RU2424535C1 - Method for x-ray inspection of human body - Google Patents

Abstract

FIELD: physics. ^ SUBSTANCE: flat beam of low-power X-ray radiation is formed using a collimator. A fixed body is scanned with said radiation. Radiation passing through the body is picked up by a detector and converted to electronic signals which are then analysed and an electronic image is formed. The body is scanned through vertical synchronous movement of the X-ray source, the collimator and the detector. The radiation source, collimator and detector are moved vertically at the same speed while maintaining coaxiality of the radiator-collimator-detector optical system. Coaxiality of the radiator-collimator-detector optical system is ensured through rigid attachment of said system onto a special beam which is moved vertically during scanning, and the ends of the beam are also turned in the vertical plane. ^ EFFECT: high efficiency of detecting dangerous objects and substances when scanning a human body with low-dose X-ray radiation. ^ 6 cl, 6 dwg

Description

The invention relates to the field of registration of x-ray radiation and can be used both in medical radiography and for screening people for security purposes to detect dangerous and hidden objects and substances hidden in / in the body, in clothes.

Known methods of x-ray control of the body, which are that they form a flat beam of low-power x-ray radiation, scan the body with this radiation, receive radiation passing through the body with a detector in which the x-ray radiation is converted into visible light radiation and then into electronic signals, which process and form an image in electronic form, while scanning the body by moving a plane vertically formed radiation beam and detector in a horizontal direction phenomenon with the help of electric drives with stepper motors (for example, patent RU No. 2126550, IPC G03B 42/02 of 02/12/99; patent RU No. 2261465, IPC G03B 42/02 of 09/27/2005, USA patent No. 5959302, IPC G01T 1/185 from 09/28/99). Basically, the known methods differ in the design of the detector and methods for converting x-ray radiation into visible light radiation and further into electronic signals.

A disadvantage of the known methods of x-ray control of the body is that in the presence of shoes in humans, low-power x-rays do not allow a clear image of what is in the area of the shoe. This is due to the fact that, no matter how you place the x-ray beam, its components in the known methods are directed strictly horizontally or close to horizontal and the contours of the shoes and especially the soles are an obstacle to obtaining a clear image.

The second disadvantage is that it is necessary to strictly synchronize the frequencies of the stepper motors in order to withstand the same speed of movement of the radiation source and the detector, ensuring the alignment of the optical system. In addition, exact matching of the movement step with the scanning frequency of the read signals from the detector output is required, which determines the presence of a complex electronic circuit for controlling the scanning process.

The closest solution to the proposed method is the solution described in patent RU No. 2257639, IPC H01J 47/02 from 07/27/2005, bull. No. 21. In this patent, a flat beam of low-power x-ray radiation is formed, a stationary body is scanned by this radiation, received and converted into visible light radiation, which is converted into electronic signals, analyzed and formed into an electronic image, while the formation of a flat x-ray beam radiation is carried out in the horizontal direction using a collimator, and the reception of radiation and its conversion into electronic signals is carried out using a detector, moreover, scanning the body about uschestvlyayut by vertical synchronous movement of the radiation source, the collimator and the detector, i.e. at the same speed. The same speeds are supported through the use of drives with stepper motors with special control circuits. This decision is made as a prototype.

The disadvantage of this solution is that with horizontal directivity of low-power x-ray radiation, safe for humans, and vertical scanning, it is impossible to obtain a clear image in the area of the shoe, in the contour of which, and especially in the contour of the sole, can be prohibited substances and dangerous objects for society. The effectiveness of installations implemented by this method is low and almost unacceptable in the inspection area at airports and customs.

The second disadvantage is that it is necessary to strictly synchronize the frequencies of the stepper motors in order to withstand the same speeds of the radiation source, the collimator and the detector, ensuring the alignment of the optical system. In addition, exact matching of the movement step with the scanning frequency of the read signals from the detector output is required, which determines the presence of a complex electronic circuit for controlling the scanning process.

The technical problem solved by the invention is to increase the detection efficiency of dangerous objects and substances when scanning a human body with low-power x-ray radiation and to simplify the scanning process control system.

The problem is solved due to the fact that in the method of x-ray control of the body, which consists in forming a flat beam of low-power x-ray radiation using a collimator, the stationary body is scanned by this radiation, the radiation passing through the body is received by the detector, the radiation is converted into electronic signals analyze them and form an image in electronic form, moreover, the body is scanned by synchronous vertical movement of the x-ray source, collimator and a tector, the radiation source, the collimator and the detector moving in the vertical direction at different speeds, while maintaining the coaxiality of the optical system of the emitter-collimator-detector. The vertical velocity of the detector, collimator and radiation source are related by the expressions:

where V _∂ , V _to , V _from are, respectively, the vertical velocity of the detector, collimator and radiation source;

h is the distance from the lower extreme position of the detector to its middle position in the vertical direction;

L is the distance between the detector and the radiation source;

l is the distance between the collimator and the radiation source;

α is the angle between the horizontal plane and the axis of the optical system, changing during scanning from + 15 ° to -15 ° in one direction of scanning and from -15 ° to + 15 ° in the opposite direction of scanning.

