actual dose value, and comparing the irradiation dose plan value and the irradiation dose actual value, based on the comparison result, a determination means for controlling the irradiation of radiation, Radiation irradiation equipment. 4. The method according to claim 1, wherein the determining unit controls to stop the irradiation when the comparison result between the irradiation dose plan value and the irradiation dose actual value exceeds a predetermined value. The radiation irradiation device according to claim 1. 5. When the comparison result between the irradiation dose plan value and the irradiation dose actual value exceeds a predetermined value, the determination means controls the irradiation so that the irradiation is not more than the predetermined value. The radiation irradiating apparatus according to claim 1. 6. The radiation irradiation apparatus according to claim 1, further comprising recording means for recording a comparison result between the planned irradiation dose value and the actual irradiation dose value.