The alignment of the optical system of the emitter-collimator-detector is ensured by rigidly fixing them on a special beam, which is moved in the vertical direction during the scanning process, while its ends are additionally rotated in a vertical plane. Moving a special beam in the vertical direction is carried out using a system of ropes associated with the drive through a system of rollers located on the cover and base of the complex and on the beam. The ends of the special beam are rotated in the vertical plane due to their articulated connection with the carriages, one of which is moved vertically along a rigid stand, and the other along the rocker swinging in the vertical plane, while the first carriage is moved using an additional rope of the rope system.

An example implementation of the method is illustrated by drawings:

figure 1 shows the General structure explaining the principle of formation of x-ray radiation of low power, its passage through the human body, conversion in the detector and the final reproduction on the computer of an electronic image;

figure 2, 3, 4 shows a kinematic diagram of the location of the emitter-collimator-detector system, respectively, in the middle, upper and lower positions during scanning;

figure 5 schematically shows a special beam (top view of figure 1), at the ends of which are located and rigidly fixed x-ray source and detector, and between them a collimator, forming a narrow horizontal beam of x-ray radiation;

figure 6 shows the geometric arrangement of the special beams in the middle and lower extreme positions with the corresponding dimensions.

In the drawings, the following notation:

1 - a special beam; 2 - source of x-ray radiation; 3 - collimator; 4 - human location zone, 5 - human, 6 - detector, for example, which is a sealed enclosure filled with gas and allowing the introduction of x-ray radiation, while a flat capacitor is placed in the enclosure with a solid anode and cathode located parallel to the radiation beam on both sides of it, broken into strips associated with storage capacitors, the charges from which are read electronically and processed by a computer, and the plates of a flat capacitor are connected to a high-voltage voltage source niya; 7 - computer, 8 - electric motor; 9 - gear; 10 - ropes; 11, 17 - rollers fixed on the base and cover of the complex; 12 - a hinge to which one of the ends of the rope 10 is fixed, the second end of which is fixed to a special beam between the collimator 3 and the detector 6; 13 - roller mounted on a special beam 1 near the source of x-ray radiation 2; 14 - the link, connected through a hinge 22 with the base of the complex with the possibility of rotation in a vertical plane; 15 - the second carriage mounted on the wings 14 with the possibility of vertical movement on the wings and articulated with a special beam 1 through the hinge 16, which is located between the collimator 3 and the radiation source 2; 18 - vertical rack, 19 - the first carriage mounted on the rack 18 and connected through a hinge 21, rollers 17 with an additional rope 10 and through a hinge 20 with one of the ends of a special beam 1; NN (Fig.6) is the level of location of the sole of a person’s shoes relative to the horizontal plane on which the detector is in the lower extreme position; Ao, Bo, Co - the location of the detector, collimator and X-ray source, respectively, on a special beam located in the average vertical position during scanning; A, B, C - the location of the detector, collimator, and X-ray source, respectively, on a special beam located in the lowermost position when scanning; h is the distance from the lower extreme position of the detector to its middle position in the vertical direction; L is the distance between the detector and the radiation source; l is the distance between the collimator and the radiation source; α is the angle between the horizontal plane and the axis of the optical system, which changes during scanning.

The process of controlling the human body according to this method is as follows. After person 5 occupies an appropriate position in zone 4 of the measuring complex (FIG. 1), the x-ray source 2 is turned on and the radiation source 2, the collimator 3 and the detector 6 are moved in the vertical direction at different speeds, while maintaining the alignment of the optical system "Emitter-collimator-detector." X-ray radiation passing through the collimator 3 is formed in the form of a flat horizontal beam and then passes through the human body to the detector 6, in which, under the influence of high-voltage voltage, the values of the charges on the storage capacitors change, which is recorded by the electronics, and in the computer 7 the electronic signals are converted into a visible image .

The vertical velocity of the radiation source, collimator and detector are related by the expressions:

where V _∂ , V _to , V _from are, respectively, the vertical velocity of the detector, collimator and radiation source;

h is the distance from the lower extreme position of the detector to its middle position in the vertical direction (Fig.6);

L is the distance between the radiation source and the detector along the optical axis of the "emitter-collimator-detector" system;

l is the distance between the radiation source and the collimator along the optical axis of the system "emitter-collimator-detector";

α is the angle between the horizontal plane and the optical axis of the "emitter-collimator-detector" system located in the lower fixed position. The indicated speeds are realized by the kinematic diagram shown in Figs. 2, 3, 4, respectively, in the middle, extreme upper, and lowermost positions, and the coaxiality of the emitter-collimator-detector system is provided by rigidly mounting the emitter, collimator, and detector on a special beam 1 (Fig. 5 ), which is moved in the vertical direction during scanning, while its ends are additionally rotated in a vertical plane.

This happens as follows. Let the special beam 1 move from the middle position (Fig. 2) to the extreme upper (Fig. 3). The engine 8 transmits through the gear 9 the movement of the rope 10, which through the rollers 17 pulls the first carriage 19 along the vertical strut 18 up. The carriage 19 pulls the left end of the beam 1 upward, while simultaneously turning it in a vertical plane through the hinge 20. The second part of the rope 10 through the rollers 11, 13 and the hinge 12 raises the second end of the beam 1, while the second carriage 15 moves up the link 14 and due to the hinge connection 16 provides the rotation of the second end of the special beam 1. When moving the beam 1 from the middle position ( figure 2) in the extreme lower position (figure 4) everything will happen in the opposite direction, only the rotation of the right edge of the beam 1 will be additionally carried out by turning the rocker 14 in the vertical plane using the hinge 22. The level of the person’s shoes NN (figure 6 ) in the measuring the complex is located above the level of detector 6, when it is in the lower extreme position, therefore, the X-ray radiation will shine through the shoes from above, so that everything inside the shoe and the sole will be reflected on the computer image.

=~40 мм/с и скорость вертикального перемещения источника излучения V_из=~20 мм/с, что соответствует времени одноразового сканирования в 5 с. Это время может легко быть изменено путем изменения коэффициента передачи редуктора, не нарушая процесса плавного перемещения балки. С другой стороны, отсутствует, как таковая, система управления вертикальным перемещением детектора, коллиматора и источника излучения. Все управление сканированием сводится к включению электропривода на заданное время. Проведенные испытания на различных типах обуви с пластмассовыми ножами в подметках, со ступинаторами в виде железных прокладок, а также с рядом наркотических веществ показали хорошую обнаруживаемость этих материалов и веществ.According to this method, an X-ray unit was manufactured with the following data: type of X-ray lamp — RTM 101 SH06-1.2 with a radiation dose after the collimator of 0.5 μSv (microsievert); electric motor (5 kW, n = 2850 rpm); L = 2 m; l = 0.8 m; h = 1 m; α = ± 15 °, while the vertical velocity of the detector V

= ~ 40 mm / s and the vertical velocity of the radiation source V _from = ~ 20 mm / s, which corresponds to a one-time scan time of 5 s. This time can easily be changed by changing the gear ratio of the gearbox without disturbing the process of smoothly moving the beam. On the other hand, there is no, as such, a control system for the vertical movement of the detector, collimator and radiation source. All scan management is reduced to turning on the drive for a given time. The tests carried out on various types of shoes with plastic knives in the outsole, with steppers in the form of iron pads, as well as a number of narcotic substances showed good detectability of these materials and substances.

Claims (6)

1. The method of x-ray control of the human body, which consists in the fact that they form a flat beam of x-ray radiation of low power, scan the stationary body with this radiation, receive the radiation passing through the body, convert it into visible light that is converted into electronic signals, analyze them and form an image in electronic form, while the formation of a flat beam of x-ray radiation is carried out in the horizontal direction using a collimator, and the reception of radiation and its conversion electronic signals are carried out using a detector, which is converted into a visible image using a computer, and the body is scanned by vertical movement of the x-ray source, the collimator and the detector, characterized in that the radiation source, collimator and detector are moved in the vertical direction at different speeds, while maintaining the alignment of the optical system "emitter-collimator-detector." 2. The method of x-ray control of the human body according to claim 1, characterized in that the vertical velocity of the radiation source, collimator and detector are related by the expressions
V _∂ = K ₁ · V _out , for K ₁ = h / (hL · sinα)
V _∂ = K ₂ · V _k , for K ₂ = h / [h- (Ll) · sinα],
where V _∂ , V _to , V _from are, respectively, the vertical velocity of the detector, collimator and radiation source;
h is the distance from the lower extreme position of the detector to its middle position in the vertical direction;
L is the distance between the radiation source and the detector along the optical axis of the "emitter-collimator-detector"system;
l is the distance between the radiation source and the collimator along the optical axis of the system "emitter-collimator-detector";
α is the angle between the horizontal plane and the optical axis of the "emitter-collimator-detector" system located in the lower fixed position. 3. The method according to PP.1 and 2, characterized in that the angle between the horizontal plane and the optical axis of the "emitter-collimator-detector" system during scanning is changed from 15 to minus 15 degrees in one scanning direction and from minus 15 to plus 15 degrees in the opposite direction of scanning. 4. The method according to claim 1, characterized in that the coaxiality of the "emitter-collimator-detector" system when moving is provided by rigidly fixing them on a special beam, which is moved in the vertical direction, while its ends are additionally rotated in a vertical plane. 5. The method according to claims 1 and 4, characterized in that the movement of the special beam in the vertical direction is carried out by a system of ropes connected to the drive through a system of rollers located on the beam, in the base and cover of the measuring complex. 6. The method according to PP.1 and 4, characterized in that the rotation of the ends of the special beams in the vertical plane during its movement is carried out by articulating them with the carriages, one of which is moved vertically on a stationary rack, and the other on a swinging vertical plane rocker, while the movement of the first carriage is carried out through an additional rope associated with the drive.

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